Vector Dark Matter Detection using the Quantum Jump of Atoms

The hidden sector U(1) vector bosons created from inflationary fluctuations can be a substantial fraction of dark matter if their mass is around $10^{-5}$eV. The creation mechanism makes the vector bosons' energy spectral density $\rho_{cdm}/\Delta E$ very high. Therefore, the dark electric dipole transition rate in atoms is boosted if the energy gap between atomic states equals the mass of the vector bosons. By using the Zeeman effect, the energy gap between the 2S state and the 2P state in hydrogen atoms or hydrogen like ions can be tuned. The $2S$ state can be populated with electrons due to its relatively long life, which is about $1/7$s. When the energy gap between the semi-ground $2S$ state and the 2P state matches the mass of the cosmic vector bosons, induced transitions occur and the 2P state subsequently decays into the 1S state. The $2P\to1S$ decay emitted Lyman-$\alpha$ photons can then be registered. The choices of target atoms depend on the experimental facilities and the mass ranges of the vector bosons. Because the mass of the vector boson is connected to the inflation scale, the proposed experiment may provide a probe to inflation.Comment: 5 pages, 3 figures; references added; matches version published in PL

Land Rental Market and Rural Economic Development : Evidence from Rural Chongqing, China

This study investigates the role of the land rental market in rural economic development with the province Chongqing, China, as case study region. The study focuses on the question participation in the land rental market can improve agricultural production efficiency and alleviate income inequality in rural areas. Finally, the factors that affect rental market participation of farm households are examined. A stochastic frontier approach was employed to measure effect of the land rental market participation on agricultural productivity. Two competing hypotheses are tested: 1) Less efficient farm households rent out land to more efficient farm households and agricultural productivity is improved; 2) More efficient farm households rent out land and work off of farm, which results in lower agricultural productivity. The results showed that both of these hypotheses are possibly true, but more efficient farm households are more likely to rent land rather than rent it out, which implies the productivity enhancive effect of land rental market. To investigate the impact of land rental market development on rural income distribution, firstly the income inequality was decomposed to measure the contribution of land rental income to total income inequality and the interactions between land rental income and other income sources. Then, relying on the inequality index calculated, a fixed effect model was used to investigate the impact of participation in the land rental market and land rental market imperfection on income inequality index. The results showed that contribution of land rental income to total income inequality is increasing over the observation period. And participation in land rental market may reduce income inequality, given an imperfect land rental market. Deriving from a farm household model, farm households’ supply and demand decisions in land rental market were explored. The multinomial Logit model is used to examine factors that influence farm household participation probability in the land rental market. Tobit models are employed to measure the impact on the quantity of renting and renting out by farm households. Results show the importance of off-farm work wage and off-farm labor market imperfection in defining the rental behavior of farm households: it prevents farm households from renting land and encourage them to rent out. Simulation results show that rising off-farm work wages and participation rate in the off-farm labor market lead to a lower equilibrium land rent in a closed economy

Coupled molecular dynamics mediates interaction between long-range mutations and its application in enzyme engineering

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Fluctuation Theorems and Thermodynamic Inequalities for Nonequilibrium Processes Stopped at Stochastic Times

We investigate thermodynamics of general nonequilibrium processes stopped at stochastic times. We propose a systematic strategy for constructing fluctuation-theorem-like martingales for each thermodynamic functional, yielding a family of stopping-time fluctuation theorems. We derive second-law-like thermodynamic inequalities for the mean thermodynamic functional at stochastic stopping times, the bounds of which are stronger than the thermodynamic inequalities resulting from the traditional fluctuation theorems when the stopping time is reduced to a deterministic one. Numerical verification is carried out for three well-known thermodynamic functionals, namely, entropy production, free energy dissipation and dissipative work. These universal equalities and inequalities are valid for arbitrary stopping strategies, and thus provide a comprehensive framework with new insights into the fundamental principles governing nonequilibrium systems.Comment: 7 pages, 2 figure

Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method.

Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm(2) at a current density of 3 mA/cm(2) when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm(2), and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work