Observation of electron spin resonance of negative ions in liquid helium

Electron spin resonance signals of negative ions in liquid helium were observed. The line width and g-value were measured. Electrons injected into helium by field emission from ferromagnetic tips are shown to be polarized. A new technique for the measurement of electron spin polarization is presented

Studies of nozzle ablative material performance for large solid boosters Final report

Carbon phenolic, graphite phenolic, and silica phenolic nozzle ablative materials performance for large solid propellant rocket booster

Nonlinear microwave response of MgB2

We calculate the intrinsic nonlinear microwave response of the two gap superconductor MgB2 in the clean and dirty limits. Due to the small value of the pi band gap, the nonlinear response at low temperatures is larger than for a single gap Bardeen-Cooper-Schrieffer (BCS) s-wave superconductor with a transition temperature of 40 K. Comparing this result with the intrinsic nonlinear d-wave response of YBa2Cu3O7 (YBCO) we find a comparable response at temperatures around 20 K. Due to its two gap nature, impurity scattering in MgB2 can be used to reduce the nonlinear response if the scattering rate in the pi band is made larger than the one in the sigma band.Comment: 4 pages, 4 figure

¹⁴C dating of modern marine and estuarine shellfish

We measured the ¹⁴C content of 36 living marine molluscs from Tairua Harbour and the rocky coast on the Coromandel Peninsula of New Zealand. We identified species suitable for radiocarbon dating and show that the open marine intertidal zone is enriched in ¹⁴C compared to the open marine subtidal zone or estuary. We also found a uniform ¹⁴C distribution in the Tairua Harbour, by analyzing samples of the estuarine bivalveAustrovenus stutchburyi collected up to 5 km from the harbor entrance

The Italian Response to the Growing U.S. Wine Demand

Americans are learning more about wines and consuming them in increasingly greater quantities. Italian wines have experienced a tremendous growth in their share of the U. S. market during the last decade. This article analyzes the marketing and success of the wines of Italy with the American consumer

China Maritime Report No. 25: More Chinese Ferry Tales: China\u27s Use of Civilian Shipping in Military Activities, 2021-2022

This report provides a comprehensive assessment of Chinese civilian shipping support to the People’s Liberation Army (PLA), examining civil maritime-military activities from October 2021 through September 2022. As of 2022, the PLA and its reserve civilian merchant fleet are still probably unable to provide significant amphibious landing capabilities or the maritime logistics in austere or challenging environments necessary to support a major cross-strait invasion of Taiwan. However, large volume lift exercises conducted in 2022 suggest that the PLA has made significant progress in the use of civilian vessels for the large-scale lift of PLA troops and equipment into undefended ports, a capability that may be leveraged in a military assault on Taiwan. This report also discusses other civil maritime-military activities not previously observed, including the use of civilian vessels and infrastructure to conceal PLA troop movements, operations from austere ports, use of ocean-going vessels to transport PLA forces along inland waterways, and logistics support for China’s South China Sea outposts.https://digital-commons.usnwc.edu/cmsi-maritime-reports/1024/thumbnail.jp

Nodal Quasiparticle Lifetimes in Cuprate Superconductors

A new generation of angular-resolved photoemission spectroscopy (ARPES) measurements on the cuprate superconductors offer the promise of enhanced momentum and energy resolution. In particular, the energy and temperature dependence of the on-shell nodal (k_x=k_y) quasiparticle scattering rate can be studied. In the superconducting state, low temperature transport measurements suggest that one can describe nodal quasiparticles within the framework of a BCS d-wave model by including forward elastic scattering and spin-fluctuation inelastic scattering. Here, using this model, we calculate the temperature and frequency dependence of the on-shell nodal quasiparticle scattering rate in the superconducting state which determines the momentum width of the ARPES momentum distribution curves. For a zero-energy quasiparticle at the nodal momentum k_N, both the elastic and inelastic scattering rate show a sudden decrease as the temperature drops below Tc, reflecting the onset of the gap amplitude. At low temperatures the scattering rate decreases as T^3 and approaches a zero temperature value determined by the elastic impurity scattering. For T>T_c, we find a quasilinear dependence on T. At low reduced temperatures, the elastic scattering rate for the nodal quasiparticles exhibits a quasilinear increase at low energy which arises from elastic scattering processes. The inelastic spin-fluctuation scattering leads to a low energy omega^3 dependence which, for omega>~Delta_0, crosses over to a quasilinear behavior.Comment: 8 pages, 7 figures, minor revision