Maxon and roton measurements in nanoconfined 4^4He

We investigate the behavior of the collective excitations of adsorbed $^4$He in an ordered hexagonal mesopore, examining the crossover from a thin film to a confined fluid. Here we present the inelastic scattering results as a function of filling at constant temperature. We find a monotonic transition of the maxon excitation as a function of filling. This has been interpreted as corresponding to an increasing density of the adsorbed helium, which approaches the bulk value as filling increases. The roton minimum exhibits a more complicated behavior that does not monotonically approach bulk values as filling increases. The full pore scattering resembles the bulk liquid accompanied by a layer mode. The maxon and roton scattering, taken together, at intermediate fillings does not correspond to a single bulk liquid dispersion at negative, low, or high pressure.Comment: 9 pages, 10 figure

Reduced Victim Participation: A Misstep by the Extraordinary Chambers in the Courts of Cambodia

The article focuses on the ruling of the Extraordinary Chambers in the Courts of Cambodia (ECCC) which reduces the participation of the victims of the Cambodian conflict in the criminal trial proceedings of their tormentors and former members of the Khmer Rouge. It explores the goals of the ECCC. A brief historical overview of the Khmer Rouge conflict from April 17, 1975 to January 6, 1979, which resulted in the need for an international tribunal, is presented

NMR relaxation in half-integer antiferromagnetic spin chains

Nuclear relaxation in half-integer spin chains at low temperatures (T << J, the antiferromagnetic exchange constant) is dominated by dissipation from a gas of thermally-excited, overdamped, spinons. The universal low temperature dependence of the relaxation rates $1/T_1$ and $1/T_{2G}$ is computed.Comment: 7 pages, 1 uuencoded postscript figure appende

Quantum Critical Scaling in a Moderately Doped Antiferromagnet

Using high temperature expansions for the equal time correlator $S(q)$ and static susceptibility $\chi(q)$ for the t-J model, we present evidence for quantum critical (QC), $z\!=\!1$, behavior at intermediate temperatures in a broad range of $t/J$ ratio, doping, and temperatures. We find that the dynamical susceptibility is very close to the universal scaling function computable for the asymptotic QC regime, and that the dominant energy scale is temperature. Our results are in excellent agreement with measurements of the spin-echo decay rate, $1/T_{\rm 2G}$, in La$_2$CuO$_4$, and provide qualitative understanding of both $1/T_1$ and $1/T_{\rm 2G}$ nuclear relaxation rates in doped cuprates.Comment: 11 pages, REVTeX v3.0, PostScript file for 3 figures is attached, UIUC-P-93-07-068. In this revised version, we calculate the scaling functions and thus present new and more direct evidence in favor of our original conclusion

Performance of alkaline battery cells used in emergency locator transmitters

The characteristics of battery power supplies for emergency locator transmitters (ELT's) were investigated by testing alkaline zinc/manganese dioxide cells of the type typically used in ELT's. Cells from four manufacturers were tested. The cells were subjected to simulated environmental and load conditions representative of those required for survival and operation. Battery cell characteristics that may contribute to ELT malfunctions and limitations were evaluated. Experimental results from the battery cell study are discussed, and an evaluation of ELT performance while operating under a representative worst-case environmental condition is presented

The Momentum Distribution of Liquid 3^3He

We present high-resolution neutron Compton scattering measurements of liquid $^3$He below its renormalized Fermi temperature. Theoretical predictions are in excellent agreement with the experimental data when instrumental resolution and final state effects are accounted for. Our results resolve the long-standing inconsistency between theoretical and experimental estimates of the average atomic kinetic energy.Comment: 5 pages, 4 figure