Scalar Gravity and Higgs Mechanism

The role that the auxiliary scalar field $\phi$ played in Brans-Dicke cosmology is discussed. If a constant vacuum energy is assumed to be the origin of dark energy, then the corresponding density parameter would be a quantity varying with $\phi$; and almost all of the fundamental components of our universe can be unified into the dynamical equation for $\phi$. As a generalization of Brans-Dicke theory, we propose a new gravity theory with a complex scalar field $\phi$ which is coupled to the cosmological curvature scalar. Through such a coupling, the Higgs mechanism is naturally incorporated into the evolution of the universe, and a running density of the field vacuum energy is obtained which may release the particle standard model from the rigorous cosmological constant problem in some sense. Our model predicts a running mass scale of the fundamental particles in which the gauge symmetry breaks spontaneously. The running speed of the mass scale in our case could survive all existing experiments.Comment: 6 page

Matter Power Spectra in Viable f(R)f(R) Gravity Models with Massive Neutrinos

We investigate the matter power spectra in the power law and exponential types of viable $f(R)$ theories along with massive neutrinos. The enhancement of the matter power spectrum is found to be a generic feature in these models. In particular, we show that in the former type, such as the Starobinsky model, the spectrum is magnified much larger than the latter one, such as the exponential model. A greater scale of the total neutrino mass, $\Sigma m_{\nu}$, is allowed in the viable $f(R)$ models than that in the $\Lambda$CDM one. We obtain the constraints on the neutrino masses by using the CosmoMC package with the modified MGCAMB. Explicitly, we get $\Sigma m_{\nu} < 0.451 \ (0.214)\ \mathrm{eV}$at 95the corresponding one for the$\Lambda$CDM model is$\Sigma m_{\nu} < 0.200\ \mathrm{eV}$. Furthermore, by treating the effective number of neutrino species$N_{\mathrm{eff}}$as a free parameter along with$\Sigma m_{\nu}$, we find that$N_{\mathrm{eff}} = 3.78^{+0.64}_{-0.84} (3.47^{+0.74}_{-0.60})$and$\Sigma m_{\nu} = 0.533^{+0.254}_{-0.411}$($< 0.386) \ \mathrm{eV}$ at 95% C.L. in the Starobinsky (exponential) model.Comment: 15 pages, 5 figures, updated version accepted by PL

Democracy and Nation Formation: National Identity Change and Dual Identity in Taiwan, 1991-2011

Using the data collected from various national poll surveys conducted after the transition to democracy in the late 1980's, this study analyzes the trend of national identity change among the general populace in Taiwan. Counter to the popular view that the nascent Taiwanese national identity rose at the cost of the orthodox Chinese national identity, this study argues that most people in fact upheld dual identity in the first two decades following the democratic transition. They acquired a new Taiwanese national identity without forsaking the old Chinese identity. In analyzing the phenomenon of dual identity, this dissertation challenges the conventional view that national identities are mutually exclusive. It also shows that the trajectories of the two national identities are different processes, having occurred during different historical stages and in different international environments. They were also the results of different political forces. In explaining the rise of Taiwanese national identity, this study focuses on the factors of state and politics, rather than history and ethnicity. It is contended that the new national identity is largely engendered by democratic institutions and political participation. It thus was able to co-exist with existing Chinese national identity. This dissertation then explains the decline of Chinese national identity not with the rise of Taiwanese identity, but with the rise of China. The dominance of the People's Republic of China (PRC) in the international community along with its staunch One China Principle has removed the important component of the Republic of China (ROC) from the Chinese national identity in Taiwan. Chinese unification no longer means the fulfillment of self-rule but to be ruled by another state (the PRC). People who have identified with the ROC no longer opt for a unified great China and hence forgo their Chinese national identity

Learning Unmanned Aerial Vehicle Control for Autonomous Target Following

While deep reinforcement learning (RL) methods have achieved unprecedented successes in a range of challenging problems, their applicability has been mainly limited to simulation or game domains due to the high sample complexity of the trial-and-error learning process. However, real-world robotic applications often need a data-efficient learning process with safety-critical constraints. In this paper, we consider the challenging problem of learning unmanned aerial vehicle (UAV) control for tracking a moving target. To acquire a strategy that combines perception and control, we represent the policy by a convolutional neural network. We develop a hierarchical approach that combines a model-free policy gradient method with a conventional feedback proportional-integral-derivative (PID) controller to enable stable learning without catastrophic failure. The neural network is trained by a combination of supervised learning from raw images and reinforcement learning from games of self-play. We show that the proposed approach can learn a target following policy in a simulator efficiently and the learned behavior can be successfully transferred to the DJI quadrotor platform for real-world UAV control