Spin-glass behaviour on random lattices

The ground-state phase diagram of an Ising spin-glass model on a random graph with an arbitrary fraction $w$ of ferromagnetic interactions is analysed in the presence of an external field. Using the replica method, and performing an analysis of stability of the replica-symmetric solution, it is shown that $w=1/2$, correponding to an unbiased spin glass, is a singular point in the phase diagram, separating a region with a spin-glass phase ($w<1/2$) from a region with spin-glass, ferromagnetic, mixed, and paramagnetic phases ($w>1/2$)

Vesico-bullous subacute cutaneous lupus erythematosus – An uncommon entity successfully treated with dapsone and hydroxychloroquine

Vesico-bullous subacute cutaneous lupus erythematosus is an uncommon and severe presentation. The authors report an exuberant case of vesico-bullous subacute cutaneous lupus erythematosus successfully treated with dapsone and hydroxychloroquin

Ashy Dermatosis - Treatment with Clofazimine

A Ashy dermatosis, ou erythema dyscromicum perstans, é uma dermatose rara de etiologia desconhecida. Os autores descrevem o caso de um homem de 46 anos saudável, com história de lesões cutâneas cinzentas assintomáticas no tronco com 1 ano de evolução. A constelação dos achados clínicos, histológicos e laboratoriais permitiu efectuar o diagnóstico de Ashy dermatosis. O doente iniciou tratamento com clofazimina oral, verificando-se resolução completa do quadro clínico e mantendo-se sem lesões cutâneas ao fim de 6 meses de vigilância. Estão descritas inúmeras opções terapêuticas para a Ashy dermatosis, no entanto nenhuma eficaz de forma consistente. O tratamento com clofazimina tem sido defendido devido ao seu efeito cosmético e a uma possível acção anti-inflamatória e imunomoduladora. Este caso documenta a eficácia terapêutica da clofazimina num doente com Ashy dermatosi

Dermatofibroma múltiplo agrupado congênito e dermatofibromas múltiplos eruptivos - apresentações singulares de uma entidade comum

Dermatofibroma is one of the most common entities seen in dermatology clinical practice. Several clinical subtypes have nevertheless been described, all of them of uncommon occurrence. The authors present two rare clinical variants of dermatofibromas: congenital multiple clustered dermatofibroma (the presented case is the 4th congenital case to be reported so far) and multiple eruptive dermatofibromas developing in the setting of a Sjögren's syndrome. Since the uncommon subtypes may not be clinically evident, dermatologists should familiarize themselves with their main features and we advise a high level of clinical suspicion in order to reach the correct diagnosis

Diluted antiferromagnet in a ferromagnetic enviroment

The question of robustness of a network under random ``attacks'' is treated in the framework of critical phenomena. The persistence of spontaneous magnetization of a ferromagnetic system to the random inclusion of antiferromagnetic interactions is investigated. After examing the static properties of the quenched version (in respect to the random antiferromagnetic interactions) of the model, the persistence of the magnetization is analysed also in the annealed approximation, and the difference in the results are discussed

High magnetic field induced charge density wave states in a quasi-one dimensional organic conductor

We have measured the high field magnetoresistence and magnetization of quasi-one- dimensional (Q1D) organic conductor (Per)2Pt(mnt)2 (where Per = perylene and mnt = maleonitriledithiolate), which has a charge density wave (CDW) ground state at zero magnetic field below 8 K. We find that the CDW ground state is suppressed with moderate magnetic fields of order 20 T, as expected from a mean field theory treatment of Pauli effects[W. Dieterich and P. Fulde, Z. Physik 265, 239 - 243 (1973)]. At higher magnetic fields, a new, density wave state with sub-phases is observed in the range 20 to 50 T, which is reminiscent of the cascade of field induced, quantized, spin density wave phases (FISDW) observed in the Bechgaard salts. The new density wave state, which we tenatively identify as a field induced charge density wave state (FICDW), is re-entrant to a low resistance state at even higher fields, of order 50 T and above. Unlike the FISDW ground state, the FICDW state is only weakly orbital, and appears for all directions of magnetic field. Our findings are substantiated by electrical resistivity, magnetization, thermoelectric, and Hall measurements. We discuss our results in light of theoretical work involving magnetic field dependent Q1D CDW ground states in high magnetic fields [D. Zanchi, A. Bjelis, and G. Montambaux, Phys. Rev. B 53, (1996)1240; A. Lebed, JETP Lett. 78,138(2003)].Comment: 16 pages, 5 figure