Entangling power of the quantum baker's map

We investigate entanglement production in a class of quantum baker's maps. The dynamics of these maps is constructed using strings of qubits, providing a natural tensor-product structure for application of various entanglement measures. We find that, in general, the quantum baker's maps are good at generating entanglement, producing multipartite entanglement amongst the qubits close to that expected in random states. We investigate the evolution of several entanglement measures: the subsystem linear entropy, the concurrence to characterize entanglement between pairs of qubits, and two proposals for a measure of multipartite entanglement. Also derived are some new analytical formulae describing the levels of entanglement expected in random pure states.Comment: 22 pages, 11 figure

Stability of small plastic cylinders subjected to internal pressure and axial compression progress report no. 3

Stability of small cellulose acetate plastic cylinders subjected to internal pressure and axial compressio

Free Riding and Sales Strategies for the Internet

We examine manufacturers' decisions of whether and how to offer their products for sale over the internet. Manufacturers that rely on promotion of their products by brick and mortar retailers must consider the possibility that internet retailers can free ride off of that promotional effort. This creates an incentive for manufacturers to limit the availability of their products over the internet and to control the pricing of their products over the internet. We examine three categories of products: fragrances, DVD players, and side by side refrigerators. Our evidence suggests that manufacturers that limit distribution in the physical world also use various mechanisms to limit distribution online. In particular, we find evidence that these manufacturers attempt to prevent the sale of their products by online retailers who sell goods at deep discounts. Furthermore, we show that manufacturers who distribute their goods directly through manufacturer websites tend to charge very high prices for the products, consistent with the hypothesis that manufacturers internalize free rider issues. While our main focus is on free riding, our evidence on pricing practices is germane to the growing literature on price dispersion on the internet.

An Analysis of Kinetic Response Variability

Studies evaluating variability of force as a function of absolute force generated are synthesized. Inconsistencies in reported estimates of this relationship are viewed as a function of experimental constraints imposed. Typically, within-subject force variability increases at a negative accelerating rate with equal increments in force produced. Current pulse-step and impulse variability models are unable to accommodate this description, although the notion of efficiency is suggested as a useful construct to explain the description outlined

On the novelty, efficacy, and significance of weak measurements for quantum tomography

The use of weak measurements for performing quantum tomography is enjoying increased attention due to several recent proposals. The advertised merits of using weak measurements in this context are varied, but are generally represented by novelty, increased efficacy, and foundational significance. We critically evaluate two proposals that make such claims and find that weak measurements are not an essential ingredient for most of their advertised features.Comment: 12 pages, 10 figure

The effects of postactivation potentiation on sprint and jump performance of male academy soccer players.

The purpose of this investigation was to evaluate the postactivation potentiation (PAP) effects of both dynamic and isometric maximum voluntary contractions (MVCs) on sprint and jump performance and establish whether PAP methods could be used effectively in warm up protocols for soccer players. Twelve male soccer players performed 4 warm up protocols in a cross-over, randomized, and counterbalanced design. In addition to a control warm up, subjects performed deadlift (5 repetitions at 5 repetitions maximum), tuck jump (5 repetitions), and isometric MVC knee extensions (3 repetitions for 3 s) as PAP treatments in an otherwise identical warm up protocol. After each treatment, the subjects underwent 3 10 m and 20 m sprints 4, 5, and 6 minutes post-warm up and 3 vertical jumps (VJ) at 7, 8, and 9 minutes post-warm up. Repeated measures analysis of variance showed no significant differences in the first 10 m (p = 0.258) and 20 m (p = 0.253) sprint and VJ (p = 0.703) performance and the average 10 m (p = 0.215), 20 m (p = 0.388), and VJ (p = 0.529) performance between conditions. There were also no significant differences in performance responses between the strongest and weakest subjects, but large variations in individual responses were found between the subjects. The findings suggest that there was no significant group PAP effect on sprint and jump performance after dynamic and isometric MVCs compared with a control warm up protocol. However, the large variation in individual responses (-7.1% to +8.2%) suggests PAP should be considered on an individual basis. Factors such as method, volume, load, recovery, and interindividual variability of PAP must be considered in the practical application of PAP and the rigorous research design of future studies to evaluate the potential for performance enhancement