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The karst area in Yunnan-Guangxi-Guizhou region in southwest China is known for widespread rocky desertification but several studies report a greening trend since the year 2000. While the start of the greening trend seems to match with the implementation of ecological conservation projects, no statistical evidence on a relationship between vegetation greening and eco-engineering exists. Moreover, dominant factors influencing the spatial patterns of vegetation trends have rarely been investigated. Here we use six comprehensive factors representing the natural conditions and human activities of the study area, and several statistical models consistently show that eco-engineering explains large parts of the positive vegetation trends in the karst areas, while negative vegetation trends in non-karst areas of Yunnan were related with a decrease in rainfall. We further show that the interaction of eco-engineering with other factors leads to a heterogeneous pattern of different vegetation trends. Knowing and understanding these patterns is crucial when planning ecological restoration, especially in diverse landscapes like China karst and the methods can be reused in other restoration areas.

We present a systematic numerical iteration approach to study the evolution properties of the spin-boson systems, which works well in whole coupling regime. This approach involves the evaluation of a set of coefficients for the formal expansion of the time-dependent Schr\"{o}dinger equation $\vert t\rangle=e^{-i\hat{H}t}\vert t=0\rangle$ by expanding the initial state $\vert t=0\rangle$ in Fock space. The main advantage of this method is that this set of coefficients is unique for the Hamiltonian studied, which allows one to calculate the time evolution based on the different initial states. To complement our numerical calculations, the method is applied to the Buck-Sukumar model. Furthermore, we pointed out that, when the ground state energy of the model is unbounded and no ground state exists in a certain parameter space, the unstable time evolution of the physical quantities is the natural results. Furthermore, we test the performance of the numerical method to the Hamiltonian that use anti-Hermitian terms for modeling open quantum systems., Comment: 8 pages, 6 figures

We study the dynamical properties of the quantum Rabi model within a systematic expansion method. Based on the observation that the parity symmetry of the Rabi model is kept during the evolution of the states, we decompose the initial state and the time-dependent one into a part of a positive and a negative parity expanded by the superposition of the coherent states. The evolutions for the corresponding positive and the negative parity are obtained, where the expansion coefficients in the dynamical equations are known from the recurrence relation derived., Comment: 10 pages

Casimir effects manifests that, the two closely paralleled plates, generally produce a macroscopic attractive force due to the quantum vacuum fluctuations of the electromagnetic fields. The derivation of the force requires an {\it artificial} regulator by removing the divergent summation. By including naturally a spectrum density factor, based on the observation that an incomplete eigenvectors of observable, such as the eigenstates for the photons in the free field, can form a complete set of eigenvectors by introducing a unique spectrum transformation, an alternative way is presented to rederive the force, without using a regulator. As a result, the Casimir forces are obtained with the first term $-\pi^2 \hbar c/(240 a^4)$ attractive, and the second one, $-\pi^4 \hbar c^3 \sigma^2/(1008 a^6)$, also attractive but smaller, with $a$ the plate separation, and $\sigma$ a to-be-determined small constant number in the spectrum density factor., Comment: 5 pages

Flavor oscillation of traveling neutrinos is treated by solving the one-dimensional Dirac equation for massive fermions. The solutions are given in terms of squeezed coherent state as mutual eigenfunctions of parity operator and the corresponding Hamiltonian, both represented in bosonic creation and annihilation operators. It was shown that a mono-energetic state is non-normalizable, and a normalizable Gaussian wave packet, when of pure parity, cannot propagate. A physical state for a traveling neutrino beam would be represented as a normalizable Gaussian wave packet of equally-weighted mixing of two parities, which has the largest energy-dependent velocity. Based on this wave-packet representation, flavor oscillation of traveling neutrinos can be treated in a strict sense. These results allow the accurate interpretation of experimental data for neutrino oscillation, which is critical in judging whether neutrino oscillation violates CP symmetry., Comment: 16 pages

We explore the spin-boson model in a special case, i.e., with zero local field. In contrast to previous studies, we find no possibility for quantum phase transition (QPT) happening between the localized and delocalized phases, and the behavior of the model can be fully characterized by the even or odd parity as well as the parity breaking, instead of the QPT, owned by the ground state of the system. Our analytical treatment about the eigensolution of the ground state of the model presents for the first time a rigorous proof of no-degeneracy for the ground state of the model, which is independent of the bath type, the degrees of freedom of the bath and the calculation precision. We argue that the QPT mentioned previously appears due to unreasonable treatment of the ground state of the model or of the infrared divergence existing in the spectral functions for Ohmic and sub-Ohmic dissipations., Comment: 5 pages, 1 figure. Comments are welcome

We study the breaking of parity in the spin-boson model and demonstrate unique scaling behavior of the magnetization and entanglement around the critical points for the parity breaking after suppressing the infrared divergence existing inherently in the spectral functions for Ohmic and sub-Ohmic dissipations. Our treatment is basically analytical and of generality for all types of the bath. We argue that the conventionally employed spectral function is not fully reasonable and the previous justification of quantum phase transition for localization needs to be more seriously reexamined., Comment: Comments are welcome

Non-dispersive wave packet for massless fermions is formulated on the basis of squeezed coherent states that are put in a form of common eigenfunction for the Hamiltonian and the helicity operator, starting from the Dirac equation. The wave packet thus constructed is demonstrated to propagate at a constant velocity as that of light. This explicit expression of wave packet for the massless fermions can facilitate theoretical analysis of problems where a wave packet is of formal significance. Furthermore, extensive wave packet may result in a superluminal velocity statistics if determined from the time-of-flight measurement, as recently done on muon neutrinos, when a threshold particle flux or energy transfer, which is eventually referred to the propagation of wave packet, to invoke a detection event is assumed., Comment: 1-eps figure and 1 tex txt

Zitterbewegung (ZB), the trembling of free relativistic electrons in a vacuum could be simulated by a single trapped ion. We focus on the variations of ZB under different parity conditions and find no ZB in the case of odd or even parity. ZB occurs only for admixture of the odd and even parity states. We also show the similar role played by the parity operator for the trapped ion in Fock-state representation and the space inversion operator for a realistic relativistic electron. Although the ZB effect is invisible in a relativistic electron, preparation of the trapped ion in different parity states is a sophisticated job, which makes it possible to observe the parity relevant ZB effects with currently available techniques., Comment: 4 pages, 1 figure

The instability, so-called the quantum-phase-like transition, in the Dicke model with a rotating-wave approximation for finite $N$ atoms is investigated in terms of the Berry phase and the fidelity. It can be marked by the discontinuous behavior of these quantities as a function of the atom-field coupling parameter. Involving an additional field $A^{2}$ term, it is observed that the instability is not eliminated beyond the characteristic atom-field coupling parameter even for strong interaction of the bosonic fields, contrarily to the previous studies., Comment: 6 pages, 6 figures

We revisit the two-site Hubbard-Holstein model by using extended phonon coherent states. The nontrivial singlet bipolaron is studied exactly in the whole coupling regime. The ground-state (GS) energy and the double occupancy probability are calculated. The linear entropy is exploited successfully to quantify bipartite entanglement between electrons and their environment phonons, displaying a maximum entanglement of the singlet-bipolaron in strong coupling regime. A dramatic drop in the crossover regime is observed in the GS fidelity and its susceptibility. The bipolaron properties is also characterized classically by correlation functions. It is found that the crossover from a two-site to single-site bipolaron is more abrupt and shifts to a larger electron-phonon coupling strength as electron-electron Coulomb repulsion increases., Comment: 6 pages, 6 figures

The polariton system is studied by a concise approach using a simple model. A new ground state with negative energy is obtained and found to exhibit the symmetry breaking., Comment: Revtex, accepted by Phys. Lett. A. E-mail: jlyang@nsc.ustc.edu.cn after Oct. 10, 1997

We evaluate potential tsunami hazards for several communities in lower Cook Inlet, including Anchor Point, Kenai, Ninilchik, and Tyonek, by numerically modeling the extent of inundation from tsunami waves generated by hypothetical earthquakes. We define an updated suite of earthquakes—including Tohoku-style megathrust ruptures and other sources in the eastern part of the Alaska–Aleutian megathrust—to calculate vertical seafloor displacements and model resulting tsunami dynamics. A hypothetical earthquake spanning from Kodiak Island to Prince William Sound with maximum slip distributed between depths of 5 and 22 km (3.1 and 13.7 mi) results in “worst case” tsunami inundation for all communities. If the tsunami arrives at high tide, the maximum predicted overland flow depths in the communities can reach up to 10 m (32.8 ft), and the currents could be as strong as 12 m/sec (23.4 knots). Dangerous wave activity is expected to last for more than 24 hours. Results presented here are intended to provide guidance to local emergency management agencies for tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami damage. [ABSTRACT FROM AUTHOR]

We assess potential tsunami hazards for six communities in Southeast Alaska: Kasaan, Klawock, Metlakatla, Pelican, Point Baker, and Port Protection. These communities have no high-resolution bathymetry or topography, therefore we conduct tsunami hazard assessments for these areas at the regional scale. The regional approach is a suitable, costeffective approximation and replacement for high-resolution tsunami inundation maps. The primary tsunami hazard considered for these communities originates from tsunamigenic earthquakes along the Alaska-Aleutian subduction zone across the Gulf of Alaska. We numerically model tsunami waves generated by four different megathrust earthquakes and develop approximate tsunami hazard maps for the six communities. The hypothetical tsunami scenarios that we examined include variations of an extended 1964 rupture, megathrust earthquakes in the Prince William Sound and Alaska Peninsula regions, and a Cascadia megathrust earthquake. We do not include impacts of subaerial or submarine landslide tsunami sources, as that is beyond the scope of this study. The maximum runup heights from tectonically-generated tsunamis are 1.4 m (4.6 ft) in Kasaan, 4 m (13 ft) in Klawock, 1 m (3.3 ft) in Metlakatla, 5 m (16 ft) in Pelican, 1.3 m (4.3 ft) in Point Baker, and 2.6 m (8.5 ft) in Port Protection. Results presented here are intended to provide guidance to local emergency management agencies in initial tsunami inundation assessment, evacuation planning, and public education for mitigation of future tsunami hazards. [ABSTRACT FROM AUTHOR]

The authors evaluated potential tsunami hazard for the communities of Kodiak, Womens Bay, and for the U.S. Coast Guard base on Kodiak Island by numerically modeling the extent of inundation from tsunami waves generated by hypothetical earthquake sources. Worst-case hypothetical scenarios are defined by analyzing results of a sensitivity study of the tsunami dynamics related to various slip distributions along the Alaska-Aleutian megathrust. The worst-case scenarios for the Kodiak communities are thought to be the subduction zone earthquakes offshore Kodiak Island with their greatest slip at 5-35 km (3.1-22 mi) depth. We also consider earthquakes as large as the 2011 Tohoku earthquake in Japan with the greatest slip located close to the trench area. The results show that the maximum predicted flow depth in downtown Kodiak could reach 13 m (42.6 ft), and the currents in Kodiak's Inner Harbor could be as strong as 3.7 m/sec (7.2 knots). The dangerous wave activity is expected to last for at least 10 hours after the earthquake. Results presented here are intended to provide guidance to local emergency management agencies in tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami hazards. This report updates the previously published assessment of tsunami hazard for the Kodiak Island communities. [ABSTRACT FROM AUTHOR]

In this report we evaluate potential tsunami hazards for the southeastern Alaska community of Yakutat and numerically model the extent of inundation from tsunami waves generated by tectonic and landslide sources. We use numerical modeling of historical tsunami events at Yakutat, such as the tsunami triggered by the 1964 Great Alaska Earthquake, and the tsunami waves generated by the recent 2011 Tohoku earthquake, to verify the tsunami model. Potential hypothetical tsunami sources include variations of the extended 1964 rupture, megathrust earthquakes in the Prince William Sound and Alaska Peninsula regions, and earthquakes in the Yakataga-Yakutat area, including the historical September 10, 1899, earthquake. Local underwater landslide events in Monti Bay are also considered as possible tsunamigenic scenarios. Numerical modeling results, combined with historical observations in the region, are intended to provide guidance to local emergency management in tsunami hazard assessment, evacuation planning, and public education for the reduction of future tsunami hazard. [ABSTRACT FROM AUTHOR]

In this report, we evaluate potential tsunami hazards for southeastern Alaska communities of Elfin Cove, Gustavus, and Hoonah and numerically model the extent of inundation from tsunami waves generated by tectonic and landslide sources. We perform numerical modeling of historic tsunami events, such as the tsunami triggered by the 1964 Great Alaska Earthquake, and the tsunami waves generated by the recent 2011 Tohoku and 2012 Haida Gwaii earthquakes. Hypothetical tsunami scenarios include variations of the extended 1964 rupture, megathrust earthquakes in the Prince William Sound and Alaska Peninsula regions, and a Cascadia megathrust earthquake. Local underwater landslide events in Taylor Bay and Port Frederick, and a rockslide in Tidal Inlet are also considered as possible tsunamigenic scenarios. Numerical modeling results, combined with historical observations in the region, are intended to provide guidance to local emergency management in tsunami hazard assessment, evacuation planning, and public education for the reduction of future tsunami risk. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate potential tsunami hazards for the community of Sitka. We numerically model the extent of inundation from tsunami waves generated by near- and far-fi eld tectonic sources. We performed numerical modeling of historic events at Sitka, such as the tsunami triggered by the 1964 Great Alaska Earthquake, and the tsunami waves generated by the recent 2011 Tohoku and 2012 Haida Gwaii earthquakes. Hypothetical tsunami scenarios include variations of the extended 1964 rupture, megathrust earthquakes in the Alaska Peninsula region and in the Cascadia subduction zone, and a thrust earthquake in the region of the Queen Charlotte--Fairweather fault zone. Results of numerical modeling combined with historical observations in the region are intended to provide guidance to local emergency management in tsunami hazard assessment, evacuation planning, and public education for the reduction of future tsunami risk. [ABSTRACT FROM AUTHOR]