General maximum likelihood empirical Bayes estimation of normal means

We propose a general maximum likelihood empirical Bayes (GMLEB) method for the estimation of a mean vector based on observations with i.i.d. normal errors. We prove that under mild moment conditions on the unknown means, the average mean squared error (MSE) of the GMLEB is within an infinitesimal fraction of the minimum average MSE among all separable estimators which use a single deterministic estimating function on individual observations, provided that the risk is of greater order than $(\log n)^5/n$. We also prove that the GMLEB is uniformly approximately minimax in regular and weak $\ell_p$ balls when the order of the length-normalized norm of the unknown means is between $(\log n)^{\kappa_1}/n^{1/(p\wedge2)}$ and $n/(\log n)^{\kappa_2}$. Simulation experiments demonstrate that the GMLEB outperforms the James--Stein and several state-of-the-art threshold estimators in a wide range of settings without much down side.Comment: Published in at http://dx.doi.org/10.1214/08-AOS638 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Coalescence of Carbon Atoms on Cu (111) Surface: Emergence of a Stable Bridging-Metal Structure Motif

By combining first principles transition state location and molecular dynamics simulation, we unambiguously identify a carbon atom approaching induced bridging metal structure formation on Cu (111) surface, which strongly modify the carbon atom coalescence dynamics. The emergence of this new structural motif turns out to be a result of the subtle balance between Cu-C and Cu-Cu interactions. Based on this picture, a simple theoretical model is proposed, which describes a variety of surface chemistries very well

Spatial variation in aragonite saturation state and the influencing factors in Jiaozhou Bay, China

Both natural processes and human activities affect seawater calcium carbonate saturation state (Ωarag), while the mechanisms are still far from being clearly understood. This study analysed the seawater surface Ωarag during summer and winter in Jiaozhou Bay (JZB), China, based on two cruises observations performed in January and June 2017. The ranges of Ωarag values were 1.55~2.92 in summer and 1.62~2.15 in winter. Regression analyses were conducted to identify the drivers of the change of Ωarag distribution, and then the relative contributions of temperature, mixing processes and biological processes to the spatial differences in Ωarag were evaluated by introducing the difference between total alkalinity (TA) and dissolved inorganic carbon (DIC) as a proxy for Ωarag. The results showed that biological processes were the main factor affecting the spatial differences in Ωarag, with relative contributions of 70% in summer and 50% in winter. The contributions of temperature (25% in summer and 20% in winter) and the mixing processes (5% in summer and 30% in winter) were lower. The increasing urbanization in offshore areas can further worsen acidification, therefore environmental protection in both offshore and onshore is needed

Spurious Relationship of Long Memory Sequences in Presence of Trends Breaks

This article extends the theoretical analysis of spurious relationship and considers the situation where the deterministic components of the processes generating the individual series are long memory sequences with structural changes. Show it by using the ordinary least squares estimator, the t-statistics become divergent and pseudo correlation. However, two long memory time series having change points can produce spurious regression. In the presence of structural change points, confirm the rate of t-statistic tends to infinity increased with the increase in sample size. Numerical simulation results show that when structural changes are a feature of the data, the presence of spurious relationship is unambiguous. And the spurious regression not only depends on long memory indexes, but also for trend of model is also very sensitive

Tangeritin attenuates oxidative stress, apoptosis and inflammation in cadmium-induced cardiotoxicity in rats by activating Nrf2 signaling pathway

Purpose: To determine the effect of tangeritin on cadmium-induced cardiotoxicity in rats.Methods: Cardiotoxicity was induced by intra-gastric administration of 5 mg/kg cadmium chloride to rats, once daily for 4 weeks. The animals were treated with tangeritin at 10 and 20 mg/kg p.o. 60 min before the administration of cadmium, for 4 weeks. Thereafter, the concentrations of cadmium in serum and cardiac tissue were determined, and markers of cardiac function, antioxidant enzyme activities and levels of pro-inflammatory mediators were evaluated in cardiac tissues. Histopathological examination and western blot assay were also performed.Results: Treatment with tangeritin significantly decreased the cadmium levels in the heart tissue and serum of the cadmium-exposed rats, when compared to the negative control group (p < 0.01). There was significant decrease in cardiac function markers in the tangeritin-treated rats, relative to negative control group (p < 0.01). However, antioxidant enzyme activity and levels of pro-inflammatory mediators were attenuated in the cardiac tissues of cadmium-treated rats by tangeritin treatment. Expressions of HO-1 and Nrf-2 were significantly enhanced in the cardiac tissues of tangeritin-treated group, relative to negative control group (p < 0.01). Histopathology revealed that tangeritin attenuated cadmium-induced cardiac injury in cadmium-exposed rats.Conclusion: These results demonstrate the protective effect of tangeritin against cadmium-induced cardiotoxicity via attenuation of oxidative stress and pro-inflammatory mediators.Keywords: Tangeritin, Cadmium, Cardiotoxicity, Oxidative stress, Anti-inflammatio

Mutual fund ownership, firm specific information, and firm performance: evidence from China

This paper shows empirically that the positive association between mutual fund ownership and firm value in China is mainly driven by the informed trading of mutual funds. Utilizing the unique short term feature of mutual fund holdings for the period from 2001 to 2010, we provide an informational link between a decomposed component of market-to-book ratio (firm specific valuation component) and mutual fund holdings. Specifically, we find that firms with a higher level of mutual fund ownership are associated with a higher specific value. Moreover, the positive association between the specific value of a firm and mutual fund ownership is more pronounced in firms with a higher level of specific information (or higher idiosyncratic volatility). We argue that in an emerging market such as China, mutual funds help to improve market efficiency by incorporating private information into stock prices through their informed trading although they are really a lack of incentive to monitor management