Cognitive-radio systems for spectrum, location, and environmental awareness

In order to perform reliable communications, a system needs to have sufficient information about its operational environment, such as spectral resources and propagation characteristics. Cognitive-radio technology has capabilities for acquiring accurate spectrum, location, and environmental information, due to its unique features such as spectrum, location, and environmental awareness. The goal of this paper is to give a comprehensive review of the implementation of these concepts. In addition, the dynamic nature of cognitive-radio systems - including dynamic spectrum utilization, transmission, the propagation channel, and reception - is discussed, along with performance limits, challenges, mitigation techniques, and open issues. The capabilities of cognitive-radio systems for accurate characterization of operational environments are emphasized. These are crucial for efficient communications, localization, and radar systems. © 2010 IEEE

Structural and energetic properties of nickel clusters: 2≤N≤1502 \le N \le 150

The four most stable structures of Ni$_N$ clusters with $N$ from 2 to 150 have been determined using a combination of the embedded-atom method in the version of Daw, Baskes and Foiles, the {\it variable metric/quasi-Newton} method, and our own {\it Aufbau/Abbau} method. A systematic study of energetics, structure, growth, and stability of also larger clusters has been carried through without more or less severe assumptions on the initial geometries in the structure optimization, on the symmetry, or on bond lengths. It is shown that cluster growth is predominantly icosahedral with $islands$ of {\it fcc}, {\it tetrahedral} and {\it decahedral} growth. For the first time in unbiased computations it is found that Ni$_{147}$ is the multilayer (third Mackay) icosahedron. Further, we point to an enhanced ability of {\it fcc} clusters to compete with the icosahedral and decahedral structures in the vicinity of N=79. In addition, it is shown that conversion from the {\it hcp}/anti-Mackay kind of icosahedral growth to the {\it fcc}/Mackay one occurs within a transition layer including several cluster sizes. Moreover, we present and apply different analytical tools in studying structural and energetic properties of such a large class of clusters. These include means for identifying the overall shape, the occurrence of atomic shells, the similarity of the clusters with, e.g., fragments of the {\it fcc} crystal or of a large icosahedral cluster, and a way of analysing whether the $N$-atom cluster can be considered constructed from the $(N-1)$-atom one by adding an extra atom. In addition, we compare in detail with results from chemical-probe experiment. Maybe the most central result is that first for clusters with $N$ above 80 general trends can be identified.Comment: 37 pages, 11 figure

Adaptation of two types of processing gains for UWB impulse radio wireless sensor networks

Ultrawideband impulse radio systems offer two kinds of processing gains that can be adapted based on the interference level in the system so that quality of service requirements are fulfilled. An adaptive assignment scheme for two types of multiple-access parameters in cluster-based wireless sensor networks is investigated. A mathematical framework is developed for asynchronous communications using a Gaussian approximation method to model the multiple-access interference in two cases: one with fixed frame duration, where the goal is to increase the average throughput, and the other with fixed symbol duration, where the goal is to increase the network lifetime. Extension of the analysis to multipath channels is carried out, and the validity of the Gaussian approximation is investigated using the Kullback-Leibler distance

Architecture and Gender : Lessons from Building Archaeology in Africa

Peer reviewe

Sickle cell anemia patient with sarcoidosis-associated inguinal lymph node and lung infiltration

PubMedID: 16035582Sarcoidosis is a chronic, systemic inflammatory disease of unknown etiology, characterized by noncaseating granulomatous infiltration of any organ. Sickle cell anemia (SCA) is the homozygoid form of sickle cell disease (SCD), which includes a group of genetic disorders characterized by production of an abnormal hemoglobin S (HbS). There are a few case reports with coexistence of sarcoidosis and SCA. We reported a 47-year-old female with SCA and sarcoidosis

An estimation of the effect of 100% Compliance with Diabetes Treatment: Can we reduce cost of illness with higher compliance rates?

Introduction: The current study was designed to estimate the direct cost of noncompliance of diabetes patients to the US health system. Understanding these expenses can inform screening and education budget policy regarding expenditure levels that can be calculated to be cost-beneficial. Materials and Method: The study was conducted in three parts. First, a computer search of National Institutes of Health websites and professional society websites for organizations with members that treat diabetes, and a PubMed search were performed to obtain the numbers required for calculations. Second, formulas were developed to estimate the risk of non-compliance and undiagnosed diabetes. Third, risk calculations were performed using the information obtained in part one and the formulas developed in part two. Results: Direct risk reduction for diabetes-related kidney disease, stroke, heart disease, and amputation were estimated for 100% compliance with diabetes treatment. Risk, case and yearly cost reduction calculated for a 100% compliance with diabetes treatment were 13.6%, 0.9 million and US$ 9.3 billion, respectively. Conclusion: Society, insurers, policy makers and other stakeholders could invest up to these amounts in screening, education and prevention efforts in an effort to reduce these costly and traumatic sequelae of noncompliant diabetes patients

Mobility enhancements for heterogeneous networks through interference coordination

In this paper, mobility performance of heterogeneous networks (HetNets) is studied in terms of handover failure and ping-pong rates of user equipments (UEs) in co-channel deployment of macro- and pico- cells. Simulation assumptions and parameters of a related study item in 3GPP are used to investigate the impact of various handover-related parameters on mobility performance. Then, a mobility-based inter-cell interference coordination (MB-ICIC) technique is proposed, in which picocells configure almost blank subframes in order to protect high-mobility macrocell UEs. Through extensive simulations, MB-ICIC is shown to provide handover performance gains for both low-mobility and high-mobility UEs. In addition, we show through simulations that performance of the mobility state estimation technique in 3GPP standard specifications is good enough for supporting the proposed MB-ICIC in HetNets. © 2012 IEEE

Serine/threonine protein phosphatases and regulation of K-Cl cotransport in human erythrocytes

PubMedID: 10564085Activation of K-Cl cotransport is associated with activation of membrane-bound serine/threonine protein phosphatases (S/T-PPases). We characterize red blood cell S/T-PPases and K-Cl cotransport activity regarding protein phosphatase inhibitors and response to changes in ionic strength and cell size. Protein phosphatase type 1 (PP1) activity is highly sensitive to calyculin A (CalA) but not to okadaic acid (OA). PP2A activity is highly sensitive to CalA and OA. CalA completely inhibits K-Cl cotransport activity, whereas OA partially inhibits K-Cl cotransport. Membrane PP1 and membrane PP2A activities are elevated in cells suspended in hypotonic solutions, where K-Cl cotransport is elevated. Increases in membrane PP1 activity (62 ± 10% per 100 meq/l) result from decreases in intracellular ionic strength and correlate with increases in K-Cl cotransport activity (54 ± 10% per 100 meq/l). Increases in membrane PP2A activity (270 ± 77% per 100 mosM) result from volume increases and also correlate with increases in K-Cl cotransport activity (420 ± 47% per 100 mosM). The characteristics of membrane-associated PP1 and PP2A are consistent with a role for both phosphatases in K-Cl cotransport activation in human erythrocytes