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The availability of Channel State Information (CSI) and the effects of channel memory on the capacities and the achievable rates of free-space optical communication channels are investigated. For memoryless channels, the capacities and achievable rates are computed and compared for both uniform and ldquopositiverdquo Gaussian inputs subject to different assumptions on the CSI availability. For the strong turbulence regime, it is shown that the knowledge of CSI both at the transmitter and the receiver increases the achievable rates for low-to-moderate Signal-to-Noise Ratios (SNRs) in comparison to the cases for which the CSI is known only at the receiver. For the weak turbulence regime however, the availability of CSI at both ends of the link does not provide any improvement over a system with CSI known at the receiver alone, and we find that a simple channel inversion technique suffices. In addition, for low SNRs, Pulse Amplitude Modulation (PAM) with M ges 4 levels outperforms Gaussian-distributed inputs regardless of the knowledge of CSI at the transmitter. For high SNRs, a Gaussian distribution gives superior results, implying the need for new, more efficient positive signal constellations. For channels with memory and without knowledge of CSI, a change in the channel quasifrequency has negligible effects on the capacity for any turbulence regime. [ABSTRACT FROM PUBLISHER]

In this paper, coded multiple-input-multiple-output (MIMO) communication schemes for data transmission over the optical atmospheric turbulence channels are studied. Two strategies are proposed and compared. The first is based on repetition coding, and the second on space-time (ST) coding. Both approaches employ low-density parity-check (LDPC) codes. The LDPC codes are designed using the concept of pairwise balanced design (PBD), balanced incomplete block design (BIBBD), and block-circulant (array) codes. To improve the spectral efficiency, we employ a bit-interleaved (BI) LDPC-coded modulation based on the pulse amplitude modulation (PAM). A better bit error rate (BER) performance is achieved by the iteration of extrinsic information between a demapper and LDPC decoder. The simulations show that the LDPC-coded MIMO schemes can operate under a strong atmospheric turbulence and at the same time provide excellent coding gains compared with the transmission of uncoded data. To verify the efficiency of the proposed coding schemes, achievable information rates are computed when the turbulence is modeled by a gamma-gamma distribution. [ABSTRACT FROM PUBLISHER]

Magnetron sputtering, electron beam lithography and etching techniques allow us to fabricate Nb thin films on array of periodic nonsuperconducting nanometric triangles. These asymmetric pinning potentials induce a ratchet effect on the vortex lattice motion: injecting an ac current on the sample yields a dc voltage. This rectification effect does not depend on the ac frequency in the kHz range. The effect occurs for magnetic as well as nonmagnetic pinning centers. The rectification is enhanced at lower temperatures. [ABSTRACT FROM AUTHOR]

Carbon fibre reinforced polymers (CFRP) were introduced to the aerospace, automobile and civil engineering industries for their high strength and low weight. A key feature of CFRP is the polymer sizing - a coating applied to the surface of the carbon fibres to assist handling, improve the interfacial adhesion between fibre and polymer matrix and allow this matrix to wet-out the carbon fibres. In this paper, we introduce an alternative material to the polymer sizing, namely carbon nanotubes (CNTs) on the carbon fibres, which in addition imparts electrical and thermal functionality. High quality CNTs are grown at a high density as a result of a 35 nm aluminium interlayer which has previously been shown to minimise diffusion of the catalyst in the carbon fibre substrate. A CNT modified-CFRP show 300%, 450% and 230% improvements in the electrical conductivity on the 'surface', 'through-thickness' and 'volume' directions, respectively. Furthermore, through-thickness thermal conductivity calculations reveal a 107% increase. These improvements suggest the potential of a direct replacement for lightning strike solutions and to enhance the efficiency of current de-icing solutions employed in the aerospace industry. [ABSTRACT FROM AUTHOR]

Describes a case of allergic contact dermatitis from undecylenic acid in a commercial antifungal nail solution. Use of the compound as an ingredient in commercial products for the treatment of onychomycosis; Presence of undecylenic acid as a possible allergen ingredient.

By scanning near-field optical microscopy, we measured the localization of the electromagnetic field on an array of gold nanodisks illuminated in a transmission mode. We experimentally observed that the field is localized between the disks, with a pattern oriented along the incident polarization direction. We also observed that the electromagnetic field rapidly decays above the nanodisks, showing a strong vertical localization. The experimental results are in good agreement with numerical simulations performed by a finite difference time domain method. This study provides quantitative information about the local optical properties of closely-packed nanodisks that can be used for applications in biochemical sensors and nanolithography. [ABSTRACT FROM AUTHOR]

Reports on the epitaxial growth of multilayered TM/MgO/Fe heterostructures to study the dependence of the magnetic coupling between the two ferromagnetic electrodes on the insulating MgO barrier width and the lateral dimensions of the structures. Investigation of the crystal quality by reflection high-energy electron diffraction in situ at different growth stages of the heterostructures.

We demonstrated the effect of reactive ion beam etching (RIBE) process on the PL properties of CdTe/sapphire metal organic vapor phase epitaxy layers. At optimum conditions, the RIBE attack does not make significant morphological changes but it results in an increase of the concentration of acceptor impurities. This was revealed by an increase of the overall photoluminescence (PL) intensity and, simultaneously, a decrease of the PL decay time, more important on the low energy side of PL spectrum due to the recombination of carriers in acceptor pairs. [ABSTRACT FROM AUTHOR]

Presents information on a Raman study of InSb etched by reactive ion beam etching using a CH[sub4]/H[sub2]/N[sub2] plasma generated by electron cyclotron resonance. Experimental procedure; Results and discussion.

The article focuses on a study that evaluates the efficacy of transfusion service management for patients with sickle-cell disease (SCD). The study is conducted on 83 patients with SCD accompanied with high levels of various cytokines and through the use of questionnaires. The results of the study show the demographics of the patients and several issues related to SCD.

Presents a clinical microbiological case of penile ulcer and lung infiltrates in a leukemic patient. Cerebrospinal fluid puncture; Bone marrow biopsy; Intraveneous chemotherapy.

Discusses a clinical microbiological case of penile ulcer and lung infiltrates in a leukemic patient. Tolerance to therapy; Infection caused by Fusarium; Optimal therapy for disseminated fusariosis.

Background and aim: Vertebral involvement is a common occurrence in myelomas, but isolated involvement of the high cervical spine is exceptionally rare. This factor, together with the pediatric age of our patient, makes this case the first report of a plasmocytoma involving C1. Case report: A 14-year-old boy, without neurological involvement, presented with cervical pain and a palpable posterior neck mass. Cervical spine radiographs showed an osteolytic lesion at C1 compressing the cervical spinal canal and instability of the craniocervical junction. After a complete study, the patient was diagnosed with solitary plasmocytoma. A sequential treatment was instituted that consisted of radiotherapy after craniocervical junction stabilization with an halo-jacket, followed by occipitocervical stabilization with instrumented arthrodesis that was accompanied by resection of the residual C1 tumor and, finally, with consolidation of the oncological treatment with further radiotherapy. Conclusion: The treatment of choice for a cervical solitary plasmocytoma consists of a combination of chemotherapy, corticosteroids, radiotherapy, and immunotherapy, but the main neurosurgical problem is the craniocervical instability as occurred in other tumor of the cervical column. [ABSTRACT FROM AUTHOR]