4,539 research outputs found
Bell's Inequality and Entanglement in Qubits
We propose an alternative evaluation of quantum entanglement by measuring the
maximum violation of the Bell's inequality without performing a partial trace
operation. This proposal is demonstrated by bridging the maximum violation of
the Bell's inequality and the concurrence of a pure state in an -qubit
system, in which one subsystem only contains one qubit and the state is a
linear combination of two product states. We apply this relation to the ground
states of four qubits in the Wen-Plaquette model and show that they are
maximally entangled. A topological entanglement entropy of the Wen-Plaquette
model could be obtained by relating the upper bound of the maximum violation of
the Bell's inequality to the concurrences of a pure state with respect to
different bipartitions.Comment: 10 page
Globalization and Knowledge Spillover: International Direct Investment, Exports and Patents
This paper examines the impact of the three main channels of international trade on domestic innovation, namely outward direct investment, inward direct investment (IDI) and exports. The number of Triadic patents serves as a proxy for innovation. The data set contains 37 countries that are considered to be highly competitive in the world market, covering the period 1994 to 2005. The empirical results show that increased exports and outward direct investment are able to stimulate an increase in patent output. In contrast, IDI exhibits a negative relationship with domestic patents. The paper shows that the impact of IDI on domestic innovation is characterized by two forces, and the positive effect of cross-border mergers and acquisitions by foreigners is less than the negative effect of the remaining IDI.International direct investment; Export; Triadic Patent; Outward Direct Investment; Inward Direct Investment; R&D; negative binomial model
Evolution of entanglement spectra under generic quantum dynamics
We characterize the early stages of the approach to equilibrium in isolated
quantum systems through the evolution of the entanglement spectrum. We find
that the entanglement spectrum of a subsystem evolves with at least three
distinct timescales. First, on an o(1) timescale, independent of system or
subsystem size and the details of the dynamics, the entanglement spectrum
develops nearest-neighbor level repulsion. The second timescale sets in when
the light-cone has traversed the subsystem. Between these two times, the
density of states of the reduced density matrix takes a universal, scale-free
1/f form; thus, random-matrix theory captures the local statistics of the
entanglement spectrum but not its global structure. The third time scale is
that on which the entanglement saturates; this occurs well after the light-cone
traverses the subsystem. Between the second and third times, the entanglement
spectrum compresses to its thermal Marchenko-Pastur form. These features hold
for chaotic Hamiltonian and Floquet dynamics as well as a range of quantum
circuit models.Comment: 12 pages, 15 figure
Self-protecting bactericidal titanium alloy surface formed by covalent bonding of daptomycin bisphosphonates.
Infections are a devastating complication of titanium alloy orthopedic implants. Current therapy includes antibiotic-impregnated bone cement and antibiotic-containing coatings. We hypothesized that daptomycin, a Gram-positive peptide antibiotic, could prevent bacterial colonization on titanium alloy surfaces if covalently bonded via a flexible, hydrophilic spacer. We designed and synthesized a series of daptomycin conjugates for bonding to the surface of 1.0 cmÂČ Ti6Al4V foils through bisphosphonate groups, reaching a maximum yield of 180 pmol/cmÂČ. Daptomycin-bonded foils killed 53 ± 5% of a high challenge dose of 3 Ă 10â” cfu Staphylococcus aureus ATCC 29213
Efficiency and Returns to Scale Measurements with Shared Inputs in Multi-Activity Data Envelopment Analysis: An Application to Farmers' Organizations in Taiwan
This paper addresses the question how team production promotes efficiency of a firm when some inputs can be rewarded on the basis of outputs but some cannot because they are shared among outputs and non-separable. A multi-activity DEA model with variable returns to scale is proposed to provide information on the efficiency performance for organizations with inputs shared among several closely related activities. The model is applied to study the case of 279 farmers' associations in Taiwan. The result suggests that it is important to improve the efficiency of the non-profit oriented activities to improve their overall performances. Three out of four departments of TFAs can gain from economies of scale through expansion, while the remaining one gains through contraction. Thus, policies promoting structural adjustment and consolidations of TFAs would not be inconsistent with public interests.multi-activity DEA, shared inputs, efficiency measure, directional distance function, Productivity Analysis,
SK channels and ventricular arrhythmias in heart failure
Small-conductance Ca2+-activated K+ (SK) currents are important in the repolarization of normal atrial (but not ventricular) cardiomyocytes. However, recent studies showed that the SK currents are upregulated in failing ventricular cardiomyocytes, along with increased SK channel protein expression and enhanced sensitivity to intracellular Ca2+. The SK channel activation may be either antiarrhythmic or proarrhythmic, depending on the underlying clinical situations. While the SK channel is a new target of antiarrhythmic therapy, drug safety is still one of the major concerns
Productivity Change in Taiwan's Farmers' Credit Unions: A Nonparametric Risk-Adjusted Malmquist Approach
This article proposes an extended three-stage DEA methodology similar to Fried et al. (2002) to improve the measurement of productivity growth then the assumption of free disposability of undesirable outpu t does not apply. A directional distance function is used to construct adjusted Malmquist-Luenberger productivity indexes which simultaneously account for the impacts of undesirable outputs, environmental variables, and statistical noise. Panel data for 264 farmers' credit unions (FCUs) in Taiwan covering the 1998-2000 period are employed to illustrate the advantages of this method. On average, the productivity of Taiwan's FCUs is found to have deteriorated over the 1998-2000 period. Although an improvement in efficiency has been observed, the major reason for the deterioration is found to be due to the regression of techno logy.Malmquist-Luenberger productivity index, three-stage DEA, undesirable outputs, directional distance function, Agricultural Finance, Productivity Analysis,
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