Magnetized Domain Walls in the Deconfined Sakai-Sugimoto Model at Finite Baryon Density

The magnetized pure pion gradient ($\mathcal{5}\phi$) phase in the deconfined Sakai-Sugimoto model is explored at zero and finite temperature. We found that the temperature has very small effects on the phase. The thermodynamical properties of the phase shows that the excitations behave like a scalar solitonic free particles. By comparing the free energy of the pion gradient phase to the competing multiquark-pion gradient (MQ-$\mathcal{5}\phi$) phase, it becomes apparent that the pure pion gradient is less thermodynamically preferred than the MQ-$\mathcal{5}\phi$ phase. However, in the parameter space where the baryonic chemical potential is smaller than the onset value of the multiquark, the dominating magnetized nuclear matter is the pion gradient phase.Comment: 20 pages, 9 figure

Crystalline Electric Field Effects in CeMIn5: Superconductivity and the Influence of Kondo Spin Fluctuations

We have measured the crystalline electric field (CEF) excitations of the CeMIn5 (M = Co, Rh, Ir) series of heavy fermion superconductors by means of inelastic neutron scattering. Fits to a CEF model reproduce the inelastic neutron scattering spectra and the high temperature magnetic susceptibility. The CEF parameters, energy level splittings, and wavefunctions are tabulated for each member of the CeMIn5 series and compared to each other as well as to the results of previous measurements. Our results indicate that the CEF level splitting in all three materials is similar, and can be thought of as being derived from the cubic parent compound CeIn3 in which an excited state quartet at ~12 meV is split into two doublets by the lower symmetry of the tetragonal environment of the CeMIn5 materials. In each case, the CEF excitations are observed as broad lines in the inelastic neutron scattering spectrum. We attribute this broadening to Kondo hybridization of the localized f moments with the conduction electrons. The evolution of the superconducting transition temperatures in the different members of CeMIn5 can then be understood as a direct consequence of the strength of this hybridization. Due to the importance of Kondo spin fluctuations in these materials, we also present calculations within the non-crossing approximation (NCA) to the Anderson impurity model including the effect of CEF level splitting for the inelastic neutron scattering spectra and the magnetic susceptibility.Comment: 30 pages, 6 figures, submitted to Phys. Rev.

Field dependent anisotropy change in a supramolecular Mn(II)-[3x3] grid

The magnetic anisotropy of a novel Mn(II)-[3x3] grid complex was investigated by means of high-field torque magnetometry. Torque vs. field curves at low temperatures demonstrate a ground state with S > 0 and exhibit a torque step due to a field induced level-crossing at B* \approx 7.5 T, accompanied by an abrupt change of magnetic anisotropy from easy-axis to hard-axis type. These observations are discussed in terms of a spin Hamiltonian formalism.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let

The Elastic Moduli of Thick Composites

Thick composites are in use in critical applications and are proposed for still others. It is important to measure the elastic moduli of thick composites for two reasons: (1) for design data on stiffness, and (2) for prediction of feasible wave paths for ultrasonic waves for NDE. Previously only relatively thin composites of relatively simple symmetries have been measured for their elastic moduli. Now, it is becoming necessary to measure thick composites of feasible engineering lay-ups. These generally provide the complexity of orthorhombic symmetry locally in a specimen combined with curvature in the gross structure. In this work, specimens cut from thick structures will be treated in the same way as crystals to measure the elastic moduli by means of ultrasonic wave velocities. Results on one structure will be presented. Difficulties will be analyzed

The Halo Beaming Model for Gamma-Ray Bursts

We consider a model for gamma-ray bursts (GRBs) from high-velocity neutron stars in the galactic halo. In this model, bursters are born in the galactic disk with large recoil velocities V_r, and GRBs are beamed to within emission cones of half-angle \phi centered on V_r. We describe scenarios for magnetically -channeled GRBs that have such beaming characteristics. We then make detailed comparisons of this halo beaming model (HBM) to BATSE and PVO data for GRB intensity & angular position distributions. Acceptable fits to observations of over 1000 bursts are obtained for \phi = 15 - 30 degrees and for a BATSE sampling depth ~ 180 kpc. Present data favor a truly isotropic (cosmological) model over the HBM, but not by a statistically compelling margin. Bursters born in nearby external galaxies, such as M31, are almost entirely undetectable in the HBM because of misdirected beaming. We analyze several refinements of the basic HBM: gamma-ray intensities that vary with angle from the beam axis; non-standard-candle GRB luminosity functions; and models including a subset of bursters that do not escape from the galaxy. We also discuss the energy budgets for the bursters, the origins of their recoils, and the physics of burst beaming and alignment. One possible physical model is based on the magnetar model of soft gamma repeaters (SGRs). Empirical bounds on the rate of formation and peculiar velocities of SGRs imply that there exist ~ 10^4 to ~ 10^7 aged SGRs in the galactic halo within a distance of 100 kpc. The HBM gives an acceptable fit to observations only if it satisfies certain conditions (e.g. \phi ~ 20 deg) which are possible, but for which there exist no clear & compelling theoretical justifications. The cosmological burster hypothesis is more generic and thus more attractive in this sense. (Abbreviated Abstract).Comment: ApJ accepted, 9 figures, AASTE

Configurational Entropy and its Crisis in Metastable States: Ideal Glass Transition in a Dimer Model as a Paragidm of a Molecular Glass

We discuss the need for discretization to evaluate the configurational entropy in a general model. We also discuss the prescription using restricted partition function formalism to study the stationary limit of metastable states. We introduce a lattice model of dimers as a paradigm of molecular fluid and study metastability in it to investigate the root cause of glassy behavior. We demonstrate the existence of the entropy crisis in metastable states, from which it follows that the entropy crisis is the root cause underlying the ideal glass transition in systems with particles of all sizes. The orientational interactions in the model control the nature of the liquid-liquid transition observed in recent years in molecular glasses.Comment: 36 pages, 9 figure

Recent Developments of NEMO: Detection of Solar Eruptions Characteristics

The recent developments in space instrumentation for solar observations and telemetry have caused the necessity of advanced pattern recognition tools for the different classes of solar events. The Extreme ultraviolet Imaging Telescope (EIT) of solar corona on-board SOHO spacecraft has uncovered a new class of eruptive events which are often identified as signatures of Coronal Mass Ejection (CME) initiations on solar disk. It is evident that a crucial task is the development of an automatic detection tool of CMEs precursors. The Novel EIT wave Machine Observing (NEMO) (http://sidc.be/nemo) code is an operational tool that detects automatically solar eruptions using EIT image sequences. NEMO applies techniques based on the general statistical properties of the underlying physical mechanisms of eruptive events on the solar disc. In this work, the most recent updates of NEMO code - that have resulted to the increase of the recognition efficiency of solar eruptions linked to CMEs - are presented. These updates provide calculations of the surface of the dimming region, implement novel clustering technique for the dimmings and set new criteria to flag the eruptive dimmings based on their complex characteristics. The efficiency of NEMO has been increased significantly resulting to the extraction of dimmings observed near the solar limb and to the detection of small-scale events as well. As a consequence, the detection efficiency of CMEs precursors and the forecasts of CMEs have been drastically improved. Furthermore, the catalogues of solar eruptive events that can be constructed by NEMO may include larger number of physical parameters associated to the dimming regions.Comment: 12 Pages, 5 figures, submitted to Solar Physic

Estimativa da erosividade nas bacias hidrográficas dos rios Guapi-Macacu e Caceribu.

As perdas de solos ocasionadas por eventos de chuvas não dependem somente da resistência que o solo oferece ao impacto das gotas, mas também da energia cinética da chuva e da intensidade e duração. A influência desses fatores na capacidade da chuva em causar erosão é estimada através de índices de erosividade, sendo mais utilizados dois índices na literatura: EI30 e KE > 25. O presente trabalho teve como objetivo estimar os índices de erosividade com base nos dados pluviométricos de 19 estações e mostrar as distribuições espaciais dos mesmos nas bacias hidrográficas dos rios Guapi- Macacu e Caceribu. Os resultados mostraram que os dois índices apresentaram padrão similar em termos de valores relativos e de distribuição na área de estudo. Os índices apresentaram maiores valores mensais no período de novembro a março que corresponde ao verão, quando é característico ocorrerem chuvas de maiores intensidades, devido ao aumento da temperatura e das movimentações de massas de ar. Ao contrário, os menores valores foram observados nos meses de junho a agosto, período no qual ocorrem chuvas com menores intensidades.bitstream/item/83413/1/BPD-205-Estimativa-erosividade.pd