Estimating Grid-Induced Errors in CFD by Discrete-Error-Transport Equations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77113/1/AIAA-2004-656-838.pd

Improved spectrum sensing for OFDM cognitive radio in the presence of timing offset

Spectrum sensing is an important aspect of an (interweave) cognitive radio network. In the particular case of orthogonal frequency division multiplexing (OFDM) transmission, many previous spectrum sensing algorithms have utilized the unique correlation properties provided by the cyclic prefix (CP). However, they have also had to both estimate and compensate for the inherent timing offset of a practical system. This is because the timing offset will affect both the test statistic and the threshold, and the inaccurate estimation of timing offset will lead to poor performance. So in this paper, we propose an improved CP detector by constructing a likelihood ratio test (LRT) based on the multivariate probability density functions (pdf) of a particular auto-correlation vector that is chosen to exploit the existence of the CP. This leads to ‘probability of detection’ (Pd) and ‘probability of false alarm’ (Pf) terms that are actually independent of timing offset, and we can get an accurate threshold without estimating timing offset. Simulation results illustrate that the proposed algorithm outperforms existing methods, even for low SNR values. Finally, we show how the algorithm’s parameters must be carefully chosen in a trade-off between spectrum sensing success and overall system performance

Identification of Pns6, a putative movement protein of RRSV, as a silencing suppressor

RNA silencing is a potent antiviral response in plants. As a counterdefense, most plant and some animal viruses encode RNA silencing suppressors. In this study, we showed that Pns6, a putative movement protein of Rice ragged stunt virus (RRSV), exhibited silencing suppressor activity in coinfiltration assays with the reporter green fluorescent protein (GFP) in transgenic Nicotiana benthamiana line 16c. Pns6 of RRSV suppressed local silencing induced by sense RNA but had no effect on that induced by dsRNA. Deletion of a region involved in RNA binding abolished the silencing suppressor activity of Pns6. Further, expression of Pns6 enhanced Potato virus × pathogenicity in N. benthamiana. Collectively, these results suggested that RRSV Pns6 functions as a virus suppressor of RNA silencing that targets an upstream step of the dsRNA formation in the RNA silencing pathway. This is the first silencing suppressor to be identified from the genus Oryzavirus

TRAF6 Promotes Myogenic Differentiation via the TAK1/p38 Mitogen-Activated Protein Kinase and Akt Pathways

p38 mitogen-activated protein kinase (MAPK) is an essential kinase involved in myogenic differentiation. Although many substrates of p38 MAPK have been identified, little is known about its upstream activators during myogenic differentiation. TRAF6 is known to function in cytokine signaling during inflammatory responses. However, not much is known about its role in myogenic differentiation and muscle regeneration. We showed here that TRAF6 and its intrinsic ubiquitin E3 ligase activity are required for myogenic differentiation. In mouse myoblasts, knockdown of TRAF6 compromised the p38 MAPK and Akt pathways, while deliberate activation of either pathway rescued the differentiation defect caused by TRAF6 knockdown. TAK1 acted as a key signal transducer downstream of TRAF6 in myogenic differentiation. In vivo, knockdown of TRAF6 in mouse muscles compromised the injury-induced muscle regeneration without impairing macrophage infiltration and myoblast proliferation. Collectively, we demonstrated that TRAF6 promotes myogenic differentiation and muscle regeneration via the TAK1/p38 MAPK and Akt pathways