A new iterative algorithm for probabilistic performance measure

Compared to traditional Reliability Index Approach (RIA), Performance Measure Approach (PMA) is considered to be more efficient and stable for evaluation of probabilistic constraints in reliability-based design optimization of structures. In PMA, the probabilistic performance measure is obtained through locating the minimum performance target point (MPTP) with the specified target reliability index in standard normal space. The advanced mean-value (AMV) method is well suitable for locating MPTP due to its simplicity and efficiency. However, the iterative sequence may converge very slowly, or oscillate and fail to converge if the performance function is highly nonlinear. Several modified algorithms were suggested to enhance the convergence of AMV, but their implementation is complicated and the prior knowledge of convexity or concavity of the performance function is needed. In this paper an easy iterative algorithm, which introduces a “new” step size to control the convergence of the sequence, is proposed. This step size is new because it may be constant during the iteration or decreases successively using a self-adjust strategy. It is proved that the AMV method is a special case of this proposed algorithm when the step size tends to infinity. Numerical results of several nonlinear performance functions indicate that the proposed algorithm is effective and as simple as the AMV but more robust

Meson Mass Decomposition

Hadron masses can be decomposed as a sum of components which are defined through hadronic matrix elements of QCD operators. The components consist of the quark mass term, the quark energy term, the glue energy term and the trace anomaly term. We calculate these components of mesons with lattice QCD for the first time. The calculation is carried out with overlap fermion on $2+1$ flavor domain-wall fermion gauge configurations. We confirm that $\sim 50\%$ of the light pion mass comes from the quark mass and $\sim 10\%$ comes from the quark energy, whereas, the contributions are found to be the other way around for the $\rho$ mass. The combined glue components contribute $\sim 40 - 50\%$ for both mesons. It is interesting to observe that the quark mass contribution to the mass of the vector meson is almost linear in quark mass over a large quark mass region below the charm quark mass. For heavy mesons, the quark mass term dominates the masses, while the contribution from the glue components is about $400\sim500$ MeV for the heavy pseudoscalar and vector mesons. The charmonium hyperfine splitting is found to be dominated by the quark energy term which is consistent with the quark potential model.Comment: 7 Pages, 4 figures, contribution to the 32nd International Symposium on Lattice Field Theory (Lattice 2014), 23-28 June 2014, Columbia University, New York, NY, US

Testing Technicolor Models via Top Quark Pair Production in High Energy Photon Collisions

Pseudo-Goldstone boson contributions to $t\bar{t}$ production rates in technicolor models with and without topcolor at the $\sqrt{s}=0.5 and 1.5$ TeV photon colliders and hadron colliders are reviewed. For reasonable ranges of the parameters, the contributions are large enough to be experimentally observable. Models with topcolor, without topcolor and the MSSM with $\tan\beta\geq 1$ can be experimentally distinguished.Comment: Talk given by H.Y. Zhou at the III International Conference on Hyperons,Charm and Beauty Hadrons,Genova,Italy,June 30-July 3 199

Loss of Jak2 Selectively Suppresses DC-Mediated Innate Immune Response and Protects Mice from Lethal Dose of LPS-Induced Septic Shock

Given the importance of Jak2 in cell signaling, a critical role for Jak2 in immune cells especially dendritic cells (DCs) has long been proposed. The exact function for Jak2 in DCs, however, remained poorly understood as Jak2 deficiency leads to embryonic lethality. Here we established Jak2 deficiency in adult Cre+/+Jak2fl/fl mice by tamoxifen induction. Loss of Jak2 significantly impaired DC development as manifested by reduced BMDC yield, smaller spleen size and reduced percentage of DCs in total splenocytes. Jak2 was also crucial for the capacity of DCs to mediate innate immune response. Jak2−/− DCs were less potent in response to inflammatory stimuli and showed reduced capacity to secrete proinflammatory cytokines such as TNFα and IL-12. As a result, Jak2−/− mice were defective for the early clearance of Listeria after infection. However, their potency to mediate adaptive immune response was not affected. Unlike DCs, Jak2−/− macrophages showed similar capacity secretion of proinflammatory cytokines, suggesting that Jak2 selectively modulates innate immune response in a DC-dependent manner. Consistent with these results, Jak2−/− mice were remarkably resistant to lethal dose of LPS-induced septic shock, a deadly sepsis characterized by the excessive innate immune response, and adoptive transfer of normal DCs restored their susceptibility to LPS-induced septic shock. Mechanistic studies revealed that Jak2/SATA5 signaling is pivotal for DC development and maturation, while the capacity for DCs secretion of proinflammatory cytokines is regulated by both Jak2/STAT5 and Jak2/STAT6 signaling

Meson Mass Decomposition from Lattice QCD

Hadron masses can be decomposed as a sum of quark and glue components that are defined through hadronic matrix elements of QCD operators. The components consist of the quark mass term, the quark energy term, the glue energy term, and the trace anomaly term. We calculate these components for mesons with lattice QCD for the first time. The calculation is carried out with overlap fermion on 2+1 flavor domain-wall fermion gauge configurations. We confirm that ~50% of the light pion mass comes from the quark mass term and ~10% comes from the quark energy; whereas, for the ρ meson, the quark energy contributes roughly half of its mass but the quark mass term contributes little. The combined glue components contribute ~40–50% for both mesons. It is interesting to observe that the quark mass contribution to the mass of the vector meson is almost linear in quark mass over a large quark mass region below the charm quark mass. For heavy mesons, the quark mass term dominates the masses, while the contribution from the glue components is about 200 MeV (a bare value around 2 GeV) for the heavy pseudoscalar and vector mesons. The charmonium hyperfine splitting is found to be dominated by the quark energy term which is consistent with the picture of the quark potential model