The schistosome granuloma: characterization of lymphocyte migration, activation, and cytokine production

Granuloma formation and its regulation are dependent on lymphocytes. Therefore, we compared the characteristics of lymphocytes derived from the spleens and granulomas of Schistosoma mansoni-infected mice during the course of their disease. We examined lymphocyte cell cycle kinetics, migration, expression of activation Ags (CD69 and IL-2R), cytokine production (IL-2, IL-4, IFN-gamma), and apoptosis. Lymphocytes in the G2/M phase of the cell cycle and high levels of lymphocyte intracellular IL-2 were found in the spleen but not in the granuloma. Cell trafficking experiments showed Ag-specific recruitment of schistosomal egg Ag (SEA)-reactive lymphoblasts into granulomas in vivo, as well as recruitment to, residence within, and egress from granulomas in vitro. Granuloma-derived lymphocytes were more highly activated than splenic lymphocytes based on higher levels of CD69 and IL-2R expression. While the granuloma microenvironment was rich in Th2 cytokines, during peak granuloma formation, the lymphocytes per se from the spleen and granuloma did not exhibit a dominant Th1 or Th2 cytokine profile, producing low but similar levels of IL-4 and IFN-gamma. The discrepancy between high IL-2R expression and low levels of IL-2 protein production by granuloma lymphocytes was associated with increased apoptosis in the granuloma compared with the spleen. These findings support the hypothesis that granulomas may play a role in the regulation of systemic pathology in schistosomiasis by adversely affecting the survival of SEA-reactive, immunopathogenic T lymphocytes.     

Transmit diversity via oscillating-beam-pattern adaptive antennas: an evaluation using geometric-based stochastic circular-scenario channel modeling

Applying carefully-selected time-varying phases (delays) to array elements of an adaptive antenna, the beam pattern oscillates in a controlled manner. This creates a time varying channel with a controllable coherence time. With an adaptive antenna at the base station (BS) and a single omnidirectional antenna at the mobile, the controllable coherence time is used by the mobile to exploit time diversity and enhance performance. In this work, assuming an oscillating-beam-pattern antenna array at the BS, the channel is properly modeled and the coherence time is evaluated. A so-called geometric-based stochastic channel model is presented, assuming a circular coverage area, and the channel is simulated in an urban environment. We demonstrate the relationship between coherence time and the antenna array control parameters and show that seven-fold-diversity can be created via small beam pattern oscillation.     

Power-azimuth-spectrum modeling for antenna array systems: a geometric-based approach

In this paper, we propose the geometric-based channel modeling technique as a means to establish innovative models for the power azimuth spectrum (PAS). When the geometry of the environment is matched to that of the TSUNAMI II project, the PAS model we achieve (referred to as the secant-square model) may be compared to the Laplacian model introduced previously in the literature. In this case, we observe that our model is a better fit to the TSUNAMI II project measurements. Specifically, our model has a simple mathematical representation and demonstrates a lower squared error when compared to measurement data, and considers effects ignored in the earlier modeling (e.g., the nonzero values at the edge of the PAS). Moreover, the proposed geometric-based channel modeling technique extends to other environments with different topologies, whereas the earlier Laplacian model is limited to the TSUNAMI II measurement environment.     

Lipids ofEchinococcus granulosus protoscolices

The fatty acid composition of the triglyceride and the total phospholipid fractions of ovine liverEchinococcus granulosus protoscolices was determined by gas chromatography and compared with that of the healthy and Echinococcus infected livers. The chain length of the major saturated fatty acids identified in both the host tissues and the parasite ranged from 12–22 carbons. Oleic and linoleic acids were the only detectable unsaturated fatty acids identified in protoscolices and the liver samples. Comparison of the amounts of the fatty acids from the three different sources mentioned above by analysis of variance and the contrast method of Scheffe, revealed a significant decrease in the level of oleic acid in triglyceride fraction of the infected livers compared with normals. Thinlayer chromatography of the polar lipid fraction of the protoscolices resulted in tentative identification of lysolecithin, sphingomyelin, lecithin, phosphatidyl inositol, sulfatides, cerebrosides, cephalins and cholesterol.     

Introduction to Special Issue on New Paradigms in Intelligent Spectrum Management

International Journal of Wireless Information Networks -     

Achieving high-capacity wireless by merging multicarrier CDMA systems and oscillating-beam smart antenna arrays

We establish the network capacity (measured in terms of number of users) of a wireless system merging multicarrier code-division multiple-access (MC-CDMA) and smart antennas with oscillating-beam patterns. The MC-CDMA component supports high performance (in a probability-of-error sense) via frequency diversity and high network capacity via code division. The smart antenna with oscillating-beam pattern further enhances performance via transmit diversity (in the form of an induced time diversity) and further enhances network capacity via spatial division. The proposed merger has been shown to achieve a very high performance by exploiting a two-dimensional time-frequency diversity. We demonstrate the impressive network capacity gains achieved by this merger.     

Electromagnetic Spectrum Contribution in Astronomy,Health, Atmospheric,Geology and Environment Applications

International Journal of Wireless Information Networks - Spectrum technologies are shaping the way our world connects, communicates, and functions. Radio nodes connect through a nearly ubiquitous...     

High Resolution Cognitive Radio-Based Concatenated Spectrum Time-of-Arrival Estimation

This paper proposes high-precision, time-of-arrival (TOA) estimation by concatenating non-contiguous and non-equal white spaces in the spectrum. White spaces are identified and allocated by the capabilities of cognitive radios (CR). A simple radio system that enables sequential concatenation of non-contiguous bands is introduced. The paper aims to design signal-processing techniques for the proposed radio that maintain a TOA performance comparable to that of utilizing a bandwidth equivalent to the addition of all white spaces. This work also investigates two potential high resolutions, TOA estimation architectures that are applicable to CR-based systems. The first approach estimates TOA over each sub-band and then optimally fuses the estimated TOAs. In the second technique, channels estimated over sub-bands are concatenated and a TOA-estimation method is applied to the whole available spectrum. The Cramer?CRao bound (CRB) of the TOA estimation for both approaches is computed. Minimum mean square estimation (MMSE) algorithm is applied to evaluate the performance of the proposed system. Simulations are concluded to study the performance in terms of the variance of error. Moreover, the complexity of the proposed concatenation method is evaluated.     

Merging multicarrier CDMA and oscillating-beam smart antenna arrays: exploiting directionality, transmit diversity, and frequency diversity

In this paper, a novel merger of multicarrier code-division multiple access (MC-CDMA) and smart antenna arrays is introduced. Here, a group of Q carriers in the MC-CDMA system is applied to its own M-element smart antenna array at the base station (BS). The smart antennas are located in close proximity to one another. We generate a transmit diversity gain at the receiver by carefully moving (oscillating) the antenna array's pattern. The pattern oscillation is achieved by applying appropriate time-varying phases to array elements of each smart antenna. The beam pattern oscillation ensures a mainlobe at the position of the intended user and small oscillations in the beam pattern. This beam pattern oscillation leads to a time-varying channel with a controllable coherence time; hence, a transmit diversity benefit, in the form of a time diversity benefit, is available at the receiver. Employing MC-CDMA with the proposed smart antenna at the BS, we achieve: 1) directionality which creates high network capacity via space-division multiple access; 2) a transmit diversity gain which supports high performance at the receiver in the mobile unit; and 3) increased capacity and performance via MC-CDMA's ability to support both CDMA and frequency diversity benefits, respectively.     

Oscillating-beam smart antenna arrays and multicarrier systems: achieving transmit diversity, frequency diversity, and directionality

We introduce a novel merger of smart antenna arrays and multicarrier code-division multiple-access (MC-CDMA) systems. Here, each group of Q carriers in the MC-CDMA system is applied to its own M-element smart antenna at the base station (BS). The smart antennas are separated by a distance that ensures that signals generated by each smart antenna are independent. Applying proper time-varying phases to array elements of each smart antenna array, the beam pattern is carefully controlled to generate a mainlobe at the position of the intended user and small oscillations in the beam pattern. This beam-pattern oscillation creates a time-varying channel with a controllable coherence time and a time diversity benefit at the receiver. Employing MC-CDMA with the proposed antenna array at the BS, we achieve: 1) directionality, which supports space-division multiple access (SDMA); 2) a time diversity gain; 3) increased capacity and performance via MC-CDMA's ability to support both CDMA and frequency diversity benefits. Hence, merging MC-CDMA and BS antenna arrays in an innovative fashion, we achieve high performance at the mobile via joint frequency-time diversity, and high network capacity via joint space-code division multiple access.