bluuebunny/crossref_metadata_2025 huggingface dataset:
p53 Expression and p53 Gene Mutation in Oral Cancer and Dysplasia
Authors: Rowley Helena , Sherrington Paul , Helliwell Timothy R. , Kinsella Anne , Jones Andrew S.
Published: October 2005

BACKGROUND

The aim of the current study was to examine the possible association of the p53 tumor suppressor gene with the development of oral cancer. We examined biopsy material from patients with oral squamous cell carcinoma for p53 protein expression and p53 mutations.

METHODS

Eighteen samples were analyzed. These comprised oral squamous cell carcinoma biopsy samples and oral dysplastic biopsy material taken from nine patients. An immunohistochemical technique was used to determine p53 protein expression. A direct sequencing technique was used to detect mutations in the p53 gene itself.

RESULTS

Overall seven of nine (77%) oral squamous cell carcinomas and seven of nine (77%) oral dysplastic lesions analyzed showed evidence of p53 protein over‐expression. Mutations in exons 5 and 6 of the p53 gene were detected in five of nine (55%) oral squamous cell carcinomas and four of nine (44%) dysplastic lesions analyzed.

CONCLUSIONS

Both p53 protein over‐expression and p53 mutations were noted in dysplastic oral lesions. Over‐expression of the p53 protein and p53 gene mutations were not always coexistent, however, suggesting that gene mutation may be only one of the mechanisms responsible for stabilization of the p53 protein.
Complications and Functional Outcome after Supracricoid Partial Laryngectomy with Cricohyoidoepiglottopexy
Authors: Naudo Philippe , Laccourreye Ollivier , Weinstein Gregory , Jouffre Véronique , Laccourreye Henri , Brasnu Daniel
Published: October 2005

We present a review of the postoperative course, complications, and functional outcome of 190 patients consecutively treated with supracricoid partial laryngectomy with cricohyoidoepiglottopexy. The average times until removal of the tracheostomy and nasogastric feeding tubes were 9 and 16 days, respectively. The postoperative mortality rate was 1%. Major complications included pneumonia from aspiration, cervical wound infection, symptomatic laryngocele, ruptured pexis, laryngeal chondroradionecrosis, and laryngeal stenosis in 8.5%, 4.2%, 3.1%, 1%, 0.5%, and 0.5% of the patients, respectively. Completion total laryngectomy, permanent gastrostomy, and permanent tracheostomy were requested in 0.5% of the patients. Normal swallowing without gastrostomy and respiration without tracheostomy was achieved by the first postoperative year in 98.4% (187/190) of the patients. This article presents a univariate analysis of the potential correlation between various variables and the duration of tracheostomy and the length of time the nasogastric feeding tubes were inserted, the mortality incidence and causes, the incidence and type of the various complications, and the duration of hospitalization. Comparison of our data with the reported functional results after vertical partial laryngectomy suggested that supracricoid partial laryngectomy with cricohyoidoepiglottopexy does not result in an increased rate of postoperative complications.
Soft-bodied fossils from the Shipai Formation, Lower Cambrian of the Three Gorge area, South China
Authors: ZHANG XING LIANG , HUA HONG
Published: October 2005

Mudstones and shales in the Lower Cambrian Shipai Formation in the Three Gorge area, Hubei, China, are richly fossiliferous, containing common shelly fossils and some soft-bodied fossils. The latter provide important new information about the nature and variety of Cambrian soft-bodied organisms. Identifiable, non-mineralized taxa include components of the Chengjiang fauna, such as Vetulicola Hou, 1987, a palaeoscolecidan referable to Maotianshania Sun & Hou, 1987, and a brachiopod Diandongiapista with pedicle preserved (not illustrated). Cambrorhytium Conway Morris & Robison, 1988, co-occurring both in the Burgess Shale and the Chengjiang Lagerstätte, was also recovered. Additionally, a new worm is described based on two specimens. This taxon, in common with many other fossil worms, has a slender, cylindrical body with annulations, but it is characterized by each annulus bearing an elevated ridge and lacking surface ornamentation. The occurrence of exceptional preservation in the Shipai Formation has likely been overlooked due to the relatively poor resolution of soft-bodied fossils; nevertheless, this occurrence is an important extension of the Burgess Shale-type biotas in China, over 1500 km northeast of the provenance of the Chengjiang Lagerstätte.
Information about open-system magma chambers derived from textures in magmatic enclaves: the Kameni Islands, Santorini, Greece
Authors: HOLNESS M. B. , MARTIN V. M. , PYLE D. M.
Published: October 2005

Post-caldera eruptions of Santorini, Greece, over the past 3000 years resulted in the formation of the Kameni Islands, which comprise a series of compositionally similar dacitic lava flows. Each lava flow has a distinct population of partially-crystalline mafic enclaves, which we propose were derived from the break-up of a layer of replenishing magma responsible for triggering the eruption. Five of the recent flows (erupted in 1570, 1939, 1940, 1941 and 1950) include enclaves of essentially identical andesitic bulk compositions, which formed by crystallization of originally aphyric melts prior to eruption. Detailed examination of angles subtended at the junctions between pairs of plagioclase grains demonstrates that enclaves from each flow have a characteristic textural signature, with distinct differences in the extent of quench-related modification of the original population of dihedral angles formed by impingement of growing grains. These variations suggest that the temperature difference between the host dacite and the replenishing andesite at the time of layer overturn and eruption differed between flows. The uniformity of major element compositions of both the replenishing magma and the host dacitic lava flows demonstrates that the critical parameter in determining the timing of layer-overturn is the pre-eruptive H2O content of both host dacite and replenishing magma. We suggest that the replenishing magma responsible for two of the three eruptions in the period 1939–1941 was significantly wetter than that responsible for the later 1950 eruption. The enclaves with the least amount of quench-related modification occur in the 1570 flow. We suggest that in this case the intruding magma was relatively dry.
Ireland's Nice Referenda
Authors: Costello Cathryn
Published: October 2005

Part One: Referenda required to amend Irish Constitution. Referenda on accession to EEC, the Single European Act, Maastricht and Amsterdam. Development by courts of rules for fairness of referendum campaigns. Referendum Acts and Referendum Commission.

Part Two: First Nice Referendum dominated by euro-anxiety, Irish neutrality and enlargement. Second referendum on same subject not unusual and acceptable according to domestic criteria. Concessions and clarifications. Effect on the Convention on the Future of Europe.

Part Three: implications for the Constitutional Treaty.
France: The Come-Back of Political Parties
Authors: Wolff Sarah , Mounier Gregory
Published: October 2005

On 21 September 1792, at Danton's proposal, the French National Assembly declared that ‘there can be no constitution but one approved by the people’. In France, the idea of direct democracy dates back to the Revolution. However, due to the Terror and the practice under Napoleonic Empires, in which they were turned into plebiscites, referendums acquired a negative connotation. Under the Vth Republic, De Gaulle turned referendums into an instrument of personalisation and presidentialisation, and since his day, there have been few referendums staged. In 10 years of office, President Jacques Chirac only used it twice with much less success and political courage.
The Dutch Referendum
Authors: Nijeboer Arjen
Published: October 2005

Origin of referendum discussion in the Convention. The national debate on referenda. The crucial role of the liberal party. Referendum bill private members initiative. Referendum Act an ad hoc consultative referendum. Referendum the first opportunity for a broad political debate on the EU. Complacency and disorganised arguments of the ‘yes’ campaign. First analyses of referendum.
The Birth of the European Citizen Out of the Dutch No Vote
Authors: van Gunsteren Herman
Published: October 2005

Dutch government disoriented and confused. Confusion and surprise are normal. Confusion becomes visible. Gapap between authorities and people is part of political life. Citizenship aspects. Citizenship cannot be produced. Community of fate. Institutions and routines needed.
Rethinking EU Scholarship
Authors: Zemanek Jiri , Xuereb Peter G. , de Witte Bruno , Weiler J.H.H. , Roobol W.H. , Shaw Jo , Pernice Ingolf , Maduro Miguel Poiares , Louis Jean-Victor , Lawson Rick , Eijsbouts W.T. , Curtin Deirdre , de Búrca Gráinne , Benz Arthur , Michaelis Lars
Published: October 2005

Following the dramatic No votes in the French and Dutch referendums on 29 May and 1 June 2005, a need was felt in the European constitutional law profession to react to the shock.

EuConst invited members of its Board and members of the European Constitutional Law Network to write a short comment about possible and possibly salutary effects of the events on the ways of European scholarship and teaching. Below are the reactions received. Authors are all members of ECLN and/or the Board of EuConst.

The contributions to this issue of EuConst by Jacques Ziller, Sacha Prechal and Herman van Gunsteren carry their comments on the events incorporated.
The Treaty of Nice, the Convention Draft and the Constitution for Europe Under a Veto Players Analysis
Authors: Yataganas Xenophon , Tsebelis George
Published: October 2005

Triple majority for changing the status quo in Treaty of Nice (2001): qualified majority of weighted votes, majority of countries, qualified majority of the population. Convention proposal (2003): requirements from three to two by dropping the qualified majority of weighted votes and reducing the qualified majority threshold of the population from 62% to 60%. Important consequences for the political institutions of the Union: 1) facilitates political decision-making; 2) reduces relative weight of governments participating in the Council and increases the importance of the European Parliament; 3) reduces the role of the judiciary and bureaucracies in the Union in favor of the political process. Consequences of the Treaty establishing a Constitution for Europe signed in Rome 29 October 2004. Exactly in the middle between Nice and the European Convention.
United Kingdom: Banning the Jilbab: Reflections on Restricting Religious Clothing in the Light of the Court of Appeal in SB v. Denbigh High School. Decision of 2 March 2005.
Authors: Davies Gareth
Published: October 2005

A wave of bans and restrictions on religious clothing is sweeping Europe. Schoolchildren, judges, jurors, civil servants, and employees are among the groups whose freedom to wear clothing which indicates their religion has been questioned, as has the right of governments, employers or schools to impose restrictions. The resulting debate has led to new laws or legal judgments in, among other countries, France, Germany, Denmark and the United Kingdom.
United Kingdom: House of Lords on Anti-terrorism, Crime and Security Act 2001 in A. and others v. Secretary of State for the Home Department and X and another v. Secretary of State for the Home Department, Decision of 16 December 2004
Authors: Feldman David
Published: October 2005

After the attacks by Al-Qaeda on the World Trade Centre in New York and other sites on 11 September 2001, the UK Parliament enacted the Anti-terrorism, Crime and Security Act 2001 (ATCSA). Part 4 of the Act allowed the Home Secretary to certify a person as a suspected international terrorist if he reasonably believed that the person's presence in the UK was a threat to national security and reasonably suspected that he or she was an international terrorist. If the person was subject to UK immigration control (i.e., had no right of abode in the UK, not being a British national), he or she could be removed from the UK and detained pending removal under immigration legislation. If a practical consideration (such as the absence of transport links between UK and the place to which the person could be removed) or a point of law which wholly or partly related to an international agreement (for example, where removing a person to his or her country of origin would render him or her liable to torture contrary to Article 3 of the European Convention for the Protection of Human Rights and Fundamental Freedoms (ECHR)) prevented a person's removal or departure temporarily or indefinitely, the Act permitted their detention.
Sea spray emission from the surface of the open Baltic Sea
Authors: Petelski T. , Piskozub J. , Paplińska‐Swerpel B.
Published: October 2005

Vertical aerosol flux values collected in the marine atmospheric boundary layer during Baltic cruises of the R/V Oceania have been analyzed. It has been determined that the aerosol emission from the sea surface in the open Baltic is proportional to the average energy dissipation rate raised to the 2/3 power. A similar relationship has been derived using dimensional analysis and a simple model of aerosol emission. It has been demonstrated that aerosol emission from the open Baltic may be parameterized using significant wave height and wind velocity.
Probabilistic climate change projections for CO2 stabilization profiles
Authors: Knutti Reto , Joos Fortunat , Müller Simon A. , Plattner Gian‐Kasper , Stocker Thomas F.
Published: October 2005

Probabilistic projections of future climate change for a range of CO2 stabilization profiles intended for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change are presented. A very large ensemble of simulations with the reduced complexity, Bern2.5D climate model is used to explore the uncertainties in projected long‐term changes in surface air temperature and sea level due to uncertainties in climate sensitivity and ocean heat uptake. Previously published probability density functions of climate sensitivity are used to calculate probabilistic projections for different CO2 stabilization levels and to calculate the probability of not exceeding a certain global mean surface temperature for a given stabilization level. This provides a new way of communicating long‐term uncertainty which can serve as a basis for selecting a CO2 stabilization level given a temperature limit and help to estimate the overshoot risk society is willing to accept.
Atlantic SST gradient and the influence of ENSO
Authors: Huang Huei‐Ping , Robertson Andrew W. , Kushnir Yochanan
Published: October 2005

The relationship between the boreal winter El Niño SST anomaly and boreal spring tropical Atlantic SST gradient (North Atlantic minus South Atlantic) is investigated using a long, detrended SST record. For both El Niño and La Niña, concordant cases (same sign for NINO3 index and Atlantic SST gradient) slightly dominate over discordant ones, reflecting the fact that the NINO3 index correlates more strongly with the North Atlantic than the South Atlantic SST anomaly. The ratio of the numbers of concordant and discordant cases is 4:3 overall, indicating strong non‐ENSO influences on the Atlantic SST gradient. The composite of the concordant cases shows an SST anomaly in the North Atlantic with the same sign as NINO3 and an opposite‐signed anomaly off the southwest coast of Africa resembling “Benguela Niño”. That of the discordant cases is dominated by a pre‐existing SST anomaly with the same sign as NINO3 in the south‐central South Atlantic.
Evidence of Enceladus and Tethys microsignatures
Authors: Paranicas C. , Mitchell D. G. , Livi S. , Krimigis S. M. , Roussos E. , Krupp N. , Woch J. , Lagg A. , Saur J. , Turner F. S.
Published: October 2005

We present evidence of two icy satellite microsignatures in the Cassini LEMMS data. Just upstream of Enceladus, a deep and narrow decrease in the flux of several MeV electrons is consistent with a recent absorption by that moon. This microsignature is collocated with a deep depletion in the MeV proton flux. The proton feature is much wider than the satellite diameter, suggesting multiple interactions and/or losses to the E Ring and neutral gas. An observed increase in proton flux toward the planet suggests a possible inner magnetospheric source. A decrease in the low energy electron intensity downstream of Tethys is also consistent with a microsignature approximately the size of the satellite that has drifted slightly toward the planet near midnight. Modeling suggests that microsignatures near Tethys' orbit would persist for more than a complete rotation of Saturn and the radial diffusion coefficient is about 10−9 RS2/s.
Geomagnetic pulsations caused by the Sumatra earthquake on December 26, 2004
Authors: Iyemori Toshihiko , Nose Masahito , Han Desheng , Gao Yufen , Hashizume Michio , Choosakul Nithiwatthn , Shinagawa Hiroyuki , Tanaka Yoshikazu , Utsugi Mitsuru , Saito Akinori , McCreadie Heather , Odagi Yoko , Yang Fuxi
Published: October 2005

A long period Pc5 pulsation was observed at Phimai in Thailand, shortly after the origin time of the Sumatra earthquake on December 26, 2004. The localized nature and the period of oscillations suggest that the long period magnetic pulsation was generated by dynamo action in the lower ionosphere, set up by an atmospheric pressure pulse which propagated vertically as an acoustic wave when the ocean floor suddenly moved vertically. It is speculated that a Pc3 type pulsation observed at Tong Hai in China, 10 degrees north of Phimai in latitude, was the result of magnetic field line resonance with a magneto‐sonic wave generated from the electric and magnetic fields of the dynamo current caused by the Earthquake.
Evolution of two-dimensional lump nanosolitons for the Zakharov-Kuznetsov and electromigration equations
Authors: Jorge M. C. , Cruz-Pacheco Gustavo , Mier-y-Teran-Romero Luis , Smyth Noel F.
Published: October 2005

The evolution of lump solutions for the Zakharov-Kuznetsov equation and the surface electromigration equation, which describes mass transport along the surface of nanoconductors, is studied. Approximate equations are developed for these equations, these approximate equations including the important effect of the dispersive radiation shed by the lumps as they evolve. The approximate equations show that lumplike initial conditions evolve into lump soliton solutions for both the Zakharov-Kuznetsov equation and the surface electromigration equations. Solutions of the approximate equations, within their range of applicability, are found to be in good agreement with full numerical solutions of the governing equations. The asymptotic and numerical results predict that localized disturbances will always evolve into nanosolitons. Finally, it is found that dispersive radiation plays a more dominant role in the evolution of lumps for the electromigration equations than for the Zakharov-Kuznetsov equation.
Solitons in a linearly coupled system with separated dispersion and nonlinearity
Authors: Zafrany Arik , Malomed Boris A. , Merhasin Ilya M.
Published: October 2005

We introduce a model of dual-core waveguide with the cubic nonlinearity and group-velocity dispersion (GVD) confined to different cores, with the linear coupling between them. The model can be realized in terms of photonic-crystal fibers. It opens a way to understand how solitons are sustained by the interplay between the nonlinearity and GVD which are not “mixed” in a single nonlinear Schrödinger (NLS) equation, but are instead separated and mix indirectly, through the linear coupling between the two cores. The spectrum of the system contains two gaps, semi-infinite and finite ones. In the case of anomalous GVD in the dispersive core, the solitons fill the semi-infinite gap, leaving the finite one empty. This soliton family is entirely stable, and is qualitatively similar to the ordinary NLS solitons, although shapes of the soliton’s components in the nonlinear and dispersive cores are very different, the latter one being much weaker and broader. In the case of the normal GVD, the situation is completely different: the semi-infinite gap is empty, but the finite one is filled with a family of stable gap solitons featuring a two-tier shape, with a sharp peak on top of a broad “pedestal.” This case has no counterpart in the usual NLS model. An extended system, including weak GVD in the nonlinear core, is analyzed too. In either case, when the solitons reside in the semi-infinite or finite gap, they persist if the extra GVD is anomalous, and completely disappear if it is normal.
Generation of Bragg solitons through modulation instability in a Bragg grating structure
Authors: Porsezian K. , Senthilnathan K.
Published: October 2005

In this article, we consider the continuous wave (cw) propagation through the nonlinear periodic structure that consists of alternating layers of both positive and negative Kerr coefficients along the propagation direction. We investigate the modulational instability (MI) conditions required for the generation of ultrashort pulses for the nonlinearity management system. We study the occurrence of MI at the top and bottom edges of the photonic band gap (PBG) where the forward and backward propagating waves are strongly coupled because of the presence of the grating structure. We also study the MI when cw is detuned from the edges of the PBG into the anomalous and normal dispersion regimes. In addition, we discuss the existence of gap solitons for the nonlinearity management system in the upper and lower branches of the dispersion curve through the MI gain spectra. We observe the generation of higher order solitons in the nonlinear periodic structure when the input power is increased beyond a certain critical level. Finally, we discuss the generation of higher order Bragg grating solitons through the intensity evolution of the forward and backward propagating fields.
Analytic model for a weakly dissipative shallow-water undular bore
Authors: El G. A. , Grimshaw R. H. J. , Kamchatnov A. M.
Published: October 2005

We use the integrable Kaup–Boussinesq shallow water system, modified by a small viscous term, to model the formation of an undular bore with a steady profile. The description is made in terms of the corresponding integrable Whitham system, also appropriately modified by viscosity. This is derived in Riemann variables using a modified finite-gap integration technique for the Ablowitz–Kaup–Newell–Segur (AKNS) scheme. The Whitham system is then reduced to a simple first-order differential equation which is integrated numerically to obtain an asymptotic profile of the undular bore, with the local oscillatory structure described by the periodic solution of the unperturbed Kaup–Boussinesq system. This solution of the Whitham equations is shown to be consistent with certain jump conditions following directly from conservation laws for the original system. A comparison is made with the recently studied dissipationless case for the same system, where the undular bore is unsteady.
Averaging of nonlinearity-managed pulses
Authors: Zharnitsky Vadim , Pelinovsky Dmitry
Published: October 2005

We consider the nonlinear Schrödinger equation with the nonlinearity management which describes Bose–Einstein condensates under Feshbach resonance. By using an averaging theory, we derive the Hamiltonian averaged equation and compare it with other averaging methods developed for this problem. The averaged equation is used for analytical approximations of nonlinearity-managed solitons.
Steady dark solitary waves emerging from wave-generated meanflow: The role of modulation equations
Authors: Bridges Thomas J.
Published: October 2005

Various classes of steady and unsteady dark solitary waves (DSWs) are known to exist in modulation equations for water waves in finite depth. However, there is a class of steady DSWS of the full water-wave problem which are missed by the classical modulation equations such as the Hasimoto–Ono, Benney–Roskes, and Davey–Stewartson. These steady DSWs, recently discovered by Bridges and Donaldson, are pervasive in finite depth, arise through secondary criticality of Stokes gravity waves, and are synchronized with the Stokes wave. In this paper, the role of DSWs in modulation equations for water waves is reappraised. The intrinsic unsteady nature of existing modulation equations filters out some interesting solutions. On the other hand, the geometry of DSWs in modulation equations is very similar to the full water wave problem and these geometrical properties are developed. A model equation is proposed which illustrates the general nature of the emergence of steady DSWs due to wave-generated mean flow coupled to a periodic wave. Although the existing modulation equations are intrinsically unsteady, it is shown that there are also important shortcomings when one wants to use them for stability analysis of DSWs.
Stability analysis of embedded solitons in the generalized third-order nonlinear Schrödinger equation
Authors: Pelinovsky Dmitry E. , Yang Jianke
Published: October 2005

We study the generalized third-order nonlinear Schrödinger (NLS) equation which admits a one-parameter family of single-hump embedded solitons. Analyzing the spectrum of the linearization operator near the embedded soliton, we show that there exists a resonance pole in the left half-plane of the spectral parameter, which explains linear stability, rather than nonlinear semistability, of embedded solitons. Using exponentially weighted spaces, we approximate the resonance pole both analytically and numerically. We confirm in a near-integrable asymptotic limit that the resonance pole gives precisely the linear decay rate of parameters of the embedded soliton. Using conserved quantities, we qualitatively characterize the stable dynamics of embedded solitons.
Resolution of a shock in hyperbolic systems modified by weak dispersion
Authors: El G. A.
Published: October 2005

We present a way to deal with dispersion-dominated “shock-type” transition in the absence of completely integrable structure for the systems that one may characterize as strictly hyperbolic regularized by a small amount of dispersion. The analysis is performed by assuming that the dispersive shock transition between two different constant states can be modeled by an expansion fan solution of the associated modulation (Whitham) system for the short-wavelength nonlinear oscillations in the transition region (the so-called Gurevich-Pitaevskii problem). We consider both single-wave and bidirectional systems. The main mathematical assumption is that of hyperbolicity of the Whitham system for the solutions of our interest. By using general properties of the Whitham averaging for a certain class of nonlinear dispersive systems and specific features of the Cauchy data prescription on characteristics we derive a set of transition conditions for the dispersive shock, actually bypassing full integration of the modulation equations. Along with the Korteweg-de Vries (KdV) and modified KdV (mKdV) equations as model examples, we consider a nonintegrable system describing fully nonlinear ion-acoustic waves in collisionless plasma. In all cases our transition conditions are in complete agreement with previous analytical and numerical results.
Solitary wave dynamics in shallow water over periodic topography
Authors: Nakoulima Ousseynou , Zahibo Narcisse , Pelinovsky Efim , Talipova Tatiana , Kurkin Andrey
Published: October 2005

The problem of long-wave scattering by piecewise-constant periodic topography is studied both for a linear solitary-like wave pulse, and for a weakly nonlinear solitary wave [Korteweg–de Vries (KdV) soliton]. If the characteristic length of the topographic irregularities is larger than the pulse length, the solution of the scattering problem is obtained analytically for a leading wave in the framework of linear shallow-water theory. The wave decrement in the case of the small height of the topographic irregularities is proportional to δ2, where δ is the relative height of the topographic obstacles. An analytical approximate solution is also obtained for the weakly nonlinear problem when the length of the irregularities is larger than the characteristic nonlinear length scale. In this case, the Korteweg–de Vries equation is solved for each piece of constant depth by using the inverse scattering technique; the solutions are matched at each step by using linear shallow-water theory. The weakly nonlinear solitary wave decays more significantly than the linear solitary pulse. Solitary wave dynamics above a random seabed is also discussed, and the results obtained for random topography (including experimental data) are in reasonable agreement with the calculations for piecewise topography.
Quasiclassical dynamics simulation of the collision-induced dissociation of Cr(CO)6+ with Xe
Authors: Martínez-Núñez Emilio , Fernández-Ramos Antonio , Vázquez Saulo A. , Marques Jorge M. C. , Xue Mingying , Hase William L.
Published: October 2005

Quasiclassical trajectory calculations are employed to investigate the dynamics of collision-induced dissociation (CID) of Cr(CO)6+ with Xe atoms at collision energies ranging from 1.3to5.0eV. The trajectory simulations show that direct elimination of CO ligands, during the collision, becomes increasingly important as the collision energy increases. In a significant number of cases, this shattering mechanism is accompanied with a concomitant formation of a transient Xe–Cr(CO)x+(x<6) complex. The calculated results are in very good agreement with the experimental results presented previously [F. Muntean and P. B. Armentrout, J. Chem. Phys. 115, 1213 (2001)]. In particular, the computed cross sections and scattering maps for the product ions Cr(CO)x+(x=3–5) compare very favorably with the reported experimental data. However, in contrast with the conclusions of the previous study, the present calculations suggest that CID dynamics for this system exhibits a significant impulsive character rather than proceeding via a complex surviving more than a rotational period.
Solitons in nonintegrable systems
Authors: Grimshaw Roger H. J. , Ostrovsky Lev A. , Pelinovsky Dmitry E.
Published: October 2005

We introduce the concept of this special focus issue on solitons in nonintegrable systems. A brief overview of some recent developments is provided, and the various contributions are described. The topics covered in this focus issue are the modulation of solitons, bores, and shocks, the dynamical evolution of solitary waves, and existence and stability of solitary waves and embedded solitons.
Generation, propagation, and breaking of internal solitary waves
Authors: Grue John
Published: October 2005

Tidal, two-layer flow over topography generates a kink of the interface separating an upstream interfacial elevation from a depression above the topography. Upstream undular bores and solitary waves of large amplitude are generated from the interfacial kink. The waves propagate upstream when the tide turns. Interfacial simulations of this kind of generation process fit with the observations at Knight Inlet in British Columbia, in the Sulu Sea experiment, and undular bores generated by internal tides in the Strait of Gibraltar. Fully nonlinear interfacial computations compare successfully with experimental observations of solitary waves in the laboratory and in the field for wave amplitudes ranging from small to maximal values. The waves exhibit only minor sensitivity to a finite thickness of the pycnocline. Analytical solitary waves are recaptured in the small amplitude limit. Shear-induced breaking appears first in the top part of the pycnocline and is expressed in terms of the Richardson number. Convective breaking in the top part of the water column occurs beyond a threshold amplitude when a pronounced stratification continues all the way to the ocean surface.
Relativistic harmonic oscillator
Authors: Li Zhi-Feng , Liu Jin-Jin , Lucha Wolfgang , Ma Wen-Gan , Schöberl Franz F.
Published: October 2005

We study the semirelativistic Hamiltonian operator composed of the relativistic kinetic energy and a static harmonic-oscillator potential in three spatial dimensions and construct, for bound states with vanishing orbital angular momentum, its eigenfunctions in “compact form,” i.e., as power series, with expansion coefficients determined by an explicitly given recurrence relation. The corresponding eigenvalues are fixed by the requirement of normalizability of the solutions.
Competition of mesoscales and crossover to theta-point tricriticality in near-critical polymer solutions
Authors: Anisimov M. A. , Kostko A. F. , Sengers J. V. , Yudin I. K.
Published: October 2005

The approach to asymptotic critical behavior in polymer solutions is governed by a competition between the correlation length of critical fluctuations diverging at the critical point of phase separation and an additional mesoscopic length scale, the radius of gyration. In this paper we present a theory for crossover between two universal regimes: a regime with Ising (fluctuation-induced) asymptotic critical behavior, where the correlation length prevails, and a mean-field tricritical regime with theta-point behavior controlled by the mesoscopic polymer chain. The theory yields a universal scaled description of existing experimental phase-equilibria data and is in excellent agreement with our light-scattering experiments on polystyrene solutions in cyclohexane with polymer molecular weights ranging from 2×105 up to 11.4×106. The experiments demonstrate unambiguously that crossover to theta-point tricriticality is controlled by a competition of the two mesoscales. The critical amplitudes deduced from our experiments depend on the polymer molecular weight as predicted by de Gennes [Phys. Lett. 26A, 313 (1968)]. Experimental evidence for the presence of logarithmic corrections to mean-field tricritical theta-point behavior in the molecular-weight dependence of the critical parameters is also presented.
Rigid body mechanics in Galilean spacetimes
Authors: Bhand Ajit , Lewis Andrew D.
Published: October 2005

An observer-independent formulation of rigid body dynamics is provided in the general setting of a Galilean spacetime. The equations governing the motion of a rigid body undergoing a rigid motion in a Galilean spacetime are derived on the basis of the principle of conservation of spatial momentum. The formulation of rigid body dynamics is then studied in the presence of an observer. It is seen that an observer defines a connection such that there exist rigid motions that are horizontal with respect to this connection that give the same physical motion of the rigid body, and for which the general equations of motion are exactly the usual Euler equations for a rigid body undergoing rigid motion.
Application of pseudo-Hermitian quantum mechanics to a PT-symmetric Hamiltonian with a continuum of scattering states
Authors: Mostafazadeh Ali
Published: October 2005

We extend the application of the techniques developed within the framework of the pseudo-Hermitian quantum mechanics to study a unitary quantum system described by an imaginary PT-symmetric potential v(x) having a continuous real spectrum. For this potential that has recently been used, in the context of optical potentials, for modeling the propagation of electromagnetic waves traveling in a waveguide half and half filled with gain and absorbing media, we give a perturbative construction of the physical Hilbert space, observables, localized states, and the equivalent Hermitian Hamiltonian. Ignoring terms of order three or higher in the non-Hermiticity parameter ζ, we show that the equivalent Hermitian Hamiltonian has the form p2∕2m+(ζ2∕2)∑n=0∞{αn(x),p2n} with αn(x) vanishing outside an interval that is three times larger than the support of v(x), i.e., in 2∕3 of the physical interaction region the potential v(x) vanishes identically. We provide a physical interpretation for this unusual behavior and comment on the classical limit of the system.
Molecular dynamics in the isothermal-isobaric ensemble: The requirement of a “shell” molecule. I. Theory and phase-space analysis
Authors: Uline Mark J. , Corti David S.
Published: October 2005

Current constant pressure molecular-dynamics (MD) algorithms are not consistent with the recent reformulation of the isothermal-isobaric (NpT) ensemble. The NpT ensemble partition function requires the use of a “shell” molecule to identify uniquely the volume of the system, thereby avoiding the redundant counting of configurations [e.g., G. J. M. Koper and H. Reiss, J. Phys. Chem. 100, 422 (1996); D. S. Corti, Phys. Rev. E, 64, 016128 (2001)]. So far, only the NpT Monte Carlo method has been updated to allow the system volume to be defined by a shell particle [D. S. Corti, Mol. Phys. 100, 1887 (2002)]. A shell particle has yet to be incorporated into MD simulations. The proper modification of the NpT MD algorithm is therefore the subject of this paper. Unlike Andersen’s method [H. C. Andersen, J. Chem. Phys. 72, 2384 (1980)] where a piston of unknown mass serves to control the response time of volume fluctuations, the newly proposed equations of motion impose a constant external pressure via the introduction of a shell particle of known mass. Hence, the system itself sets the time scales for pressure and volume fluctuations. The new algorithm is subject to a number of fundamentally rigorous tests to ensure that the equations of motion sample phase space correctly. We also show that the Hoover NpT algorithm [W. G. Hoover, Phys. Rev. A. 31, 1695 (1985); 34, 2499 (1986)] does sample phase correctly, but only when periodic boundary conditions are employed.
Molecular dynamics in the isothermal-isobaric ensemble: The requirement of a “shell” molecule. II. Simulation results
Authors: Uline Mark J. , Corti David S.
Published: October 2005

The results of a series of constant pressure and temperature molecular-dynamics (MD) simulation studies based on the rigorous shell particle formulation of the isothermal-isobaric (NpT) ensemble are presented. These MD simulations validate the newly proposed constant pressure equations of motion in which a “shell” particle is used to define uniquely the volume of the system [M. J. Uline and D. S. Corti, J. Chem. Phys. (to be published), preceding paper]. Ensemble averages obtained with the new MD NpT algorithm match the ensemble averages obtained using the previously derived shell particle Monte Carlo NpT method [D. S. Corti, Mol. Phys. 100, 1887 (2002)]. In addition, we also verify that the Hoover NpT MD algorithm [W. G. Hoover, Phys. Rev. A 31, 1695 (1985); 34, 2499 (1986)] generates the correct ensemble averages, though only when periodic boundary conditions are employed. The extension of the shell particle MD algorithm to multicomponent systems is also discussed, in which we show for equilibrium properties that the identity of the shell particle is completely arbitrary when periodic boundary conditions are applied. Self-diffusion coefficients determined with the shell particle equations of motion are also identical to those obtained in other ensembles. Finally, since the mass of the shell particle is known, the system itself, and not a piston of arbitrary mass, controls the time scales for internal pressure and volume fluctuations. We therefore consider the effects of the shell particle on the dynamics of the system. Overall, the shell particle MD algorithm is an effective simulation method for studying systems exposed to a constant external pressure and may provide an advantage over other existing constant pressure approaches when developing nonequilibrium MD methods.
Primitive model for cation hydrolysis: A molecular-dynamics study
Authors: Holovko M. , Druchok M. , Bryk T.
Published: October 2005

A model of primitive cation MZ+ in water is introduced in order to clarify the influence of ion charge on the hydration structure and dynamic properties of highly charged cations in aqueous solutions. A flexible nonconstrained model for water molecules is used. The considered model in the case of monovalent cation M+ reduces to the realistic model for the hydration structure of Na+. It is shown that for divalent ion M2+ the strong cation-water electrostatic interaction leads to the formation of stable structures constituted by six water molecules octahedrally arranged around the cation. The cation-oxygen attraction and cation-hydrogen repulsion modify the octahedral hydration configuration of the model cations M3+ and M4+ and additional water molecules can join the hydration shell. The increase of cation charge results in the increase of O–H bond length of water molecules in the cation hydration shell. Further increase of ion-water electrostatic interaction causes the loss of some protons from the hydration shell of cations M4+, M5+, and M6+ that is interpreted as a cation hydrolysis effect. For a correct description of this phenomenon the considered model is improved by modeling the effects of the charge redistribution between hydrolysis products, which essentially modified and stabilized the hydrated-hydrolyzed structure of cation. The influence of cation charge on dynamical properties of cation MZ+ and oxygens in its hydration shell was investigated and analyzed.
Effects of nonpolar solutes on the thermodynamic response functions of aqueous mixtures
Authors: Chatterjee Swaroop , Ashbaugh Henry S. , Debenedetti Pablo G.
Published: October 2005

We investigate the effect of adding nonpolar solutes at atmospheric pressure on water’s temperature of maximum density, isothermal compressibility, and isobaric heat capacity, using a statistical mechanical model of water solutions [H. S. Ashbaugh, T. M. Truskett, and P. G. Debenedetti, J. Chem. Phys. 116, 2907 (2002)]. We find that the temperature of maximum density increases with solute hydrophobicity, as characterized by its size, and decreases with its van der Waals attractive parameter a, in agreement with experiment. We predict similar trends for the addition of solutes on the isothermal compressibility and isobaric heat capacity: solute hydrophobicity causes an upward shift in water’s anomalies, whereas dispersive interactions as measured by the solute’s van der Waals attractive parameter shift the anomalies to lower temperatures. The locus along which the competing contributions of solute size σ and interaction strength a to the shift in water’s response functions balance each other obeys the scaling relationship σ6∼a.
One-color two-photon mass-analyzed threshold ionization spectroscopy of ethyl bromide through a dissociative intermediate state
Authors: Tang Bifeng , Zhang Song , Wang Yanmei , Tang Ying , Zhang Bing
Published: October 2005

Mass-analyzed threshold ionization (MATI) spectra of ethyl bromide were obtained using one-color two-photon ionization through a dissociative intermediate state. Accurate values for the adiabatic ionization energy have been obtained, 83099±5 and 85454±5cm−1 for the X̃1E2 and X̃2E2 states of the ethyl bromide cation, respectively, giving a splitting of 2355±10cm−1. Compared with conventional photoelectron data, the two-photon MATI spectrum exhibited a more extensive vibrational structure with a higher resolution, mainly containing the modes involving the dissociation coordinate. The observed modes were analyzed and discussed in terms of wave packet evolving on the potential-energy surface of the dissociative state.
Electron microscopy and photoelectron spectromicroscopy study of catalyst-free transformation of carbon nanoparticles into nanotubes
Authors: Botti S. , Ciardi R. , Fabbri F. , Larciprete R. , Goldoni A. , Gregoratti L. , Kaulich B. , Kiskinova M.
Published: October 2005

The reorganization of the morphologically complex amorphous carbon nanoparticle layers deposited on a Si substrate into ordered sp2 entities was investigated by means of two complementary techniques, synchrotron radiation x-ray photoelectron microscopy and scanning electron microscopy, which provided the necessary chemical and structural information at submicrometer length scales. The studies were focused on the effect of the local thickness of the carbon nanoparticle layer on the extent of the restructuring process. The lateral distribution of the phases formed on the surface and their local chemical configuration were revealed by measuring C 1s and the Si 2p core level spectra with photoelectron spectromicroscopy. The results showed that an effective graphitization, which on the basis of complementary characterization techniques was associated to the formation of single-wall nanotubes, occurs only in areas with a high density of nanoparticles. These findings indicate that tube self-assembling is promoted by the interaction between neighboring nanoparticles.
Metal-organic chemical-vapor deposition of (Ba,Sr)TiO3: Nucleation and growth on Pt-(111)
Authors: Regnery S. , Ding Y. , Ehrhart P. , Jia C. L. , Szot K. , Thomas R. , Waser R.
Published: October 2005

Thin films of the (BaxSr1−x)TiO3 (BST) solid solution series were grown by metal-organic chemical-vapor deposition (MOCVD) on platinized silicon wafers with emphasis to (Ba0.7Sr0.3)TiO3 and SrTiO3. The nucleation behavior and the size of the stable nuclei were investigated by different scanning probe microscope techniques including local conductivity scanning. The characteristic differences were observed for different deposition temperatures, i.e., a homogeneous nucleation of small BST grains on the larger Pt grains at 565 °C and a dominating grain-boundary nucleation at 655 °C. X-ray photoelectron spectroscopy indicates a stoichiometric composition from the beginning. The microstructural evolution was investigated by high-resolution transmission electron microscopy and revealed randomly oriented grains (typical in-plane size 10–20 nm) with a high density of twins at 565 °C and (100)-oriented defect-free grains of slightly increased size at 655 °C. This remarkably stable (100) texture seems specific for MOCVD as it is not observed for other deposition methods. The grain structure and surface morphology and their dependence on film stoichiometry (group-II/Ti ratio) are investigated. The relation between the structural and the electrical properties, capacitance, and leakage current, is finally discussed.
Synthesis and characterization of crystalline microporous cobalt phosphite nanowires
Authors: Che R. C. , Peng L.-M. , Zhou W. Z.
Published: October 2005

Crystalline microporous Co11(HPO3)8(OH)6 nanowires have been synthesized through a soft hydrothermal reaction between red phosphor, KOH, and metal halides. These nanowires were found to have their main hexagonal channels along the long axis and a narrow distribution around 30–40nm in diameter. The growth of the nanowires were found to initiate at Co(OH)2 nuclei. The length of the nanowires depends mainly on the hydrothermal reaction time and the amount of Co(OH)2 available at the nuclei to feed the growth of the nanowires. Blue shift of up to 85nm was observed in UV-visible absorption spectra from the Co11(HPO3)8(OH)6 nanowires in comparing with that from the micro-size particle sample, giving an absorption edge deep in the ultraviolet region at about 255nm or a bandgap Eg∼4.9eV.