Cross Psi(B)-energy operator-based signal detection

In this paper, two methods for signal detection and time-delay estimation based on the cross Psi(B)-energy operator are proposed. These methods are well suited for mono-component AM-FM signals. The Psi(B) energy operator measures how much one signal is present in another one. The peak of the Psi(B) operator corresponds to the maximum of interaction between the two signals. Compared to the cross-correlation function, the Psi(B) operator includes temporal information and relative changes of the signal which are reflected in its first and second derivatives. The discrete version of the continuous-time form of the Psi(B) operator, which is used in its implementation, is presented. The methods are illustrated on synthetic and real signals and the results compared to those of the matched filter and the cross correlation. The real signals correspond to impulse responses of buried objects obtained by active sonar in iso-speed single path environments.     

Measurements of inner and outer streaming vortices in a standing waveguide using laser doppler velocimetry

Measurements of the axial streaming velocity are performed by means of laser doppler velocimetry in an experimental apparatus consisting of a waveguide having loudspeakers at each end for high intensity sound levels. Streaming is characterized by an appropriate Reynolds number Re(NL), the case Re(NL)<1 corresponding to the so-called slow streaming and the case Re(NL)>/=1 being referred to as fast streaming. The variation of axial streaming velocity with respect to the transverse coordinate is compared to the available slow streaming theory. Streaming fluid flow is measured both in the core region and in the near wall region. Streaming velocity in the center of the guide agrees reasonably well with the slow streaming theory for small Re(NL) but deviates significantly from such predictions for Re(NL)>20 and its evolution for further increasing Re(NL) is discussed. Then streaming behavior in the near wall region is particularly studied. For Re(NL)<70, two vortices are present across the guide section as predicted by slow streaming theory. Then it appears that, when the Reynolds number is increased, two other vortices become visible in the near wall region. Different stages for the generation and evolution of these inner streaming vortices are presented.     

Thermal optimization of 1.55 μm OP-VECSEL with hybrid metal–metamorphic mirror for single-mode high power operation

We report on the thermal design and the characterization of InP-based 1.55 μm wavelength large diameter (～100 μm) optically pumped vertical external cavity surface emitting lasers (OP-VECSELs). The device is thermally optimized for high power ( > 70 mW) room-temperature (RT) continuous-wave (CW) single-mode operation. Efficient bottom heat dissipation in the 1/2-VCSEL chip is obtained thanks to the use of a hybrid metal– metamorphic GaAs/AlAs mirror integrated to the InP-based active region, and to subsequent soldering on a SiC substrate. A single-mode output power of 77mW is obtained under CW-RT laser operation, limited by the pump power. Moreover thermal simulations and characterizations of the 1/2-VCSEL chip show that even higher power could be obtained at higher pumping levels, using a CVD diamond substrate.     

Creep motion of a granular pile induced by thermal cycling

We report a time-resolved study of the dynamics associated with the slow compaction of a granular column submitted to thermal cycles. The column height displays a complex behavior: for a large amplitude of the temperature cycles, the granular column settles continuously, experiencing a small settling at each cycle. By contrast, for a small-enough amplitude, the column exhibits a discontinuous and intermittent activity: successive collapses are separated by quiescent periods whose duration is exponentially distributed. We then discuss potential mechanisms which would account for both the compaction and the transition at finite amplitude.     

Synthesis and Structure–Activity Relationship Studies of Pyrido [1,2-e]Purine-2,4(1H,3H)-Dione Derivatives Targeting Flavin-Dependent Thymidylate Synthase in Mycobacterium tuberculosis

In 2002, a new class of thymidylate synthase (TS) involved in the de novo synthesis of dTMP named Flavin-Dependent Thymidylate Synthase (FDTS) encoded by the thyX gene was discovered; FDTS is present only in 30% of prokaryote pathogens and not in human pathogens, which makes it an attractive target for the development of new antibacterial agents, especially against multi-resistant pathogens. We report herein the synthesis and structure-activity relationship of a novel series of hitherto unknown pyrido[1,2-e]purine-2,4(1H,3H)-dione analogues. Several synthetics efforts were done to optimize regioselective N¹-alkylation through organopalladium cross-coupling. Modelling of potential hits were performed to generate a model of interaction into the active pocket of FDTS to understand and guide further synthetic modification. All those compounds were evaluated on an in-house in vitro NADPH oxidase assays screening as well as against Mycobacterium tuberculosis ThyX. The highest inhibition was obtained for compound 23a with 84.3% at 200 µM without significant cytotoxicity (CC₅₀ > 100 μM) on PBM cells.     

First Evidence of a Combination of Terpinen-4-ol and α-Terpineol as a Promising Tool against ESKAPE Pathogens

Antimicrobial resistance is a major public health issue raising growing concern in the face of dwindling response options. It is therefore urgent to find new anti-infective molecules enabling us to fight effectively against ever more numerous bacterial infections caused by ever more antibiotic-resistant bacteria. In this quest for new antibacterials, essential oils (or compounds extracted from essential oils) appear to be a promising therapeutic option. In the present work, we investigate the potential antibacterial synergy between a combination of terpinen-4-ol and α-terpineol (10:1) compared to standard tea tree oil. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined. Then, time kill assays, in vitro cytotoxicity and bactericidal activity on latent bacteria (persisters) were investigated. Finally, an in silico study of the pharmacokinetic parameters of α-terpineol was also performed. Altogether, our data demonstrate that the combination of terpinen-4-ol and α-terpineol might be a precious weapon to address ESKAPE pathogens.