Quantum phase transitions in skewed ladder systems.

In this brief review, we introduce a new spin ladder system called skewed spin ladders and discuss the exotic quantum phases of this system. The spin ladders studied are the 5/7, 3/4 and 3/5 systems corresponding to alternately fused 5 and 7 membered rings; 3 and 4 membered rings; and 3 and 5 membered rings. These ladders show completely different behaviour as the Hamiltonian model parameter is changed.

Numerical study of incommensurate and decoupled phases of spin-1/2 chains with isotropic exchange J1, J2 between first and second neighbors.

The spin-1/2 chain with isotropic exchange J1, J2 > 0 between first and second neighbors is frustrated for either sign of J1 and has a singlet ground state (GS) for J1/J2 ⩾ -4. Its rich quantum phase diagram supports gapless, gapped, commensurate (C), incommensurate (IC) and other phases. Critical points J1/J2 are evaluated using exact diagonalization and density matrix renormalization group calculations.

Dielectric properties of crystalline organic molecular films in the limit of zero overlap.

We present the calculation of the static dielectric susceptibility tensor and dipole field sums in thin molecular films in the well-defined limit of zero intermolecular overlap. Microelectrostatic and charge redistribution approaches are applied to study the evolution of dielectric properties from one to a few molecular layers in films of different conjugated molecules with organic electronics applications. Because of the conditional convergence of dipolar interactions, dipole fields depend on the shape of the sample and different values are found in the middle layer of a thick film and in the bulk.

Electronic Polarization in Organic Crystals: A Comparative Study of Induced Dipoles and Intramolecular Charge Redistribution Schemes.

Static dielectric tensors and charge carrier polarization energies of a wide set of organic molecules of interest for organic electronics application are calculated with two different approaches: intramolecular charge redistribution and induced dipoles (microlectrostatics). Our results show that, while charge redistribution is better suited for calculating the collective response to an external field, both methods reliably describe the effect of a localized charge carrier in the crystal. Advantages and limitations inherent to the different methods are discussed, also in relation to previous theoretical studies.

Level crossing, spin structure factor and quantum phases of the frustrated spin-1/2 chain with first and second neighbor exchange.

The spin-1/2 chain with isotropic Heisenberg exchange J1, J2  >  0 between first and second neighbors is frustrated for either sign of J1. Its quantum phase diagram has critical points at fixed J1/J2 between gapless phases with nondegenerate ground state (GS) and quasi-long-range order (QLRO) and gapped phases with doubly degenerate GS and spin correlation functions of finite range. In finite chains, exact diagonalization (ED) estimates critical points as level crossing of excited states.

Anti glutamate-decarboxylase antibodies: a liaison between localisation related epilepsy, stiff-person syndrome and type-1 diabetes mellitus.

We present two patients with partial epilepsy, type-1 diabetes and stiff person syndrome associated with high serum auto-antibody levels to glutamate-decarboxylase (anti-GAD). Both patients were or have suffered from additional autoimmune conditions. The presence of stiff person syndrome and elevated anti-GAD levels have to make clinicians look for additional autoimmune conditions including type-1 diabetes.

LADA type diabetes, celiac diasease, cerebellar ataxia and stiff person syndrome. A rare association of autoimmune disorders.

Celiac disease--in its typical form--is a chronic immune-mediated enteropathy with typical clinical symptoms that develops against gliadin content of cereal grains, and is often associated with other autoimmune diseases. In cases of atypical manifestation classic symptoms may be absent or mild, and extra-intestinal symptoms or associated syndromes dominate clinical picture. The authors present a longitudinal follow-up of such a case.

Model for triplet state engineering in organic light emitting diodes.

Engineering the position of the lowest triplet state (T1) relative to the first excited singlet state (S1) is of great importance in improving the efficiencies of organic light emitting diodes and organic photovoltaic cells. We have carried out model exact calculations of substituted polyene chains to understand the factors that affect the energy gap between S1 and T1. The factors studied are backbone dimerisation, different donor-acceptor substitutions, and twisted geometry.

[De Quervain thyroiditis. Corner points of the diagnosis].

Inflammatory disorders of the thyroid gland are divided into three groups according to their duration (acute, subacute and chronic). De Quervain's thyroiditis (also termed giant cell or granulomatous thyroiditis) is a subacute inflammation of the thyroid, which accounts for 5% of thyroid disorders. The etiology is unknown, it usually appears two weeks after an upper viral respiratory infection.

[Wernicke encephalopathy accompanying linitis plastica].

Wernicke encephalopathy (or Wernicke-Korsakoff encephalopathy) is a rarely diagnosed neurological disorder, which is caused by vitamin B1 deficiency. In the classical form it is characterized by a typical triad (confusion, oculomotor disturbance and ataxia), however, in the majority of the cases only confusion is present. It can be frequently observed in subjects with chronic alcohol consumption, but it may accompany different pathological states of which end stage malignant diseases are the most importants, where confusion may have different backgrounds.

[Comparison of the effectiveness of two internationally recommended screening methods for the diagnosis of gestational diabetes].

Introduction: Early diagnosis and adequate care of gestational diabetes is of great importance for both the mother and her fetus. Although several national and international guidelines are known on the methodology for screening gestational diabetes, a not negligible part of the cases remain unrecognized when applying even the most widely used criteria recommended by the World Health Organization (1st recommendation). A connection has been found between the maternal blood glucose values and the prevalence of still-birth, preeclampsia and large for gestational age neonates in several studies, from which the Hyperglycaemia and Adverse Pregnancy Outcomes study has come into prominence.

Spin-flop and antiferromagnetic phases of the ferromagnetic half-twist ladder compounds Ba3Cu3In4O12 and Ba3Cu3Sc4O12.

The title compounds have dominant ferromagnetic exchange interactions within one-dimensional (1D) half-twist ladders of s = 1/2 Cu(2+) ions and antiferromagnetic (AFM) interactions between ladders, leading to ordered 3D phases at temperatures below 20 K. Here we show that a microscopic 1D model of the paramagnetic (PM) phase combined with a phenomenological model based on sublattice magnetization describes the observed temperature and field dependent magnetism. The model identifies AFM, spin-flop and PM phases whose boundaries have sharp features in the experimental magnetization M(T,H) and specific heat C(P)(T,H).

[A case of glucose-sensitive insulinoma accompanied by slightly elevated serum insulin levels and persisting convulsions after the surgically removed neuroendocrine tumor].

Insul(in)oma is a usually solitary or, in some cases, multifocal tumor of pancreatic beta cells. It may be a component of multiple endocrine neoplasia type 1. or von Hippel-Lindau syndrome.

Essential state model for two-photon absorption spectra of polymethine dyes.

A four essential-state model is proposed for a detailed description of optical spectra of a family of anionic polymethine dyes. Extensive spectroscopic data from the literature are quantitatively described within a model that accounts for non-adiabatic electron-vibration coupling and for polar solvation.

Quantum spin liquid in frustrated one-dimensional LiCuSbO4.

A quantum magnet, LiCuSbO4, with chains of edge-sharing spin-1/2 CuO6 octahedra is reported. While short-range order is observed for T<10  K, no zero-field phase transition or spin freezing occurs down to 100 mK. Specific heat indicates a distinct high-field phase near the 12 T saturation field.

Dominant ferromagnetism in the spin-1/2 half-twist ladder 334 compounds, Ba3Cu3In4O12 and Ba3Cu3Sc4O12.

The magnetic properties of polycrystalline samples of Ba(3)Cu(3)In(4)O(12) (In-334) and Ba(3)Cu(3)Sc(4)O(12) (Sc-334) are reported. Both 334 phases have a structure derived from perovskite, with CuO(4) squares interconnected to form half-twist ladders along the c-axis. The Cu-O-Cu angles, ~90°, and the positive Weiss temperatures indicate the presence of significant ferromagnetic (FM) interactions along the Cu ladders.

Magnetic susceptibility of alkali-tetracyanoquinodimethane salts and extended Hubbard models with bond order and charge density wave phases.

The molar spin susceptibilities χ(T) of Na-tetracyanoquinodimethane (TCNQ), K-TCNQ, and Rb-TCNQ(II) are fit quantitatively to 450 K in terms of half-filled bands of three one-dimensional Hubbard models with extended interactions using exact results for finite systems. All three models have bond order wave (BOW) and charge density wave (CDW) phases with boundary V = V(c)(U) for nearest-neighbor interaction V and on-site repulsion U. At high T, all three salts have regular stacks of TCNQ(-) anion radicals.

[Verrucous carcinoma of the anal margin. The importance of adequate biopsy technique].

Buschke-Löwenstein tumor (verrucous carcinoma, giant condylomata) of the anal margin is a locally invasive, destructively growing carcinoma that does not metastasize. The lesions are rare despite the increased incidence of anal condylomata and anal carcinomas. Authors report a case of a 63-year-old woman suffering from verrucous carcinoma (Buschke-Löwenstein tumor) of the anal margin.

[Multiple hepatic abscesses due to actinomycosis: difficulties of diagnosis].

Authors present the case of a 65 year-old man without any remarkable previous illness, hospitalized because of having prolonged fever caused probably by an infection due to a tick bite. Tularaemia and bartonellosis based on serological results as well as neoplasm of the sigma with multiple metastases to the liver raised by ultrasonography and abdominal CT could be excluded with detailed investigations. Multiple abscesses of the liver were diagnosed, followed by a percutaneuos ultrasonography directed aspiration of one of the abscesses which resulted in 150 ml buffy pus.

Neutral and charged excited states in polar organic films: origin of unusual electroluminescence in tri-p-tolylamine-based hole conductors.

The photoluminescence (PL) and electroluminescence (EL) of thin films of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) are remarkably different. Similar PL and EL are instead observed in films of the closely related donors tri- p-tolylamine (TTA) and N, N'-diphenyl- N, N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD). Such films show a wide range of hole transport that depends on the morphology and on external parameters such as temperature and electric field.

Anomalous dispersion of optical phonons at the neutral-ionic transition: evidence from diffuse x-ray scattering.

Diffuse x-ray data for mixed-stack organic charge-transfer crystals approaching the neutral-ionic phase transition can be quantitatively explained as due to the softening of the optical phonon branch. The interpretation is fully consistent with vibrational spectra, and underlines the importance of electron-phonon coupling in low-dimensional systems with delocalized electrons.

Peierls transitions in ionic organic charge-transfer crystals with spin and charge degrees of freedom.

The quasi-one-dimensional electronic structure of organic charge-transfer (CT) salts rationalizes Peierls transitions in mixed or segregated stacks of pi-electron donors (D) and acceptors (A). A microscopic Peierls-Hubbard model, HCT, is presented for CT salts with mixed stacks (Drho+Arho-)n and ionicity rho > 0.7.

Yield of singlet excitons in organic light-emitting devices: a double modulation photoluminescence-detected magnetic resonance study.

Double-modulation (DM) photoluminescence (PL) detected magnetic resonance (PLDMR) measurements on poly(2-methoxy-5-(2(')-ethyl)-hexoxy-1,4-phenylene vinylene) are described. In these measurements, the laser excitation power is modulated at 1 View Article and Find Full Text PDF

Disorder in organic charge-transfer single crystals: dipolar disorder in ClMePD-DMeDCNQI.

The unusual electronic, vibrational, and structural properties of the title compound are associated with the polar donor D=2-chloro-5-methyl-p-phenylenediamine, which is twofold disordered in single crystals. Its 3 D dipole generates random site energies with standard deviation sigma=0.35 eV that significantly alter the standard description of charge-transfer (CT) salts with nonpolar donors and acceptors.