Forward on the <Emphasis Type="Italic">N</Emphasis> = <Emphasis Type="Italic">Z</Emphasis> line with GASP

The experimental study of the proton-rich nuclei close to the N = Z line is a constant challenge for nuclear spectroscopy, mainly due to the difficulty to produce them with the currently available beam/target combinations. Significant advances on this direction were obtained from experiments performed with the GASP array during the last two years: the yrast line of ⁸⁴Mo was extended up to 10 ⁺ , ⁸⁸Ru observed for the first time, and the N = Z + 1 line was mapped from ⁸¹Zr to ⁹⁵Ag. These new results allow us to have a more complete image of the transition from the well-deformed shell closure at N,Z = 40 to the spherical-shell closure at N,Z = 50, and highlights some particular effects that can be observed only in the vicinity of the N = Z line.Received: 10 January 2003, Published online: 23 March 2004PACS: 21.10.-k Properties of nuclei; nuclear energy levels - 21.10.Pc Single-particle levels and strength functions - 21.10.Re Collective levels - 23.20.-g Electromagnetic transitions     

A reanalysis of finite temperature <Emphasis Type="Italic">SU</Emphasis>(<Emphasis Type="Italic">N</Emphasis>) gauge theory

We revise the SU(N _c ), N _c =3,4,6, lattice data on pure gauge theories at finite temperature by means of a quasi-particle approach. In particular, we focus on the relation between the effective mass of the quasi-particle and the order of the deconfinement transition, the scaling of the interaction measure with N²_c -1N^{2}_{c} -1, the role of gluon condensate, and the screening mass.     

Noncommutative electromagnetism as a large <Emphasis Type="Italic">N</Emphasis> gauge theory

We map noncommutative (NC) U(1) gauge theory on ℝ _C ^d ×ℝ _NC ²ⁿ to U(N→∞) Yang–Mills theory on ℝ _C ^d , where ℝ _C ^d is a d-dimensional commutative spacetime while ℝ _NC ²ⁿ is a 2n-dimensional NC space. The resulting U(N) Yang–Mills theory on ℝ _C ^d is equivalent to that obtained by the dimensional reduction of (d+2n)-dimensional U(N) Yang–Mills theory onto ℝ _C ^d . We show that the gauge-Higgs system (A _μ ,Φ ^a ) in the U(N→∞) Yang–Mills theory on ℝ _C ^d leads to an emergent geometry in the (d+2n)-dimensional spacetime whose metric was determined by Ward a long time ago. In particular, the 10-dimensional gravity for d=4 and n=3 corresponds to the emergent geometry arising from the 4-dimensional N=4{\mathcal{N}}=4 vector multiplet in the AdS/CFT duality. We further elucidate the emergent gravity by showing that the gauge-Higgs system (A _μ ,Φ ^a ) in half-BPS configurations describes self-dual Einstein gravity.     

Improvement of <Emphasis Type="Italic">n</Emphasis>-ZnO/<Emphasis Type="Italic">p</Emphasis>-Si photodiodes by embedding of silver nanoparticles

The photo-current of n-ZnO/p-Si heterojunction photodiodes was improved by embedding Ag nanoparticles in the interface (ZnO/nano-P_Ag/p-Si), and the ratio between photo- and dark-current increased by about three orders more than that of a n-ZnO/p-Si specimen. The improvement in the photo-current resulted from the light scattering of embedded Ag nanoparticles. The I–V curve of n-ZnO/p-Si degraded after thermal treatment (A-ZnO/p-Si) because the silicon robbed the oxygen from ZnO to form amorphous silicon dioxide and left an oxygen vacancy. Notably, the properties of ZnO/nano-P_Ag/p-Si were better in the time-dependent photoresponse under 10 V bias. Ag nanoparticles (15–20 nm) scattered the UV light randomly and increased the probability for the absorption of ZnO to enhance the properties of the photodiode.     

1/<Emphasis Type="Italic">N</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis></Subscript> countings in baryons

The 1/N _c -power countings for baryon decays and configuration mixings are determined by means of a nonrelativistic quark picture. Such countings are expected to be robust under changes in the quark masses and, therefore, valid as these become light. It is shown that excited baryons have natural widths of \(\mathcal{O}(N_c^0 )\). These dominant widths are due to the decays that proceed directly to the ground-state baryons, with cascade decays being suppressed to \(\mathcal{O}(1/N_c )\). Configuration mixings, defined as mixings between states belonging to different O(3) × SU(2N _f ) multiplets, are shown to be subleading in an expansion in \(1/\sqrt {N_c }\) when they involve the ground-state baryons, while the mixings between excited states can be \(\mathcal{O}(N_c^0 )\).     

Enhancement of antibacterial effect of quaternary ammonium with inorganic nanosheets against <Emphasis Type="Italic">Enterobacter cloacae</Emphasis>

To suppress nosocomial infections, numerous studies of quaternary ammonium cations (R₄N⁺) to improve the antibiotic properties have been investigated. However, most of them reported developments of novel organic or polymeric materials with R₄N⁺. To pioneer antibacterial inorganic materials hybridized with R₄N⁺, a colloidal solution of metal oxide nanosheets, which have a small particle size (typically less than 10 nm), is considered to be a suitable option because oxide nanosheets with a negative surface charge strongly interact R₄N⁺. Herein, we demonstrate for the first time that the high antibacterial/bactericidal effects of titanate nanosheets (TNS) adsorbing tetramethylammonium (TMA-TNS) or tetrabultylammonium ions (TBA-TNS). Their antibacterial effects against Enterobacter cloacae were evaluated using a colony forming unit (CFU) counting method. The results showed that the synthesized TNS composites had superior antibacterial and bactericidal effects to those of free R₄N⁺ and TBA-TNS exhibited the strongest effect (69% CFU reduction compared with that of free TBA⁺ and 98% CFU reduction compared with the control) among the samples examined. Dark incubation was employed to ensure that photocatalytic reaction of semiconducting TNS did not contribute to the process. Compared with TiO₂ spherical particles, such high bactericidal effect would be induced by a synergistic function of TBA⁺ and TNS, which physically damages bacteria due to long hydrophobic alkyl chains and an anisotropic nanocrystalline structure with sharp edges, respectively.     

The <Emphasis Type="Italic">N</Emphasis> = <Emphasis Type="Italic">Z</Emphasis><Emphasis Type="Italic">f</Emphasis><Subscript>7/2</Subscript>-shell nuclei: Experimental highlights

During the last decade, as the experimental and computing means and techniques have rapidly evolved, the experimental investigation of the f_7/2-shell nuclei has gained renewed interest. TheN = Z nuclei studied with the GASP array range from ⁴⁴Ti to ⁵²Fe. The results extended the knowledge of their structure up to high spins and excitation energies, above band terminations, where the competition with the charged-particles emission was initially thought to obscure the possibility of gamma-ray spectroscopy investigation. The paper highlights some of the most outstanding properties of these nuclei such as the nuclear rotation and backbending effects, band termination states, yrast traps, non-natural parity bands, competition between T = 0 and T = 1 pn pairing modes.Received: 30 October 2002, Published online: 16 March 2004PACS: 21.10.-k Properties of nuclei; nuclear energy levels - 21.60.Cs Shell model - 23.20.Lv transitions and level energies - 27.40. + z C.A. Ur: On leave from NIPNE Bucharest, Romania     

The effect of the valence nucleons off the shells with <Emphasis Type="Italic">Z</Emphasis> = 82 and <Emphasis Type="Italic">N</Emphasis> = 126 on rotational characteristics of actinide nuclei

Our earlier results obtained for moments of inertia (M) in the case of 54 rotational level bands built on the ground state of actinide nuclei are taken for further analysis. In the current paper, resulting dynamic rotational characteristics, such as a ₀, a ₁, s ₀ and the R _4/2 parameter, are studied from the standpoint of their dependence on the valence nucleon number product N _p N _n and on the variable P = N _p N _n /(N _p + N _n ). New features of the nuclei deformation phenomenon in the actinide area arise when their dynamic rotational characteristics, mentioned above, are plotted in such a way as shown in the current work. The method of analysis presented here makes it possible to reveal nuclei with valence nucleon numbers for which the nuclear interactions are notable and those in which they are inconspicuous. E. g. when N _p N _n < 200 and P < 6 the strength of nuclear interaction gradually decreases with the increase of these variables. The strength of the nuclear interaction does not change significantly for N _p N _n > 200 and P > 6 — the rotational characteristics stabilise. Moreover, it is possible to establish the P variable as representing the effective number of interactions of each valence nucleon with those of the other type.     

On the Sutherland Spin Model of <Emphasis Type="Italic">B</Emphasis><Subscript><Emphasis Type="Italic">N</Emphasis></Subscript> Type and Its Associated Spin Chain

 The B _N hyperbolic Sutherland spin model is expressed in terms of a suitable set of commuting Dunkl operators. This fact is exploited to derive a complete family of commuting integrals of motion of the model, thus establishing its integrability. The Dunkl operators are shown to possess a common flag of invariant finite-dimensional linear spaces of smooth scalar functions. This implies that the Hamiltonian of the model preserves a corresponding flag of smooth spin functions. The discrete spectrum of the restriction of the Hamiltonian to this spin flag is explicitly computed by triangularization. The integrability of the hyperbolic Sutherland spin chain of B _N type associated with the dynamical model is proved using Polychronakos's ``freezing trick'. Received: 14 February 2002 / Accepted: 19 June 2002 Published online: 10 December 2002 RID="*" ID="*" Corresponding author. E-mail: artemio@fis.ucm.es RID="**" ID="**" On leave of absence from Institute of Mathematics, 3 Tereschenkivska St., 01601 Kyiv-4 Ukraine Communicated by L. Takhtajan     

Trace anomaly and quasi-particles in finite temperature <Emphasis Type="Italic">SU</Emphasis>(<Emphasis Type="Italic">N</Emphasis>) gauge theory

We consider deconfined matter in SU(N) gauge theory as an ideal gas of transversely polarized quasi-particle modes having a temperature-dependent mass m(T). Just above the transition temperature, the mass is assumed to be determined by the critical behavior of the energy density and the screening length in the medium. At high temperature, it becomes proportional to T as the only remaining scale. The resulting (trace anomaly based) interaction measure Δ=(ϵ−3P)/T ⁴ and energy density are found to agree well with finite temperature SU(3) lattice calculations.     

Non-Semisimple and Complex Gaugings of <Emphasis Type="Italic">N</Emphasis>=16 Supergravity

Maximal and non-maximal supergravities in three dimensions allow for a large variety of semisimple (Chern-Simons) gauge groups. In this paper, we analyze non-semisimple and complex gauge groups that satisfy the pertinent consistency relations for a maximal (N=16) gauged supergravity to exist. We give a general procedure how to generate non-semisimple gauge groups from known admissible semisimple gauge groups by a singular boost within E₈₍₈₎. Examples include the theories with gauge group SO(8)×T₂₈ that describe the reduction of IIA/IIB supergravity on the seven-sphere. In addition, we exhibit two strange embeddings of the complex gauge group into (real) E₈₍₈₎ and prove that both can be consistently gauged. We discuss the structure of the associated scalar potentials as well as their relation to those of D4 gauged supergravities.This work is partly supported by EU contract HPRN-CT-2000-00122 and HPRN-CT-2000-00131.     

The <Emphasis Type="Italic">N</Emphasis> = 2 Heavenly Equation

This paper presents report of the joint work with Z. Popowicz, which appeared in J. Phys. A, concerning the construction of a manifestly N = 2 supersymmetric heavenly equation in 2 + 1 dimensions. Its integrability properties have been derived from an N = 2 supersymmetric Lax pair, based on the n limit of the sl(n;n + 1) superalgebra series. The superhydrodynamical type of restrictions to 1+1 dimensions have been analyzed.     

A Confined <Emphasis Type="Italic">N</Emphasis>-Dimensional Harmonic Oscillator

We compute the energy eigenvalues for the N-dimensional harmonic oscillator confined in an impenetrable spherical cavity. The results show their dependence on the size of the cavity and the space dimension N. The obtained results are compared with those for the free N-dimensional harmonic oscillator, and as a result, the notion of fractional dimensions is pointed out. Finally, we examine the correlation between eigenenergies for confined oscillators in different dimensions.     

Study of <Emphasis Type="Italic">N</Emphasis> = <Emphasis Type="Italic">Z</Emphasis> nuclei in variation-after-projection framework

Variation-after-projection (VAP) calculations in conjunction with the Hartree- Bogoliubov (HB) ansatz have been carried out for A = 68-88, N = Z nuclei. In this framework, the yrast spectra with , B(E2) transition probabilities and deformation parameter ( ) have been obtained. A pairing interaction for like particles as well as protons and neutrons has been included in the model for a two-body interaction.Received: 28 April 2003, Revised: 20 March 2004, Published online: 14 September 2004PACS: 21.10.-k Properties of nuclei; nuclear energy levels - 21.60.-n Nuclear structure models and methods - 27.50. + e      

The Effect of the Complexation of <Emphasis Type="Italic">p-N,N</Emphasis>-Dimethylaminobenzoic Acid and <Emphasis Type="Italic">p-N,N</Emphasis>-Dimethylaminobenzonitrile with LaCl<Subscript>3</Subscript> on Spectral-luminescent Parameters of Fluorophores

The LE band fluorescence enhancement of p-N,N-dimethylaminobenzoic acid (DMABA) and p-N,N-dimethylaminobenzonitrile (DMABN) was found in aprotic acetonitrile and butyronitrile at the addition of LaCl₃. The corresponding ICT fluorescence band remains unchanged. This enhancement is explained by the decrease of the internal conversion rate constant in a coordination complex with LaCl₃. The formation of the coordination complex between DMABA and LaCl₃ in ethanol is accompanied by the efficient fluorescence quenching in LE and ICT bands, in parallel with the enhancement of ICT/LE emission ratio. The experimental data are well described by the proposed kinetic schemes.     

Polynomial Realization of <Emphasis Type="Italic">s</Emphasis>l<Subscript><Emphasis Type="Italic">q</Emphasis></Subscript>(2) and Fusion Rules at Exceptional Values of <Emphasis Type="Italic">q</Emphasis>

Representations of the sℓ_q(2) algebra are constructed in the space of polynomials of real (complex) variable for q^N=1. The spin addition rule based on eigenvalues of Casimir operator is illustrated on few simplest cases and conjecture for general case is formulated.     

On the degeneracy of <Emphasis Type="Italic">SU</Emphasis>(3)<Subscript><Emphasis Type="Italic">k</Emphasis></Subscript> topological phases

The ground state degeneracy of an SU(N) _k topological phase with n quasiparticle excitations is a relevant quantity for quantum computation, condensed matter physics, and knot theory. It is an open question to find a closed formula for this degeneracy for any N >2. Here we present the problem in an explicit combinatorial way and analyze the case N = 3. While not finding a complete closed-form solution, we obtain generating functions and solve some special cases.     

Electronic structure of crystal-forming fulborenes B<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>N<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

A general approach is formulated to the design of crystal-forming fullerene-like clusters X _n Y _n from which zeolite-like covalent crystals based on IV-IV, III-V, and II-VI binary semiconductor compounds with diamond-like sp ³ bonds can be constructed and synthesized by means of copolymerization through faces. A number of the smallest sized crystal-forming boron nitride clusters are constructed, such as the B₁₂N₁₂, B₁₆N1₆, B₁₈N₁₈, B₂₄N₂₄, B₃₆N₃₆, and B ₆₀N₆₀ fulborenes. The optimized configurations, electronic structures, charge transfers, band gaps, total energies, cohesive energies, and electron density maps of the clusters are calculated using the spin-restricted Hartree-Fock method in the 6–31G basis set. Comparative calculations of the B₆₀N₆₀ fulborene with the use of the density functional theory method have demonstrated that the spin-restricted Hartree-Fock method in the 6–31G basis set is optimum from the standpoint of the accuracy and efficiency.