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Search Results: 1 - 10 of 362718 matches for " R. H. He "
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Robustness of the global non-analytical fit to the analysis of peak-dip-hump lineshape in bilayer-split spectra of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$
R. H. He
Physics , 2004,
Abstract: The application of global non-analytical fit to the quantitative spectral analysis of the bilayer-split peak-dip-hump lineshape of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ at $(\pi,0)$ are revisited. The robustness of the results is verified by various fitting schemes confirming physically the correlation of the superconducting peak with the superfluid density.
Impact of Management Practices on Water Extractable Organic Carbon and Nitrogen from 12-Year Poultry Litter Amended Soils  [PDF]
Zhongqi He, Mingchu Zhang, Aiqing Zhao, Heidi M. Waldrip, Paulo H. Pagliari, R. Daren Harmel
Open Journal of Soil Science (OJSS) , 2017, DOI: 10.4236/ojss.2017.710019
Abstract: Water extractable organic carbon (WEOC) and nitrogen (WEON) are two key parameters of soil water extractable organic matter (WEOM). Proper management of manure application rate in combination with tillage and cropping management could maintain appropriate WEOC and WEON concentrations in soils while decreasing the risk of their runoff from cropland and pastures. The objective of this research was to determine the effect of poultry litter (PL) application on WEOC and WEON in soils under different crops, tillage regimes, and grazing strategies. From 2001 to 2012, PL was applied at multiple rates to cultivated fields in a corn-oat/wheat-hay rotation or to pastures grazed by cattle or ungrazed. Soil samples (0 - 15 cm) were analyzed for KCl-extractable mineral N, and WEOC, and WEON contents. In addition, Ultraviolet-visible (UV-vis) and fluorescence spectroscopies were used to characterize WEOC stability. Organic N levels were higher at the high PL application rates. The soil C:N ratio narrowed as the PL application rate increased. However, the soil from pastures which received PL tended to have a wider range of C:N ratios than soil from the cultivated fields, despite identical PL application rates. The spectral analyses indicated that WEOC properties were responsive to management and PL application rate; therefore, this parameter may be used as a guide to provide best management strategy for manure application.
Properties of Thermal Photons at RHIC and LHC
R. Rapp,H. van Hees,M. He
Physics , 2014, DOI: 10.1016/j.nuclphysa.2014.08.008
Abstract: We study the emission characteristics of thermal photons at RHIC and LHC as affected by both the space-time evolution of the bulk medium and the thermal emission rates. For the former we compare the results of two evolution models (expanding fireball and hydrodynamics). For the latter, we detail the influence of hadronic emission components and study a speculative scenario by upscaling the default QGP and hadronic rates around the pseudo-critical region.
Finite lattice size effect in the ground state phase diagram of quasi-two-dimensional magnetic dipolar dots array with perpendicular anisotropy
R. H. He,X. F. Jin
Physics , 2004,
Abstract: A prototype Hamiltonian for the generic patterned magnetic structures, of dipolar interaction with perpendicular anisotropy, is investigated within the finite-size framework by Landau-Lifshift-Gilbert classical spin dynamics. Modifications on the ground state phase diagram are discussed with an emphasis on the disappearance of continuous degeneracy in the ground state of in-plane phase due to the finite lattice size effect. The symmetry-governed ground state evolution upon the lattice size increase provides a critical insight into the systematic transition to the infinite extreme.
A global non-analytical fit method for the complex lineshape analysis of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$
R. H. He,D. L. Feng
Physics , 2004,
Abstract: The implementation of global non-analytical fit is exemplified by its application to the spectral analysis of the complex lineshape of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ at $(\pi,0)$. It deals with properly a multi-level globality in the fitting parameters and efficiently the non-analytical evaluation of the fitting function, thus exhibiting a potential applicability to a wide range of systematic analysis task.
Model for a Light Z' Boson
R. Foot,X. -G. He,H. Lew,R. R. Volkas
Physics , 1994, DOI: 10.1103/PhysRevD.50.4571
Abstract: A model of a light $Z'$ boson is constructed and phenomenological bounds are derived. This $Z'$ boson arises from a very simple extension to the Standard Model, and it is constrained to be light because the vacuum expectation values which generate its mass also break the electroweak gauge group. It is difficult to detect experimentally because it couples exclusively or primarily (depending on symmetry breaking details) to second and third generation leptons. However, if the $Z'$ boson is sufficiently light, then there exists the possibility of the two-body decay $\tau \rightarrow \mu Z'$ occuring. This will provide a striking signature to test the model.
Effects of turbulent dust grain motion to interstellar chemistry
J. X. Ge,J. H. He,H. R. Yan
Physics , 2015, DOI: 10.1093/mnras/stv2560
Abstract: Theoretical studies have revealed that dust grains are usually moving fast through the turbulent interstellar gas, which could have significant effects upon interstellar chemistry by modifying grain accretion. This effect is investigated in this work on the basis of numerical gas-grain chemical modeling. Major features of the grain motion effect in the typical environment of dark clouds (DC) can be summarised as follows: 1) decrease of gas-phase (both neutral and ionic) abundances and increase of surface abundances by up to 2-3 orders of magnitude; 2) shifts of the existing chemical jumps to earlier evolution ages for gas-phase species and to later ages for surface species by factors of about ten; 3) a few exceptional cases in which some species turn out to be insensitive to this effect and some other species can show opposite behaviors too. These effects usually begin to emerge from a typical DC model age of about 10^5 yr. The grain motion in a typical cold neutral medium (CNM) can help overcome the Coulomb repulsive barrier to enable effective accretion of cations onto positively charged grains. As a result, the grain motion greatly enhances the abundances of some gas-phase and surface species by factors up to 2-6 or more orders of magnitude in the CNM model. The grain motion effect in a typical molecular cloud (MC) is intermediate between that of the DC and CNM models, but with weaker strength. The grain motion is found to be important to consider in chemical simulations of typical interstellar medium.
Radiative pumping of 1612 MHz OH masers: OH/IR sources with IRAS LRS spectra and 34.6 micrometer absorption feature
R. Szczerba,J. H. He,P. S. Chen
Physics , 2002,
Abstract: The population inversion which leads to the 1612 MHz OH maser emission has long been thought to be radiatively pumped. Since OH rotational lines involved in this pumping scheme lie in the far-infrared they became observable only after the launch of the ISO satellite. With the aim to investigate the pumping conditions of the 1612 MHz OH maser emission in more details we have searched the ISO Archive for SWS observations around 34.6 um of 1024 OH/IR sources with IRAS LRS spectra from compilation of Chen et al. (2001). Surprisingly, among 81 OH/IR sources which have appropriate SWS data only already reported objects: VY CMa, IRC+10420 and the Galactic center, show clear 34.6 um absorption line. We discuss possible reasons for non-detection of this pumping line.
Superconducting order parameter in heavily overdoped $Bi_2 Sr_2 Ca Cu_2 O_{8+δ}$: a global quantitative analysis
R. H. He,D. L. Feng,H. Eisaki,J. -i. Shimoyama,K. Kishio,G. D. Gu
Physics , 2004, DOI: 10.1103/PhysRevB.69.220502
Abstract: A systematic analysis of the complex lineshape at $(\pi,0)$ of heavily overdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ is presented. We show that a coherent component in the quasi-particle excitation is correlated with the superfluid density throughout the entire doping range and suggest it is a direct measure of the order parameter of high temperature superconductors.
Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere
H. Tian,H. E. Potts,E. Marsch,R. Attie,J. -S. He
Physics , 2010, DOI: 10.1051/0004-6361/200913254
Abstract: We study horizontal supergranule-scale motions revealed by TRACE observation of the chromospheric emission, and investigate the coupling between the chromosphere and the underlying photosphere. A highly e?cient feature-tracking technique called balltracking has been applied for the first time to the image sequences obtained by TRACE (Transition Region and Coronal Explorer) in the passband of white light and the three ultraviolet passbands centered at 1700 {\AA}, 1600 {\AA}, and 1550 {\AA}. The resulting velocity fields have been spatially smoothed and temporally averaged in order to reveal horizontal supergranule-scale motions that may exist at the emission heights of these passbands. We find indeed a high correlation between the horizontal velocities derived in the white-light and ultraviolet passbands. The horizontal velocities derived from the chromospheric and photospheric emission are comparable in magnitude. The horizontal motions derived in the UV passbands might indicate the existence of a supergranule-scale magnetoconvection in the chromosphere, which may shed new light on the study of mass and energy supply to the corona and solar wind at the height of the chromosphere. However, it is also possible that the apparent motions reflect the chromospheric brightness evolution as produced by acoustic shocks which might be modulated by the photospheric granular motions in their excitation process, or advected partly by the supergranule-scale flow towards the network while propagating upward from the photosphere. To reach a firm conclusion, it is necessary to investigate the role of granular motions in the excitation of shocks through numerical modeling, and future high-cadence chromospheric magnetograms must be scrutinized.
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