Evidence of Raleigh-Hertz surface waves and shear stiffness anomaly in granular media

Due to the non-linearity of Hertzian contacts, the speed of sound in granular matter increases with pressure. Under gravity, the non-linear elastic description predicts that acoustic propagation is only possible through surface modes, called Rayleigh-Hertz modes and guided by the index gradient. Here we directly evidence these modes in a controlled laboratory experiment and use them to probe the elastic properties of a granular packing under vanishing confining pressure. The shape and the dispersion relation of both transverse and sagittal modes are compared to the prediction of non-linear elasticity that includes finite size effects. This allows to test the existence of a shear stiffness anomaly close to the jamming transition.Comment: 4 pages 4 figure

Brownell H. Cole of Valley City: Japan, World War II

North Dakota Prisoner of War Report by Brownell Cole (1916-2009) of Valley City. Cole was POW of Japan during the Second World War. 40 page

Lowest Order Constrained Variational Calculation of the Polarized Nuclear Matter with the Modern AV18AV_{18} Potential

The lowest order constrained variational method is applied to calculate the polarized symmetrical nuclear matter properties with the modern $AV_{18}$ potential performing microscopic calculations. Results based on the consideration of magnetic properties show no sign of phase transition to a ferromagnetic phase.Comment: 19 pages, 6 figure

Polarized Neutron Matter: A Lowest Order Constrained Variational Approach

In this paper, we calculate some of the polarized neutron matter properties, using the lowest order constrained variational method with the $AV_{18}$ potential and employing a microscopic point of view. A comparison is also made between our results and those of other many-body techniques.Comment: 23 pages, 8 figure

Anomalies in electrostatic calibrations for the measurement of the Casimir force in a sphere-plane geometry

We have performed precision electrostatic calibrations in the sphere-plane geometry and observed anomalous behavior. Namely, the scaling exponent of the electrostatic signal with distance was found to be smaller than expected on the basis of the pure Coulombian contribution and the residual potential found to be distance dependent. We argue that these findings affect the accuracy of the electrostatic calibrations and invite reanalysis of previous determinations of the Casimir force.Comment: 4 pages, 4 figure

英國底手織機織工

約百年前，大不列典與愛爾蘭的地方曾有一大幫勞動者，在他們的家中用手織機從事于紡織工作。他們的生活情形惡劣，已成為顯明的事實，因此便惹起一般中等階段的注意。為要請求政府解救他們，乃上請願書於議院。一八三四年時，議院指定一個精選的委員會去考慮這件事，并且從有經驗的人士中去蒐集事實，以期草成建議案提交議院解決

Spin polarized neutron matter within the Dirac-Brueckner-Hartree-Fock approach

The relation between energy and density (known as the nuclear equation of state) plays a major role in a variety of nuclear and astrophysical systems. Spin and isospin asymmetries can have a dramatic impact on the equation of state and possibly alter its stability conditions. An example is the possible manifestation of ferromagnetic instabilities, which would indicate the existence, at a certain density, of a spin-polarized state with lower energy than the unpolarized one. This issue is being discussed extensively in the literature and the conclusions are presently very model dependent. We will report and discuss our recent progress in the study of spin-polarized neutron matter. The approach we take is microscopic and relativistic. The calculated neutron matter properties are derived from realistic nucleon-nucleon interactions. This makes it possible to understand the nature of the EOS properties in terms of specific features of the nuclear force model.Comment: 6 pages, 11 figures, revised/extended calculation

Detectability of dissipative motion in quantum vacuum via superradiance

We propose an experiment for generating and detecting vacuum-induced dissipative motion. A high frequency mechanical resonator driven in resonance is expected to dissipate energy in quantum vacuum via photon emission. The photons are stored in a high quality electromagnetic cavity and detected through their interaction with ultracold alkali-metal atoms prepared in an inverted population of hyperfine states. Superradiant amplification of the generated photons results in a detectable radio-frequency signal temporally distinguishable from the expected background.Comment: 4 pages, 2 figure