Elastic Spin Hall effect in Mechanical Graphene

We show that spin-orbit interaction and elastic spin-Hall effect can exist in a classical mechanical system consisting of a two-dimensional honeycomb lattice of masses and springs. The band structure shows the presence of splitting at K point induced by the difference of longitudinal and transverse elastic constant, and this splitting can be regarded as an effective Dresselhaus-type spin-orbit coupling. Interestingly, as an initial displacement away from the equilibrium is applied, the time evolution simulation shows that waves of different spin polarization propagates along different directions at the Gamma and K point, which is characteristic of spin-Hall effect. Several cases for spin-Hall effect are also discussed.Comment: 15 pages, 5 figures, and 3395 word

Analyst Forecast Dispersion and Market Return Predictability: Does Conditional Equity Premium Play a Role?

Prior studies found that analyst forecast dispersion predicts future market returns. Some prior studies attribute this predictability to the short-sale constraints in the market according to the overpricing theory. Using the U.S. data from 1981 to 2014, we find that the return predictive power of aggregate dispersion only exists prior to 2005. The investor sentiment index, as a proxy of short-sale constraints used by many studies, can only explain the dispersion effect prior to 2005. The investor sentiment index and other proxies such as institutional ownership and put options cannot explain the significant weakening of the dispersion effect after the global financial crisis. We argue that the dispersion-return relation is partly driven by the correlation between dispersion and conditional equity premium. Our evidence suggests that the short-sale constrained stocks do not experience a higher dispersion effect, which is contrary to what the overpricing theory predicts.</jats:p

Ultimate bearing capacity of circular shallow foundations in frozen clay

This paper presents a study on the ultimate bearing capacity of circular shallow foundation in frozen clay. The bearing capacity were determined by model test, numerical simulation and analytical solution. In numerical simulation, the temperature field considering the phase transition was transformed into a temperature load and applied to a three-dimensional solid model. The generalized Kelvin model was used to describe the creep of frozen clay, and step loading was used. Based on the tests results that frozen soil fails because of local shear, we proposed an analytical model to estimate the ultimate bearing capacity of circular shallow foundation with local shear failure mechanisms. Based on the limit equilibrium theory, it was assumed that the fracture plane of the model only develops to the boundary between the transition zone and the passive zone. The results from present study and some other method are presented and compared, which has shown and verified the feasibility of our method. And the analytical solution is in good consistent with the results of the model test and numerical simulation

GRO J1655-40: from ASCA and XMM-Newton Observations

We have analysed four ASCA observations (1994--1995, 1996--1997) and three XMM-Newton observations (2005) of this source, in all of which the source is in high/soft state. We modeled the continuum spectra with relativistic disk model kerrbb, estimated the spin of the central black hole, and constrained the spectral hardening factor f_col and the distance. If kerrbb model applies, for normally used value of f_col, the distance cannot be very small, and f_col changes with observations.Comment: 2 pages, 1 figure, Conference proceedings to appear in "The Central Engine of Active Galactic Nuclei", ed. L. C. Ho and J.-M. Wang (San Francisco: ASP

Nonparametric Estimation of Derivative Functions with Data-Driven Optimally Selected Smoothing Parameters

Estimating gradients is of crucial importance across a broad range of applied economic domains. Here we consider data-driven bandwidth selection based on the gradient of an unknown regression function. This is a difficult problem empirically given that direct observation of the value of the gradient is typically not observed.The procedure developed here delivers bandwidths which behave asymptotically as though they were selected knowing the true gradient. This procedure is shown valid for semiparametric single index models. Simulated examples showcase the finite sample attraction of this new mechanism and confirm the theoretical predictions

Application of directed divergent evolution strategy in natural product biosynthesis

Genetic diversity is a result of evolution, enabling multiple ways for one particular physiological activity. Here, we introduce this strategy into bioengineering. We design two hydroxytyrosol biosynthetic pathways using tyrosine as substrate. We show that the synthetic capacity is significantly improved when two pathways work simultaneously comparing to each individual pathway. Next, we engineer flavin-dependent monooxygenase HpaBC for tyrosol hydroxylase, tyramine hydroxylase, and promiscuous hydroxylase active on both tyrosol and tyramine using directed divergent evolution strategy. Then, the mutant HpaBCs are employed to catalyze two missing steps in the hydroxytyrosol biosynthetic pathways designed above. Our results demonstrate that the promiscuous tyrosol/tyramine hydroxylase can minimize the cell metabolic burden induced by protein overexpression and allow the biosynthetic carbon flow to be divided between two pathways. Thus, the efficiency of the hydroxytyrosol biosynthesis is significantly improved by rearranging the metabolic flux among multiple pathways

A self-organizing routing algorithm for wireless sensor networks

Wireless sensor networks (WSN) are designed to collect and process sensory data from environments. Some environments are dangerous or un-reachable to human beings and it is difficult to replace sensor nodes when they are out of battery or even destroyed, i.e. wireless sensor nodes are in general prone to failure. This kind of characteristics require WSN to detect whether or not its next destination is still available (alive) and to maintain a transferring path if the next destination in the route does not exist (dead). In the normal state, nodes are in power-saving 'sleep' state. When a route is created for some purpose, all nodes in this route will be active and be ready to respond requests from its neighbors. Our approach is to maintain the routing table up-to-date by sending message from a last node to its next node and judging whether the next node is alive according to the response. If problems happen, node will self-organize and try to maintain transferring