Beyond backscattering: Optical neuroimaging by BRAD

Optical coherence tomography (OCT) is a powerful technology for rapid volumetric imaging in biomedicine. The bright field imaging approach of conventional OCT systems is based on the detection of directly backscattered light, thereby waiving the wealth of information contained in the angular scattering distribution. Here we demonstrate that the unique features of few-mode fibers (FMF) enable simultaneous bright and dark field (BRAD) imaging for OCT. As backscattered light is picked up by the different modes of a FMF depending upon the angular scattering pattern, we obtain access to the directional scattering signatures of different tissues by decoupling illumination and detection paths. We exploit the distinct modal propagation properties of the FMF in concert with the long coherence lengths provided by modern wavelength-swept lasers to achieve multiplexing of the different modal responses into a combined OCT tomogram. We demonstrate BRAD sensing for distinguishing differently sized microparticles and showcase the performance of BRAD-OCT imaging with enhanced contrast for ex vivo tumorous tissue in glioblastoma and neuritic plaques in Alzheimer's disease

Analysis of the exactness of mean-field theory in long-range interacting systems

Relationships between general long-range interacting classical systems on a lattice and the corresponding mean-field models (infinitely long-range interacting models) are investigated. We study systems in arbitrary dimension d for periodic boundary conditions and focus on the free energy for fixed value of the total magnetization. As a result, it is shown that the equilibrium free energy of the long-range interacting systems are exactly the same as that of the corresponding mean-field models (exactness of the mean-field theory). Moreover, the mean-field metastable states can be also preserved in general long-range interacting systems. It is found that in the case that the magnetization is conserved, the mean-field theory does not give correct property in some parameter region.Comment: 4 pages, 5 figures; clarifications and discussion about boundary effects is added; the title is change

DAPSONE AS AN ALTERNATIVE THERAPY IN CHILDREN WITH FAMILIAL MEDITERRANEAN FEVER

Objective: Familial Mediterranan Fever is an hereditary autoinflammatory disease that presents with recurrent febrile attacks and poly serositis. Colchicine is the only known treatment in this diease. However, nearly 5-10% of patients are resistant to colchicines. There are many different modalities in colchicine resistant patients, biologic and immunosupressive drugs being the known ones. We studied the efficacy of Dapsone as an anti inflammatory drug in children with FMF who did not tolerate colchicine well. Methods: This is a case series study in 10 patients who had FMF on the base of Tel-Hashomer criteria and did not tolerate colchicine or did not respond to it well. Patients took 2mg/kg dapsone in single dose, during 6 months. Findings In four patients episodic attacks returned after 27 days, so the drug was discontinued. One patient refused to continue the study; in five patients dapsone was taken in average for 8 months and 6 days, at least for 6 months. These five patients had no episodes of attack during the following observation. Conclusion: Dapsone could control episodic attacks of FMF in 50% of cases. It might be considered as an alternative therapy in FMF cases not responding to colchicine

Dimensional crossover of the fundamental-measure functional for parallel hard cubes

We present a regularization of the recently proposed fundamental-measure functional for a mixture of parallel hard cubes. The regularized functional is shown to have right dimensional crossovers to any smaller dimension, thus allowing to use it to study highly inhomogeneous phases (such as the solid phase). Furthermore, it is shown how the functional of the slightly more general model of parallel hard parallelepipeds can be obtained using the zero-dimensional functional as a generating functional. The multicomponent version of the latter system is also given, and it is suggested how to reformulate it as a restricted-orientation model for liquid crystals. Finally, the method is further extended to build a functional for a mixture of parallel hard cylinders.Comment: 4 pages, no figures, uses revtex style files and multicol.sty, for a PostScript version see http://dulcinea.uc3m.es/users/cuesta/cross.p

Familial Mediterranean fever in northwest of Iran (Ardabil): The first global report from Iran

Familial Mediterranean fever (FMF), which is the prototype of the hereditary periodic fever syndromes, is common in the countries around the Mediterranean Sea. Considering its geographical position in the northwest of Iran, with its population of Turkish origin and its vicinity to the Mediterranean Sea, the incidence of FMF should be high in Ardabil. The goal of this study was to introduce FMF as a disease with significant outbreak in this area. Based on the Tel-Hashomer criteria, patients suffering from FMF were collected from private clinics together with the medical records of adult and pediatric rheumatology clinics. Of 112 total patients determined, 74 were studied. All of the patients were interviewed and completed a questionnaire. Familial Mediterranean fever was common among children under 18 years (76%), and it was more common in males than females (M/F 1.17). Abdominal pain was the most common complaint (74%) and abdominal pain and fever (95% and 84%, respectively) were the main clinical symptoms. The average duration of pain was 12-72 hours and the average recovery (attack-free period) was from one week to one month (63.5%). The majority of the patients had hospital admission for diagnostic work-up (85%) and some (32%) had undergone surgical operation erroneously; 92% of the patients had taken medications with incorrect diagnosis; and 20% had positive familial history of FMF. Fifty percent of the patients' parents were first-degree relatives and in 59.5% delay in diagnosis was more than three years. It seems that FMF is more common in the Northwest of Iran than previously thought, although physicians are not familiar with it. The common age for manifestation of this disease is under 18 years and its presentation after the age of 40 years is very rare

Equilibrium Properties of Quantum Spin Systems with Non-additive Long-Range Interactions

We study equilibrium states of quantum spin systems with non-additive long-range interactions by adopting an appropriate scaling of the interaction strength, i.e., the so called Kac prescription. In classical spin systems, it is known that the equilibrium free energy is obtained by minimizing the free energy functional over the coarse-grained magnetization. Here we show that it is also true for quantum spin systems. From this observation, it is found that when the canonical ensemble and the microcanonical ensemble are not equivalent in some parameter region, it is not necessarily justified to replace the actual long-range interaction by the infinite-range interaction (Curie-Weiss type interaction). On the other hand, in the parameter region where the two ensembles are equivalent, this replacement is always justified. We examine the Heisenberg XXZ model as an illustrative example, and discuss the relation to experiments.Comment: 13 pages, two columns; to appear in Phys. Rev.

All-fiber fused directional coupler for highly efficient spatial mode conversion

We model and demonstrate a simple mode selective all-fiber coupler capable of exciting specific higher order modes in two- and few-mode fibres with high efficiency and purity. The coupler is based on inter-modally phase-matching the propagation constants in each arm of the asymmetric fused coupler, formed by dissimilar fibres. At a specific coupler diameter, the launched fundamental LP01 mode is coupled into the higher order mode (LP11, LP21, LP02) in the other arm, over a broadband wavelength range around 1550 nm. Unlike other techniques, the demonstrated coupler is composed of a multimode fiber that is weakly fused with a phase matched conventional single mode telecom fiber (SMF-28). The beating between the supermodes at the coupler waist produces a periodic power transfer between the two arms, and therefore, by monitoring the beating while tapering, it is possible to obtain optimum selection for the desired mode. High coupling efficiencies in excess of 90% for all the higher order modes were recorded over 100 nm spectral range, while insertion losses remain as low as 0.5 dB. Coupling efficiency can be further enhanced by performing slow tapering at high temperature, in order to precisely control the coupler cross-section geometry