137 research outputs found
Recovering Multiplexing Loss Through Successive Relaying Using Repetition Coding
In this paper, a transmission protocol is studied for a two relay wireless
network in which simple repetition coding is applied at the relays.
Information-theoretic achievable rates for this transmission scheme are given,
and a space-time V-BLAST signalling and detection method that can approach them
is developed. It is shown through the diversity multiplexing tradeoff analysis
that this transmission scheme can recover the multiplexing loss of the
half-duplex relay network, while retaining some diversity gain. This scheme is
also compared with conventional transmission protocols that exploit only the
diversity of the network at the cost of a multiplexing loss. It is shown that
the new transmission protocol offers significant performance advantages over
conventional protocols, especially when the interference between the two relays
is sufficiently strong.Comment: To appear in the IEEE Transactions on Wireless Communication
On the Performance of Selection Relaying
Interest in selection relaying is growing. The recent developments in this
area have largely focused on information theoretic analyses such as outage
performance. Some of these analyses are accurate only at high SNR regimes. In
this paper error rate analyses that are sufficiently accurate over a wide range
of SNR regimes are provided. The motivations for this work are that practical
systems operate at far lower SNR values than those supported by the high SNR
analysis. To enable designers to make informed decisions regarding network
design and deployment, it is imperative that system performance is evaluated
with a reasonable degree of accuracy over practical SNR regimes. Simulations
have been used to corroborate the analytical results, as close agreement
between the two is observed.Comment: Proceedings of the 2008 IEEE Vehicular Technology Conference,
Calgary, Alberta, September 21-24, 200
On pseudo-Anosov autoequivalences
Motivated by results of Thurston, we prove that any autoequivalence of a
triangulated category induces a filtration by triangulated subcategories,
provided the existence of Bridgeland stability conditions. The filtration is
given by the exponential growth rate of masses under iterates of the
autoequivalence, and only depends on the choice of a connected component of the
stability manifold. We then propose a new definition of pseudo-Anosov
autoequivalences, and prove that our definition is more general than the one
previously proposed by Dimitrov, Haiden, Katzarkov, and Kontsevich. We
construct new examples of pseudo-Anosov autoequivalences on the derived
categories of quintic Calabi-Yau threefolds and quiver Calabi-Yau categories.
Finally, we prove that certain pseudo-Anosov autoequivalences on quiver
3-Calabi-Yau categories act hyperbolically on the space of Bridgeland stability
conditions.Comment: 35 page
Effect of Vitamin D on the HMGB1/RAGE Pathway and Adipokines Levels in Obese Asthmatic Mice
Compared to common asthma, obese asthma is difficult to control. Previous studies have shown that vitamin D (Vit D) has a therapeutic effect on asthma. Nevertheless, the action mechanism of Vit D for obese asthma are not well known.
In this study, we, therefore, induced obesity and established an obese asthma mouse model using ovalbumin (OVA) stimulation and applied treatment with Vit D (100 ng/kg). Accordingly, thirty mice were randomly divided into 5 equal groups of normal control, asthma, obese asthma, asthma+Vit D, and obese asthma+ Vit D. The levels of inflammatory factors and adipokines were measured by the ELISA assay; then the quantitative reverse transcription PCR (qRT-PCR) method was used to evaluate the expression of high mobility group box 1(HMGB1) and receptor for advanced glycation end products [RAGE] genes.T
he results showed that OVA sensitization significantly increased airway resistance, the levels of inflammatory cytokines, and HMGB and RAGE expression in asthmatic and obese asthmatic mice, as compared to the control group. Also, these changes in the obese asthmatic group were notably higher than those in the asthmatic one. In addition, the treatment of asthmatic and obese asthmatic mice with Vit D significantly reduced the raw, serum and BALF levels of inflammatory cytokines, as well as the expression of HMGB1 and RAGE mRNA.
To conclude, the present study showed that vitamin D might attenuate lung injury by up-regulating HMGB1 and RAGE expression. Our findings, thus, may offer new concepts and approaches for the treatment and prevention of obese asthma
Дослідження мотиваційних чинників професійного становлення вчителя
This paper studies two-hop cooperative demodulate-and-forward relaying using multiple relays in wireless networks. A threshold based relay selection scheme is considered, in which the reliable relays are determined by comparing source-relay SNR to a threshold, and one of the reliable relays is selected by the destination based on relay-destination SNR. The exact bit error rate of this scheme is derived, and a simple threshold function is proposed. It is shown that the network achieves full diversity order (N +1) under the proposed threshold, where N is the number of relays in the network. Unlike some other full diversity achieving protocols in the literature, the requirement that the instantaneous/average SNRs of the source-relay links be known at the destination is eliminated using the appropriate SNR threshold
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