3,375 research outputs found
Superconducting transmon qubit-resonator quantum baterry
Quantum battery (QB) is the miniature energy storage and release device and
plays a crucial role in future quantum technology. Here, an implementation
scheme of a QB is proposed on a superconducting circuit which is composed by
coupled transmon qubits and a one-dimensional transmission line resonator.
We derive the Hamiltonian of the QB system and investigate its charging
performance by considering three decay channels. We find that the presence of
the decay channels suppresses the high oscillation of the energy storage
process, thereby realizing a stable and powerful QB. In particular, compared
with the resonator decay and the qubit relaxation, the qubit dephasing shows a
counterintuitive advantage in our QB. We show that the nearest neighbor
interaction always have a positive impact on the stable energy and the coupling
only significantly influences the maximum charging power in the fully
nondegenerate ground state region. We also demonstrate the feasibility of our
approach by evaluating the QB performance under experimental parameters.Comment: 8 pages, 6 figure
Three-level Dicke quantum battery
Quantum battery (QB) is the energy storage and extraction device that is
governed by the principles of quantum mechanics. Here we propose a three-level
Dicke QB and investigate its charging process by considering three quantum
optical states: a Fock state, a coherent state, and a squeezed state. The
performance of the QB in a coherent state is substantially improved compared to
a Fock and squeezed states. We find that the locked energy is positively
related to the entanglement between the charger and the battery, and
diminishing the entanglement leads to the enhancement of the ergotropy. We
demonstrate the QB system is asymptotically free as . The
stored energy becomes fully extractable when , and the charging power
follows the consistent behavior as the stored energy, independent of the
initial state of the charger.Comment: 9 Pages, 9 Figure
Analytically solvable many-body Rosen-Zener quantum battery
Quantum batteries are energy storage devices that satisfy quantum mechanical
principles. How to obtain analytical solutions for quantum battery systems and
achieve a full charging is a crucial element of the quantum battery. Here, we
investigate the Rosen-Zener quantum battery with two-level systems, which
includes atomic interactions and external driving field. The analytical
solutions of the stored energy, changing power, energy quantum fluctuations,
and von Neumann entropy are derived by employing the gauge transformation. We
demonstrate that full charging process can be achieved when the external
driving field strength and scanning period conforms to a quantitative
relationship. The local maximum value of the final stored energy corresponds to
the local minimum values of the final energy fluctuations and von Neumann
entropy. Moreover, we find that the atomic interaction induces the quantum
phase transition and the maximum stored energy of the quantum battery reaches
the maximum value near the quantum phase transition point. Our result provides
an insightful theoretical scheme to realize the efficient quantum battery.Comment: 9 pages,7 figure
Variance Reduced Random Relaxed Projection Method for Constrained Finite-sum Minimization Problems
For many applications in signal processing and machine learning, we are
tasked with minimizing a large sum of convex functions subject to a large
number of convex constraints. In this paper, we devise a new random projection
method (RPM) to efficiently solve this problem. Compared with existing RPMs,
our proposed algorithm features two useful algorithmic ideas. First, at each
iteration, instead of projecting onto the subset defined by one of the
constraints, our algorithm only requires projecting onto a half-space
approximation of the subset, which significantly reduces the computational cost
as it admits a closed-form formula. Second, to exploit the structure that the
objective is a sum, variance reduction is incorporated into our algorithm to
further improve the performance. As theoretical contributions, under an error
bound condition and other standard assumptions, we prove that the proposed RPM
converges to an optimal solution and that both optimality and feasibility gaps
vanish at a sublinear rate. We also provide sufficient conditions for the error
bound condition to hold. Experiments on a beamforming problem and a robust
classification problem are also presented to demonstrate the superiority of our
RPM over existing ones
A study on transmitted intensity of disturbance for air-spaced Glan-type polarizing prisms
We study theoretically and experimentally the transmission intensity of
polarized light through the air-spaced Glan-type polarizing prsims. It is found
that the variation of the transmitted intensity with the rotation angle
deviates from Malus Law, exhibiting a cyclic fluctuation with the rotation
angle. The occurrence of the disturbance is explained by the use of an argument
based on the interference effect produced from the air-gap in the prisms. The
theoretcal results are well agreed with the experimental ones. By selecting the
proper cut angle of prism and reducing the thickness of air-gap in prism, the
disturbance may be minimized.Comment: 5 pages, 10 figures, to be published in Optics Communication
Alendronate prevents angiotensin II-induced collagen I production through geranylgeranylation-dependent RhoA/Rho kinase activation in cardiac fibroblasts
AbstractCollagen I is the main component of extracellular matrix in cardiac fibrosis. Our previous studies have reported inhibition of farnesylpyrophosphate synthase prevents angiotensin II-induced cardiac fibrosis, while the exact molecular mechanism was still unclear. This paper was designed to investigate the effect of alendronate, a farnesylpyrophosphate synthase inhibitor, on regulating angiotensin II-induced collagen I expression in cultured cardiac fibroblasts and to explore the underlying mechanism. By measuring the mRNA and protein levels of collagen I, we found that alendronate prevented angiotensin II-induced collagen I production in a dose-dependent manner. The inhibitory effect on collagen I expression was reversed by geranylgeraniol, and mimicked by inhibitors of RhoA/Rho kinase pathway including C3 exoenzyme and GGTI-286. Thus we suggested geranylgeranylation-dependent RhoA/Rho kinase activation was involved in alendronate-mediated anti-collagen I synthetic effect. Furthermore, we accessed the activation status of RhoA in alendronate-, geranylgeraniol- and GGTI-286-treated cardiac fibroblasts and gave an indirect evidence for RhoA activation via geranylgeranylation. Then we came to the conclusion that in cardiac fibroblasts, alendronate could protect against angiotensin II-induced collagen I synthesis through inhibition of geranylgeranylation and inactivation of RhoA/Rho kinase signaling. Targeting geranylgeranylation and RhoA/Rho kinase signaling will hopefully serve as therapeutic strategies to reduce fibrosis in heart remodeling
Practical formula to calculate tension of vertical cable with hinged-fixed conditions based on vibration method
Vertical cables are widely used in the tied-arch bridges and suspension bridges as the vital components to transfer load. It is very important to accurately estimate the cable tensions in the cable supported bridges during both construction and in-service stages. Vibration method is the most widely used method for in-situ measurement of cable tensions. But for the cables with hinged-fixed boundary conditions, no analytical formulas can be used to describe the relationship between the frequencies and the cable tension. According to the general solution of the vibration equation and based on its numerical computational results, practical formula to calculate tensions of vertical cables by multiple natural frequencies satisfying hinged-fixed boundary conditions is proposed in this paper. The expression of the practical formula is the same as the solution derived from an axially loaded beam with simple supported ends and can use the first 10 order frequencies to calculate the cable tension conveniently and accurately. Error analysis showed that when using the fundamental frequency to estimate cable force, the estimated tension errors of the cables with its dimensionless parameter ξ≥ 2.8 are less than 2 %. It contained nearly all of the vertical cables used in bridge engineering. In addition, with multiple natural frequencies being measured, bending stiffness of the cable can be identified by using the formulas presented in this paper with an iterative method. At last, the practical formula in this paper is verified to have high precision with several numerical examples, and can be conveniently applied to field test for cable-supported bridges
Effect of Dihuang rougui decoction on ovariectomyinduced osteoporosis in rats
Purpose: To investigate the effect of Dihuang Rougui Decoction (DRD) on ovariectomy-induced osteoporosis in rats.Methods: Female Sprague-Dawley rats were randomly assigned to a normal group (control) and five ovariectomy (OVX) subgroups: OVX with vehicle (OVX), OVX with positive control drug (alendronate sodium tablets, 1.6 mg/kg/week), and OVX + DRD (75, 150 or 300 mg/kg/day). After the rats were subjected to ovariectomy for 4 weeks, fosamax or DRD were administered daily (orally) for 16 weeks. The bone mineral density (BMD) of the L4 vertebrae and right femurs of the rats was evaluated. Serum hormones estradiol (E2), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels and serum alkaline phosphatase (ALP), osteocalcin (OC) and telopeptides of collagen type I (CTx) levels of the rats were determined. The bone tissue morphology of the rats was examined by microscopy.Results: The results show that DRD dose-dependently inhibited bone mineral density (BMD) reduction of L4 vertebrae and femurs (both p < 0.05). DRD significantly increased serum E2, FSH and LH levels (p < 0.05) in the osteoporotic rats, and significantly lowered serum ALP, CTx and OC concentrations, compared to OVX group (p < 0.01). Compared with OVX model group, bone trabeculae in all three DRD groups and nilestriol groups were wider, and the space and connections markedly increased. Furthermore, the medullary cavity reduced in size.Conclusion: These findings indicate that DRD mitigates OVX-induced osteoporosis in rats, and thus, the decoction has a potential for clinical management of osteoporosis patients.Keywords: Dihuang Rougui decoction, Osteoporosis, Ovariectomy, Bone mineral density, Serum bone marker, Bone tissue morpholog
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