This paper demonstrates the interest of a time-reversal method for the identification of source in a randomly layered medium. An active source located inside the medium emits a pulse that is recorded on a small time-reversal mirror. The wave is sent back into the medium, either numerically in a computer with the knowledge of the medium, or physically into the real medium. Our goal is to give a ...

In this paper we derive time reversal imaging functionals for two strongly causal acoustic attenuation models, which have been proposed recently. The time reversal techniques are based on recently proposed ideas of Ammari et al for the thermo-viscous wave equation. Here and there an asymptotic analysis provides reconstruction functionals from first order corrections for the attenuating effect. ...

Humans are capable of correcting their actions based on actions performed in the past, and this ability enables them to adapt to a changing environment. The computational field of reinforcement learning (RL) has provided a powerful explanation for understanding such processes. Recently, the dual learning system, modeled as a hybrid model that incorporates value update based on reward-prediction...

Low dilation embeddings are used to compare similarities between star and pancake networks. The pancake network of dimension n, Pn, has n! nodes, one for each permutation, and an undirected edge between permutations (nodes) when some prefix reversal transforms one permutation into the other. The star network of dimension n, Sn, has n! nodes, one for each permutation, and an undirected edge betw...

Two ocean acoustics experiments demonstrating the implementation of a time reversal mirror have been conducted. Pulsed sound (50-ms with center frequency 445 Hz) was refocused to the position of a probe source out to ranges as great as 30 km in 125-m deep water. In addition, a technique to refocus at ranges other than that of the probe source also was demonstrated. These results are summarized ...

Sleep supports the formation of a variety of declarative and non-declarative memories, and sleep deprivation often impairs these types of memories. In human subjects, natural sleep either during a nap or overnight leads to long-lasting improvements in visuomotor and fine motor tasks, but rodent models recapitulating these findings have been scarce. Here we present evidence that 5h of acute slee...

We have investigated magnetization reversal in nanostructured Co/Pd multilayers. Interestingly enough, reversal phenomena in this system were found to be very sensitive to the Co-sublayer thickness and very contrasting reversal behaviors were observed between the samples having 2-Å-thick Co and 4-Å-thick Co sublayers. Direct domain observation and time-dependent magnetization viscosity curves r...

There are two types of Asian options in the financial markets which differ according to the role of the average price. We give a symmetry result between the floating and fixed-strike Asian options. The proof involves a change of numéraire and time reversal of Brownian motion. Symmetries are very useful in option valuation and in this case, the result allows the use of more established fixed-str...

Permutation decoding is a technique which involves finding a subset S, called PDset, of the permutation automorphism group PAut(C) of a code C in order to assist in decoding. A method to obtain s-PD-sets of size s + 1 for partial permutation decoding for the binary linear Hadamard codes Hm of length 2 m, for all m ≥ 4 and 1 < s ≤ b(2m −m− 1)/(1 + m)c, is described. Moreover, a recursive constru...

Advantages of investigation of time reversal invariance violation with the use of three-fold (P,T-odd) and five-fold (P-even,T-odd) correlations in the interaction of resonance neutrons with nuclei are briefly considered. Possible enhancements of T-odd effects in both cases are discussed. It is shown that the study of five-fold correlation is a perspective way to test time reversal invariance. ...