Utility based cross-layer collaboration for speech enhancement in wireless acoustic sensor networks

A wireless acoustic sensor network is considered that is used to estimate a desired speech signal that has been corrupted by noise. The application layer of the WASN derives an optimal filter in a linear MMSE sense. A utility function is then used in conjunction with the MMSE estimate in order to evaluate the most significant signal components from each node in the system. The utility values are used as a cross-layer link between the application layer and the network layer so the nodes transmit the signal components that are deemed most relevant to the estimate while adhering to the power constraints of the system. The simulation results show that a high signal-to-error and signal-to-noise ratio is still achievable while transmitting a subset of signal components

Influence of electromagnetic interferences on the gravimetric sensitivity of surface acoustic waveguides

Surface acoustic waveguides are increasing in interest for (bio)chemical detection. The surface mass modification leads to measurable changes in the propagation properties of the waveguide. Among a wide variety of waveguides, Love mode has been investigated because of its high gravimetric sensitivity. The acoustic signal launched and detected in the waveguide by electrical transducers is accompanied by an electromagnetic wave; the interaction of the two signals, easily enhanced by the open structure of the sensor, creates interference patterns in the transfer function of the sensor. The influence of these interferences on the gravimetric sensitivity is presented, whereby the structure of the entire sensor is modelled. We show that electromagnetic interferences generate an error in the experimental value of the sensitivity. This error is different for the open and the closed loop configurations of the sensor. The theoretical approach is completed by the experimentation of an actual Love mode sensor operated under liquid in open loop configuration. The experiment indicates that the interaction depends on the frequency and the mass modifications.Comment: 28 pages, 8 figure

Exchange-based CNOT gates for singlet-triplet qubits with spin orbit interaction

We propose a scheme for implementing the CNOT gate over qubits encoded in a pair of electron spins in a double quantum dot. The scheme is based on exchange and spin orbit interactions and on local gradients in Zeeman fields. We find that the optimal device geometry for this implementation involves effective magnetic fields that are parallel to the symmetry axis of the spin orbit interaction. We show that the switching times for the CNOT gate can be as fast as a few nanoseconds for realistic parameter values in GaAs semiconductors. Guided by recent advances in surface codes, we also consider the perpendicular geometry. In this case, leakage errors due to spin orbit interaction occur but can be suppressed in strong magnetic fields

(Phosphanyl)phosphaketenes as building blocks for novel phosphorus heterocycles.

Although BH3 simply coordinates the endocyclic P of (phospholidino)phosphaketene 1Dipp , the bulkier B(C6F5)3 gives rise to a zwitterionic diphosphirenium, which is a novel type of 2π-electron aromatic system as shown by the calculated NICS values. While the reaction of 1Dipp with Na[PCO(dioxane) x ] is unselective, the same reaction with the sterically bulky (phospholidino)phosphaketene 1Ar** [Ar** = 2,6-bis[di(4-tert-butylphenyl)methyl]-4-methylphenyl selectively affords a sodium bridged dimer containing a hitherto unknown λ3,λ5,λ3-triphosphete core. The latter formally results from "P-" addition to a 1,3-P/C-dipole. Similarly, adamantyl isonitrile adds to 1Dipp giving a 4-membered phosphacycle. In contrast to 1, the phosphaketene derived from the electrophilic diazaphospholidine-4,5-dione is unstable and reacts with a second molecule of Na[PCO(dioxane) x ] to afford a 1,3,4-oxadiphospholonide derivative

Mean-field magnetization relaxation in conducting ferromagnets

Collective ferromagnetic motion in a conducting medium is damped by the transfer of the magnetic moment and energy to the itinerant carriers. We present a calculation of the corresponding magnetization relaxation as a linear-response problem for the carrier dynamics in the effective exchange field of the ferromagnet. In electron systems with little intrinsic spin-orbit interaction, a uniform magnetization motion can be formally eliminated by going into the rotating frame of reference for the spin dynamics. The ferromagnetic damping in this case grows linearly with the spin-flip rate when the latter is smaller than the exchange field and is inversely proportional to the spin-flip rate in the opposite limit. These two regimes are analogous to the "spin-pumping" and the "breathing Fermi-surface" damping mechanisms, respectively. In diluted ferromagnetic semiconductors, the hole-mediated magnetization can be efficiently relaxed to the itinerant-carrier degrees of freedom due to the strong spin-orbit interaction in the valence bands.Comment: 4 pages, 1 figur

PMI: A Delta Psi(m) Independent Pharmacological Regulator of Mitophagy

Mitophagy is central to mitochondrial and cellular homeostasis and operates via the PINK1/Parkin pathway targeting mitochondria devoid of membrane potential (ΔΨm) to autophagosomes. Although mitophagy is recognized as a fundamental cellular process, selective pharmacologic modulators of mitophagy are almost nonexistent. We developed a compound that increases the expression and signaling of the autophagic adaptor molecule P62/SQSTM1 and forces mitochondria into autophagy. The compound, P62-mediated mitophagy inducer (PMI), activates mitophagy without recruiting Parkin or collapsing ΔΨm and retains activity in cells devoid of a fully functional PINK1/Parkin pathway. PMI drives mitochondria to a process of quality control without compromising the bio-energetic competence of the whole network while exposing just those organelles to be recycled. Thus, PMI circumvents the toxicity and some of the nonspecific effects associated with the abrupt dissipation of ΔΨm by ionophores routinely used to induce mitophagy and represents a prototype pharmacological tool to investigate the molecular mechanisms of mitophagy

Delocalization transition for the Google matrix

We study the localization properties of eigenvectors of the Google matrix, generated both from the World Wide Web and from the Albert-Barabasi model of networks. We establish the emergence of a delocalization phase for the PageRank vector when network parameters are changed. In the phase of localized PageRank, a delocalization takes place in the complex plane of eigenvalues of the matrix, leading to delocalized relaxation modes. We argue that the efficiency of information retrieval by Google-type search is strongly affected in the phase of delocalized PageRank.Comment: 4 pages, 5 figures. Research done at http://www.quantware.ups-tlse.fr

Brans-Dicke gravity and the capture of stars by black holes: some asymptotic results

In the context of star capture by a black hole, a new noticeable difference between Brans-Dicke theory and general relativity gravitational radiation is pointed out. This feature stems from the non-stationarity of the black hole state, barring Hawking's theorem.Comment: 4 pages. Submitted to Classical and Quantum Gravit