1,765 research outputs found
Synthesizing and characterization of hole doped nickel based layer superconductor (LaSr)ONiAs
We report the synthesizing and characterization of the hole doped Ni-based
superconductor (. By substituting La with Sr, the
superconducting transition temperature is increased from 2.75 K of the
parent phase to 3.7 K at the doping levels x= 0.1 - 0.2. The curve
versus hole concentration shows a symmetric behavior as the electron
doped samples . The normal state resistivity in Ni-based
samples shows a good metallic behavior and reveals the absence of an anomaly
which appears in the Fe-based system at about 150 K, suggesting that this
anomaly is not a common feature for all systems. Hall effect measurements
indicate that the electron conduction in the parent phase is
dominated by electron-like charge carriers, while with more Sr doping, a
hole-like band will emerge and finally prevail over the conduction, and
accordingly the superconducting transition temperature increases.Comment: 4 pages, 5 figure
Rigid vortices in MgB2
Magnetic relaxation of high-pressure synthesized MgB bulks with different
thickness is investigated. It is found that the superconducting dia-magnetic
moment depends on time in a logarithmic way; the flux-creep activation energy
decreases linearly with the current density (as expected by Kim-Anderson
model); and the activation energy increases linearly with the thickness of
sample when it is thinner than about 1 mm. These features suggest that the
vortices in the MgB are rather rigid, and the pinning and creep can be well
described by Kim-Anderson model.Comment: Typo corrected & reference adde
Clinical and pathological analysis of 504 cases of elderly ocular tumors
AIM:To analyze the composition, distribution and characteristics of the elderly primary ocular tumors. <p>METHODS: This was a retrospective study and all 504 cases with primary ocular tumors aged 60 years or older were collected in Shanxi Eye Hospital, during the year 2000-2012. The onset age, location and pathological pattern were analyzed.<p>RESULTS: There were 346 cases of benign ocular tumors(68.7%), and 158 cases of malignancy(31.3%).Papillomas was the most common type of the benign with 83 cases(16.5%), followed by a variety of inflammatory cysts and lesions with 69 cases(13.7%)and 64 cases(12.7%)respectively. Among malignant tumors cases, eyelid basal cell carcinoma originated from epithelial was the most common with 72 cases(14.3%), followed by skin appendages sources malignant tumors with 39 cases(7.7%). Concerning the location of ocular tumors, there were 282 cases of eyelid tumor(56.0%)occupied the first position followed by conjunctival tumor with 157 cases(31.2%). <p>CONCLUSION: The prevalence and type of primary ocular tumor in elderly people are significant differences from the general population and children's, and the proportion of malignant tumors tended to increase along with the increase of age
Dynamic response of underground box-type structure to explosion seismic waves
The dynamic response of lined tunnels with a uniform box-type cross-section buried into elastic half-space to explosion seismic waves is studied by employing the matrix force method and treating the structure as a connecting rod system interacting with foundation. The main equations for dynamic analyzing of the hyperstatic structure are deduced and solving method is proposed. A case study is implemented to investigate the influence of span-height ratio of the structure and foundation-structure wave impedance ratio. The results are presented in nondimensional form to obtain a clear physical understanding of the dynamic response of structure. It is shown that the dynamic response of box-type structure can be significantly influenced by the span-height ratio as well as the foundation conditions. Since nondimensional parameters are adopted, the results are independent of dimension and can extend to structures with different size and working conditions. This study provides an analysis method and new insights into the dynamic response of underground box-type structures
Controlled polarization rotation of an optical field in multi-Zeeman-sublevel atoms
We investigate, both theoretically and experimentally, the phenomenon of
polarization rotation of a weak, linearly-polarized optical (probe) field in an
atomic system with multiple three-level electromagnetically induced
transparency (EIT) sub-systems. The polarization rotation angle can be
controlled by a circularly-polarized coupling beam, which breaks the symmetry
in number of EIT subsystems seen by the left- and right-circularly-polarized
components of the weak probe beam. A large polarization rotation angle (up to
45 degrees) has been achieved with a coupling beam power of only 15 mW.
Detailed theoretical analyses including different transition probabilities in
different transitions and Doppler-broadening are presented and the results are
in good agreements with the experimentally measured results.Comment: 28pages, 12figure
Doubly charmed baryon decays in the quark model
In this work we study the doubly charmed baryon decays
within the framework of the
non-relativistic quark model (NRQM). Factorizable amplitudes are expressed in
terms of transition form factors, while nonfactorizable amplitudes arising form
the inner -emission are evaluated using current algebra and the pole model
and expressed in terms of baryonic matrix elements and axial-vector form
factors. Nonperturbative parameters are then calculated using the NRQM. They
can be expressed in terms of the momentum integrals of baryon wave functions,
which are in turn expressed in terms of the harmonic oscillator parameters
and for - and -mode excitation.
The measured ratio of the branching fraction of relative to can be
accommodated in the NRQM with and being in
the vicinity of 0.51 and 0.19, respectively, where is the
parameter for and for
. Decay asymmetries are predicted to be and
for and modes, respectively,
which can be tested in the near future. We compare our results with other works
and point out that although some other models can accommodate the ratio ,
they tend to lead to a branching fraction of
too large compared to that inferred from the LHCb measurement of its rate
relative to .Comment: 17 pages, 2 figure
On the Momentum Dependence of the Flavor Structure of the Nucleon Sea
Difference between the and sea quark distributions in the
proton was first observed in the violation of the Gottfried sum rule in
deep-inelastic scattering (DIS) experiments. The parton momentum fraction
dependence of this difference has been measured over the region from Drell-Yan and semi-inclusive DIS experiments. The Drell-Yan data
suggested a possible sign-change for near ,
which has not yet been explained by existing theoretical models. We present an
independent evidence for the sign-change at
from an analysis of the DIS data. We further discuss the -dependence of
in the context of meson cloud model and the lattice QCD
formulation.Comment: 5 pages, 5 figures, final versio
Tumour chemotherapy strategy based on impulse control theory
Funding. H.-P.R. was supported in part by NSFC (60804040), Fok Ying Tong Education Foundation Young Teacher Foundation (111065), Innovation Research Team of Shaanxi Province (2013KCT-04) and the Key programme of Natural Science Foundation of Shaanxi Province (2016ZDJC-01). M.S.B. was supported in part by the EPSRC (EP/I032606/1).Peer reviewedPostprin
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