What is Minimal Model of 3He Adsorbed on Graphite? -Importance of Density Fluctuations in 4/7 Registered Solid -

We show theoretically that the second layer of 3He adsorbed on graphite and solidified at 4/7 of the first-layer density is close to the fluid-solid boundary with substantial density fluctuations on the third layer. The solid shows a translational symmetry breaking as in charge-ordered insulators of electronic systems. We construct a minimal model beyond the multiple-exchange Heisenberg model. An unexpectedly large magnetic field required for the measured saturation of magnetization is well explained by the density fluctuations. The emergence of quantum spin liquid is understood from the same mechanism as in the Hubbard model and in \kappa-(ET)_2Cu_2(CN)_3 near the Mott transitions.Comment: 9 pages, 5 figure

Hidden spin-current conservation in 2d Fermi liquids

We report the existence of regimes of the two dimensional Fermi liquid that show unusual conservation of the spin current and may be tuned by varying some parameter like the density of fermions. We show that for reasonable models of the effective interaction the spin current may be conserved in general in 2d, not only for a particular regime. Low temperature spin waves propagate distinctively in these regimes and entirely new ``spin-acoustic'' modes are predicted for scattering-dominated temperature ranges. These new high-temperature propagating spin waves provide a clear signature for the experimental search of such regimes.Comment: 4 pages, no figures, revised version, accepted for pub. in the PR

Parity violating neutron spin rotation in 4He and H

The weak interaction between nucleons leads to parity violation in various reaction observables. Neutron spin rotation, the rotation of the plane of polarization of a transversely polarized neutron beam passing through unpolarized matter, is an especially clear example of a breakdown in mirror symmetry. The Neutron Spin Rotation (NSR) Collaboration is engaged in an experimental program to observe parity-odd neutron spin rotation. We recently completed the first phase of an experiment to measure parity violating neutron spin rotation in 4He. Our result for the neutron spin rotation angle per unit length in 4He, dφ/dz = (+1.7 ± 9.1(stat.) ± 1.4(sys.)) × 10−7 rad/m, is the most sensitive search for neutron weak optical activity yet performed and represents a significant advance in precision in comparison to past measurements in heavy nuclei. This experiment was performed at the NG-6 slow neutron beamline at the National Institute of Standards and Technology (NIST) Center for Neutron Research. The systematic uncertainty is small enough to proceed to the second phase of the 4He measurement at the new NG-C slow neutron beamline under construction at NIST. The projected intensity of this beam is high enough to see parity odd neutron spin rotation in 4He and to seriously consider a future experiment to measure neutron spin rotation in hydrogen

Quantum Turbulence

The present article reviews the recent developments in the physics of quantum turbulence. Quantum turbulence (QT) was discovered in superfluid $^4$He in the 1950s, and the research has tended toward a new direction since the mid 90s. The similarities and differences between quantum and classical turbulence have become an important area of research. QT is comprised of quantized vortices that are definite topological defects, being expected to yield a model of turbulence that is much simpler than the classical model. The general introduction of the issue and a brief review on classical turbulence are followed by a description of the dynamics of quantized vortices. Then, we discuss the energy spectrum of QT at very low temperatures. At low wavenumbers, the energy is transferred through the Richardson cascade of quantized vortices, and the spectrum obeys the Kolmogorov law, which is the most important statistical law in turbulence; this classical region shows the similarity to conventional turbulence. At higher wavenumbers, the energy is transferred by the Kelvin-wave cascade on each vortex. This quantum regime depends strongly on the nature of each quantized vortex. The possible dissipation mechanism is discussed. Finally, important new experimental studies, which include investigations into temperature-dependent transition to QT, dissipation at very low temperatures, QT created by vibrating structures, and visualization of QT, are reviewed. The present article concludes with a brief look at QT in atomic Bose-Einstein condensates.Comment: 13 pages, 5 figures, Review article to appear in J. Phys. Soc. Jp

Proteostasis Dysregulation in Pancreatic Cancer

The most common form of pancreatic cancer, pancreatic ductal adenocarcinoma (PDAC), has a dismal 5-year survival rate of less than 5%. Radical surgical resection, in combination with adjuvant chemotherapy, provides the best option for long-term patient survival. However, only approximately 20% of patients are resectable at the time of diagnosis, due to locally advanced or metastatic disease. There is an urgent need for the identification of new, specific, and more sensitive biomarkers for diagnosis, prognosis, and prediction to improve the treatment options for pancreatic cancer patients. Dysregulation of proteostasis is linked to many pathophysiological conditions, including various types of cancer. In this review, we report on findings relating to the main cellular protein degradation systems, the ubiquitin-proteasome system (UPS) and autophagy, in pancreatic cancer. The expression of several components of the proteolytic network, including E3 ubiquitinligases and deubiquitinating enzymes, are dysregulated in PDAC, which accounts for approximately 90% of all pancreatic malignancies. In the future, a deeper understanding of the emerging role of proteostasis in pancreatic cancer has the potential to provide clinically relevant biomarkers and new strategies for combinatorial therapeutic options to better help treat the patients.Peer reviewe

Comparative analysis of design options for current leads for Wendelstein 7-X magnet system

The Wendelstein 7-X Project at Max Plank Institute for Plasma Physics, Germany, has a need of analytical and engineering design study for forced flow cooled 18 kA current leads. The main criteria for the current leads' design should be reliability, serviceability, investment and total operating costs. Since the magnet duty cycle has very long idle current periods, two options look worth considering: gas-cooled conventional, current leads properly optimized for the duty cycle to operate in over-current mode (so-called. overloaded leads), and binary current leads with high temperature superconducting part. The options are analyzed in detail and optimized to minimize total operating cost with holding the serviceability in emergency case