An SU(4) invariant compactification of d = 11 supergravity on a stretched seven-sphere

We construct on S⁷ an SU(4) invariant solution of d = 11 supergravity in which the metric on the seven-sphere, regarded as a U(1) bundle overCP³, is distorted by stretching the U(1) fibers, and the four-index field strength F_MNPQ is non-zero in the S⁷ directions. This solution presumably corresponds to the SU(4) invariant extremum of the de Wit-Nicolai potential.     

LTE-Advanced and the evolution to Beyond 4G (B4G) systems

Cellular networks have been undergoing an extraordinarily fast evolution in the past years. With commercial deployments of Release 8 (Rel-8) Long Term Evolution (LTE) already being carried out worldwide, a significant effort is being put forth by the research and standardization communities on the development and specification of LTE-Advanced. The work started in Rel-10 by the Third Generation Partnership Project (3GPP) had the initial objective of meeting the International Mobile Telecommunications-Advanced (IMT-Advanced) requirements set by the International Telecommunications Union (ITU) which defined fourth generation (4G) systems. However, predictions based on the wireless traffic explosion in recent years indicate a need for more advanced technologies and higher performance. Hence, 3GPP’s efforts have continued through Rel-11 and now Rel-12. This paper provides a state-of-the-art comprehensive view on the key enabling technologies for LTE-Advanced systems. Already consolidated technologies developed for Rel-10 and Rel-11 are reviewed while novel approaches and enhancements currently under consideration for Rel-12 are also discussed. Technical challenges for each of the main areas of study are pointed out as an encouragement for the research community to participate in this collective effort.     

Griffiths inequalities for noninteractingN-vector (classical heisenberg) models and applications to interacting systems

An order relation for tensors is defined. With this ordering it is shown that in noninteractingN-vector models 〈σ_Aσ_B〉?〈σ_A〉〈σ_B〉 is positive. Applications to interacting models include a proof for the alignment of spins and the subadditivity of the free energy.     

Two-photon absorption properties of aggregation systems on the basis of (E)-4-(2-nitrovinyl) benzenamine molecules

Aggregation effect caused by the intermolecular hydrogen-bonding interactions on two-photon absorption properties of (E)-4-(2-nitrovinyl) benzenamine molecules is studied at a hybrid density functional level. The geometry optimization studies indicate that there exist two probable conformations for the dimers and three for the trimers. A strong red-shift of the charge-transfer states is shown. The two-photon absorption cross sections of the molecule for certain conformations are greatly enhanced by the aggregation effect, from which a ratio of 1.0:2.6:3.6 is found for the molecule and its dimer and trimer with nearly planar structures. Namely, a 30 or 20 percent increase of the two-photon absorption cross section is observed.     

A translationally invariant shell-model treatment of (0+1) ħω states in a=4–16 nuclei (I)

Shell-model calculations on positive- and negative-parity states have been performed for thep-shell nuclei. The model space includes all 0?ω and 1?ω harmonic-oscillator basis states without the use of a core. The matrix elements of the mass-independent two-body interaction and the harmonic-oscillator size parameter are determined empirically from a fit to experimental energy levels. The interaction is required to satisfy translational invariance. The single-particle energies are compatible with this requirement. The spurious states are isolated exactly from the nonspurious states.     

Analyticity properties of trilinear SL(2, C) invariant forms in elementary representation parameters

Trilinear invariant forms over spaces transforming under the so-called elementary representations of SL (2, C) (obtained from the principal series by analytic continuation in the representation parameters) are studied with regard to their analyticity properties in the representation parameters. The method is based on a natural one-one correspondence between the invariant forms and invariant separately homogeneous distributions (called kernels of the forms) in three complex two-dimensional non-zero vectors. There exists a family Ψ of kernels of forms with analytic dependence on the representation parameters (Ψ being unique up to a family of complex multiples dependent on the parameters). Also associated kernels obtained by differentiating Ψ in the parameters are studied.     

聚铜络合物[Cu(L)μ-1,3-N3]n(ClO4)n的密度泛函计算及磁性研究

基于广义梯度近似密度泛函和全势能线性缀加平面波方法,本文对聚铜络合物[Cu(L)μ-1,3-N3]n(ClO4)n(其中L=tridentate Schiff base为三齿席夫基)的态密度和磁矩进行了计算.磁矩计算结果表明:①该聚铜络合物晶体格子的总磁矩为1.00 μB;②中心铜原子(离子)具有最大的原子磁矩,为0.531 μB;③铜原子和它周围最邻近的氮原子的原子磁矩是该聚铜络合物晶体格子总磁矩的主要来源.通过对中心铜原子及其最邻近氮原子的自旋态密度图进行分析,得出了铜原子和它周围最邻近氮原子的磁性主要分别来源于它们的d轨道和p轨道,同时还发现了中心铜离子的d轨道与叠氮末端氮原子的p轨道之间存在杂化现象, 以及中心铜离子向叠氮末端氮原子的自旋退局域化现象.自旋退局域化效应通过叠氮这一旁道使相邻两中心铜离子发生铁磁性相互作用.     

Physical properties of SrSn(4) single crystals

We present detailed thermodynamic and transport measurements on single crystals of the recently discovered binary intermetallic superconductor, SrSn(4). We find this material to be a slightly anisotropic three-dimensional, strongly coupled, possibly multiband, superconductor. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of ≈?-?0.068?K?kbar(-1). Band structure calculations are consistent with experimental data on the Sommerfeld coefficient and upper superconducting critical field anisotropy, and suggest a complex, multi-sheet Fermi surface formed by four bands.     

Noether's theorem on a quasistochastic half-group of relativistic endomorphisms (QHGRE)

The quantum theory of free fields is used with Noether's theorem to discuss the polarization features of vector and spinor fields in the QHGRE (generalized de Broglie group) from the viewpoint of local isomorphism of the QHGRE for the product of two ordinary groups (the groups of x , t deformations and rotations). Estimates are made of the contributions to the polarization tensors for the corresponding fields. In both cases the spin tensors are induced by space and time generators of the generalized de Broglie group, and the rotational component of the QHGRE is responsible for the spin properties.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, Vol. 12, No. 1, pp. 32–36, January, 1969.We are indebted to D. D. Ivanenko for discussion of these topics.     

Magnetic properties of 1d systems with a subtle stacking of copper(II) ions

In the last two decades, many studies have been reported on infinite Id networks of magnetically interacting metal ions. Until now, closed-form expressions for the partition function and related properties were mainly derived for the S = f Ising chain model (Ising, 1925), the XY model (Kastura, 1962) or for the classical limit S –t co with arbitrary spin dimensionality (Fischer, 1964). Recently, experimental and theoretical studies have focused on new Id systems made of alternating spin and/or Lande factors (Georges, Curely and Drillon, 1985; Drillon et al., 1983). This has motivated our interest in the behavior of new systems of copper(II) ions in which the magnetic sites form an exotic stacking in one direction of the crystal. Then, the specific behavior is related to the competition between different interactions, as occurs in the systems reported here, namely A₃Cu₃(PO₄)₄, with A = Ca, Sr, Cu₃(PO₄)₂ and Cu₂O(SO₄).     

Magnetic properties of HoFe3(BO3)4

The magnetic properties of an antiferromagnet with trigonal symmetry, namely, HoFe₃(BO₃)₄, have been investigated theoretically. The calculations have been performed in the molecular field approximation and in the framework of the crystal field model for the rare-earth subsystem. Extensive experimental data on the magnetic properties of HoFe₃(BO₃)₄ have been interpreted and good agreement between theory and experiment has been achieved using the obtained theoretical dependences. The spontaneous spin-reorientation transition and the spin-reorientation transition induced by a magnetic field B ‖ a from the easy-axis to easy-plane state, as well as the spin-flop transition in a magnetic field B ‖ c, have been described. It has been shown that the spontaneous spin-reorientation transition is a magnetic analog of the Jahn-Teller effect. The temperature dependences of the initial magnetic susceptibility at temperatures ranging from 2 to 300 K, the nonlinear curves of magnetization for B ‖ c and B ⊥ c in a magnetic field up to 1.2 T (which indicate the occurrence of first-order phase transitions), and their evolution with variations in the temperature have been described, as well as the temperature and field dependences of the magnetization in a magnetic field up to 9 T. The parameters of the trigonal crystal field for the rare-earth ion Ho³⁺ and the parameters of the Fe-Fe and Ho-Fe exchange interactions have been determined in the course of interpretation of the experimental data.