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Found 377 documents, displaying page 3 of 38

Bistability of a compliant cavity induced by acoustic radiation pressure

Description : We report on the first observation of multiple-order bistability due to acoustic radiation pressure in a compliant acoustic cavity formed between a spherical ultrasonic transducer immersed in water and the free liquid surface located at its focus. The hysteretic behavior of the cavity length, observ...
Repository : HAL - Hyper Article on Line
Language(s) : English

The thermal denaturation of DNA studied with neutron scattering

Description : The melting transition of deoxyribonucleic acid (DNA), whereby the strands of the double helix structure completely separate at a certain temperature, has been characterized using neutron scattering. A Bragg peak from B-form fibre DNA has been measured as a function of temperature, and its widths an...
Repository : HAL - Hyper Article on Line
Language(s) : English

Stress-Driven Phase Transformation and the Roughening of Solid-Solid Interfaces

Description : The application of stress to multiphase solid-liquid systems often results in morphological instabilities. Here we propose a solid-solid phase transformation model for roughening instability in the interface between two porous materials with different porosities under normal compression stresses. Th...
Repository : HAL - Hyper Article on Line
Language(s) : English

Terahertz Radiation Source in Air Based on Bifilamentation of Femtosecond Laser Pulses

Description : A new terahertz (THz) source in air based on the bifilamentation of femtosecond laser pulses is reported. This THz radiation is 1 order of magnitude more intense than the transition-Cherenkov THz emission from femtosecond laser filaments reported recently and shows different angular and polarization...
Repository : HAL - Hyper Article on Line
Language(s) : English

Strong Enhancement of Terahertz Radiation from Laser Filaments in Air by a Static Electric Field

Description : We observe a 3 order of magnitude enhancement of the terahertz energy radiated by a femtosecond pulse undergoing filamentation in air in the presence of a static electric field. Measurements of terahertz pulse duration, spectrum, polarization, and radiation pattern elucidate the physical processes r...
Repository : HAL - Hyper Article on Line
Language(s) : English

Anomalous Angular Dependence of the Dynamic Structure Factor near Bragg Reflections: Graphite

Description : The electron energy-loss function of graphite is studied for momentum transfers q beyond the first Brillouin zone. We find that near Bragg reflections the spectra can change drastically for very small variations in q. The effect is investigated by means of first principle calculations in the random ...
Repository : HAL - Hyper Article on Line
Language(s) : English

Energy Exchange between Femtosecond Laser Filaments in Air

Description : We report on the energy exchange between femtosecond laser filaments in air. A traveling plasma grating formed at the intersection of the filaments is proposed to explain the energy transfer. In this moving plasma grating mediated mechanism the laser energy transfers from the lower frequency pulse t...
Repository : HAL - Hyper Article on Line
Language(s) : English

Rayleigh Scattering and Atomic Dynamics in Dissipative Optical Lattices

Description : We investigate Rayleigh scattering in dissipative optical lattices. In particular, following recent proposals (S.~Guibal {\it et al}, Phys. Rev. Lett. {\bf 78}, 4709 (1997); C.~Jurczak {\it et al}, Phys. Rev. Lett. {\bf 77}, 1727 (1996)), we study whether the Rayleigh resonance originates from the d...
Repository : HAL - Hyper Article on Line
Language(s) : English

Critical Casimir effect and wetting by helium mixtures

Description : We have measured the contact angle of the interface of phase-separated$^{3}$He-$^{4}$He mixtures against a sapphire window. We have foundthat this angle is finite and does not tend to zero when thetemperature approaches $T_t$, the temperature of the tri-criticalpoint. On the contrary, it increases w...
Repository : HAL - Hyper Article on Line
Language(s) : English

Fracture of a viscous liquid

Description : When a viscous liquid hits a pool of liquid of same nature, the impact region is hollowed by the shock. Its bottom becomes extremely sharp if increasing the impact velocity, and we report that the curvature at that place increases exponentially with the flow velocity, in agreement with a theory by J...
Repository : HAL - Hyper Article on Line
Language(s) : English

Found 377 documents, displaying page 3 of 38