Granular Response to Impact: Topology of the Force Networks

Impact of an intruder on granular matter leads to formation of mesoscopic force networks seen particularly clearly in the recent experiments carried out with photoelastic particles, e.g., Clark et al., Phys. Rev. Lett., 114 144502 (2015). These force networks are characterized by complex structure and evolve on fast time scales. While it is known that total photoelastic activity in the granular system is correlated with the acceleration of the intruder, it is not known how the structure of the force network evolves during impact, and if there is a dominant features in the networks that can be used to describe intruder's dynamics. Here, we use topological tools, in particular persistent homology, to describe these features. Persistent homology allows quantification of both structure and time evolution of the resulting force networks. We find that there is a clear correlation of the intruder's dynamics and some of the topological measures implemented. This finding allows us to discuss which properties of the force networks are most important when attempting to describe intruder's dynamics. Regarding temporal evolution of the networks, we are able to define the upper bound on the relevant time scale on which the networks evolve

Porous materials show superhydrophobic to superhydrophilic switching

Switching between superhydrophobicity and superhydrophilicity in porous materials was predicted theoretically and demonstrated experimentally with the example of thermally induced contact angle change; tunability of this system was also demonstrated

Hole polaron formation and migration in olivine phosphate materials

By combining first principles calculations and experimental XPS measurements, we investigate the electronic structure of potential Li-ion battery cathode materials LiMPO4 (M=Mn,Fe,Co,Ni) to uncover the underlying mechanisms that determine small hole polaron formation and migration. We show that small hole polaron formation depends on features in the electronic structure near the valence-band maximum and that, calculationally, these features depend on the methodology chosen for dealing with the correlated nature of the transition-metal d-derived states in these systems. Comparison with experiment reveals that a hybrid functional approach is superior to GGA+U in correctly reproducing the XPS spectra. Using this approach we find that LiNiPO4 cannot support small hole polarons, but that the other three compounds can. The migration barrier is determined mainly by the strong or weak bonding nature of the states at the top of the valence band, resulting in a substantially higher barrier for LiMnPO4 than for LiCoPO4 or LiFePO4

A Pathological Study on Arteriosclerosis of Carotid

The studies made by the elders of our department have revealed that the degree of advancement of sclerotic lesions in the arteries which are distributed in various organs and that of aortic sclerosis in the same individual are not necessarily parallel with each other. The same trend between the aorta and the carotid artery has been confirmed by the author\u27s observation in which the degree of advancement of arteriosclerotic lesions was measured by applying the Gore\u27s mathod to the aorta and the Thickening Index to the carotid artery. Particularly, arteriosclerosis of the siphon portion is further advanced in many cases than that of the aorta. The main lesion of the siphon portion is atheromatous lesion being followed by calcic deposit. Calcification may begin as early as at the age of 12 and it often results in calcic tubes. In the sinus portion where frequency of atheromatous lesion is the highest, complicated lesion or occlusion is common among the Occidentals. Contrarily, however, the author\u27s investigation showed a low frequency of ulcer, calcification, thrombosis and complete occlusion. The pattern of an early lesions of arteriosclerosis in the elastic type portion is different from that in the muscular type portion. Changes of the media precede in the former and those of the internal elastic membrane are found in the latter. It is manifest that sclerotic lesions of the carotid artery are fairly different in frequency and character between the Occidentals and the Japanese

Megabits secure key rate quantum key distribution

Quantum cryptography (QC) can provide unconditional secure communication between two authorized parties based on the basic principles of quantum mechanics. However, imperfect practical conditions limit its transmission distance and communication speed. Here we implemented the differential phase shift (DPS) quantum key distribution (QKD) with up-conversion assisted hybrid photon detector (HPD) and achieved 1.3 M bits per second secure key rate over a 10-km fiber, which is tolerant against the photon number splitting (PNS) attack, general collective attacks on individual photons, and any other known sequential unambiguous state discrimination (USD) attacks.Comment: 14 pages, 4 figure