The Hawking-Page phase transitions in the extended phase space in the Gauss-Bonnet gravity

In this paper, the Hawking-Page phase transitions between the black holes and thermal anti-de Sitter (AdS) space are studied with the Gauss-Bonnet term in the extended phase space, in which the varying cosmological constant plays the role of an effective thermodynamic pressure. The Gauss-Bonnet term exhibits its effects via introducing the corrections to the black hole entropy and Gibbs free energy. The global phase structures, especially the phase transition temperature $T_{\rm HP}$ and the Gibbs free energy $G$, are systematically investigated, first for the Schwarzschild-AdS black holes and then for the charged and rotating AdS black holes in the grand canonical ensembles, with both analytical and numerical methods. It is found that there are terminal points in the coexistence lines, and $T_{\rm HP}$ decreases at large electric potentials and angular velocities and also decreases with the Gauss-Bonnet coupling constant $\alpha$.Comment: 13 pages, 13 figure

Theoretical Study of Corundum as an Ideal Gate Dielectric Material for Graphene Transistors

Using physical insights and advanced first-principles calculations, we suggest that corundum is an ideal gate dielectric material for graphene transistors. Clean interface exists between graphene and Al-terminated (or hydroxylated) Al2O3 and the valence band offsets for these systems are large enough to create injection barrier. Remarkably, a band gap of {\guillemotright} 180 meV can be induced in graphene layer adsorbed on Al-terminated surface, which could realize large ON/OFF ratio and high carrier mobility in graphene transistors without additional band gap engineering and significant reduction of transport properties. Moreover, the band gaps of graphene/Al2O3 system could be tuned by an external electric field for practical applications

Controlling doping in graphene through a SiC substrate: A first-principles study

Controlling the type and density of charge carriers by doping is the key step for developing graphene electronics. However, direct doping of graphene is rather a challenge. Based on first-principles calculations, a concept of overcoming doping difficulty in graphene via substrate is reported.We find that doping could be strongly enhanced in epitaxial graphene grown on silicon carbide substrate. Compared to free-standing graphene, the formation energies of the dopants can decrease by as much as 8 eV. The type and density of the charge carriers of epitaxial graphene layer can be effectively manipulated by suitable dopants and surface passivation. More importantly, contrasting to the direct doping of graphene, the charge carriers in epitaxial graphene layer are weakly scattered by dopants due to the spatial separation between dopants and the conducting channel. Finally, we show that a similar idea can also be used to control magnetic properties, for example, induce a half-metallic state in the epitaxial graphene without magnetic impurity doping

Transfer Knowledge from Head to Tail: Uncertainty Calibration under Long-tailed Distribution

How to estimate the uncertainty of a given model is a crucial problem. Current calibration techniques treat different classes equally and thus implicitly assume that the distribution of training data is balanced, but ignore the fact that real-world data often follows a long-tailed distribution. In this paper, we explore the problem of calibrating the model trained from a long-tailed distribution. Due to the difference between the imbalanced training distribution and balanced test distribution, existing calibration methods such as temperature scaling can not generalize well to this problem. Specific calibration methods for domain adaptation are also not applicable because they rely on unlabeled target domain instances which are not available. Models trained from a long-tailed distribution tend to be more overconfident to head classes. To this end, we propose a novel knowledge-transferring-based calibration method by estimating the importance weights for samples of tail classes to realize long-tailed calibration. Our method models the distribution of each class as a Gaussian distribution and views the source statistics of head classes as a prior to calibrate the target distributions of tail classes. We adaptively transfer knowledge from head classes to get the target probability density of tail classes. The importance weight is estimated by the ratio of the target probability density over the source probability density. Extensive experiments on CIFAR-10-LT, MNIST-LT, CIFAR-100-LT, and ImageNet-LT datasets demonstrate the effectiveness of our method

Decision Making and Analysis for Unexpected Road Blockages

The unexpected road blockage problem (URBP for short) is considered for the case when some blockages occur on the road at certain times and such blockages would be revealed only upon reaching them. Papadimitriou and Yannakakis proved that devising a strategy that guarantees a given competitive ratio is PSPACE-complete if the number of edges that might be blocked is not fixed; Bar-noy and Schieber considered the deterministic and stochastic variations of the recoverable-URBP in the worst-case criterion. In this paper, we present an offline algorithm for the recoverable-URBP optimal solution and the complexity of the algorithm is 2 O n( )( n is the number of nodes). Two online strategies, waiting strategy and the Greedy strategy, are proposed and the competitive ratios of the two strategies are given. Furthermore, we compare the two strategies based on competitive ratio analysis

Molecular Adaptation of Modern Human Populations

Modern humans have gone through varied processes of genetic adaptations when their ancestors left Africa about 100,000 years ago. The environmental stresses and the social transitions (e.g., emergence of the Neolithic culture) have been acting as the major selective forces reshaping the genetic make-up of human populations. Genetic adaptations have occurred in many aspects of human life, including the adaptation to cold climate and high-altitude hypoxia, the improved ability of defending infectious diseases, and the polished strategy of utilizing new diet with the advent of agriculture. At the same time, the adaptations once developed during evolution may sometimes generate deleterious effects (e.g., susceptibility to diseases) when facing new environmental and social changes. The molecular (especially the genome-wide screening of genetic variations) studies in recent years have detected many genetic variants that show signals of Darwinian positive selection in modern human populations, which will not only provide a better understanding of human evolutionary history, but also help dissecting the genetic basis of human complex diseases

Hybrid electromechanical actuator and actuation system

A hybrid electromechanical actuator has two different types of electromechanical elements, one that expands in a transverse direction when electric power is applied thereto and one that contracts in a transverse direction when electric power is applied thereto. The two electromechanical elements are (i) disposed in relation to one another such that the transverse directions thereof are parallel to one another, and (ii) mechanically coupled to one another at least at two opposing edges thereof. Electric power is applied simultaneously to the elements