1,117 research outputs found
Level Crossing Rate of Macrodiversity System in the Presence of Multipath Fading and Shadowing
Macrodiversity system including macrodiversity SC receiver and two microdiversity SC receivers is considered in this paper. Received signal experiences, simultaneously, both, long term fading and short term fading. Microdiversity SC receivers reduces Rayleigh fading effects on system performance and macrodiversity SC receiver mitigate Gamma shadowing effects on system performance. Closed form expressions for level crossing rate of microdiversity SC receivers output signals envelopes are calculated. This expression is used for evaluation of level crossing rate of macrodiversity SC receiver output signal envelope. Numerical expressions are illustrated to show the influence of Gamma shadowing severity on level crossing rate
The Distribution of Minimum of Ratios of Two Random Variables and Its Application in Analysis of Multi-hop Systems
The distributions of random variables are of interest in many areas of science. In this paper, ascertaining on the importance of multi-hop transmission in contemporary wireless communications systems operating over fading channels in the presence of cochannel interference, the probability density functions (PDFs) of minimum of arbitrary number of ratios of Rayleigh, Rician, Nakagami-m, Weibull and α-µ random variables are derived. These expressions can be used to study the outage probability as an important multi-hop system performance measure. Various numerical results complement the proposed mathematical analysis
On the Impact of Wireless Jamming on the Distributed Secondary Microgrid Control
The secondary control in direct current microgrids (MGs) is used to restore
the voltage deviations caused by the primary droop control, where the latter is
implemented locally in each distributed generator and reacts to load
variations. Numerous recent works propose to implement the secondary control in
a distributed fashion, relying on a communication system to achieve consensus
among MG units. This paper shows that, if the system is not designed to cope
with adversary communication impairments, then a malicious attacker can apply a
simple jamming of a few units of the MG and thus compromise the secondary MG
control. Compared to other denial-of-service attacks that are oriented against
the tertiary control, such as economic dispatch, the attack on the secondary
control presented here can be more severe, as it disrupts the basic
functionality of the MG
The Minimum Wiener Connector
The Wiener index of a graph is the sum of all pairwise shortest-path
distances between its vertices. In this paper we study the novel problem of
finding a minimum Wiener connector: given a connected graph and a set
of query vertices, find a subgraph of that connects all
query vertices and has minimum Wiener index.
We show that The Minimum Wiener Connector admits a polynomial-time (albeit
impractical) exact algorithm for the special case where the number of query
vertices is bounded. We show that in general the problem is NP-hard, and has no
PTAS unless . Our main contribution is a
constant-factor approximation algorithm running in time
.
A thorough experimentation on a large variety of real-world graphs confirms
that our method returns smaller and denser solutions than other methods, and
does so by adding to the query set a small number of important vertices
(i.e., vertices with high centrality).Comment: Published in Proceedings of the 2015 ACM SIGMOD International
Conference on Management of Dat
Entropy of water and the temperature-induced stiffening of amyloid networks
In water, networks of semi-flexible fibrils of the protein -synuclein
stiffen significantly with increasing temperature. We make plausible that this
reversible stiffening is a result of hydrophobic contacts between the fibrils
that become more prominent with increasing temperature. The good agreement of
our experimentally observed temperature dependence of the storage modulus of
the network with a scaling theory linking network elasticity with reversible
crosslinking enables us to quantify the endothermic binding enthalpy and an
estimate the effective size of hydrophobic patches on the fibril surface.Comment: 13 pages, 6 figure
Performance of Diversity System Output Signal in Mobile Cellular System in the Presence of α-μ Short Term Fading and Gamma Long Term Fading
In this paper, wireless mobile communication system with macrodiversity reception is considered. Macrodiversity system is consisting of macrodiversity selection combining (SC) receiver and three microdiversity SC receivers. Propagation channel suffers α-μ short term fading and Gamma long term fading resulting in system performance degradation. Analytical closed form expression for average level crossing rate (LCR) of macrodiversity SC receiver output signal envelope is obtained. Mathematical results are analyzed, presenting the influence of long term fading parameters and short term fading parameters on average level crossing rate. Obtained results can be used in the process of simulation and design of real-world environments mobile cellular telecommunication systems
Nitric oxide and proteoglycan biosynthesis by human articular chondrocytes in alginate culture
AbstractInterleukin-1α and β induced the production of large amounts of nitric oxide by normal, human articular chondrocytes in alginate culture; at the same time the biosynthesis of proteoglycan was strongly suppressed. In a dose-dependent manner, NG-monomethyl-l-arginine both inhibited nitric oxide formation and relieved the suppression of proteoglycan synthesis. However concentrations of NG-monomethyl-l-arginine which completely prevented nitric oxide production only partially restored proteoglycan biosynthesis, even at low doses of interleukin-1 where suppression of proteoglycan synthesis was modest. The organic donor of nitric oxide, S-nitrosyl-acetyl-d,l- penicillamine also inhibited proteoglycan biosynthesis, but not as extensively as interleukin-1. These data suggest that interleukin-1 suppresses synthesis of the cartilaginous matrix through more than one mechanism, at least one of which is dependent upon the production of nitric oxide
Thrombotic microangiopathies during pregnancy : The obstetrical and neonatal perspective
Thrombotic Microangiopathies during pregnancy and puerperium are very rare and, if undiagnosed, can be lifethreating. Pregnancy and postpartum can represent a trigger in predisposed patients. Therefore, obstetricians are usually the first to observe clinical symptoms and laboratory abnormalities suggestive of Thrombotic Microangiopathies. The aim of this review is to briefly describe the obstetrical and perinatal outcome of these entities and highlight the clues for a correct diagnosis of pregnancy-related Thrombotic Microangiopathies. (C) 2019 Elsevier B.V. All rights reserved.Peer reviewe
Diabetes and colorectal cancer risk: A new look at molecular mechanisms and potential role of novel antidiabetic agents
Epidemiological data have demonstrated a significant association between the presence of type 2 diabetes mellitus (T2DM) and the development of colorectal cancer (CRC). Chronic hyperglycemia, insulin resistance, oxidative stress, and inflammation, the processes inherent to T2DM, also play active roles in the onset and progression of CRC. Recently, small dense low-density lipoprotein (LDL) particles, a typical characteristic of diabetic dyslipidemia, emerged as another possible underlying link between T2DM and CRC. Growing evidence suggests that antidiabetic medications may have beneficial effects in CRC prevention. According to findings from a limited number of preclinical and clinical studies, glucagon-like peptide-1 receptor agonists (GLP-1RAs) could be a promising strategy in reducing the incidence of CRC in patients with diabetes. However, available findings are inconclusive, and further studies are required. In this review, novel evidence on molecular mechanisms linking T2DM with CRC development, progression, and survival will be discussed. In addition, the potential role of GLP-1RAs therapies in CRC prevention will also be evaluated
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