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Beijing Normal University , colloqiually known as 北师大 or Beishida, is a public research university located in Beijing with strong emphasis on basic disciplines of humanities and science. It is one of the oldest and most prestigious universities in China.A normal school referred to an institution that aimed to train school teachers in the early twentieth century, and this terminology is preserved in the official names of such institutions in China. Wikipedia.

Zhang Y.,Beijing Normal University | Wan W.-H.,Beijing Institute of Technology
Frontiers of Physics | Year: 2014

A network is named as mixed network if it is composed of N nodes, the dynamics of some nodes are periodic, while the others are chaotic. The mixed network with all-to-all coupling and its corresponding networks after the nonlinearity gap-condition pruning are investigated. Several synchronization states are demonstrated in both systems, and a first-order phase transition is proposed. The mixture of dynamics implies any kind of synchronous dynamics for the whole network, and the mixed networks may be controlled by the nonlinearity gap-condition pruning. © 2014, Higher Education Press and Springer-Verlag Berlin Heidelberg.

Li S.,China National Institute of Biological Sciences | Li S.,Beijing Normal University | Duan J.,China National Institute of Biological Sciences | Li D.,China National Institute of Biological Sciences | And 3 more authors.
Genes and Development | Year: 2011

Box H/ACA ribonucleoprotein particles (RNPs) mediate pseudouridine synthesis, ribosome formation, and telomere maintenance. The structure of eukaryotic H/ACA RNPs remains poorly understood. We reconstituted functional Saccharomyces cerevisiae H/ACA RNPs with recombinant proteins Cbf5, Nop10, Gar1, and Nhp2 and a two-hairpin H/ACA RNA; determined the crystal structure of a Cbf5, Nop10, and Gar1 ternary complex at 1.9 Å resolution; and analyzed the structure-function relationship of the yeast complex. Although eukaryotic H/ACA RNAs have a conserved two-hairpin structure, isolated single-hairpin RNAs are also active in guiding pseudouridylation. Nhp2, unlike its archaeal counterpart, is largely dispensable for the activity, reflecting a functional adaptation of eukaryotic H/ACA RNPs to the variable RNA structure that Nhp2 binds. The N-terminal extension of Cbf5, a hot spot for dyskeratosis congenita mutation, forms an extra structural layer on the PUA domain. Gar1 is distinguished from the assembly factor Naf1 by containing a C-terminal extension that controls substrate turnover and the Gar1-Naf1 exchange during H/ACA RNP maturation. Our results reveal significant novel features of eukaryotic H/ACA RNPs. © 2011 by Cold Spring Harbor Laboratory Press ISSN 0890-9369/11.

Wang K.,Beijing Normal University | Dickinson R.E.,University of Texas at Austin
Reviews of Geophysics | Year: 2012

This review surveys the basic theories, observational methods, satellite algorithms, and land surface models for terrestrial evapotranspiration, E (or E, i.e., latent heat flux), including a long-term variability and trends perspective. The basic theories used to estimate E are the Monin-Obukhov similarity theory (MOST), the Bowen ratio method, and the Penman-Monteith equation. The latter two theoretical expressions combine MOST with surface energy balance. Estimates of E can differ substantially between these three approaches because of their use of different input data. Surface and satellite-based measurement systems can provide accurate estimates of diurnal, daily, and annual variability of E. But their estimation of longer time variability is largely not established. A reasonable estimate of E as a global mean can be obtained from a surface water budget method, but its regional distribution is still rather uncertain. Current land surface models provide widely different ratios of the transpiration by vegetation to total E. This source of uncertainty therefore limits the capability of models to provide the sensitivities of E to precipitation deficits and land cover change. © 2012 by the American Geophysical Union.

Dong W.,Beijing Normal University | Jiang Y.,National Climate Center | Yang S.,National Oceanic and Atmospheric Administration
Climatic Change | Year: 2010

The climatic seasons in China, defined by station-specific daily temperature measures, have changed substantially during the past decades. In the majority of the country, the length of summer has extended and the length of winter has shortened since the 1950s. These changes in the lengths of seasons are linked to the changes in the starting dates of seasons. Namely, the starting date of summer has advanced and the starting date of winter has shifted back. Averaged across the whole country, the starting date of summer has been brought forward by 5. 8 days and the season has extended 9 days. On the other hand, the starting date of winter has been delayed by 5. 6 days and the season has shortened by 11 days. The changes for spring and fall are relatively smaller. Particularly, spring has started earlier by 5. 7 days but shortened by 0. 3 day, and fall has started later by 3. 2 days but lengthened by 2. 3 days. The changes in seasons exhibit apparent regional differences. They are more significant in the north than in the south where the trend of some local changes in seasons is opposite to that of the rest of the country. © 2009 Springer Science+Business Media B.V.

He Q.,Shanghai JiaoTong University | Cui B.,Beijing Normal University | An Y.,Shanghai JiaoTong University
Journal of Vegetation Science | Year: 2011

Question: What are the interactive roles of abiotic stress and plant interactions in mediating the zonation of the shrub Tamarix chinensis along a salinity gradient? Location: Yellow River estuary (37°46'N, 119°09'E), northeast China. Methods: We surveyed the zonation of T. chinensis along a salinity gradient and quantified its salt tolerance using a pot experiment. In two field experiments, we transplanted T. chinensis seedlings into salt marsh, transitional zone and upland habitats, manipulated neighbours and quantified survivorship and biomass to examine neighbour effects. We also quantified vegetation effects on abiotic conditions in each zone. Results: Tamarix chinensis dominated the transitional zone, but was absent in upland and salt marsh habitats. In the pot experiment, T. chinensis grew well in freshwater treatments, but was inhibited by increasing salinity. Field experiments revealed that competition from neighbours limited T. chinensis growth in the uplands, while T. chinensis transplants were limited, with or without neighbours, in the salt marsh by high soil salinity. In the transitional zone, however, T. chinensis transplants performed better with than without neighbours. Vegetation removal significantly elevated soil salinity in the transitional zone, but not in other zones. Conclusions: Competition, facilitation and abiotic stress are all important in mediating the zonation of T. chinensis. Within its physiological stress tolerance range, or fundamental niche, it is limited by plant competition in low salinity habitats, and facilitated by neighbours in high salt stress habitats, but cannot survive in salt marshes having salinities above its salt stress tolerance limit. Our results have implications for understanding the relationships between facilitation and stress gradients. © 2011 International Association for Vegetation Science.

In the past three decades, the electric energy industry made great contribution to support rapid social and economic development in China, and meanwhile has been grown at the highest rate in the human history owing to the economic reform. In its new national development plan, more investment has been put into installation of both electricity generating capacity and transmitting capacity in order to meet fast growing demand of electric energy. However, energy resources, both fossil fuel and renewable types, and energy consumption and load centers in China are not evenly distributed in both spatial and temporal dimensions. Moreover, dominated by coal as its primary energy source, the whole eastern China is now entering an environmental crisis in which pollutants emitted by coal power plants contribute a large part. To balance the regional differences in energy sources and energy consumption while meeting the steadily increasing demands for electric energy for the whole country, in addition to increase electric generating capacity, building large-scale, long-distance ultra high voltage power grids is the top priority for next five years.China is a country prone to almost all kinds of natural disasters due to its vast, complex geographical and climatic conditions. In recent years, frequent natural disasters, especially extreme weather and climate events, have threatened the safety, reliability and stability of electric energy system in China. Unfortunately, with fast growth rate but lacking of risk assessing and prevention mechanism, many infrastructure constructions, including national power grids, are facing integrated and complex economic, social, institutional and ecological risks.In this paper, based on a case analysis of the Great Ice Storm in southern China in January 2008, risks of building a resilient power grid to deal with increasing threats from extreme weathers are discussed. The paper recommends that a systematic approach based on the social-ecological system framework should be applied to assess the risk factors associated with the power grid, and the tools to deal with complex dynamic systems need to be applied to deal with constant changes in the whole social-ecological system. © 2014, EDP Sciences and Springer.

Liu P.S.,Beijing Normal University
Materials Science and Engineering A | Year: 2010

Porous metal foams with isotropic three-dimensional reticulated structure are excellent engineering materials with dual attributes of structural and functional characteristics, and they may bear shearing or torsional or bending loads when they are used as engineering components in various cases. With the octahedral model, the mechanical behavior is investigated for the component of these materials under shearing loads, the loading state of struts within the porous body is analyzed for these materials under torsion, and the mechanical performance is further discussed for these materials under bending moment based on their properties of uniaxial tension and compression. Using the simple manner of segregating analysis, the relevant mechanical relationships are respectively derived from the corresponding mathematical deduction for these materials under those loads. The results show that, when the porous body endures the fracture resulting from shearing loads or from torsion, the maximum nominal shearing stress or the nominal torque for the porous component can be described with the porosity and the inherent characteristic parameters of the metal foam itself. Also, the applicable maximum nominal bending moment can be expressed as a function of the porosity for the metal foams under bending moment. This mathematical relationship may be regarded as the extension of the expression about the relationship between the maximum nominal stress and the porosity for these materials under uniaxial tensile and compressive loads. From these mathematical relations, the loading criterions may be directly and conveniently achieved for these materials under the corresponding loads, respectively. © 2010.

Artymowski M.,Beijing Normal University | Lalak Z.,University of Warsaw
Journal of Cosmology and Astroparticle Physics | Year: 2014

The standard Starobinsky inflation has been extended to the R + α Rn - β R2-n model to obtain a stable minimum of the Einstein frame scalar potential of the auxiliary field. As a result we have obtained obtain a scalar potential with non-zero value of residual vacuum energy, which may be a source of Dark Energy. Our results can be easily consistent with PLANCK or BICEP2 data for appropriate choices of the value of n.

Shao J.,Beijing Normal University
Chemical Physics | Year: 2010

It is shown that the real Gaussian stationary process with zero mean can be exactly interpreted as a convolution defined by its covariance and a complex white noise plus the conjugate pair of the complex white noise. When the algorithm for generating the white noise is given, such a representation thereby offers a direct and convenient technique to numerically simulate Gaussian processes with arbitrary correlations. Moreover, the fast Fourier transform can be invoked for solving the convolution, which leads to a feasible implementation of the simulation method. As a primary test, a Gaussian process in quantum dissipation is simulated. This stochastic process has an infinitely long correlation time and is hardly treated by other approaches. © 2010 Elsevier B.V. All rights reserved.

Guo H.,Beihang University | Shen S.-Q.,University of Hong Kong | Feng S.,Beijing Normal University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We show the existence of the fractional topological phase (FTP) in a one-dimensional interacting fermion model using exact diagonalization, in which the noninteracting part has flat bands with nontrivial topology. In the presence of the nearest-neighboring interaction V 1, the FTP at filling factor ν=1/3 appears. It is characterized by the threefold degeneracy and the quantized total Berry phase of the ground states. The FTP is destroyed by a next-nearest-neighboring interaction V 2, and the phase diagrams in the (V 1,V 2) plane are determined. We also present a physical picture of the phase and discuss its existence in the nearly flat band. Within the picture, we argue that the FTP at other filling factors can be generated by introducing proper interactions. The present study contributes to a systematic understanding of the FTPs and can be realized in cold-atom experiments. © 2012 American Physical Society.

Cheng W.,Beijing Normal University | Ren S.-F.,Illinois State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Phonons of single quintuple films of Bi2Te3 and Bi2Se3 and corresponding bulk materials are calculated in detail by MedeA (a trademark of Materials Design) and Vienna ab initio simulation package (VASP). The calculated results with and without spin-orbit couplings are compared, and the important roles that the spin-orbit coupling plays in these materials are discussed. A symmetry breaking caused by the anharmonic potentials around Bi atoms in the single quintuple films is identified and discussed. The observed Raman intensity features in Bi 2Te3 and Bi2Se3 quintuple films are explained. © 2011 American Physical Society.

Guo H.,Capital Normal University | Feng S.,Beijing Normal University | Shen S.-Q.,University of Hong Kong
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We conducted a comparative study of the quantum spin Hall (QSH) effects induced by nonmagnetic and magnetic staggered potentials, respectively, and show that they have the same effect in driving the topological phase transition. The result implies that both time-reversal (T) preserving and breaking systems can host a QSH effect. We also investigate the stability of the resulting QSH effect for disorder and find that, for T invariant systems, the edge states are always robust while those of the T breaking system are also robust if there is additional symmetry in the system. © 2011 American Physical Society.

Tu Z.C.,Beijing Normal University | Tu Z.C.,CAS Institute of Theoretical Physics
Journal of Chemical Physics | Year: 2010

Only some special open surfaces satisfying the shape equation of lipid membranes can be compatible with the boundary conditions. As a result of this compatibility, the first integral of the shape equation should vanish for axisymmetric lipid membranes, from which two theorems of nonexistence are verified: (i) there is no axisymmetric open membrane being a part of torus satisfying the shape equation; (ii) there is no axisymmetric open membrane being a part of a biconcave discodal surface satisfying the shape equation. Additionally, the shape equation is reduced to a second-order differential equation while the boundary conditions are reduced to two equations due to this compatibility. Numerical solutions to the reduced shape equation and boundary conditions agree well with the experimental data [A. Saitoh, Proc. Natl. Acad. Sci. U.S.A. 95, 1026 (1998)]. © 2010 American Institute of Physics.

Zhang Q.-G.,Beijing Normal University | Buckling A.,University of Oxford | Buckling A.,University of Exeter
Ecology Letters | Year: 2011

Understanding the conditions under which rapid evolutionary adaptation can prevent population extinction in deteriorating environments (i.e. evolutionary rescue) is a crucial aim in the face of global climate change. Despite a rapidly growing body of work in this area, little attention has been paid to the importance of interspecific coevolutionary interactions. Antagonistic coevolution commonly observed between hosts and parasites is likely to retard evolutionary rescue because it often reduces population sizes, and results in the evolution of costly host defence and parasite counter-defence. We used experimental populations of a bacterium Pseudomonas fluorescens SBW25 and a bacteriophage virus (SBW25Φ2), to study how host-parasite coevolution impacts viral population persistence in the face of gradually increasing temperature, an environmental stress for the virus but not the bacterium. The virus persisted much longer when it evolved in the presence of an evolutionarily constant host genotype (i.e. in the absence of coevolution) than when the bacterium and virus coevolved. Further experiments suggest that both a reduction in population size and costly infectivity strategies contributed to viral extinction as a result of coevolution. The results highlight the importance of interspecific evolutionary interactions for the evolutionary responses of populations to global climate change. © 2011 Blackwell Publishing Ltd/CNRS.

Shao J.,Beijing Normal University
Chemical Physics | Year: 2010

The stochastic description of dissipative dynamics for both quantum and classical systems is revisited by using Itô calculus. A procedure to work out the master equation for linear systems based on this scheme is outlined. For the Caldeira-Leggett model it is shown that the master equation describing pure dephasing is Markovian-like and the solution is given. The Caldeira-Leggett master equation for Ohmic dissipation, which is valid at high temperatures, is derived. © 2009 Elsevier B.V. All rights reserved.

Guo T.,Beijing Normal University | Misra M.,Pennsylvania State University | Tam J.W.,Pennsylvania State University | Tam J.W.,Washington State University | Kroll J.F.,Pennsylvania State University
Journal of Experimental Psychology: Learning Memory and Cognition | Year: 2012

In 2 experiments, relatively proficient Chinese-English bilinguals decided whether Chinese words were the correct translations of English words. Critical trials were those on which incorrect translations were related in lexical form or meaning to the correct translation. In Experiment 1, behavioral interference was revealed for both distractor types, but event-related potentials (ERPs) revealed a different time course for the 2 conditions. Semantic distractors elicited effects primarily on the N400 and late positive component (LPC), with a smaller N400 and a smaller LPC over the posterior scalp but a larger LPC over the anterior scalp relative to unrelated controls. In contrast, translation form distractors elicited a larger P200 and a larger LPC than did unrelated controls. To determine whether the translation form effects were enabled by the relatively long, 750-ms stimulus onset asynchrony (SOA) between words, a 2nd ERP experiment was conducted using a shorter, 300-ms, SOA. The behavioral results revealed interference for both types of distractors, but the ERPs again revealed different loci for the 2 effects. Taken together, the data suggest that proficient bilinguals activate 1st-language translations of words in the 2nd language after they have accessed the meaning of those words. The implications of this pattern for claims about the nature of cross-language activation when bilinguals read in 1 or both languages are discussed. © 2012 American Psychological Association.

A chemical kinetic submechanism proposed here is an essential prerequisite to model autoignition of methyl esters at low temperature region (less than ~900K), where reactions of methyl-ester peroxy radicals (ROO) and hydroperoxy methyl-ester radicals (QOOH) are crucial and relatively unexplored. The potential energy surfaces of the methyl butanoate peroxy radicals+O2 systems are computed by the G3MP2B3 composite approach. 114 pathways are identified leading to the formation of key radicals in the ignition kernel such as OH and HO2.Particular attention is focused on: (1) intramolecular H-migration of ROO, (2) unimolecular dissociations of ROO and QOOH and (3) reactions of ROO+HO2. Using the canonical transition state theory, the high-pressure limit rate constants for reactions in the kinetic submechanism are calculated. Standard enthalpy of formation, entropy and heat capacities are evaluated for intermediates and products formed during combustion by means of the standard statistical mechanics formulae. The agreement and disagreement between our calculated kinetic parameters and previous estimates offer further insight into the uncertainty associated with theoretical estimation. We perform the branching ratio analysis for the competing channels between the reverse dissociation of ROO (ROO→R+O2) and explored unimolecular reactions decomposing ROO. Additionally, we also quantify the similarity and dissimilarity between the rate constants determined here and those previously calculated for normal alkanes. Finally, the effect of transition state size on the rate constants for the isomerizations of methyl-ester peroxy radicals is systematically analyzed. © 2014 The Combustion Institute.

Lu H.,Beijing Normal University | Perkins A.,Imperial College London | Pope C.N.,Texas A&M University | Pope C.N.,University of Cambridge | Stelle K.S.,Imperial College London
Physical Review Letters | Year: 2015

Extensions of Einstein gravity with higher-order derivative terms arise in string theory and other effective theories, as well as being of interest in their own right. In this Letter we study static black-hole solutions in the example of Einstein gravity with additional quadratic curvature terms. A Lichnerowicz-type theorem simplifies the analysis by establishing that they must have vanishing Ricci scalar curvature. By numerical methods we then demonstrate the existence of further black-hole solutions over and above the Schwarzschild solution. We discuss some of their thermodynamic properties, and show that they obey the first law of thermodynamics. © 2015 American Physical Society.

Lexical Pragmatics has focused to date on implicature by inference in lexicon and the pragmatic presupposition on statements related to sentences (utterances) and text (discourse). This paper aims to address an issue to be termed Lexical Presupposition (LP). The study elaborates on an extended notion of presupposition in the categorization construed in lexis in a historical context on a cognitive basis. In particular, it discusses LP in terms of ostensive inferences in ancient Chinese categorization: the functions of the radicals in their derivatives in Shuowen Jiezi. In fact, these radicals work to constitute a ground-figure opposition with the most salient and characteristic features resembling statement assertions in sentences, which may be called lexical assertions, or LAs, i.e., 'there is LP' and 'LP have/be/do LA' or LA (LP). This propositional analogy aims to recover or reconstruct the possible historical mechanisms of categorization and to analyze three general groups of LPs that contain a number of sub-types: constitutional (meronymic, taxonomic, material), manner (means [agent, instrument, and medium] and comparison-and-contrast), and other minor ones. In these processes, metaphors play an important role. The findings of this paper should be applicable to word formation in other languages, such as Indo-European languages. © 2015 Elsevier B.V.

Zhang Q.-G.,Beijing Normal University | Buckling A.,University of Exeter
Evolutionary Applications | Year: 2012

The evolution of multi-antibiotic resistance in bacterial pathogens, often resulting from de novo mutations, is creating a public health crisis. Phages show promise for combating antibiotic-resistant bacteria, the efficacy of which, however, may also be limited by resistance evolution. Here, we suggest that phages may be used as supplements to antibiotics in treating initially sensitive bacteria to prevent resistance evolution, as phages are unaffected by most antibiotics and there should be little cross-resistance to antibiotics and phages. In vitro experiments using the bacterium Pseudomonas fluorescens, a lytic phage, and the antibiotic kanamycin supported this prediction: an antibiotic-phage combination dramatically decreased the chance of bacterial population survival that indicates resistance evolution, compared with antibiotic treatment alone, whereas the phage alone did not affect bacterial survival. This effect of the combined treatment in preventing resistance evolution was robust to immigration of bacteria from an untreated environment, but not to immigration from environment where the bacteria had coevolved with the phage. By contrast, an isogenic hypermutable strain constructed from the wild-type P. fluorescens evolved resistance to all treatments regardless of immigration, but typically suffered very large fitness costs. These results suggest that an antibiotic-phage combination may show promise as an antimicrobial strategy. © 2012 Blackwell Publishing Ltd.

Mishra A.,University of Missouri | Li A.,University of Missouri | Jiang B.W.,Beijing Normal University
Astrophysical Journal | Year: 2015

The mysterious "21 μm" emission feature seen almost exclusively in the short-lived protoplanetary nebula (PPN) phase of stellar evolution remains unidentified since its discovery two decades ago. This feature is always accompanied by the equally mysterious, unidentified "30 μm" feature and the so-called "unidentified infrared" (UIR) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm which are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The 30 μm feature is commonly observed in all stages of stellar evolution from the asymptotic giant branch through PPN to the planetary nebula phase. We explore the interrelations among the mysterious 21, 30 μm, and UIR features of the 21 μm sources. We derive the fluxes emitted in the observed UIR, 21, and 30 μm features from published Infrared Space Observatory or Spitzer/IRS spectra. We find that none of these spectral features correlate with each other. This argues against a common carrier (e.g., thiourea) for both the 21 μm feature and the 30 μm feature. This also does not support large PAH clusters as a possible carrier for the 21 μm feature. © 2015. The American Astronomical Society. All rights reserved.

Ye Z.,Beijing Normal University
Computers and Mathematics with Applications | Year: 2015

In this paper we establish the regularity criteria of solutions to the three space dimensions generalized viscous Hall-magnetohydrodynamics. Moreover, we also prove that there exist classical solutions globally in time to the generalized viscous Hall-MHD if the initial data is small enough or the fractional Laplacian dissipation powers α and β are suitably large. These results are some improvements of very recent work (Chae and Lee, 2014) established by Chae and Lee. © 2015 Elsevier Ltd.

Liu W.,Beijing Normal University | Liu W.,Bielefeld University
Infinite Dimensional Analysis, Quantum Probability and Related Topics | Year: 2010

In this paper we investigate some regularity property for the solution to SPDE. Under certain assumptions we prove that the solution of an SPDE takes values in some subspace of the original state space if the initial condition does so. As examples, the main result is applied to different types of SPDE such as stochastic reaction-diffusion equations, the stochastic p-Laplace equation, stochastic porous media and fast diffusion equations in Hilbert space. © 2010 World Scientific Publishing Company.

Grainger S.,Center for Australian Weather and Climate Research | Frederiksen C.S.,Center for Australian Weather and Climate Research | Zheng X.,Beijing Normal University
Climate Dynamics | Year: 2013

An assessment is made of the modes of interannual variability in the seasonal mean summer and winter Southern Hemisphere 500 hPa geopotential height in the twentieth century in models from the Coupled Model Intercomparison Project phase 3 (CMIP3) dataset. The analysis is done for both the intraseasonal and slow components of the geopotential height. When the CMIP3 models are assessed against reanalysis data, the spatial structure and variance of the leading modes in the intraseasonal component are generally well reproduced. There are systematic differences between the models in their reproduction of the leading modes in the slow component. An overall score using the leading modes in the slow component allows a categorisation of CMIP3 model performance. Using an ensemble from four models that suitably reproduce the twentieth century modes, modes of variability in the slow-internal and slow-external components are estimated. The leading mode of the slow-external component is shown to be related to observed changes in greenhouse gas concentrations. In this ensemble, there is little change in the leading modes in the intraseasonal component in the twenty-first century. Larger changes in variance, and subtle changes in regional-scale structure, are found for the leading modes in the slow-internal component. These are related to changes in the slowly varying dynamics of the Southern Annular Mode and the El Niño-Southern Oscillation. By far the biggest change is in the leading mode of the slow-external component. The spatial structure becomes uniform in the twenty-first century, and the variance increases with increasing greenhouse gas concentrations. © 2013 Springer-Verlag Berlin Heidelberg.

Wang K.,Beijing Normal University | Dickinson R.E.,University of Texas at Austin
Reviews of Geophysics | Year: 2013

Atmospheric downward longwave radiation at the surface (Ld) varies with increasing CO2 and other greenhouse gases. This study quantifies the uncertainties of current estimates of global Ld at monthly to decadal timescales and its global climatology and trends during the past decades by a synthesis of the existing observations, reanalyses, and satellite products. We find that current Ld observations have a standard deviation error of ~3.5 W m-2 on a monthly scale. Observations of Ld by different pyrgeometers may differ substantially for lack of a standard reference. The calibration of a pyrgeometer significantly affects its quantification of annual variability. Compared with observations collected at 169 global land sites from 1992 to 2010, the L d derived from state-of-the-art satellite cloud observations and reanalysis temperature and humidity profiles at a grid scale of ~1° has a bias of ±9 W m-2 and a standard deviation of 7 W m -2, with a nearly zero overall bias. The standard deviations are reduced to 4 W m-2 over tropical oceans when compared to L d observations collected by 24 buoy sites from 2002 to 2011. The -4 W m-2 bias of satellite Ld retrievals over tropical oceans is likely because of the overestimation of Ld observations resulting from solar heating of the pyrgeometer. Our best estimate of global means L d from 2003 to 2010 are 342 ± 3 W m-2 (global), 307 ± 3 W m-2 (land), and 356 ± 3 W m-2 (ocean). Estimates of Ld trends are seriously compromised by the changes in satellite sensors giving changes of water vapor profiles. Key Points Ld observations have a standard deviation error of ~3.5 W m-2 at a monthly scale Satellite and reanalysis Ld has a standard deviation of 7 W m-2 Global mean Ld is 342 W m-2 (global), 307 W m-2 (land), and 356 W m-2 (ocean) ©2013. American Geophysical Union. All Rights Reserved.

Li D.,Yanshan University | Li X.,Beijing Normal University | Hagihira S.,Osaka University | Sleigh J.W.,Waikato Hospital
British Journal of Anaesthesia | Year: 2013

BackgroundFourier bicoherence has previously been applied to investigate phase coupling in the EEG in anaesthesia. However, there are significant theoretical limitations regarding its sensitivity in detecting transient episodes of inter-frequency coupling. Therefore, we used a recently developed wavelet bicoherence method to investigate the cross-frequency coupling in the EEG of patients under isoflurane anaesthesia; examining the relationship between the patterns of wavelet bicoherence and the isoflurane concentrations.MethodsWe analysed a set of previously published EEG data, obtained from 29 patients who underwent elective abdominal surgery under isoflurane anaesthesia. Artifact-free, 1 min EEG segments at different isoflurane concentrations were extracted from each subject and the wavelet bicoherence calculated for all pairs of frequencies from 0.5 to 20 Hz.ResultsIsoflurane caused two peaks in the α (6-13 Hz) and slow δ (<1 Hz) regions of the bicoherence matrix diagonal. Higher concentrations of isoflurane shifted the α peak to lower frequencies [11.3 (0.9) Hz at 0.3% to 7.1 (1.2) Hz at 1.5%], as has been previously observed in the power spectra. Outside the diagonal, we also found a significant α peak that was phase-coupled to the slow δ waves; higher concentrations of isoflurane shifted this peak to lower frequencies [10.8 (1.2) to 7.7 (0.7) Hz].ConclusionsIsoflurane caused cross-frequency coupling between α and slow δ waves. Increasing isoflurane concentration slowed the α frequencies where the coupling had occurred. This phenomenon of α-δ coupling suggests that slow cortical oscillations organize the higher α band activity, which is consistent with other studies in natural sleep. © The Author [2012].

Hao Z.,Beijing Normal University | Singh V.P.,Texas A&M University
Journal of Hydrology | Year: 2015

Drought is a recurring natural phenomenon that has plagued the civilization throughout its history. Due to the complex nature and widespread impacts of drought, there is a lack of universally accepted definition of drought, which also affects the development of drought indices to characterize drought conditions. Because an individual drought indicator is generally not sufficient for characterizing complex drought conditions and impacts, multiple drought-related variables and indices are required to capture different aspects of complicated drought conditions. To address this issue, a variety of multivariate drought indices have been developed recently to combine multiple drought-related variables and indices for integrated drought characterizations. This paper presents a comprehensive review of major multivariate drought indices developed recently. Different development methods of multivariate drought indices are introduced along with their strengths and limitations. This paper provides useful information for operational drought characterization with current multivariate drought indices and for the development of new multivariate drought indices. © 2015 Elsevier B.V.

Guo L.,Karlsruhe Institute of Technology | Guo L.,Beijing Normal University | Marthaler M.,Karlsruhe Institute of Technology | Schon G.,Karlsruhe Institute of Technology
Physical Review Letters | Year: 2013

A novel way to create a band structure of the quasienergy spectrum for driven systems is proposed based on the discrete symmetry in phase space. The system, e.g., an ion or ultracold atom trapped in a potential, shows no spatial periodicity, but it is driven by a time-dependent field coupling highly nonlinearly to one of its degrees of freedom (e.g., ∼qn). The band structure in quasienergy arises as a consequence of the n-fold discrete periodicity in phase space induced by this driving field. We propose an explicit model to realize such a phase space crystal and analyze its band structure in the frame of a tight-binding approximation. The phase space crystal opens new ways to engineer energy band structures, with the added advantage that its properties can be changed in situ by tuning the driving field's parameters. © 2013 American Physical Society.

Yuan Z.,CAS Institute of Physics | Wang S.,CAS Institute of Physics | Xia K.,Beijing Normal University
Solid State Communications | Year: 2010

We studied the spin-transfer torques acting on magnetic domain walls in the presence of a nonequilibrium thermal distribution using a generalized Landauer-Büttiker formalism, where the energy flow is described on the same footing as the electric current. First-principles transport calculations have been performed in Ni and Co domain walls as typical examples. The temperature difference between two sides of the domain wall can induce remarkable spin- transfer torques, which are comparable with the current-induced torques required for the domain wall motion. © 2009 Elsevier Ltd. All rights reserved.

Zhang Q.-G.,Beijing Normal University | Buckling A.,University of Exeter
Ecology | Year: 2016

The classical, ecological, paradox of enrichment describes a phenomenon that resource enrichment destabilizes predator-prey systems by exacerbating population oscillations. Here we suggest a new, evolutionary, paradox of enrichment. Resource enrichment can lead to more asymmetrical predator-prey coevolution (i.e., extremely high levels of prey defenses against predators) that decreases predator abundances and increases predator extinction risk. A major reason for this is that high resource availability can reduce fitness costs associated with prey defenses. In our experiments with a bacterium and its lytic phage, nutrient-balanced resource enrichment led to patterns in population demography and coevolutionary dynamics consistent with this coevolution-based paradox of enrichment; in particular, phage population extinction events were observed under nutrient-rich, not nutrient-poor, conditions. Consistent with ecological studies, carbon-biased resource enrichment (with carbon availability disproportionately increased relative to other nutrients) did not destabilize dynamics, and the asymmetry of coevolution was not altered in this context. Our work highlights the importance of integrating ecological and evolutionary thinking for studies of the consequences of nutrient pollution and other types of environmental changes. © 2016 by the Ecological Society of America.

Zhang J.,Beijing Normal University | Wu L.,City University of Hong Kong
PLoS ONE | Year: 2013

Background:An ecological flow network is a weighted directed graph in which the nodes are species, the edges are "who eats whom" relationships and the weights are rates of energy or nutrient transferred between species. Allometric scaling is a ubiquitous feature for flow systems such as river basins, vascular networks and food webs.Methodology:The "ecological network analysis" can serve to reveal hidden allometries, the power law relationship between the throughflux and the indirect impact of node i, directly from the original flow networks without any need to cut edges in the network. The dissipation law, which is another significant scaling relationship between the energy dissipation (respiration) and the throughflow of any species, is also obtained from an analysis of the empirical flow networks. Interestingly, the exponents of the allometric law (η) and the dissipation law (γ) show a strong relationship for both empirical and simulated flow networks. The dissipation law exponent γ, rather than the topology of the network, is the most important factors that affect the allometric exponent η. Conclusions:The exponent η can be interpreted as the degree of centralization of the network, i.e., the concentration of impacts (direct and indirect influences on the entire network along all energy flow pathways) on hubs (the nodes with large throughflows). As a result, we find that as γ increases, the relative energy loss of large nodes increases, η decreases, i.e., the relative importance of large species decreases. Moreover, the entire flow network is more decentralized. Therefore, network flow structure (allometry) and thermodynamic constraints (dissipation) are linked. © 2013 Zhang, Wu.

Wang K.,Beijing Normal University | Dickinson R.E.,University of Texas at Austin | Liang S.,University of Maryland University College
Journal of Climate | Year: 2012

Pan evaporation (EP), an index of atmospheric evaporative demand, has been widely reported to have weakened in the past decades. However, its interpretation remains controversial because EP observations are not globally available and observations of one of its key controls, surface incident solar radiation Rs, are even less available. Using global-distributed Rs from both direct measurements (available through the Global Energy Balance Archive) and derived from sunshine duration, the authors calculated the potential evaporation from 1982 to 2008 from approximately 1300 stations. The findings herein show that the contribution of water vapor pressure deficit (VPD) to monthly variability of EP is much larger than that of other controlling factors, of Rs, wind speed (WS), and air temperature Ta. The trend of the aerodynamic component of EP, which includes contributions of VPD, WS, and Taa, accounted for 86% of the long-term trend of EP. The aerodynamic component was then calculated from 4250 globally distributed stations and showed a negligible averaged trend from 1973 to 2008 because the reduction in WS canceled out the impact of the elevated VPD. The long-term trend of WS dominates the long-term trend of the aerodynamic component of EP at the 4250 stations. Atmospheric evaporative demand increased in most arid and semiarid areas, indicating a decrease in water availability in those areas. © 2012 American Meteorological Society.

Yoo H.,University of Maryland University College | Li Z.,University of Maryland University College | Li Z.,Beijing Normal University
Climate Dynamics | Year: 2012

Knowledge of cloud properties and their vertical structure is important for meteorological studies due to their impact on both the Earth's radiation budget and adiabatic heating within the atmosphere. The objective of this study is to evaluate bulk cloud properties and vertical distribution simulated by the US National Oceanic and Atmospheric Administration National Centers for Environmental Prediction Global Forecast System (GFS) using three global satellite products. Cloud variables evaluated include the occurrence and fraction of clouds in up to three layers, cloud optical depth, liquid water path, and ice water path. Cloud vertical structure data are retrieved from both active (CloudSat/CALIPSO) and passive sensors and are subsequently compared with GFS model results. In general, the GFS model captures the spatial patterns of hydrometeors reasonably well and follows the general features seen in satellite measurements, but large discrepancies exist in low-level cloud properties. More boundary layer clouds over the interior continents were generated by the GFS model whereas satellite retrievals showed more low-level clouds over oceans. Although the frequencies of global multi-layer clouds from observations are similar to those from the model, latitudinal variations show discrepancies in terms of structure and pattern. The modeled cloud optical depth over storm track region and subtropical region is less than that from the passive sensor and is overestimated for deep convective clouds. The distributions of ice water path (IWP) agree better with satellite observations than do liquid water path (LWP) distributions. Discrepancies in LWP/IWP distributions between observations and the model are attributed to differences in cloud water mixing ratio and mean relative humidity fields, which are major control variables determining the formation of clouds. © 2012 Springer-Verlag.

Yan D.,Beijing Normal University | Yan D.,Beijing University of Chemical Technology
Chemistry - A European Journal | Year: 2015

Molecule-based micro-/nanomaterials have attracted considerable attention because their properties can vary greatly from the corresponding macro-sized bulk systems. Recently, the construction of multicomponent molecular solids based on crystal engineering principles has emerged as a promising alternative way to develop micro-/nanomaterials. Unlike single-component materials, the resulting multicomponent systems offer the advantages of tunable composition, and adjustable molecular arrangement, and intermolecular interactions within their solid states. The study of these materials also supplies insight into how the crystal structure, molecular components, and micro-/nanoscale effects can influence the performance of molecular materials. In this review, we describe recent advances and current directions in the assembly and applications of crystalline multicomponent micro-/nanostructures. Firstly, the design strategies for multicomponent systems based on molecular recognition and crystal engineering principles are introduced. Attention is then focused on the methods of fabrication of low-dimensional multicomponent micro-/nanostructures. Their new applications are also outlined. Finally, we briefly discuss perspectives for the further development of these molecular crystalline micro-/nanomaterials. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Zhao Y.,Beijing Normal University | Deng W.,The Hong Kong Institute of Education
Resources, Conservation and Recycling | Year: 2014

The environmental impacts of food waste management strategies and the effects of energy mix wereevaluated using a life cycle assessment model, EASEWASTE. Three different strategies involving land-fill, composting and combined digestion and composting as core technologies were investigated. Theresults indicate that the landfilling of food waste has an obvious impact on global warming, althoughthe power recovery from landfill gas counteracts some of this. Food waste composting causes seri-ous acidification (68.0 PE) and nutrient enrichment (76.9 PE) because of NH3and SO2emissions duringdecomposition. Using compost on farmland, which can marginally reduce global warming (-1.7 PE),acidification (-0.8 PE), and ecotoxicity and human toxicity through fertilizer substitution, also leads tonutrient enrichment as neutralization of emissions from N loss (27.6 PE) and substitution (-12.8 PE). Acombined digestion and composting technology lessens the effects of acidification (-12.2 PE), nutrientenrichment (-5.7 PE), and global warming (-7.9 PE) mainly because energy is recovered efficiently, whichdecreases emissions including SO2, Hg, NOx, and fossil CO2during normal energy production. The changeof energy mix by introducing more clean energy, which has marginal effects on the performance of com-posting strategy, results in apparently more loading to acidification and nutrient enrichment in the othertwo strategies. These are mainly because the recovered energy can avoid fewer emissions than beforedue to the lower background values in power generation. These results provide quantitative evidence fortechnical selection and pollution control in food waste management. © 2014 Elsevier Ltd. All rights reserved.

Zhang D.,Fudan University | Zi G.,Beijing Normal University
Chemical Society Reviews | Year: 2015

Since the discovery of a stable N-heterocyclic carbene (NHC), the use of NHCs in chemistry has developed rapidly over the past two decades. These interesting compounds are predominantly employed in organometallic chemistry as ligands for various metal centers, and as organocatalysts for a variety of transformations. In particular, the NHC transition metal complexes have received widespread attention, and significant progress has been made in the development of group 4 NHC-complexes in the last few years. These group 4 NHC-complexes are of interest because of their unique structural properties, and their potential application in organic transformations and catalysis. This review covers the superior design strategies for NHC ligands to stabilize early transition metals and well-defined group 4 metal complexes with mono- and multi-dentate NHC ligands. In this context, four types of NHC-complexes, i.e., carbon-functionalized NHCs, nitrogen-functionalized NHCs, oxygen-functionalized NHCs and nitrogen/oxygen-functionalized unsymmetric NHCs, are described. In addition, the use of group 4 NHC-complexes as catalysts in olefin (co)polymerization, ring-opening polymerization of rac-lactide, copolymerization of epoxides and CO2, as well as hydroamination/cyclization of aminoalkenes, is presented. Furthermore, limitations and challenges are discussed. This journal is © The Royal Society of Chemistry.

He L.,Beijing Normal University
Solid State Communications | Year: 2010

In the literature [A. Kumar, S.M. Yusuf, L. Keller, J.V. Yakhmi, Phys. Rev. Lett. 101 (2008) 207206], the ferromagnetic ordering temperature between the Cu and Fe moments in Cu0.73Mn0.77[Fe(CN)6]{dot operator}zH2O was assumed to be 17.9 K, and the antiferromagnetic ordering temperature of the Mn moments with respect to the Cu and Fe moments in Cu0.73Mn0.77[Fe(CN)6]{dot operator}zH2O was assumed to be 13.5 K. In this paper, I give a distinct explanation about the experimental results of Cu0.73Mn0.77[Fe(CN)6]{dot operator}zH2O based on the mean field theory and propose a reasonable microscopic magnetic structure in CMF near the Curie temperature. According to my analysis, the Cu, Mn, and Fe moments become ordered at the same temperature, 17.9 K. © 2009 Elsevier Ltd. All rights reserved.

He L.,Beijing Normal University
Solid State Communications | Year: 2010

Analysis of available experimental data reveals that monodisperse Mn3O4 nanoparticles show anomalous size dependent blocking temperature. This work presents a simple analysis which provides insight into the nature of this anomaly. My analysis pointed out that the magnetic anisotropy Kmag follows the power law Kmag ∼ D- 3 in all Mn3O4 nanoparticles (D is the average diameter of particles). The influences of the size dependent magnetic anisotropy of Mn3O4 nanoparticles on the size dependent blocking temperature, the coercivity of Mn3O4 nanoparticles, and also the magnetic properties of core-shell MnO/Mn3O4 nanoparticles were analyzed. © 2010 Elsevier Ltd. All rights reserved.

Hu L.,Beijing Normal University | Jiao J.J.,University of Hong Kong
Hydrological Processes | Year: 2014

Land reclamation may have a significant influence on groundwater regimes. Analytical solutions have been developed in the past to study the impact of land reclamation on a steady-state groundwater flow and transient flow in fill materials, assuming that the reclamation site consists of a single zone of uniform hydraulic parameters. In this paper, we derive analytical solutions to describe the transient water table change in response to multi-stage land reclamation where the fill material is uniform in each stage but the hydraulic conductivity of the fill material varies from stage to stage. By introducing the method of separation of variables, we develop a transient analytical solution to study the impact of land reclamation consisting of fill material with different hydraulic properties on groundwater dynamics. The results show that the water table first increases significantly into the reclaimed zone following the fill material deposition, and then the increase gradually propagates into the original aquifer. The change of water table in the original aquifer mainly depends on the value of hydraulic conductivity of the fill materials. Examples in this paper illustrate how the aquifer system experiences a long time unsteady-state flow as a result of the reclamation, and it takes at least tens of years for the system to approach a new equilibrium. It is suggested that for a large-scale reclamation project, the response of the groundwater regime to reclamation should be carefully studied. © 2013 John Wiley & Sons, Ltd.

Wu L.-X.,Beijing Normal University | Wu L.-X.,China University of Mining and Technology | Qin K.,China University of Mining and Technology | Liu S.-J.,Northeastern University China
Proceedings of the IEEE | Year: 2012

Although earthquakes are difficult to be predicted because of the complexity of the Earth system and the uncertainty of seismogenic processes, GEOSS provides multiple sources of observation data and brings a possibility to extract a thermal anomaly that would have a significant effect on earthquake prediction. Referring to the analysis on the lithosphere-coversphere-atmosphere (LCA) coupling due to stress enhancement in seismogenic zone, six thermal parameters, including surface latent heat flux (SLHF), thermal infrared radiation (TIR), outgoing longwave radiation (OLR), diurnal temperature range (DTR), atmospheric temperature, and skin temperature, are selected for GEOSS-based earthquake anomaly recognition (EAR). The inherent relations between the six thermal parameters are preliminarily introduced in consideration of possible LCA coupling. With overquantity, quasi-synchronism, and geo-consistency being defined as three rules for data mining, a deviation-time-space-thermal (DTS-T) EAR method as well as its procedures are developed in this paper. With 2008 M7.3 Yutian earthquake, China, 2008 M8.0 Wenchuan earthquake, China, and 2010 M7.1 Christchurch earthquake, New Zealand, being examples of tectonic earthquakes, the technical procedures of DTS-T method are demonstrated, which show that the obtained compositive thermal anomaly has a significant effect on earthquake prediction. © 2012 IEEE.

Zhang J.-Z.,Beijing Normal University
Journal of Applied Physics | Year: 2014

Energy relaxation of the hot electrons in Si-doped bulk GaN is studied theoretically, taking into account non-equilibrium polar optical phonons, electron degeneracy, and screening from the mobile electrons. The electron power dissipation and energy relaxation time are calculated as functions of the electron temperature Te, the hot-phonon effect (HPE) is examined by varying the optical phonon lifetime values, and the results are compared with previous calculations for typical GaN-based heterostructures. Particular attention is paid to the distinct temperature Te dependences of the power loss and the energy relaxation time τE at the low and high electron temperatures. At low electron temperatures (Te<500 K), the exponential rise of phonon generation number, fast weakened screening and HPE result in a rapid increase of power loss and sharp drop of relaxation time with Te. At high electron temperatures (Te>1500 K), the power loss increases slowly with Te due to the decrease in phonon generation rate, and the temperature-dependence of the energy relaxation time depends on the polar optical phonon lifetime - saturation in energy relaxation occurs when the phonon lifetime increases or varies little with Te. Our calculated temperature dependences of the energy relaxation time are in good agreement with experimental findings [Liberis et al., Appl. Phys. Lett. 89, 202117 (2006); Matulionis et al., Phys. Status Solidi C 2, 2585 (2005)]. With no HPE, the electron energy relaxation is much faster in bulk GaN (τE∼several tens femtoseconds) than in the GaN-based heterostructures. However, stronger hot-phonon re-absorption occurs in bulk GaN due to rapid polar-optical phonon emission compared to phonon decay. Therefore, including HPE yields very close power loss and energy relaxation times in bulk and heterostructures with similar densities of electrons (τE∼ several tenths of a picosecond). Transparent expressions for energy relaxation are obtained in the Boltzmann approximation, which are very useful for resolving the temperature dependences of the energy relaxation in the low- and high-Te regions. © 2014 AIP Publishing LLC.

Gai N.,Beijing Normal University | Gai N.,Yale University | Basu S.,Yale University | Chaplin W.J.,University of Birmingham | Elsworth Y.,University of Birmingham
Astrophysical Journal | Year: 2011

NASA's Kepler mission is providing basic asteroseismic data for hundreds of stars. One of the more common ways of determining stellar characteristics from these data is by the so-called grid-based modeling. We have made a detailed study of grid-based analysis techniques to study the errors (and error correlations) involved. As had been reported earlier, we find that it is relatively easy to get very precise values of stellar radii using grid-based techniques. However, we find that there are small, but significant, biases that can result because of the grid of models used. The biases can be minimized if metallicity is known. Masses cannot be determined as precisely as the radii and suffer from larger systematic effects. We also find that the errors in mass and radius are correlated. A positive consequence of this correlation is that log g can be determined both precisely and accurately with almost no systematic biases. Radii and log g can be determined with almost no model dependence to within 5% for realistic estimates of errors in asteroseismic and conventional observations. Errors in mass can be somewhat higher unless accurate metallicity estimates are available. Age estimates of individual stars are the most model dependent. The errors are larger, too. However, we find that for star clusters, it is possible to get a relatively precise age if one assumes that all stars in a given cluster have the same age. © 2011. The American Astronomical Society. All rights reserved.

Wu J.,Beijing Normal University | Wu J.,Arizona State University | Wei-Ning Xiang,East China Normal University | Wei-Ning Xiang,University of North Carolina at Charlotte | Zhao J.,Chinese Institute of Urban Environment
Landscape and Urban Planning | Year: 2014

China has the largest population and the longest urban development history in the world, with primitive cities first occurring along the Yellow River in northern China more than 4000 years ago. After a long period of stagnation during recent centuries, urbanization has revived again in China since the economic reform in 1978. Strongly influenced by national land use policy and the history of urbanization after 1949, China's urban ecology has gone through three development periods: the emergent period (1983-1989), the early growth period (1990-1999), and the rapid development period (2000-present). In this paper, we first provide a historical review of urbanization and urban ecology in China; based on this retrospective analysis, we further identify the main characteristics of, and missing links in, China's urban ecological research; and finally we suggest future research directions. The amount and scope of research in urban ecology and environment conducted in China since the 1980s are impressive. Not only did Chinese scholars import Western ideas to develop urban ecological science, but also they have promoted a holistic, use-inspired, transdisciplinary philosophy for studying and managing urban systems - which has unique Chinese characteristics. After more than 5000 years of being predominantly agrarian, China is now urban, and will become only more urban in the future. This continued fast urbanization makes China a living laboratory for studying urbanization, and China's urban ecology seems poised to make strides in the coming decades. © 2014 Elsevier B.V.

Yu Z.-X.,University of Shanghai for Science and Technology | Yuan R.,Beijing Normal University
Nonlinear Analysis: Real World Applications | Year: 2011

The paper addresses the existence of traveling waves for n components delayed Reaction-diffusion systems with the weak quasi-monotonicity or the weak exponential quasi-monotonicity. The approach is based on a cross iteration scheme combining Schauder's fixed point theorem for the corresponding wave profile systems. The results are well applied to a three-species competitive LotkaVolterra Reaction-diffusion system with multiple delays. The existence of traveling waves which connects the trivial equilibrium and the positive equilibrium indicates that there is a transition zone moving the steady state with no species to the steady state with the coexistence of three species. © 2011 Elsevier Ltd. All rights reserved.

Wang K.C.,Beijing Normal University | Dickinson R.E.,University of Texas at Austin | Su L.,Beijing City University | Trenberth K.E.,U.S. National Center for Atmospheric Research
Atmospheric Chemistry and Physics | Year: 2012

Atmospheric aerosols affect both human health and climate. PMX is the mass concentration of aerosol particles that have aerodynamic diameters less than X 1/4m, PM10 was initially selected to measure the environmental impact of aerosols. Recently, it was realized that fine particles are more hazardous than larger ones and should be measured. Consequently, observational data for PM2.5 have been obtained but only for a much shorter period than that of PM10. Optical extinction of aerosols, the inverse of meteorological visibility, is sensitive to particles less than 1.0 1/4m. These fine particles only account for a small part of total mass of aerosols although they are very efficient in light extinction. Comparisons are made between PM10 and PM2.5 over the period when the latter is available and with visibility data for a longer period. PM10 has decreased by 44% in Europe from 1992 to 2009, 33% in the US from 1993 to 2010, 10% in Canada from 1994 to 2009, and 26% in China from 2000 to 2011. However, in contrast, aerosol optical extinction has increased 7% in the US, 10% in Canada, and 18% in China during the above study periods. The reduction of optical extinction over Europe of 5% is also much less than the 44% reduction in PM10. Over its short period of record PM2.5 descreased less than PM10. Hence, PM10 is neither a good measure of changes in smaller particles nor of their long-term trends, a result that has important implications for both climate impact and human health effects. The increased fraction of anthropogenic aerosol emission, such as from vehicle exhaust, to total atmospheric aerosols partly explains this contrasting trend of optical and mass properties of aerosols.

Qin R.,Henan Normal University | Bo Z.,Beijing Normal University
Macromolecular Rapid Communications | Year: 2012

A set of monodisperse 2,7-linked carbazole oligomers (3-mer, 5-mer, 7-mer, and 9-mer) was synthesized, and their photophysical, electrochemical, and thermal properties were investigated. In solutions, these oligomers exhibited bright blue emission with almost quantitative fluorescence quantum yield. The emission spectra of these oligomers in films are quite different. 3-Mer and 5-mer exhibited featureless emission spectra, whereas 7-mer and 9-mer showed well-resolved emission spectra. Four monodisperse 2,7-linked carbazole oligomers are synthesized by modular chemistry, and their photophysical, electrochemical, and thermal properties are investigated. These oligomers in solutions exhibit blue emissions with high quantum efficiency. The onset oxidation potential slightly hoists and the HOMO level becomes lower when the conjugation length increases. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang K.,Beijing Normal University | Augustine J.,National Oceanic and Atmospheric Administration | Dickinson R.E.,University of Texas at Austin
Journal of Geophysical Research: Atmospheres | Year: 2012

Surface incident solar radiation (Rs) drives weather and climate changes. Observations of Rs have been widely used as reference data to evaluate climate model simulations and satellite retrievals. However, few have studied uncertainties of Rs observations, especially long term. This paper compares Rs from 1995 to 2011 at collocated sites collected by the Surface Radiation Budget Network (SURFRAD), the U.S. Climate Reference Network (USCRN) and the AmeriFlux network. SURFRAD stations have measured separately the diffuse and direct components of Rs as well as Rs by a pyranometer, while Rs was measured by a pyranometer or a net radiometer at the USCRN and AmeriFlux sites. Rs can be calculated by summing the diffuse and direction radiation measurements. Rs measured by the summation technique was compared those measured by a pyranometer or a net radiometer at collocated sites. Agreement among these four independent Rs measurements is good with correlation coefficients higher than 0.98 and an average error (one standard deviation) of about 4% at both hourly and monthly time scales. Rs has a large spatial variability at the hourly time scale, even exceeding 100Wm-2 in ∼6km. This spatial variability is substantially reduced at the monthly time scale. The two independent measurement systems at the SURFRAD sites agree rather well in annual variability of Rs with an average relative standard deviation error of 34%. The errors are 71% and 85% for the USCRN and AmeriFlux sites. Evidently, caution should be taken when using the Rs data collected at the USCRN and AmeriFlux sites to study annual variability of Rs. © 2012. American Geophysical Union. All Rights Reserved.

Wu J.,Arizona State University | Wu J.,Beijing Normal University
Landscape and Urban Planning | Year: 2014

Ecosystems and landscapes around the world have become increasingly domesticated through urbanization. Cities have been the engines of socioeconomic development but also the centers of major environmental problems since the industrial revolution. Numerous studies have shown that our urban ecosystems and landscapes are on an unsustainable trajectory. Global sustainability depends critically on cities, and urban ecology can - and needs to - play a key role in the transition toward sustainability. In this paper, I review different definitions and perspectives of urban ecology, discuss major advances and key issues, and propose a framework to help move the field forward. After almost 90 years of development, urban ecology has evolved into a truly transdisciplinary enterprise that integrates ecological, geographical, planning, and social sciences. The most salient thrust of current research activities in the field is the emerging urban sustainability paradigm which focuses on urban ecosystem services and their relations to human well-being. While urbanization is complex in many ways, we do know a lot about its patterns, processes, and effects. More specifically, we know a great deal about urban growth patterns in space and time, the underlying drivers and mechanisms, and myriad effects of urbanization on biodiversity, ecological processes, and ecosystem services. Compared to their ancient counterparts, contemporary cities tend to be bigger in physical size and ecological footprint, faster in growth rate in terms of both population and urbanized land, and more irregular in landscape composition and configuration. As coevolving human-environment systems, cities are spatially heterogeneous, complex adaptive systems. As such, the dynamic trajectory of cities can never be fully predicted or controlled, but can and should be influenced or guided in more desirable directions through planning and design activities that are based on urban ecological knowledge and sustainability principles. © 2014 Elsevier B.V.

Fang D.,Beijing Normal University
Progress in Chemistry | Year: 2012

[2 + 2] cycloaddition reaction is one type of the most important reactions in the field of organic chemistry, and the mechanisms of [2 + 2] cycloaddition reactions are always hot topic both for experimental and theoretical researchers. In this paper, three types of [2 + 2] cycloaddition reactions, including that of simple olefins or alkynes, cumulenes, Th compounds, have been classified and reviewed. The obtained results indicate that the cycloaddition reactions involving simple olefins or alkynes are proceeding in diradical mechanism generally, and the others are proceeding in either concerted or zwitterion mechanism. All of which have been elucidated with frontier molecular orbital interactions.

Zhu L.,Capital Medical University | Zhu L.,Beijing Normal University | Zhu L.,University of Pennsylvania | Ploessl K.,University of Pennsylvania | Kung H.F.,University of Pennsylvania
Chemical Society Reviews | Year: 2014

Single photon emission computed tomography (SPECT) or positron emission computed tomography (PET) imaging agents for neurodegenerative diseases have a significant impact on clinical diagnosis and patient care. The examples of Parkinson's Disease (PD) and Alzheimer's Disease (AD) imaging agents described in this paper provide a general view on how imaging agents, i.e. radioactive drugs, are selected, chemically prepared and applied in humans. Imaging the living human brain can provide unique information on the pathology and progression of neurodegenerative diseases, such as AD and PD. The imaging method will also facilitate preclinical and clinical trials of new drugs offering specific information related to drug binding sites in the brain. In the future, chemists will continue to play important roles in identifying specific targets, synthesizing target-specific probes for screening and ultimately testing them by in vitro and in vivo assays. This journal is © the Partner Organisations 2014.

Li Z.-Y.,East China Normal University | Zhang Y.,East China Normal University | Zhang C.-W.,East China Normal University | Chen L.-J.,East China Normal University | And 5 more authors.
Journal of the American Chemical Society | Year: 2014

A new family of discrete hexakis-pillar[5]arene metallacycles with different sizes have been successfully prepared via coordination-driven self-assembly, which presented very few successful examples of preparation of discrete multiple pillar[n]arene derivatives. These newly designed hexakis-pillar[5]arene metallacycles were well characterized with one-dimensional (1-D) multinuclear NMR (1H and 31 P NMR), two-dimensional (2-D) 1H-1H COSY and NOESY, ESI-TOF-MS, elemental analysis, and PM6 semiempirical molecular orbital methods. Furthermore, the host-guest complexation of such hexakis-pillar[5]arene hosts with a series of different neutral ditopic guests G1-6 were well investigated. Through host-guest interactions of hexakis-pillar[5]arene metallacycles H2 or H3 with the neutral dinitrile guest G5, the cross-linked supramolecular polymers H2⊃(G5)3 or H3⊃(G5)3 were successfully constructed at the high-concentration region, respectively. Interestingly, these cross-linked supramolecular polymers transformed into the stable supramolecular gels upon increasing the concentrations to a relatively high level. More importantly, by taking advantage of the dynamic nature of metal-ligand bonds and host-guest interactions, the reversible multiple stimuli-responsive gel-sol phase transitions of such polymer gels were successfully realized under different stimuli, such as temperature, halide, and competitive guest, etc. The mechanism of such multiple stimuli-responsive processes was well illustrated by in situ multinuclear NMR investigation. This research not only provides a highly efficient approach to the preparation of discrete multiple pillar[n]arene derivatives but also presents a new family of multiple stimuli-responsive "smart" soft matters. © 2014 American Chemical Society.

Cai B.,Chinese Research Academy of Environmental Sciences | Zhang L.,Beijing Normal University
Energy Policy | Year: 2014

Different names/concepts and therefore different spatial boundaries for cities in China are responsible for the conflicting and confusing results associated with urban CO2 emissions accounting. In this study, four types of urban boundaries, i.e., city administrative boundary (UB1), city district boundary (UB2), city built-up area (UB3) and urban proper (UB4), were identified and defined. Tianjin was subsequently selected as the case city to illustrate the different performances of CO2 emissions with respect to these four boundaries using a 1-km grid dataset built bottom-up by point-emission sources. Different urban boundaries can induce a difference in CO2 emissions as large as 654%. UB1 and UB2 are not the appropriate proxies for urban boundaries in the analysis of urban CO2 emissions, although UB1 is a widely adopted boundary. UB3 is a good representative of city clusters and urban sprawl in a certain region, whereas UB4 is the appropriate system boundary for such issues as urban CO2 emissions in light of landscape characteristics and pertinent human activities, as well as the comparability to counterparts in developed countries. These results provide sound policy implications for the improvement of urban energy management and carbon emission abatement in China. © 2013 Elsevier Ltd.

Li X.-Q.,Beijing Normal University
Frontiers of Physics | Year: 2016

In addition to the well-known Landauer–Büttiker scattering theory and the nonequilibrium Green’s function technique for mesoscopic transports, an alternative (and very useful) scheme is quantum master equation approach. In this article, we review the particle-number (n)-resolved master equation (n-ME) approach and its systematic applications in quantum measurement and quantum transport problems. The n-ME contains rich dynamical information, allowing efficient study of topics such as shot noise and full counting statistics analysis. Moreover, we also review a newly developed master equation approach (and its n-resolved version) under self-consistent Born approximation. The application potential of this new approach is critically examined via its ability to recover the exact results for noninteracting systems under arbitrary voltage and in presence of strong quantum interference, and the challenging non-equilibrium Kondo effect. © 2016, Higher Education Press and Springer-Verlag Berlin Heidelberg.

Zhu Y.,Jiangnan University | Liu X.,Jiangnan University | Gao J.,Jiangnan University | Zhang Y.,Jiangnan University | Zhao F.,Beijing Normal University
Optics Express | Year: 2014

We develop a novel model of the probability density of the orbital angular momentum (OAM) modes for Hankel-Bessel beams in paraxial turbulence channel based on the Rytov approximation. The results show that there are multi-peaks of the mode probability density along the radial direction. The peak position of the mode probability density moves to beam center with the increasing of non-Kolmogorov turbulence-parameters and the generalized refractive-index structure parameters and with the decreasing of OAM quantum number, propagation distance and wavelength of the beams. Additionally, larger OAM quantum number and smaller non-Kolmogorov turbulence-parameter can be selected in order to obtain larger mode probability density. The probability density of the OAM mode crosstalk is increasing with the decreasing of the quantum number deviation and the wavelength. Because of the focusing properties of Hankel-Bessel beams in turbulence channel, compared with the Laguerre-Gaussian beams, Hankel-Bessel beams are a good light source for weakening turbulence spreading of the beams and mitigating the effects of turbulence on the probability density of the OAM mode. © 2014 Optical Society of America.

Chen B.,Beijing Normal University | Wang R.,CAS Research Center for Eco Environmental Sciences
Ecological Indicators | Year: 2014

The editorial section of the special issue of Ecological Indicators focuses on describing integrated ecological indicators for sustainable urban ecosystem evaluation and management. It probes we aim to probe into the regulation measures to optimize the configuration of water resources and realize the integration of the fundamental research innovation and the management practice, thus providing decision support for the integration of water security, ecological security and sustainable socio-economic development of cities and regions. A group of researchers introduces a new multi-layered indicator set for urban metabolism studies, which is designed to gather information on the definition, biophysical characteristics, and metabolic flows of megacities.

Wang N.,Guangxi Normal University | Liu M.,Guangxi Normal University | Liu M.,Beijing Normal University | Wu X.,China Institute of Atomic Energy
Physical Review C - Nuclear Physics | Year: 2010

We propose a semiempirical nuclear mass formula based on the macroscopic-microscopic method in which the isospin and mass dependence of model parameters are investigated with the Skyrme energy density functional. The number of model parameters is considerably reduced compared with the finite range droplet model. The rms deviation with respect to 2149 measured nuclear masses is reduced by 21%, falling to 0.516MeV. The new magic number N=16 in light neutron-rich nuclei and the shape coexistence phenomena for some nuclei have been examined with the model. The shell corrections of superheavy nuclei are also predicted. © 2010 The American Physical Society.

Possessing power contributes to high self-esteem, but how power enhances self-esteem is still unknown. As power is associated with both self-oriented goals and social-responsibility goals, we proposed that power predicts self-esteem through two positive personal and interpersonal results: authenticity and relationship satisfaction. Three studies were carried out with a total of 505 Chinese participants, including college students and adults, who completed surveys that assessed personal power, self-esteem, authenticity, relationship satisfaction, communal orientation, and social desirability. Hierarchical multiple regression analyses demonstrated that power, authenticity, and relationship satisfaction each uniquely contributed to self-esteem. More importantly, multiple mediation analysis showed that authenticity and relationship satisfaction both mediated the effects of power on self-esteem, even when controlling for participants' communal orientation and social desirability. Our findings demonstrate that authenticity and relationship satisfaction represent two key mechanisms by which power is associated with self-esteem. © 2015 Yi Nan Wang. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Li Z.,Beijing Normal University
European Physical Journal C | Year: 2013

A generalized scenario, which is used to characterize the attenuated dilution of cold dark matter deviating from the standard case, is proposed for the interaction of cosmological dark sectors. This generalized framework cannot only fully recover the three frequently studied phenomenological parameterizations in the limit of the characteristic parameter α→-1,0 and +1, but also admits a much wider range of cosmological solutions for other values of α. Moreover, some cosmological consequences are examined by placing constraints on this generalized interacting model with current observational data. We find that, for α in the extended range of [-1.0, 1.0], the case in which the energy flow transfers from dark matter to dark energy is slightly favored by observations. © 2013 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica.

Zhao W.,Hefei University of Technology | Zhang Y.,Hefei University of Technology | You X.-P.,Southwest University | Zhu Z.-H.,Beijing Normal University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Measurement of pulsar timing residuals provides a direct way to detect relic gravitational waves at the frequency f∼1/yr. In this paper, we investigate the constraints on the inflationary parameters, the tensor-to-scalar ratio r, and the tensor spectral index nt, by the current and future pulsar timing arrays. We find that the Five-hundred-meter Aperture Spherical Radio Telescope in China and the planned Square Kilometre Array projects have fairly strong abilities to test the phantomlike inflationary models. If r=0.1, then Five-hundred-meter Aperture Spherical Radio Telescope could give the constraint on the spectral index nt<0.56 and Square Kilometre Array could give nt<0.32, while an observation with total time T=20 yr, pulsar noise level σw=30 ns, and monitored pulsar number n=200 could even constrain nt<0.07. These are much tighter than those inferred from the current results of the Parkes Pulsar Timing Array, European Pulsar Timing Array, and North American Nanohertz Observatory for Gravitational Waves. By studying the effects of various observational factors on the sensitivities of pulsar timing arrays, we find that compared with σw and n, the total observation time T has the most significant effect. © 2013 American Physical Society.

Yang M.,CAS Research Center for Eco Environmental Sciences | Zheng S.,Beijing Normal University
Biomass and Bioenergy | Year: 2014

Microbial single-cell-protein (SCP) production from high-organic-strength industrial wastewaters is considered an attractive method for both wastewater purification and resource utilization. In the last two decades, pollutant removal-oriented yeast SCP production processes, i.e., yeast treatment processes, have attracted a great deal of attention from a variety of research groups worldwide. Different from conventional SCP production processes, yeast treatment processes are characterized by higher pollutant removal rates, lower production costs, highly adaptive yeast isolates from nature, no excess nutrient supplements, and are performed under non-sterile conditions. Furthermore, yeast treatment processes are similar to bacteria-dominated conventional activated sludge processes, which offer more choices for yeast SCP production and industrial wastewater treatment. This review discusses why highly adaptive yeast species isolated from nature are used in the yeast treatment process rather than commercial SCP producers. It also describes the application of yeast treatment processes for treating high-carboxyhydrate, oil-rich and high-salinity industrial wastewater, focusing primarily on high-strength biodegradable organic substances, which usually account for the major fraction of biochemical oxygen demand. Also discussed is the biodegradation of xenobiotics, such as color (including dye and pigment) and toxic substances (including phenols, chlorophenols, polycyclic aromatic hydrocarbons, etc.), present in industrial wastewater. Based on molecular information of yeast community structures and their regulation in yeast treatment systems, we also discuss how to maintain efficient yeast species in yeast biomass and how to control bacterial and mold proliferation in yeast treatment systems. © 2014 Elsevier Ltd.

Zhang P.,Beijing Normal University | Ding L.,Ohio State University
Physical Review Special Topics - Physics Education Research | Year: 2013

This paper reports a cross-grade comparative study of Chinese precollege students' epistemological beliefs about physics by using the Colorado Learning Attitudes Survey about Sciences (CLASS). Our students of interest are middle and high schoolers taking traditional lecture-based physics as a mandatory science course each year from the 8th grade to the 12th grade in China. The original CLASS was translated into Mandarin through a rigorous transadaption process, and then it was administered as a pencil-and-paper in-class survey to a total of 1318 students across all the five grade levels (8-12). Our results showed that although in general student epistemological beliefs became less expertlike after receiving more years of traditional instruction (a trend consistent with what was reported in the previous literature), the cross-grade change was not a monotonous decrease. Instead, students at grades 9 and 12 showed a slight positive shift in their beliefs measured by CLASS. Particularly, when compared to the 8th graders, students at the 9th grade demonstrated a significant increase in their views about the conceptual nature of physics and problem-solving sophistication. We hypothesize that both pedagogical and nonpedagogical factors may have contributed to these positive changes. Our results cast light on the complex nature of the relationship between formal instruction and student epistemological beliefs.© http://creativecommons. org/licenses/by/3.0/Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Xiao K.,Hunan Institute of Technology | He X.-K.,Hunan First Normal University | Zhu J.-Y.,Beijing Normal University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

Phenomenological effect of the super-inflation in loop quantum cosmology (LQC) is discussed. We investigate the case that the Universe is filled with the interacting field between massive scalar field and radiation. Considering the damping coefficient Γ as a constant, the changes of the scale factor during super-inflation with four different initial conditions are discussed, and we find that the changes of the scale factor depends on the initial values of energy density of the scalar field and radiation at the bounce point. But no matter which initial condition is chosen, the radiation always dominated at the late time. Moreover, we investigate whether the super-inflation can provide enough e-folding number. For the super-inflation starts from the quantum bounce point, the initial value of Hubble parameter H(ti)~0, then it is possible to solve the flatness problem and horizon problem. As an example, following the method of [18] to calculate particle horizon on the condition that the radiation dominated at bounce point, and we find that the Universe has had enough time to be homogeneous and isotopic. © 2013 Elsevier B.V.

Lu H.,Beijing Normal University | Wang Z.-L.,Korea Institute for Advanced Study
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We study the Dirac equation of a charged massless spinor on the general charged AdS black hole of conformal gravity. The equation can be solved exactly in terms of Heun's functions. We obtain the exact Green's function in the phase space (ω, k). This allows us to obtain Fermi surfaces for both Fermi and non-Fermi liquids. Our analytic results provide a more elegant approach of studying some strongly interacting fermionic systems not only at zero temperature, but also at any finite temperature. At zero temperature, we analyse the motion of the poles in the complex ω plane and obtain the leading order terms of the dispersion relation, expressed as the Laurent expansion of ω in terms of k. We illustrate new distinguishing features arising at the finite temperature. The Green's function with vanishing ω at finite temperature has a fascinating rich structure of spiked maxima in the plane of k and the fermion charge q. © 2012 Elsevier B.V.

Liu Y.,Beijing Institute of Technology | Liu Y.,Beijing Normal University | Wang R.,Beijing Institute of Technology | Zhang X.,Beijing Institute of Technology
Optics Express | Year: 2014

Recently, there are great interest in studying the interaction between chiral molecules and plasmonic particles, because a weak circular dichroism (CD) signal in the ultraviolet (UV) region from chiral molecules can be both enhanced and transferred to the visible wavelength range by using plasmonic particles. Thus, ultrasensitive probe of tiny amounts of chiral substance by CD are worth waiting for. Here we present another way to strongly enhance CD of chiral molecules by using plasmonic particle cluster, which need not transfer to the visible wavelength. The method to calculate CD of chiral molecules in nanosphere clusters has been developed by means of multiple scattering of electromagnetic multipole fields. Our calculated results show that 2 orders of magnitude CD enhancement in the UV region for chiral molecules can be realized. Such a CD enhancement is very sensitive to the cluster structure. The cluster structure can cause chiroptical illusion in which a mirror symmetry in the CD spectra ofopposite enantiomeric molecules is broken. The correction of quantum size effect on the phenomenon has also been considered. Our findings open up an alternative avenue for the ultrasensitive detection and illusion of chiral information. © 2014 Optical Society of America.

Zeng R.,Beijing Normal University | Zeng R.,University of California at Los Angeles | Greenfield P.M.,University of California at Los Angeles
International Journal of Psychology | Year: 2015

Chinese people have held collectivistic values such as obligation, giving to other people, obedience and sacrifice of personal interests for thousands of years. In recent decades, China has undergone rapid economic development and urbanisation. This study investigates changing cultural values in China from 1970 to 2008 and the relationship of changing values to ecological shifts. The conceptual framework for the study was Greenfield’s (2009) theory of social change and human development. Changing frequencies of contrasting Chinese words indexing individualistic or collectivistic values show that values shift along with ecological changes (urbanisation, economic development and enrollment in higher education), thereby adapting to current sociodemographic contexts.Words indexing adaptive individualistic values increased in frequency between 1970 and 2008. In contrast, words indexing less adaptive collectivistic values either decreased in frequency in this same period of time or else rose more slowly than words indexing contrasting individualistic values. © 2015, International Journal of Psychology. All right reserved.

Cvetic M.,University of Pennsylvania | Cvetic M.,University of Maribor | Lu H.,Beijing Normal University | Pope C.N.,Texas A&M University | Pope C.N.,University of Cambridge
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We study the universal nature of the product of the entropies of all horizons of charged rotating black holes. We argue, by examining further explicit examples, that when the maximum number of rotations and/or charges are turned on, the entropy product is expressed in terms of angular momentum and/or charges only, which are quantized. (In the case of gauged supergravities, the entropy product depends on the gauge-coupling constant also.) In two-derivative gravities, the notion of the "maximum number" of charges can be defined as being sufficiently many nonzero charges that the Reissner- Nordström black hole arises under an appropriate specialization of the charges. (The definition can be relaxed somewhat in charged anti-de Sitter black holes in D≥6.) In higher-derivative gravity, we use the charged rotating black hole in Weyl-Maxwell gravity as an example for which the entropy product is still quantized, but it is expressed in terms of the angular momentum only, with no dependence on the charge. This suggests that the notion of maximum charges in higher-derivative gravities requires further understanding. © 2013 American Physical Society.

Fan Z.,Beijing Normal University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We investigate holographic fermions in general asymptotically scaling geometries with hyperscaling violation exponent θ, which is a natural generalization of fermions in Lifshitz space-time. We prove that the retarded Green functions in this background satisfy the angle-resolved photoemission spectroscopy sum rules by introducing a dynamical source on a UV brane for zero density fermionic systems. The big difference from the Lifshitz case is that the mass of probe fermions decoupled from the UV theory and thus has no longer been restricted by the unitarity bound. We also study finite density fermions at finite temperature, with dynamical exponent z=2. We find that the dispersion relation is linear, but the logarithm of the spectral function is not linearly related to the logarithm of k=k-kF, independent of charge q and θ. Furthermore, we show that, with the increasing of charge, new branches of Fermi surfaces emerge and tend to gather together to form a shell-like structure when the charge reaches some critical value beyond which a wide band pattern appears in the momentum-charge plane. However, all sharp peaks will be smoothed out when θ increases, no matter how much large the charge is. © 2013 American Physical Society.

Deng F.-G.,Beijing Normal University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We propose an optimal nonlocal entanglement concentration protocol (ECP) for multiphoton systems in a partially entangled pure state, resorting to the projection measurement on an additional photon. One party in quantum communication first performs a parity-check measurement on her photon in an N-photon system and an additional photon, and then she projects the additional photon into an orthogonal Hilbert space for dividing the original N-photon systems into two groups. In the first group, the N parties will obtain a subset of N-photon systems in a maximally entangled state. In the second group, they will obtain some less-entangled N-photon systems which are the resource for the entanglement concentration in the next round. By iterating the entanglement concentration process several times, the present ECP has the maximal success probability, which is just equivalent to the entanglement of the partially entangled state. That is, this ECP is an optimal one. © 2012 American Physical Society.

Zhang Z.-H.,Central China Normal University | Guo X.-H.,Beijing Normal University | Yang Y.-D.,Central China Normal University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Recently, the large CP asymmetries in B±→π ±π+π- decays were found by the LHCb Collaboration to localize in the region mπ+π -2<0.4 GeV2. We find such large localized CP asymmetries may be due to the interference between a light scalar and ρ0(770) intermediate resonances. Consequently, we argue that the distribution of CP asymmetries in the Dalitz plots of three-body B decays could be very helpful for identifying the presence of the scalar resonance. © 2013 American Physical Society.

He Y.,Beijing Normal University
Progress in Biochemistry and Biophysics | Year: 2012

Alzheimer's disease (AD) is a progressive, neurodegenerative disease characterized by impaired memory and other cognitive functions. Previous neuroimaging studies have demonstrated regional structural and functional changes. Recent progressions on multi-modal imaging techniques and human brain connectome methods have allowed us to explore alterations of structural and functional networks in AD. Using these approaches, many studies have discovered AD-related network disruption, including connectivity strength, network efficiency, modular structure and network hubs. These findings provide novel insights into the understanding of AD notion of network disintegration and might lead to uncover disease biomarker for early diagnosis in AD. Most importantly, these findings in AD have been also demonstrated in the individuals at risk for AD (e.g., mild cognitive impairment), suggesting that the neuroimaging studies of AD should be moved into the prodromal stage of AD from the dementia stage.

Lu H.,Beijing Normal University | Pang Y.,Texas A&M University | Pope C.N.,Texas A&M University | Pope C.N.,University of Cambridge
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We study conformally invariant theories of gravity in six dimensions. In four dimensions, there is a unique such theory that is polynomial in the curvature and its derivatives, namely, Weyl-squared, and furthermore all solutions of Einstein gravity are also solutions of the conformal theory. By contrast, in six dimensions there are three independent conformally invariant polynomial terms one could consider. There is a unique linear combination (up to overall scale) for which Einstein metrics are also solutions, and this specific theory forms the focus of our attention in this paper. We reduce the equations of motion for the most general spherically symmetric black hole to a single fifth-order differential equation. We obtain the general solution in the form of an infinite series, characterized by five independent parameters, and we show how a finite three-parameter truncation reduces to the already known Schwarzschild-AdS metric and its conformal scaling. We derive general results for the thermodynamics and the first law for the full five-parameter solutions. We also investigate solutions in extended theories coupled to conformally invariant matter, and in addition we derive some general results for conserved charges in cubic-curvature theories in arbitrary dimensions. © 2013 American Physical Society.

Jiang P.-X.,Beijing Normal University | Jiang P.-X.,CAS Institute of Theoretical Physics | Hu J.-W.,CAS Institute of Theoretical Physics | Guo Z.-K.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The newly released Planck cosmic microwave background data place tight constraints on slow-roll inflationary models. Some commonly discussed inflationary potentials are disfavored due mainly to the large tensor-to-scalar ratio. In this paper we show that these potentials may be in good agreement with the Planck data when the inflaton has a nonminimal coupling to the Gauss-Bonnet term. Moreover, such a coupling violates the consistency relation between the tensor spectral index and tensor-to-scalar ratio. If the tensor spectral index is allowed to vary freely, the Planck constraints on the tensor-to-scalar ratio are slightly improved. © 2013 American Physical Society.

Yuan G.,Beijing Normal University | Yuan G.,China National Institute of Biological Sciences | Zhu B.,China National Institute of Biological Sciences
Biochimica et Biophysica Acta - Gene Regulatory Mechanisms | Year: 2012

Nucleosome particles, which are composed of core histones and DNA, are the basic unit of eukaryotic chromatin. Histone modifications and histone composition determine the structure and function of the chromatin; this genome packaging, often referred to as "epigenetic information", provides additional information beyond the underlying genomic sequence. The epigenetic information must be transmitted from mother cells to daughter cells during mitotic division to maintain the cell lineage identity and proper gene expression. However, the mechanisms responsible for mitotic epigenetic inheritance remain largely unknown. In this review, we focus on recent studies regarding histone variants and discuss the assembly pathways that may contribute to epigenetic inheritance. This article is part of a Special Issue entitled: Histone chaperones and Chromatin assembly. © 2011 Elsevier B.V.

Di Y.-M.,Jiangsu University | Wei H.-R.,Jiangsu University | Wei H.-R.,Beijing Normal University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We propose the generalized controlled X (gcx) gate as the two-qudit elementary gate, and based on Cartan decomposition, we also give the one-qudit elementary gates. Then we discuss the physical implementation of these elementary gates and show that it is feasible with current technology. With these elementary gates many important qudit quantum gates can be synthesized conveniently. We provide efficient methods for the synthesis of various kinds of controlled qudit gates and greatly simplify the synthesis of existing generic multi-valued quantum circuits. Moreover, we generalize the quantum Shannon decomposition (QSD), the most powerful technique for the synthesis of generic qubit circuits, to the qudit case. A comparison of ququart (d=4) circuits and qubit circuits reveals that using ququart circuits may have an advantage over the qubit circuits in the synthesis of quantum circuits. © 2013 American Physical Society.

Liu Z.,Beijing Normal University | Reddy G.,University of Maryland University College | Thirumalai D.,University of Maryland University College
Journal of Physical Chemistry B | Year: 2012

A theoretical basis for the molecular transfer model (MTM), which takes into account the effects of denaturants by combining experimental data and molecular models for proteins, is provided. We show that the MTM is a mean field-like model that implicitly takes into account denaturant-induced many body interactions. The MTM in conjunction with the coarse-grained self organized polymer model with side chains (SOP-SC) for polypeptide chains is used to simulate the folding of the src-SH3 domain as a function of temperature (T) and guanidine hydrochloride (GdmCl) concentration [C]. Besides reproducing the thermodynamic aspects of SH3 folding, the SOP-SC also captures the cooperativity of the folding transitions. A number of experimentally testable predictions are also made. First, we predict that the melting temperature Tm([C]) decreases linearly as [C] increases. Second, we show that the midpoints C m,i and melting temperatures Tm,i at which individual residues acquire 50% of their native contacts differ from the global midpoint (Cm ≈ 2.5 M) and melting temperature (Tm = 355 K) at which the folded and unfolded states coexist. Dispersion in Cm,i is greater than that found for Tm,i. Third, folding kinetics at [C] = 0 M shows that the acquisition of contacts between all the secondary structural elements and global folding occur nearly simultaneously. Finally, from the free energy profiles as a function of the structural overlap function and the radius of gyration of the protein, we find that at a fixed T the transition state moves toward the folded state as [C] increases in accord with the Hammond postulate. In contrast, we predict that along the locus of points Tm([C]) the location of the transition state does not change. The theory and the models used here are sufficiently general for studying the folding of other single domain proteins. © 2012 American Chemical Society.

Wang N.,Guangxi Normal University | Liu M.,Guangxi Normal University | Liu M.,Beijing Normal University
Physical Review C - Nuclear Physics | Year: 2010

The mass and isospin dependence of symmetry energy coefficients asym of finite nuclei are investigated with the measured nuclear masses incorporating the liquid drop mass formula. The enhanced asym for nearly symmetric nuclei are observed. To describe the mass and isospin dependence of asym, a modified formula based on the conventional surface-symmetry term is proposed and the corresponding rms deviation of nuclear masses is checked. © 2010 The American Physical Society.

Ke Y.,McGill University | Xia K.,Beijing Normal University | Guo H.,McGill University
Physical Review Letters | Year: 2010

By first principles analysis, we systematically investigate effects of oxygen vacancies (OV) in the MgO barrier of Fe/MgO/Fe magnetic tunnel junctions. The interchannel diffusive scattering by disordered OVs located at or near the Fe/MgO interface drastically reduces the tunnel magnetoresistance ratio (TMR) from the ideal theoretical limit to the presently observed much smaller experimental range. Interior OVs are far less important in influencing TMR, but they significantly increase the junction resistance. Filling OV with nitrogen atoms restores TMR to near the ideal theoretical limit. © 2010 The American Physical Society.

Mao R.,Zhejiang University | Xu J.,Beijing Normal University
China Economic Review | Year: 2014

This paper assesses the heterogeneous effects of population aging on personal budget allocation across sectors. Using China's household survey data, we break down each household expenditure component into its constituent members. We find consistent and robust age profiles of the composition of personal consumption expenditures. Young people spend larger proportions of their budget on food and education, culture, and recreation services. The middle-aged spend significantly more on clothing and transportation and communication. Lastly, the elderly spend substantially more on food and health care and medical services. After controlling for period and cohort effects as well as other socio-economic factors, we still find age to be a fundamental driver of consumption budget allocation. We also incorporate the estimated results into the population forecast data and predict the evolution of China's consumption budget allocation patterns driven by demographic change. © 2014 Elsevier Inc.

Yang J.,Peking University | Weng X.,CAS Institute of Psychology | Zang Y.,Beijing Normal University | Xu M.,CAS Institute of Psychology | Xu X.,Peking University
Cortex | Year: 2010

Recent neuroimaging studies have shown that several brain regions - namely, the posterior cingulate cortex (PCC), ventral medial prefrontal cortex (vmPFC), and the bilateral angular gyrus - are more active during resting states than during cognitive tasks (i.e., default mode network). Although there is evidence showing that the default mode network is associated with unconscious state, it is unclear whether this network is associated with unconscious processing when normal human subjects perform tasks without awareness. We manipulated the level of conscious processing in normal subjects by asking them to perform an implicit and an explicit memory task, and analyzed signal changes in the default mode network for the stimuli versus baseline in both tasks. The functional magnetic resonance imaging (fMRI) analysis showed that the level of activation in regions within this network during the implicit task was not significantly different from that during the baseline, except in the left angular gyrus and the insula. There was strong deactivation for the explicit task when compared with the implicit task in the default mode regions, except in the left angular gyrus and the left middle temporal gyrus. These data suggest that the activity in the default network is sustained and less disrupted when an implicit memory task is performed, but is suspended when explicit retrieval is required. These results provide evidence that the default mode network is associated with unconscious processing when human subjects perform an implicit memory task. © 2009 Elsevier Srl.

Luo Y.,Beijing Normal University | Wang L.-W.,Lawrence Berkeley National Laboratory
ACS Nano | Year: 2010

The electronic structures of the CdSe/CdS core-shell nanorods are systemically investigated by large-scale first-principles quality calculations. The effects of band alignment, quantum confinement, piezoelectric field, and dipole moments are analyzed and delineated by comparing the results of systems with or without some of these attributes. We found complicated interplays between these effects in determining the nanorod band gap and electron hole wave function localizations. The hole wave function is found to be localized inside the CdSe core, while the electron wave function is localized in the CdS shell, with its distance to the CdSe core depending on the surface passivation. The permanent dipole moment induced by different surface passivations can change the electron hole separation, while the piezoelectric effect plays a relatively minor role. Finally, we demonstrate that it is straightforward to manipulate the nanorod electronic structure by changing its CdSe core position. © 2010 American Chemical Society.

Thirumalai D.,University of Maryland University College | Liu Z.,Beijing Normal University | O'Brien E.P.,University of Cambridge | Reddy G.,University of Maryland University College
Current Opinion in Structural Biology | Year: 2013

A quantitative theory of protein folding should make testable predictions using theoretical models and simulations performed under conditions that closely mimic those used in experiments. Typically, in laboratory experiments folding or unfolding is initiated using denaturants or external mechanical force, whereas theories and simulations use temperature as the control parameter, thus making it difficult to make direct comparisons with experiments. The molecular transfer model (MTM), which incorporates environmental changes using measured quantities in molecular simulations, overcomes these difficulties. Predictions of the folding thermodynamics and kinetics of a number of proteins using MTM simulations are in remarkable agreement with experiments. The MTM and all atom simulations demonstrating the presence of dry globules represent major advances in the proteins folding field. © 2012 Elsevier Ltd.

Zhu X.-J.,University of Western Australia | Howell E.J.,University of Western Australia | Blair D.G.,University of Western Australia | Zhu Z.-H.,Beijing Normal University
Monthly Notices of the Royal Astronomical Society | Year: 2013

This paper reports a comprehensive study on the gravitational wave (GW) background from compact binary coalescences. We consider in our calculations newly available observationbased neutron star and black hole mass distributions and complete analytical waveforms that include post-Newtonian amplitude corrections. Our results show that: (i) post-Newtonian effects cause a small reduction in the GW background signal; (ii) below 100 Hz the background depends primarily on the local coalescence rate r0 and the average chirp mass and is independent of the chirp mass distribution; (iii) the effects of cosmic star formation rates and delay times between the formation and merger of binaries are linear below 100 Hz and can be represented by a single parameter within a factor of ~2; (iv) a simple power-law model of the energy density parameter ΩGW(f) ~ f 2/3 up to 50-100 Hz is sufficient to be used as a search template for ground-based interferometers. In terms of detection prospects of this background signal, we show that: (i) detection (a signal-to-noise ratio of 3) within one year of observation by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors (H1-L1) requires a coalescence rate of r0 = 3 (0.2) Mpc-3 Myr-1 for binary neutron stars (binary black holes); (ii) this limit on r0 could be reduced threefold for two co-located and co-aligned detectors, whereas the currently proposed worldwide network of advanced instruments gives only ~30 per cent improvement in detectability; (iii) the improved sensitivity of the planned Einstein Telescope allows not only confident detection of the background but also the high-frequency components of the spectrum to be measured, possibly enabling rate evolutionary histories and mass distributions to be probed. Finally, we show that sub-threshold binary neutron star merger events produce a strong foreground, which could be an issue for future terrestrial stochastic searches of primordial GWs. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

Reich P.B.,University of Minnesota | Reich P.B.,University of Western Sydney | Rich R.L.,University of Minnesota | Lu X.,Beijing Normal University | And 3 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Leaf life span is an important plant trait associated with interspecific variation in leaf, organismal, and ecosystem processes. We hypothesized that intraspecific variation in gymnosperm needle traits with latitude reflects both selection and acclimation for traits adaptive to the associated temperature and moisture gradient. This hypothesis was supported, because across 127 sites along a 2,160-km gradient in North America individuals of Picea glauca, Picea mariana, Pinus banksiana, and Abies balsamea had longer needle life span and lower tissue nitrogen concentration with decreasing mean annual temperature. Similar patterns were noted for Pinus sylvestris across a north-south gradient in Europe. These differences highlight needle longevity as an adaptive feature important to ecological success of boreal conifers across broad climatic ranges. Additionally, differences in leaf life span directly affect annual foliage turnover rate, which along with needle physiology partially regulates carbon cycling through effects on gross primary production and net canopy carbon export. However, most, if not all, global land surface models parameterize needle longevity of boreal evergreen forests as if it were a constant. We incorporated temperature-dependent needle longevity and %nitrogen, and biomass allocation, into a land surface model, Community Atmosphere Biosphere Land Exchange, to assess their impacts on carbon cycling processes. Incorporating realistic parameterization of these variables improved predictions of canopy leaf area index and gross primary production compared with observations from flux sites. Finally, increasingly low foliage turnover and biomass fraction toward the cold far north indicate that a surprisingly small fraction of new biomass is allocated to foliage under such conditions. © 2014 PNAS.

Zhang W.-K.,Beijing Normal University
Chinese Journal of Chemical Physics | Year: 2016

Polarization dependent time-resolved infrared (TRIR) spectroscopy has proven to be a useful technique to study the structural dynamics in a photochemical process. The angular information of transient species is obtainable in this measurement, which makes it a valuable technique for the investigation of electron distribution, molecular structure, and conformational dynamics. In this review, we briefly introduce the principles and applications of polarization dependent TRIR spectroscopy. We mainly focused on the following topics: (i) an overview of TRIR spectroscopy, (ii) principles of TRIR spectroscopy and its advantages compared to the other ultrafast techniques, (iii) examples that use polarization dependent TRIR spectroscopy to probe a variety of chemical and dynamical phenomena including protein conformational dynamics, excited state electron localization, and photoisomerization, (iv) the limitations and prospects of TRIR spectroscopy. © 2016 Chinese Physical Society.

Cui M.,Beijing Normal University
Current Medicinal Chemistry | Year: 2014

The deposition of β-amyloid (Aβ) plaques in the parenchymal and cortical brain is accepted as the main pathological hallmark of Alzheimer's disease (AD). According to the amyloid cascade hypothesis, the Aβ deposition in the brain appears to be a good diagnostic biomarker for AD and may also be a good predictive biomarker of this disease. Molecular imaging of Aβ plaques in the brain with positron emission tomography (PET), single photon emission computed tomography (SPECT) or molecular optical imaging represents a promising approach to the early diagnosis of AD and monitoring the effectiveness of novel therapies for this devastating disease. Our review focuses on the past and recent knowledge in this field with respect to small organic molecules that have been utilized for the development of Aβ imaging probes. © 2014 Bentham Science Publishers.

Zi G.,Beijing Normal University
Science China Chemistry | Year: 2014

Organoactinide complexes containing terminal metal-ligand multiple bonds have received widespread attention over the past three decades. In the last few years, significant progress has been made in the synthesis and characterization of the imido, oxo, sulfido, and carbene-containing complexes of thorium. Such thorium complexes are of interest because of their unique structural properties, their potential application in novel group transfer reactions and catalysis, as well as their ability to engage the 5f orbitals in metal-ligand bonding. This short review summarizes the synthesis and reactivity of these thorium complexes. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg.

Liu H.-S.,Zhejiang University of Technology | Lu H.,Beijing Normal University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We show that for n-dimensional Einstein gravity coupled to a scalar field with mass-squared m02=-n(n-2)/(4ℓ2), the first law of thermodynamics of (charged) AdS black holes will be modified by the boundary conditions of the scalar field at asymptotic infinity. Such scalars can arise in gauged supergravities in four and six dimensions, but not in five or seven. The result provides a guiding principle for constructing designer black holes and solitons in general dimensions, where the properties of the dual field theories depend on the boundary conditions. © 2014 The Authors.

Dong H.,CAS Beijing National Laboratory for Molecular | Bo Z.,Beijing Normal University | Hu W.,CAS Beijing National Laboratory for Molecular
Macromolecular Rapid Communications | Year: 2011

A planar conjugated copolymer named HXS-1 was applied in thin film phototransistors. Similar to organic field-effect transistors using V G to control the source-drain current, in phototransistors, the light is used to substitute V G as an independent variable to control the output of the transistors to realize light detection and signal magnification in a single organic device. All devices exhibited high performance with an on/off ratio up to 4.6×10 4 (the highest on/off ratio of organic or polymer phototransistors), which could be assigned to i) the wide absorption features of HXS-1 in the whole UV-vis range, ii) the ideal HOMO energy level of HXS-1 (5.21 eV) to align with Au electrodes (5.2 eV) and iii) the high mobility of the polymer thin films (∼0.06 cm 2/Vs). Moreover, the devices, both under continuous operation conditions and long term measurement conditions, exhibited excellent stability, indicating potential applications of the devices in polymer-based optoelectronics. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zeng X.-X.,Chongqing Jiaotong University | Liu W.-B.,Beijing Normal University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

In the spirit of AdS/CFT correspondence, we study the thermalization of a dual conformal field theory to Gauss-Bonnet gravity by modeling a thin-shell of dust that interpolates between a pure AdS and a Gauss-Bonnet AdS black brane. The renormalized geodesic length and minimal area surface, which in the dual conformal field theory correspond to two-point correlation function and expectation value of Wilson loop, are investigated respectively as thermalization probes. The result shows that as the Gauss-Bonnet coefficient increases, the thermalization time decreases for both the thermalization probes, which can also be confirmed by studying the motion profile of the geodesic and minimal area surface. In addition, for both the renormalized geodesic length and minimal area surface, there is an overlapped region for a fixed boundary separation, which implies that the Gauss-Bonnet coupling constant has little effect on the thermalization probes there. © 2013 Elsevier B.V.

Lu H.,Beijing Normal University | Pope C.N.,Texas A&M University | Pope C.N.,University of Cambridge
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We propose homogeneous metrics of Petrov type III that describe gyrating Schrödinger geometries as duals to some nonrelativistic field theories, in which the Schrödinger symmetry is broken further so that the phase space has a linear dependence of the momentum in a selected direction. We show that such solutions can arise in four-dimensional Einstein-Weyl supergravity as well as higher-dimensional extended gravities with quadratic curvature terms coupled to a massive vector. In Einstein-Weyl supergravity, the gyrating Schrödinger solutions can be supersymmetric, preserving 14 of the supersymmetry. We obtain the exact Green function in the phase space associated with a bulk free massive scalar. © 2012 American Physical Society.

Wang Y.,Beijing Normal University | Liang S.,Tsinghua University
Energy Policy | Year: 2013

China proposed a CO2 mitigation target in 2020 to deal with anthropogenic global climate change. Chinese policy makers mainly focus on three factors comprising consumption structure changes, energy technology development, and new energy increments. In addition, sectoral CO2 reduction is increasingly concerned in the world. Thus, it is significant to investigate integrated impacts of three factors to China's CO2 mitigation target as well as to identify key economic sectors for achieving this target. In this study, energy demand and CO2 emission in 2020 are predicted. Five scenarios are generated to illustrate the contributions of three factors. In addition, twelve key economic sectors for reducing energy demand and CO2 emission are identified from both production and final demand perspectives. Under integrated impacts of three factors, China's CO2 intensity per unit gross domestic product in 2020 will decrease by about 43.9% in 2020 than 2005 level. In the short term, China's CO2 mitigation will be highly dependent on energy technology development. In the long term, it will mainly rely on reshaped consumption structure changes and new energy development. In addition, China's future policies should focus on 12 identified key economic sectors. © 2013 Elsevier Ltd.

Li X.,Capital Normal University | Sun H.-L.,Beijing Normal University | Wu X.-S.,Capital Normal University | Qiu X.,Capital Normal University | Du M.,Tianjin Normal University
Inorganic Chemistry | Year: 2010

Three porous lanthanide-organic frameworks, [Ln4(OH)4(3-SBA)4(H2O)4] 3 nH2O [Ln = EuIII (1), n = 10; GdIII (2), n = 10; Tb III (3), n = 8; 3-SBA = 3-sulfobenzoate], have been prepared by a hydrothermal synthesis method. They are isomorphous and crystallize in a tetragonal system with space group P 421c. The structure can be considered to be built up by cubanelike [Ln4(OH)4]8+ secondary building units, which are further connected by 3-SBA to form a 3D coordination framework with 1D pores along the c direction for accommodation of novel T8(3) water tapes or zigzag water chains. Furthermore, in these compounds, the [Ln4(OH)4]8+ units and 3-SBA ligands serve as 12-connected and 3-connected nodes, respectively, resulting in a unique (3, 12)-connected framework with the Schläfli symbol of (43)4(4 20.628.818). The luminescent properties of the EuIII (1) and TbIII (3) complexes have been studied, showing characteristic emissions at room temperature. Variable-temperature magnetic susceptibility studies indicate that the GdIII complex 2 displays weak antiferromagnetic coupling through μ 3-OH-pathways. © 2010 American Chemical Society.

Jevrejeva S.,National Oceanography Center | Moore J.C.,Beijing Normal University | Moore J.C.,University of Lapland | Moore J.C.,Uppsala University | Grinsted A.,Copenhagen University
Global and Planetary Change | Year: 2012

Sea level rise over the coming centuries is perhaps the most damaging side of rising temperature (Anthoff et al., 2009). The economic costs and social consequences of coastal flooding and forced migration will probably be one of the dominant impacts of global warming (Sugiyama et al., 2008). To date, however, few studies (Nicholls et al., 2008; Anthoff et al., 2009) on infrastructure and socio-economic planning include provision for multi-century and multi-metre rises in mean sea level. Here we use a physically plausible sea level model constrained by observations, and forced with four new Representative Concentration Pathways (RCP) radiative forcing scenarios (Moss et al., 2010) to project median sea level rises of 0.57 for the lowest forcing and 1.10. m for the highest forcing by 2100 which rise to 1.84 and 5.49. m respectively by 2500. Sea level will continue to rise for several centuries even after stabilisation of radiative forcing with most of the rise after 2100 due to the long response time of sea level. The rate of sea level rise would be positive for centuries, requiring 200-400. years to drop to the 1.8. mm/yr 20th century average, except for the RCP3PD which would rely on geoengineering. © 2011.

Wan X.,RIKEN | Wan X.,Beijing Normal University | Cheng K.,RIKEN | Tanaka K.,RIKEN
Nature Neuroscience | Year: 2015

Humans, and animals, often encounter ambiguous situations that require a decision on whether to take an offense or a defense strategy. Behavioral studies suggest that a strategy decision is frequently made before concrete options are evaluated. It remains enigmatic, however, how a strategy is determined without exploration of options. Here we investigated neural correlates of quick offense-versus-defense strategy decision in a board game, shogi. We found that the rostral anterior cingulate cortex and the posterior cingulate cortex complementally encoded the defense and attack strategy values, respectively. The dorsolateral prefrontal cortex compared the two strategy values. Several brain regions were activated during decision of concrete moves under an instructed strategy, whereas none of them showed correlation with defense or attack strategy values in their activities during strategy decision. These findings suggest that values of alternative strategies represented in different parts of the cingulate cortex have essential roles in intuitive strategy decision-making. © 2015 Nature America, Inc. All rights reserved.

Liu Z.-H.,China Institute of Atomic Energy | Bao J.-D.,Beijing Normal University | Bao J.-D.,Accelerator Centre
Physical Review C - Nuclear Physics | Year: 2013

Synthesis of element 120 in the 249Cf(50Ti,xn)299-x120 and 248Cm(54Cr,xn)302-x120 fusion evaporation reactions has been evaluated by means of a modified fusion by diffusion model. It is found that the fusion probability of the system 54Cr+248Cm is two times smaller than that of 50Ti+249Cf. On the other hand, the survival probability of the former is obviously greater than that of the latter. As a result, the loss in the fusion probability of the 54Cr+248Cm reaction is compensated by its gain in survival probability. The calculated maximum evaporation residue cross sections in the 249Cf(50Ti,3n)296120 and 248Cm(54Cr,4n)298120 reactions are quite close: 0.034 and 0.024 pb, respectively. Besides, as compared to the system 50Ti+249Cf, the 54Cr+248Cm combination has two advantages. First, 248Cm is much easier accumulate a sufficient amount for the target material than 249Cf. Second, the isotope 298120 has 178 neutrons, two neutrons more than the isotope 296120. Therefore, the 54Cr+248Cm combination should be one of most favorable candidates to produce superheavy element 120. © 2013 American Physical Society.

Ma T.,Beijing Normal University | Ma T.,Beijing Computational Science Research Center | Lin H.-Q.,Beijing Computational Science Research Center | Hu J.,CAS Institute of Physics | Hu J.,Purdue University
Physical Review Letters | Year: 2013

We perform a systematic quantum Monte Carlo study of the pairing correlation in the S4 symmetric microscopic model for iron-based superconductors. It is found that the pairing with an extensive s-wave symmetry robustly dominates over other pairings at low temperature in a reasonable parameter region regardless of the change of Fermi surface topologies. The pairing susceptibility, the effective pairing interaction, and the (π, 0) antiferromagnetic correlation strongly increase as the on-site Coulomb interaction increases, indicating the importance of the effect of electron-electron correlation. Our nonbiased numerical results provide a unified understanding of the superconducting mechanism in iron pnictides and iron chalcogenides and demonstrate that the superconductivity is driven by strong electron-electron correlation effects. © 2013 American Physical Society.

Liu W.,State University of New York at Buffalo | Dou F.,Beijing Normal University | Feng J.,State University of New York at Buffalo | Yan Z.,State University of New York at Buffalo
Neurobiology of Aging | Year: 2011

RACK1 (receptor for activated C-kinase 1), an anchoring protein that shuttles activated PKC to cellular membranes, plays an important role in PKC-mediated signal transduction pathways. A significant loss of RACK1 has been found in the brain of aging animals and Alzheimer's disease (AD) patients, which implicates the potential involvement of RACK1 in altered PKC activation associated with dementia. Our previous studies have demonstrated that GABAergic inhibition in prefrontal cortex, which is important for cognitive processes like "working memory", is regulated by muscarinic receptors via a PKC-dependent mechanism, and this effect is impaired by β-amyloid peptide (Aβ). In this study, we found that Aβ oligomers decreased RACK1 distribution in the membrane fraction of cortical neurons. Moreover, overexpression of RACK1 rescued the effect of muscarinic receptors on GABAergic transmission in Aβ-treated cortical cultures in vitro and Aβ-injected cortical neurons in vivo. These results suggest that the Aβ-induced loss of RACK1 distribution in the cell membrane may underlie the Aβ impairment of muscarinic regulation of PKC and GABAergic transmission. Thus, RACK1 provides a potential therapeutic target that can restore some of the impaired cellular processes by Aβ. © 2009 Elsevier Inc.

Pomerantz E.M.,University of Illinois at Urbana - Champaign | Qin L.,University of Illinois at Urbana - Champaign | Wang Q.,Chinese University of Hong Kong | Chen H.,Beijing Normal University
Child Development | Year: 2011

This research examined American and Chinese children's sense of responsibility to their parents during early adolescence, with a focus on its implications for children's academic functioning. Four times over the seventh and eighth grades, 825 children (mean age=12.73years) in the United States and China reported on their sense of responsibility to their parents. Information on children's academic functioning was also collected from children as well as school records. Although children's sense of responsibility to their parents declined over the seventh and eighth grades in the United States, this was not the case in China. In both countries, children's sense of responsibility was predictive of enhanced academic functioning among children over time. © 2011 The Authors. Child Development © 2011 Society for Research in Child Development, Inc.

Chen X.,University of Pennsylvania | Wang L.,Peking University | Cao R.,Beijing Normal University
Child Development | Year: 2011

The purpose of this study was to examine how shyness-sensitivity and unsociability were associated with social, school, and psychological adjustment in rural Chinese children. Participants were third- to fifth-grade students (N = 820; M age=10years) in rural schools in P. R. China. Data on shyness-sensitivity, unsociability, and adjustment were obtained from multiple sources including peer assessments, sociometric nominations, teacher ratings, self-reports, and school records. It was found that unsociability was associated with social, school, and psychological problems, whereas shyness was generally associated with indexes of adjustment such as social status, teacher-rated competence, and academic achievement. The results indicate that rural Chinese context may play an important role in defining the functional meanings of children's social behaviors. © 2011 The Authors. Child Development © 2011 Society for Research in Child Development, Inc.

Many diffusion parameters and indices (e.g., fractional anisotropy [FA] and mean diffusivity [MD]) have been derived from diffusion magnetic resonance imaging (MRI) data. These parameters have been extensively applied as imaging markers for localizing white matter (WM) changes under various conditions (e.g., development, degeneration and disease). However, the vast majority of the existing parameters is derived from intra-voxel analyses and represents the diffusion properties solely within the voxel unit. Other types of parameters that characterize inter-voxel relationships have been largely overlooked. In the present study, we propose a novel inter-voxel metric referred to as the local diffusion homogeneity (LDH). This metric quantifies the local coherence of water molecule diffusion in a model-free manner. It can serve as an additional marker for evaluating the WM microstructural properties of the brain. To assess the distinguishing features between LDH and FA/MD, the metrics were systematically compared across space and subjects. As an example, both the LDH and FA/MD metrics were applied to measure age-related WM changes. The results indicate that LDH reveals unique inter-subject variability in specific WM regions (e.g., cerebral peduncle, internal capsule and splenium). Furthermore, there are regions in which measurements of age-related WM alterations with the LDH and FA/MD metrics yield discrepant results. These findings suggest that LDH and FA/MD have different sensitivities to specific WM microstructural properties. Taken together, the present study shows that LDH is complementary to the conventional diffusion-MRI markers and may provide additional insights into inter-subject WM variability. Further studies, however, are needed to uncover the neuronal mechanisms underlying the LDH. © 2013 Gaolang Gong.

Han Z.R.,Beijing Normal University | Shaffer A.,University of Georgia
Child Psychiatry and Human Development | Year: 2013

This study investigated the roles of parents' and children's emotion dysregulation in children's display of internalizing and externalizing symptoms by incorporating person- and variable-centered approaches. Sixty-four children (ages 8-11) participated in this study with their mothers. Study variables were collected via multiple methods, including behavioral observation and questionnaire assessment from both parents' and children's perspectives. Using model-based cluster analysis, children's profiles with regulating emotions were created by incorporating multiple measurements. Two profiles were identified and applied in a moderation model testing whether the combination of parents' and children's regulatory style influence child outcomes. Results showed that children's emotion dysregulation profiles moderated the relationship between parental emotion dysregulation and child internalizing symptoms, with children who adopted more internalizing regulatory styles display more internalizing symptoms in the context of high parental emotion dysregulation. Implications for the measurement of emotion regulation in the family context, and future directions for intervention, are discussed. © 2012 Springer Science+Business Media New York.

Liang L.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Li L.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Liu Q.,Beijing Normal University
Journal of Hydrology | Year: 2011

Variability in precipitation plays an important role in the way it influences ecological and agricultural water requirements. This is especially true for semi-humid and semi-arid regions exemplified in certain regions in Northeast China. The temporal variation and spatial distribution of precipitation in Northeast China from 1961 to 2008 was investigated in this study by means of a linear fitted model, the Mann-Kendall test, the moving t-test, and the Morlet wavelet and Kriging (exponential) interpolation methods. Results indicate that: (a) the monthly precipitation rate varied considerably wherein summer precipitation accounted for 65.7% of the annual total value; (b) a decreasing trend in precipitation was found in the data obtained from 77 (annual) and 80 (summer) of the 98 meteorological stations throughout a 48. year period (from 1961 to 2008) while climate jumps were detected in 77% (annual) and 67% (summer); (c) three climate jumps and periods of 2.3 and 3.3. years (significant at a 95% confidence level) were detected on a regional scale; (d) the mean annual and summer precipitation rates decreased in a southeastern to northwestern trajectory throughout the 48. year period due both to the influence of the East Asian monsoon and to topography. All these findings can help provide rational regulatory and managerial policy in relation to water resources to maintain the health of the various ecosystems that make up Northeast China. © 2011 Elsevier B.V.

Zhang Y.,Beijing Normal University
Environmental pollution (Barking, Essex : 1987) | Year: 2013

Urban metabolism analysis has become an important tool for the study of urban ecosystems. The problems of large metabolic throughput, low metabolic efficiency, and disordered metabolic processes are a major cause of unhealthy urban systems. In this paper, I summarize the international research on urban metabolism, and describe the progress that has been made in terms of research methodologies. I also review the methods used in accounting for and evaluating material and energy flows in urban metabolic processes, simulation of these flows using a network model, and practical applications of these methods. Based on this review of the literature, I propose directions for future research, and particularly the need to study the urban carbon metabolism because of the modern context of global climate change. Moreover, I recommend more research on the optimal regulation of urban metabolic systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

Huang Q.,Beijing Normal University | Robinson D.T.,University of Waterloo | Parker D.C.,University of Waterloo
Landscape Ecology | Year: 2014

The area of land occupied by exurban residential development is significant and has been increasing over the past several decades in the United States. Considerable attention has been drawn to the measurement of regional-scale patterns of land-cover change and assessment of its environmental and socioeconomic consequences. Yet little is known about the quantity of land-cover change within individual exurban residential parcels, which reflect homeowner preferences, land-management strategies, and the ecosystem services they generate. Similarly, little is known about the spatial autocorrelation of land cover among parcels and how it may change over time. Using a dataset delineating land-cover change within exurban residential parcels in southeastern Michigan from 1960 to 2000, the quantity and composition of land cover and carbon storage are examined. The spatial similarity of land-cover quantity among neighboring parcels is evaluated using local indicators of spatial association. Results show, among other findings, that (1) the number of exurban residential parcels, the quantity of tree cover, and amount of carbon storage increased steadily from 1960 to 2000; (2) the distribution of parcel sizes remained relatively constant and dominated by small parcels; (3) an increasing proportion of parcels were significantly similar to their neighbors; and (4) using a benefits transfer approach, new exurban parcels are estimated to store ~15,000-29,000 kg C over the study period. The measured changes in land cover and carbon storage improve our understanding of how ecosystem services may change in human-dominated landscapes and provide evidence that policy opportunities are available to increase carbon management. © 2013 Springer Science+Business Media Dordrecht.

Yuan B.-C.,Beijing Normal University | Yue D.-X.,Lanzhou University
Pedosphere | Year: 2012

Successional and seasonal effects on soil microbial and enzymatic properties were studied in Chinese pine (Pinus tabulaeformis) plantations in an age sequence of 3-, 7-, 13-, 21- and 28-year-old in northern Ziwuling region in the middle of Loess Plateau, China. The results indicated that plantation age and season affected soil microbial and enzymatic parameters significantly. Soil organic C, total N, microbial biomass C, microbial quotient, basal respiration, dehydrogenase, N-α-benzoyl-L-argininamide (BAA)-protease, urease and β-glucosidase increased quickly and tended to be highest at PF21 (21-year plantation), thereafter they remained nearly at a constant level, whereas the metabolic quotient (qCO 2) showed an initial increase and then decreased gradually. Measures of these soil properties showed significant seasonal fluctuations except for organic C and total N, which were found to be relatively stable throughout the study period, and the seasonal distributions were autumn > spring > summer > winter for microbial biomass C, microbial quotient, dehydrogenase, and β-glucosidase; autumn > summer > spring > winter for BAA-protease and urease; and summer > autumn > spring > winter for basal respiration and qCO 2. Significant season × age interaction was observed for biomass C, basal respiration, dehydrogenase and BAA-protease. © 2012 Soil Science Society of China.

Zhang F.,Beijing Normal University | Zhou L.X.,Chinese Academy of Meteorological Sciences
Tellus, Series B: Chemical and Physical Meteorology | Year: 2013

Carbon dioxide (CO2) emissions and sinks in western China are estimated and implied from atmospheric CO2 measured at Waliguan during the period of 1995-2008. The observed CO2 data are first classified as background, elevated, and sequestration, using a modified background identification method. Comparing it with two other methods tests the applicability of the method. By using this method, approximately 17.2% ± 1.2% and 10.1% ± 0.8% of all observed data are identified as elevated and sequestered CO2, respectively, the percentages (occurrence rates) for both of which increased during 1995-2008. CO2 emissions in western China have enhanced significantly in all seasons during the past 14 yr. Annual mean growth rates of CO2 emissions in the region increased by ~8.4 Tg C y-1 (3.9% y-1) during 1995-2008 but accelerated after 2000 to ~12.6 TgC y-1 (6.2% y-1). The growth rates of CO2 emission in western China are lower than the rest of the country. The annual mean emissions in the country during 1995-1999 and 2000-2006 are thought to be approximately 5.5 and 6.5 times higher than in western China, respectively. However, the growth rates of CO2 emissions in western China are higher than global increase rates as reported by other studies. CO2 sinks in western China varied from 86.0 Tg C y-1 in early 1995-1999 to 106.2 Tg C y-1 in 2005-2008. The most prominent change occurs in summer, indicating enhanced sequestration of photosynthetic CO2 taken up by vegetation. The growth rates in sequestered CO2 cannot keep up with the increase of CO2 emissions in the region. If this continues, it could potentially impact on the global carbon budget. © 2013 F. Zhang and L. X. Zhou.

Wang W.,University of Jinan | Gao L.,CSIRO | Liu P.,Beijing Normal University | Hailu A.,University of Western Australia
Journal of Hydrology | Year: 2014

Northern China has been facing severe water scarcity as a result of vigorous economic growth, population expansion and changing lifestyles. A typical case is Shandong province whose water resources per capita is approximately only a sixth of the national average and a twentieth of the global average. It is useful to assess the implications of the province's growth and trade patterns for water use and water conservation strategies. This study quantitatively analyses relationships between regional economic sectors and water use in Shandong using an input-output model for virtual water resources. The changes in key indicators for 1997-2007 are tracked and the effects of water-saving policies on these changes are examined. The results highlight the benefits of applying a virtual water trade analysis on a water-scarce region where water resources exhibit highly heterogeneous temporal and geographical distributions. The net export of virtual water in Shandong was initially large, but this declined over the years and the province has recently become a net importer. Between 1997 and 2002, water use in most sectors increased due to rapid urbanisation and industrialisation. Since then, water use in all Shandong economic sectors exhibit a downward trend despite continued increases in goods and services net exports, a trend which can be attributed to the vigorous implementation of water-saving policies and measures, especially water use quotas. Economic sectors consume water directly and indirectly and understanding the pattern of virtual water trade implied by sectoral relationships is important for managing water scarcity problems. This study fills the knowledge gap in the existing literature created by the lack of case studies that dynamically assess virtual water trade and analyse the effects of water-saving policies and measures. The study draws policy recommendations that are relevant for future water planning in Shandong and other regions in northern China. © 2014 Elsevier B.V.

Chen Z.M.,Peking University | Chen B.,Beijing Normal University | Chen G.Q.,Peking University
Ecological Modelling | Year: 2011

Wetlands research and restoration has become one of the critical concern due to their importance in providing ecosystem services. This study proposes a holistic methodology to assess the wetland ecosystem based on cosmic exergy as a thermodynamic orientor. This new approach is applied to two typical wastewater treatment facilities (an activated sludge system and a cyclic activated sludge system) and to a constructed wetland ecosystem in Beijing for comparison. Results show that the Beijing wetland ecosystem gains positive net present ecological value of 3.08E+14 J c regarding its total life cycle. Comparison with the activated sludge system and cyclic activated sludge system, shows that the wetland ecosystem has greater dependencies on local resources (22% vs. 0% vs. 0%) and renewable resources (67% vs. 38% vs. 31%) as well as a larger ecological sustainability index (0.64157 vs. 0.00005 vs. 0.00008). This implies that the wetland ecosystem is more environmentally friendly and sustainable method for water treatment. © 2010 Elsevier B.V.

Qu Z.,University of California at Los Angeles | Hu G.,Beijing Normal University | Garfinkel A.,University of California at Los Angeles | Weiss J.N.,University of California at Los Angeles
Physics Reports | Year: 2014

In a normal human life span, the heart beats about 2-3 billion times. Under diseased conditions, a heart may lose its normal rhythm and degenerate suddenly into much faster and irregular rhythms, called arrhythmias, which may lead to sudden death. The transition from a normal rhythm to an arrhythmia is a transition from regular electrical wave conduction to irregular or turbulent wave conduction in the heart, and thus this medical problem is also a problem of physics and mathematics. In the last century, clinical, experimental, and theoretical studies have shown that dynamical theories play fundamental roles in understanding the mechanisms of the genesis of the normal heart rhythm as well as lethal arrhythmias. In this article, we summarize in detail the nonlinear and stochastic dynamics occurring in the heart and their links to normal cardiac functions and arrhythmias, providing a holistic view through integrating dynamics from the molecular (microscopic) scale, to the organelle (mesoscopic) scale, to the cellular, tissue, and organ (macroscopic) scales. We discuss what existing problems and challenges are waiting to be solved and how multi-scale mathematical modeling and nonlinear dynamics may be helpful for solving these problems. © 2014 Elsevier B.V.

Fazio L.K.,Carnegie Mellon University | Bailey D.H.,Carnegie Mellon University | Thompson C.A.,University of Oklahoma | Siegler R.S.,Carnegie Mellon University | Siegler R.S.,Beijing Normal University
Journal of Experimental Child Psychology | Year: 2014

We examined relations between symbolic and non-symbolic numerical magnitude representations, between whole number and fraction representations, and between these representations and overall mathematics achievement in fifth graders. Fraction and whole number symbolic and non-symbolic numerical magnitude understandings were measured using both magnitude comparison and number line estimation tasks. After controlling for non-mathematical cognitive proficiency, both symbolic and non-symbolic numerical magnitude understandings were uniquely related to mathematics achievement, but the relation was much stronger for symbolic numbers. A meta-analysis of 19 published studies indicated that relations between non-symbolic numerical magnitude knowledge and mathematics achievement are present but tend to be weak, especially beyond 6. years of age. © 2014 Elsevier Inc.

Huang G.,Beijing Normal University
Environmental Pollution | Year: 2015

China has long been regarded as a centralized society where the public has little influence on decision-making. Such a top-down management scheme is perceived as a major obstacle to address complicated environment issues. The recent public campaign in China to urge creation of a nationwide PM2.5 monitoring network and mitigation plan provides an unprecedented case of how the public participated and influenced policy-making in a centralized society. This paper reviews key incidents in the campaign chronologically. Here we identify information technology, public awareness of air quality's health impacts and the fact air quality affects everyone as public goods as the major factors promoting public participation. This case demonstrates that public participation can happen in a centralized, top-down society such as China. Continued environmental deterioration may stimulate similar campaigns for other issues. We anticipate this essay to be a starting point for more studies on how environmental issues stimulate incremental social change by making people involved in decision-making process, especially in societies where they are rarely able to do so. ©2014 Elsevier Ltd. All rights reserved.

Moughal T.A.,Beijing Normal University
Journal of Physics: Conference Series | Year: 2013

Classification of land cover hyperspectral images is a very challenging task due to the unfavourable ratio between the number of spectral bands and the number of training samples. The focus in many applications is to investigate an effective classifier in terms of accuracy. The conventional multiclass classifiers have the ability to map the class of interest but the considerable efforts and large training sets are required to fully describe the classes spectrally. Support Vector Machine (SVM) is suggested in this paper to deal with the multiclass problem of hyperspectral imagery. The attraction to this method is that it locates the optimal hyper plane between the class of interest and the rest of the classes to separate them in a new high-dimensional feature space by taking into account only the training samples that lie on the edge of the class distributions known as support vectors and the use of the kernel functions made the classifier more flexible by making it robust against the outliers. A comparative study has undertaken to find an effective classifier by comparing Support Vector Machine (SVM) to the other two well known classifiers i.e. Maximum likelihood (ML) and Spectral Angle Mapper (SAM). At first, the Minimum Noise Fraction (MNF) was applied to extract the best possible features form the hyperspectral imagery and then the resulting subset of the features was applied to the classifiers. Experimental results illustrate that the integration of MNF and SVM technique significantly reduced the classification complexity and improves the classification accuracy. © Published under licence by IOP Publishing Ltd.

Filippi M.,Vita-Salute San Raffaele University | van den Heuvel M.P.,University Utrecht | Fornito A.,Monash University | He Y.,Beijing Normal University | And 4 more authors.
The Lancet Neurology | Year: 2013

Network-based analysis of structural and functional connections has provided a new technique to study the brains of healthy people and patients with neurological and psychiatric disorders. Graph theory provides a powerful method to quantitatively describe the topological organisation of brain connectivity. With such a framework, the brain can be depicted as a set of nodes connected by edges. Distinct modifications of network topological organisation in the brain have been identified during development and normal ageing, whereas disrupted functional and structural connectivities have been associated with several neurological and psychiatric disorders, including dementia, amyotrophic lateral sclerosis, multiple sclerosis, and schizophrenia. These assessments have improved understanding of the clinical manifestations noted in these patients, including disability and cognitive impairment. Future network-based research might enable indentification of different stages of disorders, subtypes for cognitive impairment, and connectivity profiles associated with different clinical outcomes. © 2013 Elsevier Ltd.

Zhang Z.,Tianjin Polytechnic University | Yuan R.,Beijing Normal University
Mathematical Methods in the Applied Sciences | Year: 2014

In this paper, we investigate the existence of infinitely many solutions for the following fractional Hamiltonian systems: {tD ∞ α(-∞Dt αu(t))+L(t)u(t)=∇W(t,u(t)),u∈H α(ℝ,ℝn),(FHS) where α∈(1/2,1), t ∈ ℝ, u ∈ ℝn, and L ∈ C(ℝ, ℝn2) are symmetric and positive definite matrices for all t ∈ ℝ, W ∈ C1(R × ℝn, ℝ), and ∇W is the gradient of W at u. The novelty of this paper is that, assuming L is coercive at infinity, and W is of subquadratic growth as|u|→+∞, we show that (FHS) possesses infinitely many solutions via the genus properties in the critical theory. Recent results in the literature are generalized and significantly improved. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.

Ye Y.,Beijing Normal University
Mathematical Methods in the Applied Sciences | Year: 2015

C. Miao In this paper, we are concerned with the 1D Cauchy problem of the compressible Navier-Stokes equations with the viscosity μ(ρ) = 1+ρβ(β≥0). The initial density can be arbitrarily large and keep a non-vacuum state ρ¯>0 at far fields. We will establish the global existence of the classical solution for 0≤β < γ via a priori estimates when the initial density contains vacuum in interior interval or is away from the vacuum. We will show that the solution will not develop vacuum in any finite time if the initial density is away from the vacuum. To study the well-posedness of the problem, it is crucial to obtain the upper bound of the density. Some new weighted estimates are applied to obtain our main results. © 2015John Wiley & Sons, Ltd.

Kunsagi-Mate S.,University of Pecs | Nie J.C.,Beijing Normal University
Surface Science | Year: 2010

According to the aim to compose combinatorial material by adsorption of carbon nanotubes onto the structured CeO2 surface the interaction of the armchair (5,5) and zigzag (8,0) nanotubes with the (0 0 1) and (1 1 1) surfaces of CeO2 islands have been investigated by theoretical methods. The thermodynamics of the adsorption were studied at the low surface coverage region. The interaction energy between the nanotube and the different CeO2 surfaces shows significant increase when the size of the interface reaches 7-8 unit cells of CeO2 and it remains unchanged in the larger interface region. However, the entropy term of the adsorption is significantly high when the distances of CeO2 islands are equal to 27 nm (adsorption of armchair (5,5) nanotube) or 32 nm (adsorption of zigzag (8,0) nanotube). This property supports adsorption of nanotubes onto CeO2 surfaces which possesses a very specific surface morphology. A long-wave vibration of nanotubes was identified as background of this unexpected phenomenon. This observation could be applicable in the development of such procedures where the nanotube adsorption parallel to the surface is aimed to perform. © 2010 Elsevier B.V. All rights reserved.

Dong Y.,Shanxi University | Zhang J.,Beijing Normal University
Ecotoxicology and Environmental Safety | Year: 2010

The coking wastewater induces severe environmental problems in China, however, its toxicity has not been well known. In the present study, the genotoxicity of coking wastewater was studied using Vicia faba and Hordeum vulgare root tip cytogenetic bioassays. Results show that the tested coking wastewater decreased the mitotic index, and significantly enhanced the frequencies of micronucleus, sister chromatid exchange and pycnotic cell in concentration-dependent manners. Exposure to the same concentration wastewater, the increasing ratios of above genetic injuries were higher in V. faba than that in H. vulgare. The results imply that coking wastewater is a genotoxic agent in plant cells and exposure to the wastewater in environment may pose a potential genotoxic risk to organisms. It also suggests that both bioassays can be used for testing the genotoxicity of coking wastewater, but the V. faba assay is more sensitive than H. vulgare assay during the process. © 2010.

Zhang Z.,Tianjin Polytechnic University | Yuan R.,Beijing Normal University
Mathematical Methods in the Applied Sciences | Year: 2014

In this paper, we are concerned with the existence of infinitely many solutions for the following fractional Hamiltonian systems where is the gradient of at The novelty of this paper is that, assuming L is bounded in the sense that there are constants such that for all and is of subquadratic growth as we show that (FHS) possesses infinitely many solutions via the genus properties in the critical theory. Recent results in [Z. Zhang and R. Yuan, Variational approach to solutions for a class of fractional Hamiltonian systems, Math. Methods Appl. Sci., DOI:10.1002/mma.2941] are generalized and significantly improved. © 2013 John Wiley &Sons, Ltd.

Hu F.,Beijing Normal University | Jia Q.,CAS Institute of Chemistry | Li Y.,CAS Institute of Chemistry | Gao M.,CAS Institute of Chemistry
Nanotechnology | Year: 2011

The development of new types of high-performance nanoparticulate MR contrast agents with either positive (T1) or dual-contrast (both positive and negative, T1 + T2) ability is of great importance. Here we report a facile synthesis of ultrasmall PEGylated iron oxide nanoparticles for dual-contrast T1-and T2-weighted MRI. The produced superparamagnetic iron oxide nanoparticles (SPIONs) are of high crystallinity and size uniformity with an average diameter of 5.4nm, and can be individually dispersed in the physiological buffer with high stability. The SPIONs reveal an impressive saturation magnetization of 94 emug -1Fe3O4, the highest r1 of 19.7 mM-1s-1 and the owest r2/r1 ratio of 2.0 at 1.5T reported so far for PEGylated iron oxide nanoparticles. T 1-and T2-weighted MR images showed that the SPIONs could not only improve surrounding water proton signals in the T1-weighted image, but induce significant signal reduction in the T2-weighted image. The good contrast effect of the SPIONs as T1 + T2 dual-contrast agents might be due to its high magnetization, optimal nanoparticle size for T1 + T2 dual-contrast agents, high size monodispersity and excellent colloidal stability. In vitro cell experiments showed that the SPIONs have little effect on HeLa cell viability. © 2011 IOP Publishing Ltd.

Ouyang S.-X.,Bielefeld University | Ouyang S.-X.,Beijing Normal University
Infinite Dimensional Analysis, Quantum Probability and Related Topics | Year: 2011

By the method of coupling and Girsanov transformation, Harnack inequalities (F.-Y. Wang, 1997) and strong Feller property are proved for the transition semigroup associated with the multivalued stochastic evolution equation on a Gelfand triple. The concentration property of the invariant measure for the semigroup is investigated. As applications of Harnack inequalities, explicit upper bounds of the Lp-norm of the density, contractivity, compactness and entropy-cost inequality for the semigroup are also presented. © 2011 World Scientific Publishing Company.

Patel D.J.,Sloan Kettering Cancer Center | Wang Z.,Sloan Kettering Cancer Center | Wang Z.,Beijing Normal University
Annual Review of Biochemistry | Year: 2013

This review focuses on a structure-based analysis of histone posttranslational modification (PTM) readout, where the PTMs serve as docking sites for reader modules as part of larger complexes displaying chromatin modifier and remodeling activities, with the capacity to alter chromatin architecture and templated processes. Individual topics addressed include the diversity of reader-binding pocket architectures and common principles underlying readout of methyl-lysine and methyl-arginine marks, their unmodified counterparts, as well as acetyl-lysine and phosphoserine marks. The review also discusses the impact of multivalent readout of combinations of PTMs localized at specific genomic sites by linked binding modules on processes ranging from gene transcription to repair. Additional topics include cross talk between histone PTMs, histone mimics, epigenetic-based diseases, and drug-based therapeutic intervention. The review ends by highlighting new initiatives and advances, as well as future challenges, toward the promise of enhancing our structural and mechanistic understanding of the readout of histone PTMs at the nucleosomal level. © 2013 by Annual Reviews. All rights reserved.

Gu Z.-H.,Beijing Normal University
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2012

The prediction of crop grain protein by hyperspectral data has the nondestructive and quick advantages. At present, there are only a few reports about the prediction of barley grain protein by remote sensing. The present research focuses on the malt barley of Northeast China. Firstly, we analyzed the sensitive band area, compared many vegetation indexes related with the plant nitrogen. According to the mechanism of nitrogen transfer, the authors built the prediction model based on the hyperspectral vegetation indexes. Finally, we validated the results. It can meet the standard. The outcome shows that (1) the sensitive band region of barley plant nitrogen is 550~590 nm and 670~710 nm. (2) GRVI was significantly correlated with plant nitrogen. The relationship between GRVI and barley plant nitrogen had a coefficient of determination of R 2=0.6651. The results indicated that the prediction of barley grain protein by hyperspectral data is feasible. This research will be a strong scientific support for barley purchase.

Yu X.-F.,Anhui University of Science and Technology | Zhang C.,Anhui University of Science and Technology | Zhang C.,Beijing Normal University | Wang Z.-X.,Anhui University of Science and Technology
Organometallics | Year: 2013

The synthesis and characterization of N,N,O-chelate zinc enolate complexes and the catalysis of the complexes for the ROP of rac-lactide are reported. The pyrazole-based ligand precursors o-(3,5-Me2C3HN 2)C6H4N=C(Me)CH=C(OH)R1 (R 1 = Me, 1; R1 = Ph, 2; R1 = t-Bu, 3; R 1 = CF3, 4)were synthesized by reaction of 2-(3,5-dimethyl-1H-pyrazol-1-yl)benzenamine with 1,3-diketones, including pentane-2,4-dione,1-phenylbutane-1,3-dione, 5,5-dimethylhexane-2,4-dione, and 1,1,1-trifluoropentane-2,4-dione. Treatment of 1-4 with ZnEt2 generated the N,N,O-coordinated zinc complexes [Zn(Et){o-(OC(R 1)=CHC(Me)=N)C6H4(3,5-Me2C 3HN2)}] (R1 = Me, 5; R1 = Ph, 6; R1 = t-Bu, 7; R1 = CF3, 8). The iminophosphoranyl-moiety-containing ligand precursors o-(3,5-Me 2C3HN2)C6H4N=P(Ph 2)CH2C(O)R2 (R2 = Ph, 9; R 2 = t-Bu, 10) were synthesized by reaction of 1-(2-azidophenyl)-3,5- dimethyl-1H-pyrazole with 1-phenyl-2-(diphenylphosphino)ethanone and 3,3-dimethyl-1-(diphenylphosphino)butan-2-one, respectively. Treatment of 9 and 10 with ZnEt2 afforded the zinc complexes [Zn(Et){o-(OC(R 2)=CHP(Ph2)=N)C6H4(3,5-Me 2C3HN2)}] (R2 = Ph, 11; R 2 = t-Bu, 12). The ligand precursors and complexes were characterized by NMR spectroscopy and elemental analyses. Complexes 5 and 11 were also characterized by single-crystal X-ray diffraction techniques. In the presence of BnOH complexes 5-8 efficiently catalyzed the ring-opening polymerization of rac-lactide in a controlled fashion, whereas complexes 11 and 12 showed much lower catalytic activity under the same conditions. © 2013 American Chemical Society.

Wu X.T.,Beijing Normal University
Physica A: Statistical Mechanics and its Applications | Year: 2016

The first order wetting transition with two defect lines, one near a wall and another at a distance N1, in the d=2 Ising model is studied by the bond propagation algorithm. The numerical calculations are carried out on very large lattices with size up to 1602×160. The finite size effects of the first order transition in that model are discussed. The magnetization profile is also calculated. The numerical results agree with the exact results very well. © 2016 Elsevier B.V. All rights reserved.

Li Z.,Yanshan University | Li X.,Beijing Normal University
PLoS ONE | Year: 2013

Estimating the causal interaction between neurons is very important for better understanding the functional connectivity in neuronal networks. We propose a method called normalized permutation transfer entropy (NPTE) to evaluate the temporal causal interaction between spike trains, which quantifies the fraction of ordinal information in a neuron that has presented in another one. The performance of this method is evaluated with the spike trains generated by an Izhikevich's neuronal model. Results show that the NPTE method can effectively estimate the causal interaction between two neurons without influence of data length. Considering both the precision of time delay estimated and the robustness of information flow estimated against neuronal firing rate, the NPTE method is superior to other information theoretic method including normalized transfer entropy, symbolic transfer entropy and permutation conditional mutual information. To test the performance of NPTE on analyzing simulated biophysically realistic synapses, an Izhikevich's cortical network that based on the neuronal model is employed. It is found that the NPTE method is able to characterize mutual interactions and identify spurious causality in a network of three neurons exactly. We conclude that the proposed method can obtain more reliable comparison of interactions between different pairs of neurons and is a promising tool to uncover more details on the neural coding. © 2013 Li, Li.

Tu Z.C.,Beijing Normal University | Ou-Yang Z.C.,CAS Institute of Theoretical Physics
Advances in Colloid and Interface Science | Year: 2014

Recent theoretical advances in elasticity of membranes following Helfrich's famous spontaneous curvature model are summarized in this review. The governing equations describing equilibrium configurations of lipid vesicles, lipid membranes with free edges, and chiral lipid membranes are presented. Several analytic solutions to these equations and their corresponding configurations are demonstrated. © 2014 Elsevier B.V.

Xu L.,University of California at Los Angeles | Xu L.,Beijing Normal University | Qu Z.,University of California at Los Angeles
PLoS ONE | Year: 2012

Protein ubiquitination and degradation play important roles in many biological functions and are associated with many human diseases. It is well known that for biochemical oscillations to occur, proper degradation rates of the participating proteins are needed. In most mathematical models of biochemical reactions, linear degradation kinetics has been used. However, the degradation kinetics in real systems may be nonlinear, and how nonlinear degradation kinetics affects biological oscillations are not well understood. In this study, we first develop a biochemical reaction model of protein ubiquitination and degradation and calculate the degradation rate against the concentration of the free substrate. We show that the protein degradation kinetics mainly follows the Michaelis-Menten formulation with a time delay caused by ubiquitination and deubiquitination. We then study analytically how the Michaelis-Menten degradation kinetics affects the instabilities that lead to oscillations using three generic oscillation models: 1) a positive feedback mediated oscillator; 2) a positive-plus-negative feedback mediated oscillator; and 3) a negative feedback mediated oscillator. In all three cases, nonlinear degradation kinetics promotes oscillations, especially for the negative feedback mediated oscillator, resulting in much larger oscillation amplitudes and slower frequencies than those observed with linear kinetics. However, the time delay due to protein ubiquitination and deubiquitination generally suppresses oscillations, reducing the amplitude and increasing the frequency of the oscillations. These theoretical analyses provide mechanistic insights into the effects of specific proteins in the ubiquitination-proteasome system on biological oscillations. © 2012 Xu, Qu.

Han E.,Otto Von Guericke University of Magdeburg | Li J.,Beijing Normal University | Tang H.,Peking University
Communications in Computational Physics | Year: 2011

The adaptive generalized Riemann problem (GRP) scheme for 2-D compressible fluid flows has been proposed in [J. Comput. Phys., 229 (2010), 1448-1466] and it displays the capability in overcoming difficulties such as the start-up error for a single shock, and the numerical instability of the almost stationary shock. In this paper, we will provide the accuracy study and particularly show the performance in simulating 2-D complex wave configurations formulated with the 2-D Riemann problems for compressible Euler equations. For this purpose, we will first review the GRP scheme briefly when combined with the adaptive moving mesh technique and consider the accuracy of the adaptive GRP scheme via the comparison with the explicit formulae of analytic solutions of planar rarefaction waves, planar shock waves, the collapse problem of a wedge-shaped dam and the spiral formation problem. Then we simulate the full set of wave configurations in the 2-D four-wave Riemann problems for compressible Euler equations [SIAM J. Math. Anal., 21 (1990), 593-630], including the interactions of strong shocks (shock reflections), vortex-vortex and shock-vortex etc. This study combines the theoretical results with the numerical simulations, and thus demonstrates what Ami Harten observed "for computational scientists there are two kinds of truth: the truth that you prove, and the truth you see when you compute" [J. Sci. Comput., 31 (2007), 185-193]. © 2011 Global-Science Press.

Wang S.,Beijing University of Posts and Telecommunications | Hu G.,Beijing Normal University
Information Sciences | Year: 2012

A new hash function based on a coupled chaotic map lattice is proposed. By combining floating-point chaotic computations with algebraic operations as well as local and global couplings, the system reaches high bit confusion and diffusion rates and thus desirable collision resistance with even one-iteration computation. The algorithm can be used to calculate hash values of 128, 160, 192, 256, 384 and 512 bits with little difference in performance for the different hash values. The algorithm has both strong collision resistance and high efficiency and can serve as a new type of candidate hash function in software. © 2012 Elsevier Inc. All rights reserved.

In this paper, a multi-objective optimization model has been developed for allocating freshwater to meet the environmental flow requirements of the restored wetlands in the Yellow River Delta, China. The model seeks a rational balance among appropriate water allocation for the wetlands, a healthy ecosystem, and optimum economic returns for the humans that use the wetlands to earn their livelihood, with the degree of ecosystem health represented by the difference between actual and ideal water levels. And then a holistic method has been used for satisfying multiple objectives to avoid the problem of decision-maker subjectivity, and then solved the resulting optimal allocation model for environmental flows of the wetlands using a genetic algorithm. With water from the Yellow River as the source, the model shows how the optimal monthly water release into the restored wetlands can be achieved in dry, average, and wet years. Using the model, 20-56% reductions in water use could be achieved compared with the current pattern of water release, and the optimal water level in each month would coincide better with the ideal value based on an indicator plant community (reeds). The results of the study demonstrate the capability of the multi-objective programming model to optimize ecological water allocation and management for the wetlands of the Yellow River Delta. © 2010 Elsevier B.V.

Xie X.,Wuhan University | Xie X.,Beijing Normal University | Cui Y.,Wuhan University
Journal of Hydrology | Year: 2011

The water movement in irrigation districts, especially for paddy rice cultivation, is characterized by complicated factors. Soil and Water Assessment Tool (SWAT) is a popular tool for understanding the hydro-agronomic processes. However, it fails to simulate the hydrological processes and crop yields in paddy rice areas. In this study, we develop the SWAT model by incorporating new processes for irrigation and drainage. The evapotranspiration process in paddy fields is simulated on the basis of water storage conditions, and a controlling irrigation scheme is introduced to manage the irrigation and drainage operations. The irrigation function of local water storages, such as ponds and reservoirs, is extended for these storages in order to provide water in a timely manner to paddy fields. Moreover, an agronomic model is incorporated to estimate crop yields when available data sets are not satisfactory. The model is tested in Zhanghe Irrigation District, China. The simulated runoff matches well to the measurements and the results indicate the developed model is preferable to the original edition of SWAT. The estimate of the paddy rice yield is acceptable and the dynamics of water balance components approximately characterize the state of water movements in paddy fields. Therefore, the developed framework for SWAT is practical and capable of representing the hydrological processes in this irrigation district. Further work is still needed to more broadly test the model in areas with paddy rice cultivation. © 2010 Elsevier B.V.

Zi G.,Beijing Normal University
Journal of Organometallic Chemistry | Year: 2011

Group 4 metal complexes based on chiral biaryl ligands are readily prepared by a convenient amine elimination procedure, and they are efficient catalysts for the asymmetric hydroamination/cyclization of aminoalkenes. The biaryl-based ligands are highly modular enabling facile tuning of the catalyst reactivity and selectivity. The corresponding heterocyclic products have been obtained in excellent enantiomeric excesses (up to 93%) using sterically hindered C 2-symmetric titanium and zirconium mesitoylamidate complexes such as [1,1′-(C10H10)2-2,2′-{NCO(2,4,6- Me3C6H2)}2]M(NMe2) 2 (M = Ti, Zr). These results are presented in this short review. © 2010 Elsevier B.V. All rights reserved.

Fan Z.,Beijing Normal University
Journal of High Energy Physics | Year: 2013

We investigate holographic superconductors in asympototically geometries with hyperscaling violation. The mass of the scalar field decouples from the UV dimension of the dual scalar operator and can be chosen as negative as we want, without disturbing the Breitenlohner-Freedman bound. We first numerically find that the scalar condenses below a critical temperature and a gap opens in the real part of the conductivity, indicating the onset of superconductivity. We further analytically explore the effects of the hyperscaling violation on the superconducting transition temperature. We find that the critical temperature increases with the increasing of hyperscaling violation. © 2013 SISSA, Trieste, Italy.

Fan Z.,Beijing Normal University
Journal of High Energy Physics | Year: 2013

We investigate a dynamically generated Mott gap from holographic fermions in asymptotical geometries with hyperscaling violation by employing a bulk dipole coupling for fermions. We find that when the coupling strength increases, the spectral function first appears at the negative frequency region but is soon transferred to the positive region. A stable gap and two bands emerge for all momentums when the coupling strength exceeds a critical value. Generally, the upper band on the positive frequency axis is much sharper than the lower band on the negative side. When the diploe coupling increases further, the gap becomes larger. The upper band keeps sharp while the lower band disperses and widens, concentrating on the small momentum space. We also find that the bands will be smoothed out gradually with the increasing of hyperscaling violation. © 2013 SISSA, Trieste, Italy.

Tan Y.,Beijing Normal University
Acta Mathematica Scientia | Year: 2016

In this paper, we discuss the uniqueness problem of algebroid functions on annuli, we get several uniqueness theorems of algebroid functions on annuli, which extend the Nevanlinna value distribution theory for algebroid functions on annuli. © 2016 Wuhan Institute of Physics and Mathematics.

Lv M.-Z.,CAS Institute of High Energy Physics | Xia J.-Q.,Beijing Normal University
Physics of the Dark Universe | Year: 2016

In this paper, we use the model dependent method to revisit the constraint on the well-known cosmic distance duality relation (CDDR). By using the latest SNIa samples, such as Union2.1, JLA and SNLS, we find that the SNIa data alone cannot constrain the cosmic opacity parameter ε, which denotes the deviation from the CDDR, dL=dA(1+z)2+ε, very well. The constraining power on ε from the luminosity distance indicator provided by SNIa and GRB is hardly to be improved at present. When we include other cosmological observations, such as the measurements of Hubble parameter, the baryon acoustic oscillations and the distance information from cosmic microwave background, we obtain the tightest constraint on the cosmic opacity parameter ε, namely the 68% C.L. limit: ε=0.023±0.018. Furthermore, we also consider the evolution of ε as a function of z using two methods, the parametrization and the principle component analysis, and do not find the evidence for the deviation from zero. Finally, we simulate the future SNIa and Hubble measurements and find the mock data could give very tight constraint on the cosmic opacity ε and verify the CDDR at high significance. © 2016 Elsevier B.V..

Liao W.-J.,Beijing Normal University | Harder L.D.,University of Calgary
American Naturalist | Year: 2014

Angiosperms engage in distributed reproduction, producing sex organs in multiple flowers on one or more inflorescences, including on different physical individuals of clonal plants. We investigated the effects of alternative deployments of artificial flowers for pollinator behavior and simulated pollen dispersal. Plants presented 18 flowers on either one inflorescence (1-I plants) or three inflorescences (3-I plants) spaced either closely or widely. Bees often skipped inflorescences on 3-I plants, visiting an average of 1.5 fewer flowers overall than on 1-I plants. In simulations with all flowers receiving and donating pollen, this behavior caused 7% less geitonogamy for 3-I plants, contradicting a common supposition that clonality increases geitonogamy. Bees generally moved upward within inflorescences and downward between inflorescences. Consequently, in simulations, segregation of pollen receipt to lower flowers and pollen donation to upper flowers reduced self-pollination and enhanced pollen export much more for 1-I plants. Nectar volume per flower had little relevant influence on bee behavior. The observed bee responses and simulated mating results suggest that production of multiple inflorescences and clonality promote pollination quality when flowers simultaneously receive and donate pollen, whereas a single large inflorescence is advantageous when segregation of sex roles among flowers reduces geitonogamy effectively. © 2014 by The University of Chicago. All rights reserved.

Zhou S.,Chinese University of Hong Kong | Leung A.,Chinese University of Hong Kong | Li X.,Beijing Normal University
Journal of Counseling Psychology | Year: 2012

This study examined Chinese university students' conceptualization of the meaning of work. One hundred and ninety students (93 male, 97 female) from Beijing, China, participated in the study. Prototype research methodology (J. Li, 2001) was used to explore the meaning of work and the associations among the identified meanings. Cluster analysis was used to organize the identified meanings into a structure consisting of lateral and hierarchical levels. The themes that emerged fell into 2 large categories named "ideal" and "reality." A series of superordinate-level and basic-level prototypes were found under each of these 2 categories. These prototypes reflected influences from both Chinese traditional and Western value orientations, as well as perceptions that are to be understood in the contemporary social and economic contexts of China. Implications for career development theory, research, and practice are discussed. © 2012 American Psychological Association.

A recent model by Currat et al. indicates that when one species colonizes an area already occupied by a closely related species, massive introgression of neutral genes should take place primarily in the direction from the local to the invasive species. Here, I show that this model relies on an assumption that might not capture the true dynamics of how species exchange migrants during admixture. As an alternative, I formulate a new model, based on a different and perhaps more biologically realistic assumption of interbreeding, that demonstrates symmetric introgression as compared to the large and asymmetric introgression predicted by the original model. The new model indicates that asymmetry is not a default property of introgressions, thus necessitating alternative explanations for the common observation of massive asymmetric introgression including sex-biased dispersal. © 2013 Institute of Botany, Chinese Academy of Sciences.

Zhou J.,Fudan University | Yu M.,Fudan University | Sun Y.,Fudan University | Zhang X.,Beijing Normal University | And 4 more authors.
Biomaterials | Year: 2011

Molecular imaging modalities provide a wealth of information that is highly complementary and rarely redundant. To combine the advantages of molecular imaging techniques, 18F-labeled Gd3+/Yb3+/Er3+ co-doped NaYF4 nanophosphors (NPs) simultaneously possessing with radioactivity, magnetic, and upconversion luminescent properties have been fabricated for multimodality positron emission tomography (PET), magnetic resonance imaging (MRI), and laser scanning upconversion luminescence (UCL) imaging. Hydrophilic citrate-capped NaY0.2Gd0.6Yb0.18Er0.02F4 nanophosphors (cit-NPs) were obtained from hydrophobic oleic acid (OA)-coated nanoparticles (OA-NPs) through a process of ligand exchange of OA with citrate, and were found to be monodisperse with an average size of 22 × 19 nm. The obtained hexagonal cit-NPs show intense UCL emission in the visible region and paramagnetic longitudinal relaxivity (r1 = 0.405 s-1·(mM)-1). Through a facile inorganic reaction based on the strong binding between Y3+ and F-, 18F-labeled NPs have been fabricated in high yield. The use of cit-NPs as a multimodal probe has been further explored for T1-weighted MR and PET imaging in vivo and UCL imaging of living cells and tissue slides. The results indicate that 18F-labeled NaY0.2Gd0.6Yb0.18Er0.02 is a potential candidate as a multimodal nanoprobe for ultra-sensitive molecular imaging from the cellular scale to whole-body evaluation. © 2010 Elsevier Ltd.

Yu H.-Z.,Simon Fraser University | Li Y.,Simon Fraser University | Li Y.,Beijing Normal University | Ou L.M.-L.,Simon Fraser University
Accounts of Chemical Research | Year: 2013

Traditional methods of disease diagnosis are both time-consuming and labor-intensive, and many tests require expensive instrumentation and trained professionals, which restricts their use to biomedical laboratories. Because patients can wait several days (even weeks) for the results, the consequences of delayed treatment could be disastrous. Therefore, affordable and simple point-of-care (POC) biosensor devices could fill a diagnostic niche in the clinic or even at home, as personal glucose meters do for diabetics. These devices would allow patients to check their own health conditions and enable physicians to make prompt treatment decisions, which could improve the chances for rapid recovery and cure.Compact discs (CDs) provide inexpensive substrate materials for the preparation of microarray biochips, and conventional computer drives/disc players can be adapted as precise optical reading devices for signal processing. Researchers can employ the polycarbonate (PC) base of a CD as an alternative substrate to glass slides or silicon wafers for the preparation of microanalytical devices. Using the characteristic optical phenomena occurring on the metal layer of a CD, researchers can develop biosensors based on advanced spectroscopic readout (interferometry or surface plasmon resonance). If researchers integrate microfluidic functions with CD mechanics, they can control fluid transfer through the spinning motion of the disc, leading to "lab-on-a-CD" devices.Over the last decade, our laboratory has focused on the construction of POC biosensor devices from off-the-shelf CDs or DVDs and standard computer drives. Besides the initial studies of the suitability of CDs for surface and materials chemistry research (fabrication of self-assembled monolayers and oxide nanostructures), we have demonstrated that an ordinary optical drive, without modification of either the hardware or the software driver, can function as the signal transducing element for reading disc-based bioassays quantitatively.In this Account, we first provide a brief introduction to CD-related materials chemistry and microfluidics research. Then we describe the mild chemistry developed in our laboratory for the preparation of computer-readable biomolecular screening assays: photochemical activation of the polycarbonate (PC) disc surface and immobilization and delivery of probe and target biomolecules. We thoroughly discuss the analysis of the molecular recognition events: researchers can "read" these devices quantitatively with an unmodified optical drive of any personal computer. Finally, and critically, we illustrate our digitized molecular diagnosis approach with three trial systems: DNA hybridization, antibody-antigen binding, and ultrasensitive lead detection with a DNAzyme assay. These examples demonstrate the broad potential of this new analytical/diagnostic tool for medical screening, on-site food/water safety testing, and remote environmental monitoring. © 2012 American Chemical Society.

Zhang L.,Beijing University of Posts and Telecommunications | Yang J.,Beijing University of Posts and Telecommunications | Fu X.,Beijing University of Posts and Telecommunications | Zhang M.,Beijing Normal University
Applied Physics Letters | Year: 2013

We report a plasmonic structure consisting of a graphene ribbon and a graphene disk. The plasmonic structure can work as a promising waveguide-ring resonator in ultra compact devices, in which the ribbon and the disk support different surface plasmons. We prove that disk's resonant modes are edge propagating surface plasmons. Strong optical coupling between the ribbon and the disk occurs when the momentum mismatch between plasmons in the ribbon and plasmons in the disk is weak. We also investigate the dependence of the optical coupling on the distances between the ribbon and the disk in parallel and vertical directions. © 2013 AIP Publishing LLC.

Xu F.,CAS Beijing National Laboratory for Molecular | Qiu D.,CAS Beijing National Laboratory for Molecular | Yan D.,Beijing Normal University
Applied Physics Letters | Year: 2013

We propose that the polaron transport in organic semiconductors is remarkably tuned by the fluctuation of polarization energy. The tuning effect of energetic fluctuation not only causes a continuous transition from non-Arrhenius to Arrhenius temperature activated charge transport with increasing moderate disorder strengths but also results in a band-like conduction in the low disorder regime which benefits from the enhanced mobilities in shallow trap states. As a result, a unified description of polaron transport is obtained for a set of typical organic semiconductors. © 2013 American Institute of Physics.

Wang F.,Yale University | Mcintosh A.M.,University of Edinburgh | He Y.,Beijing Normal University | Gelernter J.,Yale University | Blumberg H.P.,Yale University
Bipolar Disorders | Year: 2011

Objectives: A single nucleotide polymorphism at the CACNA1C gene (rs1006737) has been reported in genome-wide association studies to be associated with bipolar disorder (BD) with genome-wide significance. However, the neural system effects of CACNA1C that mediate the association are not known. In this study, we assessed associations between rs1006737 variation and both morphology and functional connectivity within a corticolimbic frontotemporal neural system implicated in BD. Methods: A total of 55 European Americans were divided into two groups: a GG group homozygous for the 'G' allele (n=30) and carriers of the high risk A allele ('A-carrier' group, AA/AG genotypes; n=25). The subjects participated in both high-resolution structural magnetic resonance imaging (MRI) scans and functional MRI scans during emotional face-processing. Voxel-based morphometry and functional connectivity analyses were performed. Results: Compared to the GG group, the A-carrier group showed significantly increased gray matter volume and reduced functional connectivity within a corticolimbic frontotemporal neural system (p<0.05, corrected). Conclusion: The findings support effects of the rs1006737 variation on the frontotemporal neural system implicated in BD, both in gray matter morphology and in functional connectivity. This suggests that influence of CACNA1C variation on corticolimbic structure and function may be a mechanism contributing to the neural circuitry of BD. © 2011 John Wiley and Sons A/S.

Wu Y.,Nanjing University | Wu Y.,Beijing Normal University
Geochimica et Cosmochimica Acta | Year: 2012

Major elements such as Fe, Ti, Mg, Al, Ca, and Si play very important roles in understanding the origin and evolution of the Moon. Up to now there are still no high resolution maps for all the six major elements and Mg# showing their abundances and distributions. The objective of this paper is to introduce the techniques and results to create high resolution maps of the six major elements with Chang'E-1 Interference Imaging Spectrometer (IIM) data. The elemental contents of returned soils and feldspathic lunar meteorites are used as ground truth and correlated with the reflectance of the landing sites and northern farside highlands extracted from Chang'E-1 IIM data. The relationships linking geochemical information and optical data are established with empirical methods. The final maps of the abundances of the six major oxides are produced with the modified partial least squares regression (PLSR) model at a spatial resolution of 200 m/pixel at the equator. Finally some implications (for example, producing the high resolution map of Mg#; identifying the crustal heterogeneity of lunar highlands; helping to search for HA basalts; assessing the average elemental abundances of each terrane and the whole Moon) of these new maps are shown. © 2012 Elsevier Ltd.

Du J.,Beijing Normal University
Geophysical Research Letters | Year: 2012

Knowledge of the spatial distribution and temporal changes of the global soil moisture for a long period of time is crucial to the understanding of climate changes and hydrological processes. By applying Fourier analysis to the time-series observations from the space-borne passive microwave sensors, this paper proposes a method to extract the high-frequency part of the satellite observed signals that reflect the soil moisture changes and help to generate the historical soil moisture datasets with an improved accuracy. The method is applied to the observations from Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E). Validations using field sampled soil moisture from two watersheds in the U.S. indicate that the method can effectively improve the sensitivity of current National Aeronautics and Space Administration (NASA) soil moisture products to the temporal changes of the surface soil moisture, with the correlation coefficients of the retrievals and measurements increased from 0.462 to 0.595 and 0.403 to 0.613 for the two watersheds, respectively. © 2012. American Geophysical Union. All Rights Reserved.

Yang L.,Stevens Institute of Technology | Fang W.,Beijing Normal University | Zhang Y.,Stevens Institute of Technology
Chemical Communications | Year: 2012

HNO binds to many different metals in organometallic and bioinorganic chemistry. To help understand experimentally observed metal centre effects, a quantum chemical investigation was performed, revealing clear general binding trends with respect to metal centre characteristics and the electronic origin for the first time. This journal is © The Royal Society of Chemistry 2012.

Hardie R.C.,University of Cambridge | Juusola M.,University of Sheffield | Juusola M.,Beijing Normal University
Current Opinion in Neurobiology | Year: 2015

Phototransduction in Drosophila's microvillar photoreceptors is mediated by phospholipase C (PLC) resulting in activation of two distinct Ca2+-permeable channels, TRP and TRPL. Here we review recent evidence on the unresolved mechanism of their activation, including the hypothesis that the channels are mechanically activated by physical effects of PIP2 depletion on the membrane, in combination with protons released by PLC. We also review molecularly explicit models indicating how Ca2+-dependent positive and negative feedback along with the ultracompartmentalization provided by the microvillar design can account for the ability of fly photoreceptors to respond to single photons 10-100× more rapidly than vertebrate rods, yet still signal under full sunlight. © 2015 Elsevier Ltd.

Chiou D.-W.,Beijing Normal University | Geiller M.,CNRS Astroparticle and Cosmology Lab
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

Unimodular gravity is based on a modification of the usual Einstein-Hilbert action that allows one to recover general relativity with a dynamical cosmological constant. It also has the interesting property of providing, as the momentum conjugate to the cosmological constant, an emergent clock variable. In this paper we investigate the cosmological reduction of unimodular gravity, and its quantization within the framework of flat homogeneous and isotropic loop quantum cosmology. It is shown that the unimodular clock can be used to construct the physical state space, and that the fundamental features of the previous models featuring scalar field clocks are reproduced. In particular, the classical singularity is replaced by a quantum bounce, which takes place in the same condition as obtained previously. We also find that requirement of semiclassicality demands the expectation value of the cosmological constant to be small (in Planck units). The relation to spin foam models is also studied, and we show that the use of the unimodular time variable leads to a unique vertex expansion. © 2010 The American Physical Society.

Zhang H.,Southwest University | Liu J.,Beijing Normal University | Zhang Q.,Southwest University
Cortex; a journal devoted to the study of the nervous system and behavior | Year: 2014

Inventive conceptions amount to creative ideas for designing devices that are both original and useful. The generation of inventive conceptions is a key element of the inventive process. However, neural mechanisms of the inventive process remain poorly understood. Here we employed functional feature association tasks and event-related functional magnetic resonance imaging (MRI) to investigate neural substrates for the generation of inventive conceptions. The functional MRI (fMRI) data revealed significant activations at Brodmann area (BA) 47 in the left inferior frontal gyrus and at BA 18 in the left lingual gyrus, when participants performed biological functional feature association tasks compared with non-biological functional feature association tasks. Our results suggest that the left inferior frontal gyrus (BA 47) is associated with novelty-based representations formed by the generation and selection of semantic relatedness, and the left lingual gyrus (BA 18) is involved in relevant visual imagery in processing of semantic relatedness. The findings might shed light on neural mechanisms underlying the inventive process. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gao S.,Beijing Normal University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We consider a self-gravitating system consisting of perfect fluid with spherical symmetry. Using the general expression of entropy density, we extremize the total entropy S under the constraint that the total number of particles is fixed. We show that extrema of S coincides precisely with the relativistic Tolman-Oppenheimer-Volkoff equation of hydrostatic equilibrium. Furthermore, we apply the maximum entropy principle to a charged perfect fluid and derive the generalized Tolman-Oppenheimer-Volkoff equation. Our work provides strong evidence for the fundamental relationship between general relativity and ordinary thermodynamics. © 2011 American Physical Society.

Nan Y.,Beijing Normal University | Friederici A.D.,MPI for Human Cognitive and Brain science
Human Brain Mapping | Year: 2013

Superior temporal and inferior frontal cortices are involved in the processing of pitch information in the domain of language and music. Here, we used fMRI to test the particular roles of these brain regions in the neural implementation of pitch in music and in tone language (Mandarin) with a group of Mandarin speaking musicians whose pertaining experiences in pitch are similar across domains. Our findings demonstrate that the neural network for pitch processing includes the pars triangularis of Broca's area and the right superior temporal gyrus (STG) across domains. Within this network, pitch sensitive activation in Broca's area is tightly linked to the behavioral performance of pitch congruity judgment, thereby reflecting controlled processes. Activation in the right STG is independent of performance and more sensitive to pitch congruity in music than in tone language, suggesting a domain-specific modulation of the perceptual processes. These observations provide a first glimpse at the cortical pitch processing network shared across domains. © 2012 Wiley Periodicals, Inc.

Ren F.,Laboratory for Climate Studies | Liang J.,Nanjing University | Wu G.,CAS Institute of Atmospheric Physics | Dong W.,Beijing Normal University | Yang X.,Nanjing University
Journal of Climate | Year: 2011

Data homogeneity has become a significant issue in the study of tropical cyclones (TCs) and climate change. In this study, three historical datasets for the western North Pacific TCs from the Joint Typhoon Warning Center (JTWC), Japan Meteorological Agency (JMA), and China Meteorological Administration (CMA) are compared with a focus on TC intensity. Over the past 55 years (1951-2005), significant discrepancies are found among the three datasets, especially between the CMA and JTWC datasets. The TC intensity in the CMA dataset was evidently overestimated in the 1950s and from the late 1960s to the early 1970s, while it was overestimated after 1988 in the JTWC dataset, especially during 1993-2003. Large discrepancies in TC tracks exist in two periods of 1951-early 1960s and 1988-1990s. Further analysis reveals that the discrepancies are obviously related to the TC observational techniques. Before the era of meteorological satellites (1951-the early 1960s), and after the termination of aircraft reconnaissance (since 1988), large discrepancies exist in both TC intensity and track. That the intensity discrepancy was smallest during the period (1973-87) when aircraft reconnaissance data and the Dvorak technique were both available suggests that availability of the aircraft reconnaissance and the Dvorak method helps in reducing the TC intensity discrepancy. For those TCs that were included in all the three datasets, no significant increasing or decreasing trend was found over the past 50 years. Each of the three TC datasets has individual characteristics that make it difficult to tell which one is the best. For TCs that affect China, the CMA dataset has obvious advantages such as more complete and more accurate information. © 2011 American Meteorological Society.

Zhang Z.,Beijing Normal University
Ecological Indicators | Year: 2014

Due to wide spatial distribution, high annual resolution, calendar-exact dating, and high climate sensitivity, tree-rings play an important role in reconstructing past environment and climate change over the past millennium at regional, hemispheric or even global scales, so tree-rings can help us to better understand climate behaviour and its mechanisms in the past and then predict variation trends for the future. In this paper, we will review latest advances in tree-ring-based climate reconstructions in China and their applications in modelling past local/regional climate change, capturing historical climatic extreme events, as well as analyzing their link to large-scale climate patterns. © 2014 Elsevier Ltd. All rights reserved.

Hubacek K.,University of Maryland University College | Feng K.,University of Maryland University College | Chen B.,Beijing Normal University
Energies | Year: 2012

China has achieved notable success in developing its economy with approximate 10 percent average annual GDP growth over the last two decades. At the same time, energy consumption and CO 2 emissions almost doubled every five years, which led China to be the world top emitter in 2007. In response, China's government has put forward a carbon mitigation target of 40%-45% reduction of CO 2 emission intensity by 2020. To better understand the potential for success or failure of such a policy, it is essential to assess different driving forces such as population, lifestyle and technology and their associated CO 2 emissions. This study confirms that increase of affluence has been the main driving force for China's CO 2 emissions since the late 1970s, which outweighs reductions achieved through technical progress. Meanwhile, the contribution of population growth to CO 2 emissions was relatively small. We also found a huge disparity between urban and rural households in terms of changes of lifestyle and consumption patterns. Lifestyles in urban China are beginning to resemble Western lifestyles, and approaching their level of CO 2 emissions. Therefore, in addition to the apparent inefficiencies in terms of production technologies there is also a lot of room for improvement on the consumption side especially in interaction of current infrastructure investments and future consumption. © 2012 by the authors.

He L.,Beijing Normal University | Guo L.,Beihang University
Applied Physics Letters | Year: 2010

Here we report the competition of superexchange and double exchange interactions in the molecule [(NH3)4 Co (OH)2 Co (NH3)4]4+. Magnetic data reveal a S=3 ground state arising from the competition. The canting angle between the magnetic moments of the Co2+ and Co4+ ions is about 92.5°. The double exchange parameter is estimated to be sevenfold of the superexchange parameter. The result presented here opens a way to introducing of ferromagnetic double exchange interaction to the single molecular magnets via the charge disproportionation between valence-variable transition-metal ions. © 2010 American Institute of Physics.

Wang Z.,Tianjin University | Wang Z.,Beijing Normal University | Li M.,Tianjin University | Li J.,Tsinghua University
Information Sciences | Year: 2015

Feature selection is an important task in data mining and pattern recognition, especially for high-dimensional data. It aims to select a compact feature subset with the maximal discriminative capability. The discriminability of a feature subset requires that selected features have a high relevance to class labels, whereas the compactness demands a low redundancy within the selected feature subset. This paper defines a new feature redundancy measurement capable of accurately estimating mutual information between features with respect to the target class (MIFS-CR). Based on a relevance measure and this new redundancy measure, a multi-objective evolutionary algorithm with class-dependent redundancy for feature selection (MECY-FS) is presented. The MECY-FS algorithm employs the Pareto optimality to evaluate candidate feature subsets and finds compact feature subsets with both the maximal relevance and the minimal redundancy. Experiments on benchmark datasets are conducted to validate the effectiveness of the new redundancy measure, and the MECY-FS algorithm is verified to be able to generate compact feature subsets with a high predictive capability. © 2015 Elsevier Inc. All rights reserved.

Lu H.,Beijing Normal University | Pang Y.,Texas A&M University | Pope C.N.,Texas A&M University | Pope C.N.,University of Cambridge
Journal of High Energy Physics | Year: 2013

We obtain spherically-symmetric and ℝ2-symmetric dyonic black holes that are asymptotic to anti-de Sitter space-time (AdS), which are solutions in maximal gauged four-dimensional supergravity, with just one of the U(1) fields carrying both the electric and magnetic charges (Q, P ). We study the thermodynamics, and find that the usually-expected first law does not hold unless P = 0, Q = 0 or P = Q. For general values of the charges, we find that the first law requires a modification with a new pair of thermodynamic conjugate variables. We show that they describe the scalar hair that breaks some of the asymptotic AdS symmetries. © SISSA 2013.

Lu H.,Beijing Normal University
Journal of High Energy Physics | Year: 2013

We consider D-dimensional Einstein gravity coupled to two U(1) fields and a dilaton with a scalar potential. We derive the condition that the analytical AdS black holes with two independent charges can be constructed. Turning off the cosmological constant, the extremal Reissner-Nordstrøm black hole emerges as the harmonic superposition of the two U(1) building blocks. With the non-vanishing cosmological constant, our extremal solutions contain the near-horizon geometry of AdS2 x RD-2 with or without a hyperscaling. We also obtain the magnetic AdSD-2 × Y 2 vacua where Y2 can be R2, S2 or hyperbolic 2-space. These vacua arise as the fix points of some super potentials and recover the known supersymmetric vacua when the theory can be embedded in gauged supergravities. The AdSD-2 × R2 vacua are of particular interest since they are dual to some quantum field theories at the lowest Landau level. By studying the embedding of some of these solutions in the string and M-theory, we find that the M2/M5-system with the equal M2 and M5 charges can intersect with another such M2/M5 on to a dyonic black hole. Analogous intersection rule applies also to the D1/D5-system. The intersections are non-supersymmetric but in the manner of harmonic superpositions. © SISSA 2013.

Suo T.,CAS Beijing National Laboratory for Molecular | Yan D.,Beijing Normal University
Polymer | Year: 2011

A theoretical study on the phase behaviors of a polymer solution confined between two coaxial cylindrical walls is presented. For the case of a neutral inner cylinder, the spinodal point derived by the Gaussian fluctuation theory is confinement-independent because of the existence of a free dimension in the system. The kinetic analysis indicates that the fluctuation modes always have a component of a plane wave along the axial direction, which can lead to the formation of a periodic-like concentration pattern. On the other hand, the equilibrium structure of the system is obtained by the self-consistent mean-field theory (SCMFT) and the interplay between the "wetting" phenomenon and the phase separation is observed by modifying the property of the inner cylindrical wall. In particular, our results can be regarded as a hint to interpret the mechanism of the formation of the shish-kebab structure observed in the field of polymer crystallization. © 2011 Elsevier Ltd.

Liu H.-S.,Zhejiang University of Technology | Lu H.,Beijing Normal University
Journal of High Energy Physics | Year: 2013

We obtain the charged rotating black hole in conformal gravity. The metric is asymptotic to the (anti-)de Sitter spacetime. The contribution to the metric from the charges has a slower falloff than that in the Kerr-Newman AdS black hole. We analyse the global structure and obtain all the thermodynamical quantities including the mass, angular momentum, electric/magnetic charges and their thermodynamical conjugates. We verify that the first law of thermodynamics holds. We also obtain the new neutral rotating black holes that are beyond Einstein metrics. In contrast to the static ones, these rotating black holes have no parameters associated with the massive spin-2 hair. © 2013 SISSA.

Chen S.,Zhejiang University of Technology | Li X.,Beijing Normal University
Computational and Mathematical Methods in Medicine | Year: 2012

Functional magnetic resonance imaging (fMRI) is recently developed and applied to measure the hemodynamic response related to neural activity. The fMRI can not only noninvasively record brain signals without risks of ionising radiation inherent in other scanning methods, such as CT or PET scans, but also record signal from all regions of the brain, unlike EEG/MEG which are biased towards the cortical surface. This paper introduces the fundamental principles and summarizes the research progress of the last year for imaging neural activity in the human brain. Aims of functional analysis of neural activity from fMRI include biological findings, functional connectivity, vision and hearing research, emotional research, neurosurgical planning, pain management, and many others. Besides formulations and basic processing methods, models and strategies of processing technology are introduced, including general linear model, nonlinear model, generative model, spatial pattern analysis, statistical analysis, correlation analysis, and multimodal combination. This paper provides readers the most recent representative contributions in the area. Copyright © 2012 Shengyong Chen and Xiaoli Li.

Nearing G.S.,University of Arizona | Gupta H.V.,University of Arizona | Crow W.T.,U.S. Department of Agriculture | Gong W.,Beijing Normal University
Water Resources Research | Year: 2013

Data assimilation is the Bayesian conditioning of uncertain model simulations on observations to reduce uncertainty about model states. In practice, it is common to make simplifying assumptions about the prior and posterior state distributions, and to employ approximations of the likelihood function, which can reduce the efficiency of the filter. We propose metrics that quantify how much of the uncertainty in a Bayesian posterior state distribution is due to (i) the observation operator, (ii) observation error, and (iii) approximations of Bayes' Law. Our approach uses discrete Shannon entropy to quantify uncertainty, and we define the utility of an observation (for reducing uncertainty about a model state) as the ratio of the mutual information between the state and observation to the entropy of the state prior. These metrics make it possible to analyze the efficiency of a proposed observation system and data assimilation strategy, and provide a way to examine the propagation of information through the dynamic system model. We demonstrate the procedure on the problem of estimating profile soil moisture from observations at the surface (top 5 cm). The results show that when synthetic observations of 5 cm soil moisture are assimilated into a three-layer model of soil hydrology, the ensemble Kalman filter does not use all of the information available in observations. © 2013. American Geophysical Union. All Rights Reserved.

Zhang P.,Beijing Normal University
Frontiers of Environmental Science and Engineering | Year: 2013

In this study, reduction in sulfur dioxide (SO2) emission is decomposed into three parts: source prevention, process control and end-of-pipe treatment, using the Logarithmic Mean Divisia Index method (LMDI). Source prevention and process control are defined as processintegrated treatment. It is found that from 2001 to 2010 the reduction of SO2 emission density in China was mainly contributed by end-of-pipe treatment. From the 10th Five Year Plan (FYP) period (2001-2005) to the 11th FYP period (2006-2010), the Chinese government has attempted to enhance process-integrated treatment. However, given its initial effort, the effect is limited compared with that of the end-of-pipe treatment. The effectiveness of environmental regulation and technology in the reduction of SO2 density in 30 provinces (municipality/autonomous regions) from 2001 to 2010 is also investigated. This implies that environmental regulation and technology promote process control and end-of-pipe treatment significantly, but does not influence source prevention. Furthermore, environmental technology will only take effect under the circumstances of stringent environmental regulation. Therefore, to fulfill the whole process treatment, environmental regulation should be strengthened and environmental technology upgraded at the same time. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.

Abutalebi J.,Vita-Salute San Raffaele University | Abutalebi J.,University of Hong Kong | Della Rosa P.A.,Vita-Salute San Raffaele University | Ding G.,Beijing Normal University | And 3 more authors.
Cortex | Year: 2013

Language proficiency should modulate the regions involved in language control in predictable ways during language switching. However, prior studies reveal inconsistent effects on the regions involved in language monitoring [pre-Supplementary Motor Area/Anterior Cingulate Cortex (pre-SMA/ACC)] and language selection (left caudate) conceivably because variations in relative proficiency are confounded with other between-group differences. We circumvented this problem in an fMRI (functional Magnetic Resonance Imaging) study of overt picture naming in trilingual participants. In this case, the difference between a high-proficient and a low-proficient further language can be assessed within subjects with no between-group confound. We also used a monolingual group to assess the neural correlates of switching between two categories of response within the same language. We report a novel result: relative language proficiency dissociates response of the pre-SMA/ACC and left caudate during language switching. Switching between languages increased pre-SMA/ACC response regardless of proficiency differences. By contrast, left caudate response did vary with proficiency differences. Switching from the most to the least proficient language increased the response. Within-language switching, as contrasted with between-language switching, elicited a comparable increase in pre-SMA/ACC response but a decrease in left caudate response. Taken together, our data support a wider role of pre-SMA/ACC in task monitoring and establish the critical role of the left caudate in the selection of the less proficient language in language switching. © 2012 Elsevier Ltd.

Zhao W.,Beijing Normal University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

Arable land is an essential resource for the production of food and thus constitutes one of the most fundamental resources for mankind. This resource is burdened by population growth and economic development. The statistic data from the Food and Agriculture Organization of the United Nations showed that the world's arable land area was 1. 401 billion hectares in 1990, and dropped to 1. 381 billion hectares in 2008; with the continued population growth, the world's per capita arable land was 0. 265 ha in 1990, and dropped to 0. 205 ha in 2008. By 2050, the world's population will reach 9. 1 billion. Assuming that the world's arable land area in 2008 remains unchanged to 2050, the world's per capita arable land would fall to 0. 151 hectares. Having enough arable land to feed the world population in 2050 is a major challenge, and it is a meaningful task to explore the arable land dynamics for the major countries of the world. This paper selected 21 countries for a case study, and the arable land dynamics and their possible driving factors for these countries were discussed. These countries includes ten countries with the largest cultivated areas in the world, and the countries whose population will exceed 1 billion by 2050. The research results show that, from 1961 to 2007, increasingly more countries' arable land areas were declining, and almost all of the countries are facing the shortage challenges of arable land. In fact, 90. 5% countries have suffered a downward trend of per capita arable land, which implies that the world food crisis is constantly increasing. Considering the change of total arable land area and per capita arable land area, the 21 countries can be divided into four groups: (1) Total arable land area and per capita arable land area increase at the same time; (2) Total arable land area and per capita arable land area decrease at the same time; (3) Total arable land area increases but per capita arable land area decreases; or (4) Total arable land area decreases but per capita arable land area increases. Among the different situations, population growth and economic development have been two of the key driving forces for the arable land changes. However, due to different land use potentials and different degrees of political stability, the influence factors of arable land are different among the referenced counties. For Brazil, agricultural acreage expansion and the ethanol production increase are important reasons for deforestation and arable land increases. For Bangladesh, Japan, Russia and the United States, urbanization and industrialization are the main reasons behind the reduction of arable land. However, for the Ukraine, the reduced total arable land and increased per capita arable land are closely connected to the sharp population drop and increased urban development. For the other 15 countries, rapid population growth and urbanization lead to reduced per capita arable land; at the same time, population growth has also become an important driving force for these countries to increase the total amount of cultivated land to ensure food security. However, because different countries have different reserve land resources, the arable land growth rate among these countries is significantly different.

Li S.,Beijing Normal University | Li S.,China National Institute of Biological Sciences | Duan J.,China National Institute of Biological Sciences | Li D.,China National Institute of Biological Sciences | And 2 more authors.
EMBO Journal | Year: 2011

Shq1 is a conserved protein required for the biogenesis of eukaryotic H/ACA ribonucleoproteins (RNPs), including human telomerase. We report the structure of the Shq1-specific domain alone and in complex with H/ACA RNP proteins Cbf5, Nop10 and Gar1. The Shq1-specific domain adopts a novel helical fold and primarily contacts the PUA domain and the otherwise disordered C-terminal extension (CTE) of Cbf5. The structure shows that dyskeratosis congenita mutations found in the CTE of human Cbf5 likely interfere with Shq1 binding. However, most mutations in the PUA domain are not located at the Shq1-binding surface and also have little effect on the yeast Cbf5-Shq1 interaction. Shq1 binds Cbf5 independently of the H/ACA RNP proteins Nop10, Gar1 and Nhp2 and the assembly factor Naf1, but shares an overlapping binding surface with H/ACA RNA. Shq1 point mutations that disrupt Cbf5 interaction suppress yeast growth particularly at elevated temperatures. Our results suggest that Shq1 functions as an assembly chaperone that protects the Cbf5 protein complexes from non-specific RNA binding and aggregation before assembly of H/ACA RNA. © 2011 European Molecular Biology Organization | All Rights Reserved.

Yao W.,Munich University of Applied Sciences | Wei Y.,Beijing Normal University
IEEE Geoscience and Remote Sensing Letters | Year: 2013

An automated approach to extracting 3-D individual trees in urban areas is developed based on jointly analyzing airborne LiDAR data and imagery. First, the spectral, geometric, and spatial context attributes are defined and integrated at the LiDAR point level. Then, a binary AdaBoost classifier is used to separate points belonging to trees from other urban objects. Once the classification is completed, a spectral clustering method by applying the normalized cuts to a graph structure of point clouds of the vegetation class is performed to segment single trees. The geometric and spectral attributes play an important role in establishing the weight matrix, which measures the similarity between every two graph nodes and determines the cut function. The performance of the approach is validated by real urban data sets, which were acquired over two European cities. The results show that 3-D individual trees can be detected with mean accuracy of up to 0.65 and 0.12 m for tree position and height. Based on the results of this work, geometric and biophysical properties of individual trees can be further retrieved. © 2013 IEEE.

Zhang F.,Beijing Normal University | Zhang F.,West Virginia University
Astrophysical Journal | Year: 2016

Analytical studies have raised the concern that a mysterious expulsion of magnetic field lines by a rapidly spinning black hole (dubbed the black hole Meissner effect) would shut down the Blandford-Znajek process and quench the jets of active galactic nuclei and microquasars. This effect is, however, not seen observationally or in numerical simulations. Previous attempts at reconciling the predictions with observations have proposed several mechanisms to evade the Meissner effect. In this paper, we identify a new evasion mechanism and discuss its observational significance. Specifically, we show that the breakdown of stationarity is sufficient to remove the expulsion of the magnetic field at all multipole orders, and that the associated temporal variation is likely turbulent because of the existence of efficient mechanisms for sharing energy across different modes. Such an intrinsic (as opposed to being driven externally by, e.g., changes in the accretion rate) variability of the electromagnetic field can produce the recorded linear correlation between microvariability amplitudes and mean fluxes, help create magnetic randomness and seed sheared magnetic loops in jets, and lead to a better theoretical fit to the X-ray microvariability power spectral density. © 2016. The American Astronomical Society. All rights reserved.

Ma Y.,Beijing Normal University | Soo C.,National Cheng Kung University | Yang J.,National Cheng Kung University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

An alternative expression for the length operator in loop quantum gravity is presented. The operator is background independent, symmetric, positive semidefinite, and well defined on the kinematical Hilbert space. The expression for the regularized length operator can moreover be understood both from a simple geometrical perspective as the average of a formula relating the length to area, volume and flux operators, and also consistently as the result of direct substitution of the densitized triad operator with the functional derivative operator into the regularized expression of the length. Both these derivations are discussed, and the origin of an undetermined overall factor in each case is also elucidated. © 2010 The American Physical Society.

Zhang X.B.,CAS National Astronomical Observatories | Luo C.Q.,CAS National Astronomical Observatories | Fu J.N.,Beijing Normal University
Astrophysical Journal | Year: 2013

We have deduced a theoretical relation between the pulsation and orbital-periods of pulsating stars in close binaries based on their Roche lobe filling. It appears to be of a simple linear form, with the slope as a function of the pulsation constant, the mass ratio, and the filling factor for an individual system. Testing the data of 69 known eclipsing binaries containing δ-Sct-type components yields an empirical slope of 0.020 ± 0.006 for the P pul-P orb relation. We have further derived the upper limit of the P pul/P orb ratio for the δ-Sct stars in eclipsing binaries with a value of 0.09 ± 0.02. This value could serve as a criterion to distinguish whether or not a pulsator in an eclipsing binary pulsates in the p-mode. Applying the deduced P pul-P orb relation, we have computed the dominant pulsation constants for 37 δ-Sct stars in eclipsing systems with definite photometric solutions. These ranged between 0.008 and 0.033 days with a mean value of about 0.014 days, indicating that δ-Sct stars in eclipsing binaries mostly pulsate in the fourth or fifth overtones. © 2013. The American Astronomical Society. All rights reserved.

Zhao R.,Iowa State University | Zhao R.,Beijing Normal University | Koschny T.,Iowa State University | Koschny T.,University of Crete | And 2 more authors.
Optics Express | Year: 2010

After the prediction that strong enough optical activity may result in negative refraction and negative reflection, more and more artificial chiral metamaterials were designed and fabricated at difference frequency ranges from microwaves to optical waves. Therefore, a simple and robust method to retrieve the effective constitutive parameters for chiral metamaterials is urgently needed. Here, we analyze the wave propagation in chiral metamaterials and follow the regular retrieval procedure for ordinary metamaterials and apply it in chiral metamaterial slabs. Then based on the transfer matrix technique, the parameter retrieval is extended to treat samples with not only the substrate but also the top layers. After the parameter retrieval procedure, we take two examples to check our method and study how the substrate influences on the thin chiral metamaterials slabs. We find that the substrate may cause the homogeneous slab to be inhomogeneous, i.e. the reflections in forward and backward directions are different. However, the chiral metamaterial where the resonance element is embedded far away from the substrate is insensitive to the substrate. © 2010 Optical Society of America.

Liu Z.-H.,China Institute of Atomic Energy | Bao J.-D.,Beijing Normal University | Bao J.-D.,Accelerator Centre
Physical Review C - Nuclear Physics | Year: 2012

A generalized version of the fusion by diffusion model is proposed, in which evolution from dinuclear to mononuclear regimes is taken into account in terms of the coupled Langevin equations in the three-dimensional collective space of neck, radial, and asymmetric degrees of freedom. By simulating numerically these dynamic equations, the probability distribution of s inj, the separation between the surfaces of two approaching nuclei at the injection point in the asymmetric fission valley, is obtained. From the injection points, the system starts its climb uphill over the saddle point in the presence of thermal fluctuation; thus for very heavy systems the injection-point distance is a very critical constituent in the calculations of fusion probability. The present model is applied for the study of the mass asymmetric system 58Fe+208Pb. The excitation function for the 208Pb(58Fe,n)265Hs reaction is calculated and compared with the experimental data. By comparing the theoretical results with and without taking the asymmetric degree of freedom into account, we have arrived at the conclusion that nucleon flow between the asymmetric reaction partners in the early stage of the fusion process plays an important role in the formation of superheavy nuclei in the cold fusion reactions. © 2012 American Physical Society.

Li X.,Beijing Normal University | Li X.,University of Maryland University College | Cohen A.B.,University of Maryland University College | Murphy T.E.,University of Maryland University College | Roy R.,University of Maryland University College
Optics Letters | Year: 2011

We describe an optoelectronic system for simultaneously generating parallel, independent streams of random bits using spectrally separated noise signals obtained from a single optical source. Using a pair of nonoverlapping spectral filters and a fiber-coupled superluminescent LED (SLED), we produced two independent 10 Gb=s random bit streams, for a cumulative generation rate of 20 Gb/s. The system relies principally on chip-based optoelectronic components that could be integrated in a compact, economical package. © 2011 Optical Society of America.

Chen B.,Beijing Normal University
Journal of Hydrology | Year: 2013

Understanding the fate of contaminant in wetland flows is essential in applications such as ecological risk assessment and environmental hydraulic design. Presented in this paper is an analytical study on the dispersion of contaminant in a two-zone wetland, with the effect of ecological degradation taken into consideration. Environmental dispersion is discussed separately via an exponential transformation for the general formulation of contaminant transport. Taylor's classical analysis for solute dispersion in a long and thin tube flow is rigorously generalized for the dispersion of the lateral mean contaminant concentration in the longitudinal direction. A method of asymptotic analysis is adopted instead of the concentration moment method in order to simplify the process of deduction and the expression of the analytical solution. Gill's method of mean concentration expansion is applied to model the concentration deviation terms produced in an averaging operation. With the velocity profile obtained previously, the enhancement of the environmental dispersivity under long time evolution is determined and shown to be consistent with that obtained by the method of concentration moment. Analytical solutions for the evolution of the contaminant concentration and the influenced region of the contaminant cloud are obtained by combining both the hydraulic and the ecological effects. For typical pollutant as the heavy metal Hg, the evolution of contaminant cloud is illustrated by critical length and duration in an application with concentration beyond some given environmental standard level. Results show that for wetland flows with a two-zone structure, the influenced region is reduced evidently while the duration of the contaminant cloud remains nearly unchanged, compared with that for the single-zone wetland flow. © 2013 Elsevier B.V.

Tu Z.C.,Beijing Normal University
European Physical Journal E | Year: 2013

The efficiency at maximum power (EMP) for tight-coupling molecular motors is investigated within the framework of irreversible thermodynamics. It is found that the EMP depends merely on the constitutive relation between the thermodynamic current and force. The motors are classified into four generic types (linear, superlinear, sublinear, and mixed types) according to the characteristics of the constitutive relation, and then the corresponding ranges of the EMP for these four types of molecular motors are obtained. The exact bounds of the EMP are derived and expressed as the explicit functions of the free energy released by the fuel in each motor step. A phase diagram is constructed which clearly shows how the region where the parameters (the load distribution factor and the free energy released by the fuel in each motor step) are located can determine whether the value of the EMP is larger or smaller than 1/2. This phase diagram reveals that motors using ATP as fuel under physiological conditions can work at maximum power with higher efficiency (> 1/2 for a small load distribution factor (< 0.1.) © 2013 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Ruan Y.,National University of Singapore | Hang C.C.,National University of Singapore | Wang Y.M.,Beijing Normal University
Technovation | Year: 2014

The role of the government has rarely been examined in the previous literature on Disruptive Innovation (DI). We present a case study of how government shaped the development trajectory of a DI through both promotional and restrictive policies in the emergence of the electric bike (E-bike) industry in China. We also show how the distinctive nature of DI influenced the strategies of the E-bike firms and how the industry and the institutional environment co-evolved in the process. We believe our study has practical implications for policy makers in making catching-up strategies as well as strategies about the pollution prevention industry and the new energy automobile industry in transition economies. © 2014 Elsevier Ltd. All rights reserved.

Zeng X.-X.,Chongqing Jiaotong University | Liu X.-M.,Hubei University for Nationalities | Liu W.-B.,Beijing Normal University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

Gravitational collapse of a shell of dust in noncommutative geometry is probed by the renormalized geodesic length, which is dual to probe the thermalization by the two-point correlation function in the dual conformal field theory. We find that the larger the noncommutative parameter is, the longer the thermalization time is, which implies that the large noncommutative parameter delays the thermalization process. We also investigate how the noncommutative parameter affects the thermalization velocity and thermalization acceleration. © 2015 The Authors.

Ren J.,Beijing Institute of Technology | Yuan J.,Beijing Normal University | Zhang X.,Beijing Institute of Technology
Journal of the Optical Society of America B: Optical Physics | Year: 2014

The Dicke subradiance and superradiance resulting from the interaction between surface plasmons of a nanosphere and an ensemble of quantum emitters have been investigated using a Green's function approach. Based on such an investigation, we propose a scheme for a deterministic multi-qubit quantum phase gate. As an example, two-qubit, three-qubit, and four-qubit quantum phase gates have been designed and analyzed in detail. Phenomena due to the losses in the metal are discussed. Potential applications of these phenomena to quantum-information processing are anticipated. © 2014 Optical Society of America.

Chen Q.,Beijing Normal University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

Since MIT announced its OpenCourseWare Program in 2001, Open educational resources has gradually developed into a practical hotspot and got rapidly development in the higher education field of the world. In a sense, the essence and ultimate purpose of the existing and development of OER is effective sharing and utilization of it. How to facilitate the sharing and utilization of OER among the society is one of the key issues in the OER research and development area at present. This paper, based on the literature research and web search methods, has studied the present status of utilization of OER and related researches, analyzed the challenges or problems in OER's sharing and using, and put forward a series of strategies which are expected to facilitate the effective utilization of OER from the three perspectives of technology, mechanism, and pedagogy. © Springer-Verlag 2010.

Long R.,Beijing Normal University | Long R.,University College Dublin | Prezhdo O.V.,University of Southern California
Nano Letters | Year: 2016

Two-dimensional transition metal dichalcogenides (MX2, M = Mo, W; X = S, Se) hold great potential in optoelectronics and photovoltaics. To achieve efficient light-to-electricity conversion, electron-hole pairs must dissociate into free charges. Coulomb interaction in MX2 often exceeds the charge transfer driving force, leading one to expect inefficient charge separation at a MX2 heterojunction. Experiments defy the expectation. Using time-domain density functional theory and nonadiabatic (NA) molecular dynamics, we show that quantum coherence and donor-acceptor delocalization facilitate rapid charge transfer at a MoS2/MoSe2 interface. The delocalization is larger for electron than hole, resulting in longer coherence and faster transfer. Stronger NA coupling and higher acceptor state density accelerate electron transfer further. Both electron and hole transfers are subpicosecond, which is in agreement with experiments. The transfers are promoted primarily by the out-of-plane Mo-X modes of the acceptors. Lighter S atoms, compared to Se, create larger NA coupling for electrons than holes. The relatively slow relaxation of the hot hole suggests long-distance bandlike transport, observed in organic photovoltaics. The electron-hole recombination is notably longer across the MoS2/MoSe2 interface than in isolated MoS2 and MoSe2, favoring long-lived charge separation. The atomistic, time-domain studies provide valuable insights into excitation dynamics in two-dimensional transition metal dichalcogenides. © 2016 American Chemical Society.

Liu Z.-H.,China Institute of Atomic Energy | Bao J.-D.,Beijing Normal University | Bao J.-D.,Accelerator Centre
Physical Review C - Nuclear Physics | Year: 2011

The evaporation residue (ER) cross sections for 3n and 4n evaporation channels in the 50Ti+249Bk reaction leading the formation of 296119 and 295119 isotopes are evaluated by means of a modified fusion-by-diffusion model. In the model, the dynamic evolution from dinucleus to mononucleus is taken into account with the two-dimensional coupled Langenvin equations. The calculated maximum ER cross sections in 3n and 4n evaporation channels of the 50Ti+249Bk reaction are 0.17 and 0.57 pb, respectively. The cross section of 0.57 pb is close to the present experimental limit for the registration of the evaporation residual nuclei. Therefore, superheavy element 119 may be the most hopeful new element with Z>118 to be synthesized under somehow improved experimental conditions in the near future. © 2011 American Physical Society.

He L.,Beijing Normal University
Journal of Physical Chemistry C | Year: 2010

On the basis of recent experimental results reported in the literature (Science 2010, 327, 843.), we introduce a model in which the up and down spins within ultrafine diamagnetic system are spatially separated. The net magnetic moments within these systems arise from the imbalance between the spatial spin density distributions. This mechanism is distinct from that of the two well-known paradigms for magnetism, i.e., the localized ferromagnetism and the itinerant ferromagnetism. The influences of diameter and protective agents on the magnetic moments of these systems are also quantitatively taken into account in the proposed model. Our finding opens a new route toward room temperature ferromagnetic semiconductors without doping magnetic ions. © 2010 American Chemical Society.

Luo Y.-L.,Beijing Normal University
Computing in Science and Engineering | Year: 2013

Three-dimensional visualizations of cerebral vessel structures are helpful for diagnosing diseases. However, when viewing several overlapping cerebral vessels using traditional ray casting, it's difficult to decide clear depth ordering. As a solution, distance color blending and stereoscopic depth enhancement are combined with CUDA-based pre-integrated volume rendering and its advanced transfer function for improved depth perception. © 2013 IEEE.

Chen B.,Beijing Normal University | Xu B.,Tsinghua University
IEEE Geoscience and Remote Sensing Letters | Year: 2014

In this letter, we present a novel efficient automated tracing algorithm, called Compound Ray Recorder (CRR), to measure landscape heterogeneity efficiently without any supporting data sets. The main advantages of this method are: 1) the definition of a unified calculation framework for landscape heterogeneity is proposed and 2) no ancillary data are required, and the whole procedure can be automatically performed without any expert support or subjective evaluation. The results of tests using the proposed CRR method with actual satellite data show that it can accurately quantify the level of heterogeneity of a variety of landscapes. By normalizing the image size, the method constructs a unified framework for comparison of different regions or image extents. Meanwhile, the CRR method has been applied to time-series tracing of urban expansion and seasonal changes in the Poyang Lake area, thereby providing a new approach for monitoring landscape changes. Furthermore, heterogeneity changes mapping, and quantitative comparisons between the proposed method and existing methods are also performed. © 2014 IEEE.

Zhang M.,Beijing Normal University | Zhang X.,Beijing Institute of Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

The Mie theory for electromagnetic scattering is extended to the case of coated metal sphere with liquid crystals. A new set of vector basis functions for the electric displacement vector inside the liquid crystal layer has been constructed. The expansion coefficients of transmitted and scattered fields are obtained analytically by applying the continuous boundary conditions. The dependence of the scattering property on the geometrical parameters has been investigated in detail. The appearance of photonic Hall effect for such a Mie scatterer is confirmed. It is interesting that such a photonic Hall effect not only depends on the ratio of the inner to outer radius of coated sphere, it is also tunable by the application of an external voltage. © 2014 Elsevier B.V.

Zhang F.,Beijing Normal University | Zhang F.,West Virginia University | Yang H.,Perimeter Institute for Theoretical Physics | Yang H.,University of Waterloo | Lehner L.,Perimeter Institute for Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

The ability of a plasma surrounding spinning black holes to extract rotational energy and power energetic emissions has been recognized as a key astrophysical phenomenon. Important insights into the nature of this process are obtained through the analysis of the interplay between a force-free magnetosphere and the black hole. This task involves solving a complicated system of equations, often requiring complex numerical simulations. Recent analytical attempts at tackling this problem have exploited the fact that the near-horizon region of extreme Kerr (NHEK) is endowed with an enhanced symmetry group. We continue in this direction and show that for some conformally self-similar solutions, the NHEK force-free equations reduce to a single nonlinear ordinary differential equation which is difficult to solve with straightforward integration. We here introduce a new approach specifically tailored to this problem and describe how one can obtain physically meaningful solutions. © 2014 American Physical Society.

Zhang J.,Harvard University | Liu J.,Beijing Normal University | Xu Y.,Harvard University
Journal of Neuroscience | Year: 2015

Most of human daily social interactions rely on the ability to successfully recognize faces. Yet~2%of the human population suffers from face blindness without any acquired brain damage [this is also known as developmental prosopagnosia (DP) or congenital prosopagnosia]). Despite the presence of severe behavioral face recognition deficits, surprisingly, a majority of DP individuals exhibit normal face selectivity in the right fusiform face area (FFA), a key brain region involved in face configural processing. This finding, together with evidence showing impairments downstream from the right FFA in DP individuals, has led some to argue that perhaps the right FFA is largely intact in DP individuals. Using fMRI multivoxel pattern analysis, here we report the discovery of a neural impairment in the right FFA of DP individuals that may play a critical role in mediating their face-processing deficits. In seven individuals with DP, we discovered that, despite the right FFA’s preference for faces and it showing decoding for the different face parts, it exhibited impaired face configural decoding and did not contain distinct neural response patterns for the intact and the scrambled face configurations. This abnormality was not present throughout the ventral visual cortex, as normal neural decoding was found in an adjacent object-processing region. To our knowledge, this is the first direct neural evidence showing impaired face configural processing in the rightFFAin individuals with DP. The discovery of this neural impairment provides a new clue to our understanding of the neural basis of DP. ©2015 the authors.

Yin H.,Shandong Agricultural University | Zhou Y.,Beijing Normal University | Zhang H.,Shandong Agricultural University | Meng X.,Shandong Agricultural University | Ai S.,Shandong Agricultural University
Biosensors and Bioelectronics | Year: 2012

MicroRNAs (miRNAs), a kind of small, endogenous, noncoding RNAs (∼22 nucleotides), might play a crucial role in early cancer diagnose due to its abnormal expression in many solid tumors. As a result, label-free and PCR-amplification-free assay for miRNAs is of great significance. In this work, a highly sensitive biosensor for sequence specific miRNA-21 detection without miRNA-21 labeling and enrichment was constructed based on the substrate electrode of dendritic gold nanostructure (DenAu) and graphene nanosheets modified glassy carbon electrode. Sulfydryl functionalized locked nucleic acid (LNA) integrated hairpin molecule beacon (MB) probe was used as miRNA-21 capture probe. After hybridized with miRNA-21 and reported DNA loading in gold nanoparticles (AuNPs) and biotin multi-functionalized bio bar codes, streptavidin-HRP was brought to the electrode through the specific interaction with biotin to catalyze the chemical oxidation of hydroquinone by H 2O 2 to form benzoquinone. The electrochemical reduction signal of benzoquinone was utilized to monitor the miRNA-21 hybridization event. The effect of experimental variables on the amperometric response was investigated and optimized. Based on the specific confirmation of probe and signal amplification, the biosensor showed excellent selectivity and high sensitivity with low detection limit of 0.06pM. Successful attempts are made in miRNA-21 expression analysis of human hepatocarcinoma BEL-7402 cells and normal human hepatic L02 cells. © 2012 Elsevier B.V.

Muhtadie L.,University of California at Berkeley | Zhou Q.,University of California at Berkeley | Eisenberg N.,Arizona State University | Wang Y.,Beijing Normal University
Development and Psychopathology | Year: 2013

The additive and interactive relations of parenting styles (authoritative and authoritarian parenting) and child temperament (anger/frustration, sadness, and effortful control) to children's internalizing problems were examined in a 3.8-year longitudinal study of 425 Chinese children (aged 6-9 years) from Beijing. At Wave 1, parents self-reported on their parenting styles, and parents and teachers rated child temperament. At Wave 2, parents, teachers, and children rated children's internalizing problems. Structural equation modeling indicated that the main effect of authoritative parenting and the interactions of Authoritarian Parenting × Effortful Control and Authoritative Parenting × Anger/Frustration (parents' reports only) prospectively and uniquely predicted internalizing problems. The above results did not vary by child sex and remained significant after controlling for co-occurring externalizing problems. These findings suggest that (a) children with low effortful control may be particularly susceptible to the adverse effect of authoritarian parenting and (b) the benefit of authoritative parenting may be especially important for children with high anger/frustration. Copyright © Cambridge University Press 2013.

Wu X.-T.,Beijing Normal University | Wu X.-T.,Catholic University of Leuven | Abraham D.B.,NYUSH ECNU Institute of Mathematical science | Indekeu J.O.,Catholic University of Leuven
Physical Review Letters | Year: 2016

The global phase diagram of wetting in the two-dimensional Ising model is obtained through the exact calculation of the surface excess free energy. In addition to a surface field for inducing wetting, a surface-coupling enhancement is also included. The wetting transition (of second order) is critical for any finite ratio of surface coupling Js to bulk coupling J, and becomes of first order in the limit Js/J→. However, for Js/J1, the critical region is exponentially small and is practically invisible to numerical studies. A distinct preasymptotic regime exists in which the transition displays first-order character. In this regime, surprisingly, the surface susceptibility and surface specific heat develop a divergence and show anomalous scaling with an exponent equal to 3/2. © 2016 American Physical Society.

Jia X.,Henan Polytechnic University | Wang S.,Beijing Normal University | Qin M.,South China Normal University
New Journal of Physics | Year: 2016

Based on atomic first principles, we predict enhanced thermal spin transfer (TST) effects and small switching temperature gradient in Fe |MgO|Fe |MgO|Fe double-barrier magnetic tunnel junctions (MTJs). At room temperature, temperature gradient δ10 K with ∇T ∼10Knm?1 across barriers would be sufficient to switch the magnetic configurations circularly in a junction with 3MgOatomic layers (L), which is about one order smaller than that in Fe |MgO(3L) |Fe MTJs. This temperature gradient is under the current experimental capability. The resonant quantum-well states in companion with resonant interfacial states are responsible for the enhancement. Moreover, a thermal induced 'off' state is found in a double-barrier MTJ. © 2016 IOP Publishing Ltd.

Zeng X.-X.,Chongqing Jiaotong University | Zeng X.-X.,CAS Institute of Theoretical Physics | Zhang H.,Beijing Normal University | Zhang H.,Vrije Universiteit Brussel | Li L.-F.,Chinese Academy of Sciences
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

The phase structure of holographic entanglement entropy is studied in massive gravity for the quantum systems with finite and infinite volumes, which in the bulk is dual to calculating the minimal surface area for a black hole and black brane respectively. In the entanglement entropy-temperature plane, we find for both the black hole and black brane there is a Van der Waals-like phase transition as the case in thermal entropy-temperature plane. That is, there is a first order phase transition for the small charge and a second order phase transition at the critical charge. For the first order phase transition, the equal area law is checked and for the second order phase transition, the critical exponent of the heat capacity is obtained. All the results show that the phase structure of holographic entanglement entropy is the same as that of thermal entropy regardless of the volume of the spacetime on the boundary. © 2016 The Authors.

Liu Z.-H.,China Institute of Atomic Energy | Bao J.-D.,Beijing Normal University | Bao J.-D.,Accelerator Centre
Physical Review C - Nuclear Physics | Year: 2011

The coupled Langevin equations in two-dimensional collective space are used to study the dynamics of nuclear neck growth. Special attention is paid to the effects of coupling between neck and radial degrees of freedom on the evolution from dinucleus to mononuleus. The dynamic model is applied for the study of neck evolution of the mass asymmetric system Ti50 + Cf249. In order to estimate the effects of the coupling, we use the equations in the coupled and uncoupled cases. Our results show that the coupling between neck and radial motions reduces the neck growth velocity and delays the transition from dinuclear to mononuclear regimes. In addition, by solving these dynamic equations we get the probability distributions of radial degree of freedom at the injection point sin in the asymmetric fission valley. In this way, sin is no longer an adjustable parameter in the fusion-by-diffusion model. The distributions obtained are located at positions very close to s=0. Moreover, the coupling significantly reduces the fluctuation in the sin space. Our results show that the quasifissionlike events are unlikely to take place during the transition period for the mass asymmetric systems. Based on the s in distribution obtained, the evaporation residue (ER) cross sections for 3n and 4n evaporation channels in the Ti50 + Cf249 reaction leading to formation of 296120 and 295120 isotopes are calculated. The maximum ER cross sections in 3n and 4n channels with the sin distributions are equal to 0.1 and 0.065 pb, respectively, which are more than two times larger than those obtained by the fusion-by-diffusion model with the sin=0 assumption. © 2011 American Physical Society.

Zhang Y.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Zhang Y.,Northwest Normal University | Yan G.,Beijing Normal University | Bai Y.,Northwest Normal University
IEEE Geoscience and Remote Sensing Letters | Year: 2015

Topographic correction has become very important in areas with rugged terrain. Many studies have suggested that a digital elevation model (DEM) with an inadequate spatial resolution undesirably removes topographic effects. In this letter, a scientific experiment was performed to explore the sensitivity of the topographic correction to the DEM spatial scale based on remote sensing images simulated with a 5-m resolution DEM. Topographic corrections with different DEM resolutions that ranged from 5 to 500 m were performed for simulated images with resolutions of 30-500 m to estimate surface spectral reflectance. Five representative topographic feature points were selected for the analysis. The results demonstrate that the sensitivity to the DEM spatial scale primarily originates from the spatial heterogeneity of the terrain and from the spatial resolution of the image that is topographically corrected. More complex terrain is associated with topographic corrections that are more dependent on the spatial resolution of the DEM. In general, for 30-m resolution remote sensing images, the DEM spatial resolution must be at least 10 m, whereas for 90-to 500-m resolution remote sensing images, a 30-m DEM can achieve the required topographic correction accuracy. © 2014 IEEE.

Chen Y.,Beijing Normal University | Chen Y.,Kansas State University | Ratra B.,Kansas State University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We use Hubble parameter versus redshift data from Stern et al. (2010) [1] and Gaztañaga et al. (2009) [2] to place constraints on model parameters of constant and time-evolving dark energy cosmological models. These constraints are consistent with (through not as restrictive as) those derived from supernova Type Ia magnitude-redshift data. However, they are more restrictive than those derived from galaxy cluster angular diameter distance, and comparable with those from gamma-ray burst and lookback time data. A joint analysis of the Hubble parameter data with more restrictive baryon acoustic oscillation peak length scale and supernova Type Ia apparent magnitude data favors a spatially-flat cosmological model currently dominated by a time-independent cosmological constant but does not exclude time-varying dark energy. © 2011 Elsevier B.V.

Zeng X.-X.,Chongqing Jiaotong University | Liu X.-M.,Hubei University for Nationalities | Liu W.-B.,Beijing Normal University
Journal of High Energy Physics | Year: 2014

Holographic thermalization is studied in the framework of Einstein-Maxwell-Gauss-Bonnet gravity. We use the two-point correlation function and expectation value of Wilson loop, which are dual to the renormalized geodesic length and minimal area surface in the bulk, to probe the thermalization. The numeric result shows that larger the Gauss-Bonnet coefficient is, shorter the thermalization time is, and larger the charge is, longer the thermalization time is, which implies that the Gauss-Bonnet coefficient can accelerate the thermalization while the charge has an opposite effect. In addition, we obtain the functions with respect to the thermalization time for both the thermalization probes at a fixed charge and Gauss-Bonnet coefficient, and on the basis of these functions, we obtain the thermalization velocity, which shows that the thermalization process is non-monotonic. At the middle and later periods of the thermalization process, we find that there is a phase transition point, which divides the thermalization into an acceleration phase and a deceleration phase. We also study the effect of the charge and Gauss-Bonnet coefficient on the phase transition point. © 2014 The Author(s).

Liu H.-S.,Zhejiang University of Technology | Lu H.,Beijing Normal University
Journal of High Energy Physics | Year: 2014

We consider the subset of gauged maximal supergravities that consists of the SO(n + 1) gauge fields Aij and the scalar deformation T ij of the Sn in the spherical reduction of M-theory or type IIB. We focus on the Abelian Cartan subgroup and the diagonal entries of Tij . The resulting theories can be viewed as the STU models with additional hyperscalars. We find that the theories with only one or two such vectors can be generalized naturally to arbitrary dimensions. The same is true for the D = 4 or 5 Einstein- Maxwell theory with such a hyperscalar. The gauge fields become massive, determined by stationary points of the hyperscalars a la the analogous Abelian Higgs mechanism. We obtain classes of Lifshitz and Schrö;dinger vacua in these theories. The scaling exponent z turns out to be rather restricted, taking fractional or irrational numbers. Tweaking the theories by relaxing the mass parameter or making a small change of the superpotential, we find that solutions with z = 2 can emerge. In a different application, we find that the resolution of superstar singularity in the STU models by using bubbling-AdS solitons can be generalized to arbitrary dimensions in our theories. In particular, we obtain the smooth AdS solitons that can be viewed as the resolution of the Reissner-Nordstrøm superstars in general dimensions. © 2014 The Authors.

Liu H.-S.,Zhejiang University of Technology | Lu H.,Beijing Normal University
Journal of High Energy Physics | Year: 2014

Abstract: We specialize the Wald formalism to derive the thermodynamical first law for static black holes with spherical/torus/hyperbolic symmetries in a variety of supergravities or supergravity-inspired theories involving multiple scalars and vectors. We apply the formula to study the first law of a general class of Lifshitz black holes. We analyse the first law of three exact Lifshitz black holes and the results fit the general pattern. In one example, the first law is TdS + ΦdQ = 0 where (Φ, Q) are the electric potential and charge of the Maxwell field. The unusual vanishing of mass in this specific solution demonstrates that super-extremal charged black holes can exist in asymptotic Lifshitz spacetimes. © 2014, The Author(s).

Wang Z.,Beijing Normal University | Wang Z.,Sloan Kettering Cancer Center | Patel D.J.,Sloan Kettering Cancer Center
Quarterly Reviews of Biophysics | Year: 2014

Altered chromatin structures and dynamics are responsible for a range of human malignancies, among which the status of histone lysine methylation remains of paramount importance. Histone lysine methylation is maintained by the relative activities of sequence-specific methyltransferase (KMT) writers and demethylase (KDM) erasers, with aberrant enzymatic activities or expression profiles closely correlated with multiple human diseases. Hence, targeting these epigenetic enzymes should provide a promising avenue for pharmacological intervention of aberrantly marked sites within the epigenome. Here we present an up-to-date critical evaluation on the development and optimization of potent small molecule inhibitors targeted to histone KMTs and KDMs, with the emphasis on contributions of structural biology to development of epigenetic drugs for therapeutic intervention. We anticipate that ongoing advances in the development of epigenetic inhibitors should lead to novel drugs that site-specifically target KMTs and KDMs, key enzymes responsible for maintenance of the lysine methylation landscape in the epigenome. Copyright © 2013 Cambridge University Press.

Meng J.-Y.,Beijing Normal University | Wang H.-X.,Shandong Normal University
Laser Physics | Year: 2011

A single diode-pumped passively Q-switched composite Nd:YAG/Cr 4+:YAG laser, which cavity mirrors were deposited directly onto the crystal, was demonstrated in this paper. At the incident power of 2.75 W, the maximum average output power of 365 mW and the shortest pulse width of 1.7 ns were obtained, corresponding the repetition rate of 14.6 kHz. The single-pulse energy and the peak power were estimated to be 25 μJ and 14 kW, respectively. The corresponding optical-optical conversion efficiency was 13.3%. © 2011 Pleiades Publishing, Ltd.

He L.,Beijing Normal University | He L.,Peking University
Journal of Magnetism and Magnetic Materials | Year: 2010

I compare the lattice spacings, synthesis conditions, and magnetic properties of hexagonal close-packed (hcp) Ni with Ni3C reported recently in the literature. The reported lattice spacings and synthesis conditions of hcp Ni and Ni3C are almost indiscernible. In addition, the magnetic properties of hcp Ni and Ni3C show similar characteristics. Based on my experimental investigations on Ni3C and the reported density functional theory calculations on the magnetic properties of hcp Ni, I present an explanation for understanding the discrepancies in the experimental results regarding hcp Ni reported in the literature. © 2010 Elsevier B.V. All rights reserved.

Lu H.,Beijing Normal University | Pope C.N.,Texas A&M University | Pope C.N.,University of Cambridge | Wen Q.,Renmin University of China
Journal of High Energy Physics | Year: 2015

Abstract: We study the thermodynamics of n-dimensional static asymptotically AdS black holes in Einstein gravity coupled to a scalar field with a potential admitting a stationary point with an AdS vacuum. Such black holes with non-trivial scalar hair can exist provided that the mass-squared of the scalar field is negative, and above the Breitenlohner-Freedman bound. We use the Wald procedure to derive the first law of thermodynamics for these black holes, showing how the scalar hair (or “charge”) contributes non-trivially in the expression. We show in general that a black hole mass can be deduced by isolating an integrable contribution to the (non-integrable) variation of the Hamiltonian arising in the Wald construction, and that this is consistent with the mass calculated using the renormalised holographic stress tensor and also, in those cases where it is defined, with the mass calculated using the conformal method of Ashtekar, Magnon and Das. Similar arguments can also be given for the smooth solitonic solutions in these theories. Neither the black hole nor the soliton solutions can be constructed explicitly, and we carry out a numerical analysis to demonstrate their existence and to provide approximate checks on some of our thermodynamic results. © 2015, The Author(s).

He Q.,Beijing Normal University | Bertness M.D.,Brown University
Ecology | Year: 2014

Since proposed two decades ago, the stress-gradient hypothesis (SGH), suggesting that species interactions shift from competition to facilitation with stress, has been widely examined. Despite broad support across species and ecosystems, ecologists debate whether the SGH applies to extreme environments, arguing that species interactions switch to competition or collapse under extreme stress. We show that facilitation often expands distributions on species borders. SGH exceptions occur when weak stress gradients or stresses outside of species' niches are examined, multiple stresses co-occur canceling out their effects, temporally dependent effects are involved, or results are improperly analyzed. We suggest that ecologists resolve debates by standardizing key SGH terms, such as fundamental and realized niche, stress gradients vs. environmental gradients, by quantitatively defining extreme stress, and by critically evaluating the functionality of stress gradients. We also suggest that new research examine the breadth and relevance of the SGH. More rigor needs to be applied to SGH tests to identify actual exceptions rather than those due to failures to meet its underlying assumptions, so that the general principles of the SGH and its exceptions can be incorporated into ecological theory, conservation strategies, and environmental change predictions. © 2014 by the Ecological Society of America.

Guo Y.,University of Chinese Academy of Sciences | Guo Y.,Beijing Normal University | Li J.,University of Chinese Academy of Sciences | Li Y.,CSIRO
Journal of Climate | Year: 2012

A time-scale decomposition (TSD) approach to statistically downscale summer rainfall over North China is described. It makes use of two distinct downscaling models respectively corresponding to the interannual and interdecadal rainfall variability. The two models were developed based on objective downscaling scheme that 1) identifies potential predictors based on correlation analysis between rainfall and considered climatic variables over the global scale and 2) selects the "optimal" predictors from the identified potential predictors via cross-validation-based stepwise regression. The downscaling model for the interannual rainfall variability is linked to El Niño-Southern Oscillation and the 850-hPa meridional wind over East China, while the one for the interdecadal rainfall variability is related to the sea level pressure over the southwest Indian Ocean. Taking the downscaled interannual and interdecadal components together the downscaled total rainfall was obtained. The results show that the TSD approach achieved a good skill to predict the observed rainfall with the correlation coefficient of 0.82 in the independent validation period. The authors further apply the model to obtain downscaled rainfall projections from three climate models under present climate and the A1B emission scenario in future. The resulting downscaled values provide a closer representation of the observation than the raw climate model simulations in the present climate; for the near future, climate models simulated a slight decrease in rainfall, while the downscaled values tend to be slightly higher than the present state. © 2012 American Meteorological Society.

Hong Q.,Beijing Normal University | Lu G.,Wayne State University
Advanced Nonlinear Studies | Year: 2014

Since the work of Hörmander on linear pseudo-differential operators, the applications of pseudo-differential operators have played an important role in partial differential equations, harmonic analysis, theory of several complex variables and other branches of modern analysis (e.g., they are used to construct parametrices and establish the regularity of solutions to PDEs such as the ∂¯ problem, etc.). The work of Coifman and Meyer on multi-linear Fourier multipliers and pseudo-differential operators has stimulated further such applications. In [2], the authors developed a fairly satisfactory theory of symbolic calculus for multi-linear pseudo-differential operators. Motivated by this work [2] and Lp estimates of [34, 35] on multi-parameter and multi-linear Fourier multipliers and of [12] on multi-parameter and multi-linear pseudo-differential operators, we study and carry out the theory of symbolic calculus for multi-parameter and multi-linear pseudo-differential operators. Our results include the symbol estimates of the adjoints, asymptotic behavior, kernel estimates and boundedness properties and extend those in [2] to the multi-parameter and multi-linear setting. The estimates of the distributional kernel of associated multi-parameter and multilinear pseudo-differential operators can be found useful in establishing the boundedness of such multi-parameter and multi-linear pseudo-differential operators.