6,497 research outputs found
Enhancing quantum entanglement for continuous variables by a coherent superposition of photon subtraction and addition
We investigate how the entanglement properties of a two-mode state can be
improved by performing a coherent superposition operation of photon subtraction
and addition, proposed by Lee and Nha [Phys. Rev. A 82, 053812 (2010)], on each
mode. We show that the degree of entanglement, the EPR-type correlation, and
the performance of quantum teleportation can be all enhanced for the output
state when the coherent operation is applied to a two-mode squeezed state. The
effects of the coherent operation are more prominent than those of the mere
photon subtraction and the addition particularly in the small squeezing regime,
whereas the optimal operation becomes the photon subtraction in the
large-squeezing regime.Comment: 6 pages, 6 figures, published versio
Typical collapse modes of confined masonry buildings under strong earthquake loads
Confined masonry structures are a widely applied structural system in many developing countries. During the past Wenchuan Earthquake in 2008, numerous confined masonry buildings collapsed, while many others suffered damage. This study reviews the construction practices of confined masonry buildings in China. Simple models and hand calculation methods are proposed for quantifying the tearing failure of diaphragms, the tensile failure of tie-columns and the sway-mode strength of masonry buildings. The results indicate very good agreement with field observations. The seismic measures that are stipulated in the seismic design codes are very effective for increasing the strength and integrity, but not the ductility of masonry buildings. For those buildings that survived the earthquake, strength rather than ductility protected the confined masonry from collapse or serious damage. Design recommendations are suggested for preventing various types of premature failures and enhancing the lateral strength of masonry buildings. © Su et al.published_or_final_versio
In-medium modification of P-wave charmonia from QCD sum rules
We investigate the changes of the masses and widths of and
in hot gluonic matter near and in nuclear medium using QCD
sum rules. As in the previous works for the and , in-medium
effects are incorporated through the changes of gluon condensates. Twist-2
terms for the and are also included
for the first time. The results show that larger mass shifts and width
broadenings take place as compared to the -wave states. As the critical
change take place near , related measurements can reveal critical
phenomenon in QCD.Comment: 7 pages, 6 figures, to be published in Phys.Rev.
The Extremely High-Velocity Outflow from the Luminous Young Stellar Object G5.89-0.39
We have imaged the extremely high-velocity outflowing gas in CO (2-1) and
(3-2) associated with the shell-like ultracompact HII region G5.89-0.39 at a
resolution of ~3" (corresponding to ~4000 AU) with the Submillimeter Array. The
integrated high-velocity (>45 km/s) CO emission reveals at least three
blueshifted lobes and two redshifted lobes. These lobes belong to two outflows,
one oriented N-S, the other NW-SE. The NW-SE outflow is likely identical to the
previously detected Br_gamma outflow. Furthermore, these outflow lobes all
clearly show a Hubble-like kinematic structure. For the first time, we estimate
the temperature of the outflowing gas as a function of velocity with the large
velocity gradient calculations. Our results reveal a clear increasing trend of
temperature with gas velocity. The observational features of the extremely
high-velocity gas associated with G5.89-0.39 qualitatively favor the jet-driven
bow shock model.Comment: 14 pages, 4 figures, accepted for publication in ApJ Letter
Novel twin-roll-cast Ti/Al clad sheets with excellent tensile properties
Pure Ti or Ti alloys are recently spot-lighted in construction industries because they have excellent resistance to corrosions, chemicals, and climates as well as various coloring characteristics, but their wide applications are postponed by their expensiveness and poor formability. We present a new fabrication process of Ti/Al clad sheets by bonding a thin Ti sheet on to a 5052 Al alloy melt during vertical-twin-roll casting. This process has merits of reduced production costs as well as improved tensile properties. In the as-twin-roll-cast clad sheet, the homogeneously cast microstructure existed in the Al alloy substrate side, while the Ti/Al interface did not contain any reaction products, pores, cracks, or lateral delamination, which indicated the successful twin-roll casting. When this sheet was annealed at 350 degrees C-600 degrees C, the metallurgical bonding was expanded by interfacial diffusion, thereby leading to improvement in tensile properties over those calculated by a rule of mixtures. The ductility was also improved over that of 5052-O Al alloy (25%) or pure Ti (25%) by synergic effect of homogeneous deformation due to excellent Ti/Al bonding. This work provides new applications of Ti/Al clad sheets to lightweight-alloy clad sheets requiring excellent formability and corrosion resistance as well as alloy cost saving.112Ysciescopu
A New p53 Target Gene, RKIP, Is Essential for DNA Damage-Induced Cellular Senescence and Suppression of ERK Activation
Abstractp53, a strong tumor suppressor protein, is known to be involved in cellular senescence, particularly premature cellular senescence. Oncogenic stresses, such as Ras activation, can initiate p53-mediated senescence, whereas activation of the Ras-mitogen-activated protein kinase (MAPK) pathway can promote cell proliferation. These conflicting facts imply that there is a regulatory mechanism for balancing p53 and Ras-MAPK signaling. To address this, we evaluated the effects of p53 on the extracellular signal-regulated kinase (ERK) activation and found that p53 could suppress ERK activation through de novo synthesis. Through several molecular biologic analyses, we found that RKIP, an inhibitor of Raf kinase, is responsible for p53-mediated ERK suppression and senescence. Overexpression of RKIP can induce cellular senescence in several types of cell lines, including p53-deficient cells, whereas the elimination of RKIP by siRNA or forced expression of ERK blocks p53-mediated cellular senescence. These results suggested that RKIP is an essential protein for cellular senescence. Moreover, modification of the p53 serine 46 residue was critical for RKIP induction and ERK suppression as well as cellular senescence. These results indicated that RKIP is a novel p53 target gene that is responsible for p53-mediated cellular senescence and tumor suppressor protein expression
Free Vibration of Layered Circular Cylindrical Shells of Variable Thickness Using Spline Function Approximation
Free vibration of layered circular cylindrical shells of variable thickness is studied
using spline function approximation by applying a point collocation method. The shell is
made up of uniform layers of isotropic or specially orthotropic materials. The equations
of motions in longitudinal, circumferential and transverse displacement components, are
derived using extension of Love's first approximation theory. The coupled differential
equations are solved using Bickley-type splines of suitable order, which are cubic and
quintic, by applying the point collocation method. This results in the generalized
eigenvalue problem by combining the suitable boundary conditions. The effect of
frequency parameters and the corresponding mode shapes of vibration are studied with
different thickness variation coefficients, and other parameters. The thickness variations
are assumed to be linear, exponential, and sinusoidal along the axial direction. The results
are given graphically and comparisons are made with those results obtained using finite
element method
Design optimization of coil gun to improve muzzle velocity
Recently, a coil gun was brought to the attention of engineering community as electromagnetic alternative to the chemical launchers. Various studies were performed on coil gun systems focused on achieving the high muzzle velocity in military applications and for satellite launching. Most of these studies focused on improvement of muzzle velocity via increase in the size of the coil gun. Present paper describes the process of design optimization where the size of the coli gun system is restricted. The design of experiment approach utilizes the orthogonal array table that reduces the required number of experiments. The design of experiment is carried out with a commercial PIAnO tool, where the finite element analysis is performed at each experimental point. Then, Kriging model is created to achieve accurate approximation in problems of many design variables or strongly nonlinear model. The coil gun is optimally designed using an evolutionary algorithm (EA) as optimization technique. In order to verify the improvement of muzzle velocity by optimal design, the prototypes of coil gun system are manufactured and the experiments to launch the projectile are performed
Quantum linear amplifier enhanced by photon subtraction and addition
A deterministic quantum amplifier inevitably adds noise to an amplified
signal due to the uncertainty principle in quantum physics. We here investigate
how a quantum-noise-limited amplifier can be improved by additionally employing
the photon subtraction, the photon addition, and a coherent superposition of
the two, thereby making a probabilistic, heralded, quantum amplifier. We show
that these operations can enhance the performance in amplifying a coherent
state in terms of intensity gain, fidelity, and phase uncertainty. In
particular, the photon subtraction turns out to be optimal for the fidelity and
the phase concentration among these elementary operations, while the photon
addition also provides a significant reduction in the phase uncertainty with
the largest gain effect.Comment: published version, 7 pages, 9 figure
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