Multi-user Detection of Nonlinearly Distorted MC-CDMA Symbols by Microstatistic Filtering

Multi-carrier code division multiple access is a powerful modulation technique that is being considered in many emerging broadband communication systems. In a downlink scenario orthogonal spreading sequences are used since they reduce multiple access interference compared to non-orthogonal. However, the nonlinear amplification of the transmitted signal destroys the orthogonality and, thus, reduces the system performance. In order to avoid performance degradation without requiring large back-offs in the transmitter amplifier, it becomes necessary to use multi-user detection techniques at the receiver side. Conventional multi-user detectors (MUD) are designed for linear environments and, as a result, might not exhibit enough performance improvement. In this paper a new MUD based on microstatistic filtering is proposed. The presented MUD uses piece-wise linear filtering in conjunction with threshold decomposition of the input signal, which introduces a nonlinear effect, to improve performance when a nonlinearity is present. Maximum performance improvement compared to conventional MUD is achieved for low spreading factors and user loads no greater than 50%.

Hyperbilirubinemia Maintained by Chronic Supplementation of Unconjugated Bilirubin Improves the Clinical Course of Experimental Autoimmune Arthritis

Rheumatoid arthritis (RA) is a chronic multisystem disease, therapy of which remains a challenge for basic research. The present work examined the effect of unconjugated bilirubin (UCB) administration in adjuvant-induced arthritis (AIA)—an experimental model, in which oxidative stress (OS), inflammation and inadequate immune response are often similar to RA. Male Lewis rats were randomized into groups: CO—control, AIA—untreated adjuvant-induced arthritis, AIA-BIL—adjuvant-induced arthritis administrated UCB, CO-BIL—control with administrated UCB. UCB was administered intraperitoneally 200 mg/kg of body weight daily from 14th day of the experiment, when clinical signs of the disease are fully manifested, to 28th day, the end of the experiment. AIA was induced by a single intradermal immunization at the base of the tail with suspension of Mycobacterium butyricum in incomplete Freund’s adjuvant. Clinical, hematologic, biochemical and histologic examinations were performed. UCB administration to animals with AIA lead to a significant decrease in hind paws volume, plasma levels of C-reactive protein (CRP) and ceruloplasmin, drop of leukocytes, lymphocytes, erythrocytes, hemoglobin and an increase in platelet count. UCB administration caused significantly lowered oxidative damage to DNA in arthritic animals, whereas in healthy controls it induced considerable oxidative damage to DNA. UCB administration also induced atrophy of the spleen and thymus in AIA and CO animals comparing to untreated animals. Histological signs of joint damage assessed by neutrophils infiltration and deposition of fibrin were significantly reduced by UCB administration. The effects of exogenously administered UCB to the animals with adjuvant-induced arthritis might be identified as therapeutic, in contrast to the effects of UCB administration in healthy animals rather classified as toxic.     

Optimal temperature control of a stirred adsorber

Two optimal control problems concerning a stirred continuous flow adsorber are studied, with temperature being the control variable: (i) minimize time at which a given amount is adsorbed, (ii) maximize time for which the outlet adsorbate concentration does not exceed a given level. An iterative gradient type method for the computation of the optimal control is proposed and the results obtained by its use in particular cases are discussed.     

Structural properties and Mössbauer spectroscopy of Finemet™ doped with Ge

Structural and magnetic properties of amorphous and crystalline alloys Fe_73.5Cu₁Nb₃B₉Si_13?xGe_{x=1;5;10;13.5} were studied by means of energy dispersive X-rays (SEM + EDX), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Mössbauer spectroscopy (MS), as-quenched (a-q) and after annealing (a). EDX show agreement between the nominal and the measured atomic contents for all alloys. DSC provided three phase transition temperatures of the materials, MS spectra reveal amorphous structure of as-quenched alloys and a mixture of amorphous and crystalline structures of annealed alloys. The XRD spectra of annealed alloys allow us to resolve three crystalline phases of Fe.     

Polypropylene fibers modified by polyvinyl alcohol and montmorillonite

This paper describes the preparation of modified polypropylene (PP) fibers. The modified PP composite was prepared by compounding PP in the presence of polyvinyl alcohol (PVA), PP grafted with maleic anhydrate (PPMAH), and montmorillonite (MMT). The resultant PP/PVA/PPMAH/MMT nanocomposite was easily spinnable and the obtained fibers were able to undergo orientation, using the drawing process at which the PP matrix is oriented in the direction of the fiber axis. The thermal properties, degradation, and dyeability of the fibers were studied. The presence of PVA in the fibers supports both the formation of β-modification of PP crystallinity and facilitates the dyeability of the modified PP fibers.     

Surface characteristics enhancement of MWCNT alumina composites using multi-pass WEDM process

Machining of ceramic composites in electrical discharge machining process is often associated with high roughness, unwanted surface and subsurface defects. This situation is generally not desired as it will reduce the life of the ceramic components fabricated in this machining process. Thus, an improvement towards enhancement of surface characteristics is desired. Multi-pass wire electrical discharge machining process can serve as an effective means of enhancing the surface characteristics in machining of ceramic composite. The current work utilizes the multi-pass concept to improve the surface properties of multi-walled carbon nanotubes filled alumina composites. A decreasing nature of surface roughness is observed with increase in the number of machining passes. A lesser appearance of unwanted debris and cracks is observed at the end of the final pass on the machined surface. The spalling effect is found to be more dominant at the initial first pass while melting and evaporation effect is more dominating in higher passes. Also, a better subsurface characteristic with lesser porous recast layer is observed with increase in the number of passes.     

Electrically conductive silicon carbide with the addition of TiNbC

The work deals with the preparation of dense SiC based ceramics with high electrical conductivity. SiC samples with different content of conductive TiNbSiCO based phase were hot pressed at 1820 °C for 1 h in Ar atmosphere under mechanical pressure of 30 MPa. The conductive phase is a mixture of 50 wt% TiNbC (molar ratio of Ti/NbC is 1:1.8) and 50 wt% eutectic composition of Y₂O₃SiO₂. Composite with 30% of conductive TiNbSiCO phase showed the highest electrical conductivity 28.4 S mm^?1, while the good mechanical properties of SiC matrix were preserved (fracture toughness K_IC = 5.4 MPa m^1/2 and Vickers hardness 17.8 GPa).The obtained results show that the developed additive system is suitable for the preparation of SiC-based composite with sufficient electrical conductivity for electric discharge machining.     

Cancer Microenvironment: What Can We Learn from the Stem Cell Niche

Epidermal stem cells (ESCs) are crucial for maintenance and self- renewal of skin epithelium and also for regular hair cycling. Their role in wound healing is also indispensable. ESCs reside in a defined outer root sheath portion of hair follicle—also known as the bulge region. ECS are also found between basal cells of the interfollicular epidermis or mucous membranes. The non-epithelial elements such as mesenchymal stem cell-like elements of dermis or surrounding adipose tissue can also contribute to this niche formation. Cancer stem cells (CSCs) participate in formation of common epithelial malignant diseases such as basal cell or squamous cell carcinoma. In this review article, we focus on the role of cancer microenvironment with emphasis on the effect of cancer-associated fibroblasts (CAFs). This model reflects various biological aspects of interaction between cancer cell and CAFs with multiple parallels to interaction of normal epidermal stem cells and their niche. The complexity of intercellular interactions within tumor stroma is depicted on example of malignant melanoma, where keratinocytes also contribute the microenvironmental landscape during early phase of tumor progression. Interactions seen in normal bulge region can therefore be an important source of information for proper understanding to melanoma. The therapeutic consequences of targeting of microenvironment in anticancer therapy and for improved wound healing are included to article.     

Microstructure evolution and tribological properties of TiB2/Ni–Ta cermets

Cermets containing TiB₂ and single or mixed metals were produced by conventional hot-pressing technique at 2100 °C for 1 h. Nickel, tantalum and their mixtures were used as alloying substances to enhance the density of TiB₂ composites. The influence of metal addition on the microstructure and tribological properties were investigated. The addition of Ta powder greatly refined the microstructure of sintered samples. Similarly, the mixture of Ni and Ta metals hindered the grain growth of TiB₂ particles during the hot-pressing while the samples were sintered up to 98% of theoretical density. The wear behaviour of the composites was assessed by ball on disk tests. The wear rate against alumina counterbody varied in the range of (5.9–21.2) × 10^?6 mm³/Nm. The friction coefficient was not affected significantly by the alloying substances and only slightly increased from 0.58 for pure TiB₂ to 0.67 for samples with Ta addition.