Quantum de Finetti theorem under fully-one-way adaptive measurements

We prove a version of the quantum de Finetti theorem: permutation-invariant quantum states are well approximated as a probabilistic mixture of multi-fold product states. The approximation is measured by distinguishability under fully one-way LOCC (local operations and classical communication) measurements. Our result strengthens Brand\~{a}o and Harrow's de Finetti theorem where a kind of partially one-way LOCC measurements was used for measuring the approximation, with essentially the same error bound. As main applications, we show (i) a quasipolynomial-time algorithm which detects multipartite entanglement with amount larger than an arbitrarily small constant (measured with a variant of the relative entropy of entanglement), and (ii) a proof that in quantum Merlin-Arthur proof systems, polynomially many provers are not more powerful than a single prover when the verifier is restricted to one-way LOCC operations.Comment: V2: minor changes. V3: new title, more discussions added, presentation improved. V4: minor changes, close to published versio

Air cushioning with a lubrication/ inviscid balance

The air cushioning effect in the gap between an almost inviscid body of water and a nearby solid wall (or another body of water) is studied theoretically and is found to depend on predominantly lubricating forces in the air, in certain applications. The situation in which the density and viscosity in air are taken as small compared with those in water is investigated. In this situation potential-flow dynamics in the water couples with lubrication behaviour in the air, leading to a nonlinear integro-differential system for the evolution of the interface. The numerical values of the main parameters are investigated and indicate a wide range of practical applications. Specifically, the lubrication/inviscid balance holds for typical global Reynolds numbers below the order of the viscosity ratio divided by the cube of the density ratio, i.e. below about 10$^{7}$ in the case of air and water; for Reynolds numbers of that order the lubrication behaviour is replaced by an unsteady boundary-layer response, whereas above that order formally the response is totally inviscid. A variety of spatio-temporal flow solutions are presented for the lubrication/inviscid system and these all indicate a relatively rapid closure of the gap, in a common form which is analysed

A Massive Progenitor of the Luminous Type IIn Supernova 2010jl

The bright, nearby, recently discovered supernova SN2010jl is a member of the rare class of relatively luminous Type~IIn events. Here we report archival HST observations of its host galaxy UGC5189A taken roughly 10yr prior to explosion, as well as early-time optical spectra of the SN. The HST images reveal a bright, blue point source at the position of the SN, with an absolute magnitude of -12.0 in the F300W filter. If it is not just a chance alignment, the source at the SN position could be (1) a massive young (less than 6 Myr) star cluster in which the SN resided, (2) a quiescent, luminous blue star with an apparent temperature around 14,000K, (3) a star caught during a bright outburst akin to those of LBVs, or (4) a combination of option 1 and options 2 or 3. Although we cannot confidently choose between these possibilities with the present data, any of them imply that the progenitor of SN2010jl had an initial mass above 30Msun. This reinforces mounting evidence that many SNe IIn result from very massive stars, that massive stars can produce visible SNe without collapsing quietly to black holes, and that massive stars can retain their H envelopes until shortly before explosion. Standard stellar evolution models fail to account for these observed properties.Comment: 6 pages, 4 figures, submitted to Ap

A macro-level model for investigating the effect of directional bias on network coverage

Random walks have been proposed as a simple method of efficiently searching, or disseminating information throughout, communication and sensor networks. In nature, animals (such as ants) tend to follow correlated random walks, i.e., random walks that are biased towards their current heading. In this paper, we investigate whether or not complementing random walks with directional bias can decrease the expected discovery and coverage times in networks. To do so, we develop a macro-level model of a directionally biased random walk based on Markov chains. By focussing on regular, connected networks, the model allows us to efficiently calculate expected coverage times for different network sizes and biases. Our analysis shows that directional bias can significantly reduce coverage time, but only when the bias is below a certain value which is dependent on the network size.Comment: 15 page

Responding to accents after experiencing interactive or mediated speech

Very little known is about how speakers learn about and/or respond to speech experienced without the possibility for interaction. This paper reports an experiment which considers the effects of two kinds of exposure to speech (interactive or non-interactive mediated) on Scottish English speakers’ responses to another accent (Southern British English), for two processing tasks, phonological awareness and speech production. Only marginal group effects are found according to exposure type. The main findings show a difference between subjects according to exposure type before exposure, and individual shifts in responses to speech according to exposure type

Nox2 dependent redox-regulation of microglial response to amyloid-β stimulation and microgliosis in aging

Microglia express constitutively a Nox2 enzyme that is involved in neuroinflammation by the generation of reactive oxygen species (ROS). Amyloid β (Aβ) plays a crucial role in Alzheimer’s disease. However, the mechanism of Aβ-induced microglial dysfunction and redox-regulation of microgliosis in aging remains unclear. In this study, we examined Nox2-derived ROS in mediating microglial response to Aβ peptide 1–42 (Aβ42) stimulation in vitro, in aging-associated microgliosis in vivo and in post-mortem human samples. Compared to controls, Aβ42 markedly induced BV2 cell ROS production, Nox2 expression, p47phox and ERK1/2 phosphorylation, cell proliferation and IL-1β secretion. All these changes could be inhibited to the control levels in the presence of Nox2 inhibitor or superoxide scavenger. Compared to young (3–4 months) controls, midbrain tissues from wild-type aging mice (20– 22 months) had significantly higher levels of Nox2-derived ROS production, Aβ deposition, microgliosis and IL-1β production. However, these aging-related changes were reduced or absent in Nox2 knockout aging mice. Clinical significance of aging-associated Nox2 activation, microgliosis and IL-1β production was investigated using post-mortem midbrain tissues of humans at young (25–38 years) and old age (61–85 years). In conclusion, Nox2-dependent redox-signalling is crucial in microglial response to Aβ42 stimulation and in aging-associated microgliosis and brain inflammation

Short-scale break-up in unsteady interactive layers: Local development of normal pressure gradients and vortex wind-up

Following the finite-time collapse of an unsteady interacting boundary layer (step 1), shortened length and time scales are examined here in the near-wall dynamics of transitional-turbulent boundary layers or during dynamic stall. The next two steps are described, in which (step 2) normal pressure gradients come into operation along with a continuing nonlinear critical-layer jump and then (step 3) vortex formation is induced typically. Normal pressure gradients enter in at least two ways, depending on the internal or external flow configuration. This yields for certain internal flows an extended KdV equation with an extra nonlinear integral contribution multiplied by a coefficient which is proportional to the normal rate of change of curvature of the velocity profile locally and whose sign turns out to be crucial. Positive values of the coefficient lead to a further finite-time singularity, while negative values produce a rapid secondary instability phenomenon. Zero values in contrast allow an interplay between solitary waves and wave packets to emerge at large scaled times, this interplay eventually returning the flow to its original, longer, interactive, boundary-layer scales but now coupled with multiple shorter-scale Euler regions. In external or quasi-external flows more generally an extended Benjamin–Ono equation holds instead, leading to a reversal in the roles of positive and negative values of the coefficient. The next step, 3, typically involves the strong wind-up of a local vortex, leading on to explosion or implosion of the vortex. Further discussion is also presented, including the three-dimensional setting, the computational implications, and experimental links