15,409 research outputs found
Energy Spectra of Anti-nucleons in Finite Nuclei
The quantum vacuum in a many-body system of finite nuclei has been
investigated within the relativistic Hartree approach which describes the bound
states of nucleons and anti-nucleons consistently. The contributions of the
Dirac sea to the source terms of the meson-field equations are taken into
account up to the one-nucleon loop and one-meson loop. The tensor couplings for
the - and -meson are included in the model. The overall nucleon
spectra of shell-model states are in agreement with the data. The calculated
anti-nucleon spectra in the vacuum differ about 20 -- 30 MeV with and without
the tensor-coupling effects.Comment: 4 pages, to appear in the Proceedings of MENU 2004 (Beijing, Aug. 29
-- Sept. 4, 2004
Lattice dynamics and electron-phonon coupling in Sr2RuO4
The lattice dynamics in SrRuO has been studied by inelastic neutron
scattering combined with shell-model calculations. The in-plane bond-stretching
modes in SrRuO exhibit a normal dispersion in contrast to all
electronically doped perovskites studied so far. Evidence for strong electron
phonon coupling is found for c-polarized phonons suggesting a close connection
with the anomalous c-axis charge transport in SrRuO.Comment: 11 pages, 8 figures 2 table
Metallic state in La-doped YBaCuO thin films with -type charge carriers
We report hole and electron doping in La-doped YBaCuO(YBCO) thin
films synthesized by pulsed laser deposition technique and subsequent
\emph{in-situ} postannealing in oxygen ambient and vaccum. The -type samples
show a metallic behavior below the Mott limit and a high carrier density of
10 cm at room temperature (\emph{T}) at the
optimally reduced condition. The in-plane resistivity () of the
-type samples exhibits a quadratic \emph{T} dependence in the
moderate-\emph{T} range and shows an anomaly at a relatively higher \emph{T}
probably related to pseudogap formation analogous to underdoped
NdCeCuO (NCCO). Furthermore, (T), \emph{T} and
\emph{T} with minimum resistivity (\emph{T}) were investigated in both
- and -side. The present results reveal the - asymmetry (symmetry)
within the metallic-state region in an underdoped cuprate and suggest the
potential toward ambipolar superconductivity in a single YBCO system.Comment: 4 pages, 5 figure
Analysing the Security of Google's implementation of OpenID Connect
Many millions of users routinely use their Google accounts to log in to
relying party (RP) websites supporting the Google OpenID Connect service.
OpenID Connect, a newly standardised single-sign-on protocol, builds an
identity layer on top of the OAuth 2.0 protocol, which has itself been widely
adopted to support identity management services. It adds identity management
functionality to the OAuth 2.0 system and allows an RP to obtain assurances
regarding the authenticity of an end user. A number of authors have analysed
the security of the OAuth 2.0 protocol, but whether OpenID Connect is secure in
practice remains an open question. We report on a large-scale practical study
of Google's implementation of OpenID Connect, involving forensic examination of
103 RP websites which support its use for sign-in. Our study reveals serious
vulnerabilities of a number of types, all of which allow an attacker to log in
to an RP website as a victim user. Further examination suggests that these
vulnerabilities are caused by a combination of Google's design of its OpenID
Connect service and RP developers making design decisions which sacrifice
security for simplicity of implementation. We also give practical
recommendations for both RPs and OPs to help improve the security of real world
OpenID Connect systems
Emergence of intrinsic superconductivity below 1.178 K in the topologically non-trivial semimetal state of CaSn3
Topological materials which are also superconducting are of great current
interest, since they may exhibit a non-trivial topologically-mediated
superconducting phase. Although there have been many reports of pressure-tuned
or chemical-doping-induced superconductivity in a variety of topological
materials, there have been few examples of intrinsic, ambient pressure
superconductivity in a topological system having a stoichiometric composition.
Here, we report that the pure intermetallic CaSn3 not only exhibits topological
fermion properties but also has a superconducting phase at 1.178 K under
ambient pressure. The topological fermion properties, including the nearly zero
quasi-particle mass and the non-trivial Berry phase accumulated in cyclotron
motions, were revealed from the de Haas-van Alphen (dHvA) quantum oscillation
studies of this material. Although CaSn3 was previously reported to be
superconducting at 4.2K, our studies show that the superconductivity at 4.2K is
extrinsic and caused by Sn on the degraded surface, whereas its intrinsic bulk
superconducting transition occurs at 1.178 K. These findings make CaSn3 a
promising candidate for exploring new exotic states arising from the interplay
between non-trivial band topology and superconductivity, e.g. topological
superconductivityComment: 20 pages,4 figure
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Zika virus promotes CCN1 expression via the CaMKIIα-CREB pathway in astrocytes.
Zika virus (ZIKV) infection in the human central nervous system (CNS) causes Guillain-Barre syndrome, cerebellum deformity, and other diseases. Astrocytes are immune response cells in the CNS and an important component of the blood-brain barrier. Consequently, any damage to astrocytes facilitates the spread of ZIKV in the CNS. Connective tissue growth factor/Nephroblastoma overexpressed gene family 1 (CCN1), an important inflammatory factor secreted by astrocytes, is reported to regulate innate immunity and viral infection. However, the mechanism by which astrocyte viral infection affects CCN1 expression remains undefined. In this study, we demonstrate that ZIKV infection up-regulates CCN1 expression in astrocytes, thus promoting intracellular viral replication. Other studies revealed that the cAMP response element (CRE) in the CCN1 promoter is activated by the ZIKV NS3 protein. The cAMP-responsive element-binding protein (CREB), a transacting factor of the CRE, is also activated by NS3 or ZIKV. Furthermore,a specific inhibitor of CREB, i.e. SGC-CBP30, reduced ZIKV-induced CCN1 up-regulation and ZIKV replication. Moreover, co-immunoprecipitation, overexpression, and knockdown studies confirmed that the interaction between NS3 and the regulatory domain of CaMKIIα could activate the CREB pathway, thus resulting in the up-regulation of CCN1 expression and enhancement of virus replication. In conclusion, the findings of our investigations on the NS3-CaMKIIα-CREB-CCN1 pathway provide a foundation for understanding the infection mechanism of ZIKV in the CNS
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