Maxwell-Boltzmann Distribution of M 3+-F− Interstitial Pairs in Fluorite-Type Lattices

Maxwell-Boltzmann distribution curves for M3+-F− interstitials in fluorite-type lattices have been calculated and compared with spectroscopic data. The dominant sites, in the order of their relative importance for low concentrations and T\u3c700 K, are the C4v(1, 0, 0), Cs(2, 1, 0), C3v(1, 1, 1), Cs(1, 2, 2), Cs(1, 1, 3), and Cs(2, 3, 0) sites. The dominant presence of the third-nearest-neighbor monoclinic Cs(2, 1, 0) pair, which has not been reported previously, is predicted by our calculations. In view of this result, the electron spin resonance data on U3+ in CaF2 reported by Mahlab, Volterra, Low, and Yariv, which these authors interpreted in terms of the fifth-nearest-neighbor site, have been shown to arise actually from the prominent presence of the third-nearest-neighbor Cs(2, 1, 0) site

Quantum Impurities and the Neutron Resonance Peak in YBa2Cu3O7{\bf YBa_2 Cu_3 O_7}: Ni versus Zn

The influence of magnetic (S=1) and nonmagnetic (S=0) impurities on the spin dynamics of an optimally doped high temperature superconductor is compared in two samples with almost identical superconducting transition temperatures: YBa$_2$(Cu$_{0.97}$Ni$_{0.03}$)$_3$O$_7$ (T$_c$=80 K) and YBa$_2$(Cu$_{0.99}$Zn$_{0.01}$)$_3$O$_7$ (T$_c$=78 K). In the Ni-substituted system, the magnetic resonance peak (which is observed at E$_r \simeq$40 meV in the pure system) shifts to lower energy with a preserved E$_r$/T$_c$ ratio while the shift is much smaller upon Zn substitution. By contrast Zn, but not Ni, restores significant spin fluctuations around 40 meV in the normal state. These observations are discussed in the light of models proposed for the magnetic resonance peak.Comment: 3 figures, submitted to PR

Investigating the Effect of Stratospheric Radiation on Seed Germination and Growth

Three seed types: bean (Phaseolus vulgaris), corn (Zea mays) and radish (Raphanus sativus) were flown in a high altitude weather balloon into the mid-stratosphere to investigate the effects of high altitude radiation on germination success and seedling growth. After recovering and planting the seeds, the bean seeds showed lower germination success with exposure to high altitude radiation, and consequently stunted seedling growth. Cord and radish seeds experienced a statistically significant positive effect on germination success form radiation exposure compared to control seeds, but negative effect on seedling growth. Overall, the field experiments presented here support laboratory studies that show radiation exposure on vegetable seeds has a mixed effect on the germination success and negative effect on seedling growth on investigated seed types

Improving Money’s Worth Ratio Calculations: The Case of Singapore’s Pension Annuities

This paper contributes to a better understanding of the risks involved in a life annuity investment. We study the full distribution of weighted annuity benefits and quantify risk measures such as dispersion and skewness, thereby extending the usefulness of the popular money’s worth valuation framework for life annuities. Using data from pension annuities in Singapore, we also introduce several risk measures that might appeal to less financially sophisticated retirees. A more detailed and accurate picture of the risk of investing in life annuities emerges, enabling prospective annuitants to differentiate among products that may appear seemingly uniform in terms of money’s worth, but vary widely in terms of their risk attributes

High energy spin excitations in YBa_2 Cu_3 O_{6.5}

Inelastic neutron scattering has been used to obtain a comprehensive description of the absolute dynamical spin susceptibility $\chi'' (q,\omega)$ of the underdoped superconducting cuprate YBa_2 Cu_3 O_{6.5} ($T_c = 52 K$) over a wide range of energies and temperatures ($2 meV \leq \hbar \omega \leq 120 meV$ and $5K \leq T \leq 200K$). Spin excitations of two different symmetries (even and odd under exchange of two adjacent CuO_2 layers) are observed which, surprisingly, are characterized by different temperature dependences. The excitations show dispersive behavior at high energies.Comment: 15 pages, 5 figure

The 1909 Taipei earthquake—implication for seismic hazard in Taipei

The 1909 April 14 Taiwan earthquake caused significant damage in Taipei. Most of the information on this earthquake available until now is from the written reports on its macro-seismic effects and from seismic station bulletins. In view of the importance of this event for assessing the shaking hazard in the present-day Taipei, we collected historical seismograms and station bulletins of this event and investigated them in conjunction with other seismological data. We compared the observed seismograms with those from recent earthquakes in similar tectonic environments to characterize the 1909 earthquake. Despite the inevitably large uncertainties associated with old data, we conclude that the 1909 Taipei earthquake is a relatively deep (50–100 km) intraplate earthquake that occurred within the subducting Philippine Sea Plate beneath Taipei with an estimated M_W of 7 ± 0.3. Some intraplate events elsewhere in the world are enriched in high-frequency energy and the resulting ground motions can be very strong. Thus, despite its relatively large depth and a moderately large magnitude, it would be prudent to review the safety of the existing structures in Taipei against large intraplate earthquakes like the 1909 Taipei earthquake

Are Asians comfortable with discussing death in health valuation studies? A study in multi-ethnic Singapore

BACKGROUND To characterize ease in discussing death (EID) and its influence on health valuation in a multi-ethnic Asian population and to determine the acceptability of various descriptors of death and "pits"/"all-worst" in health valuation. METHODS In-depth interviews (English or mother-tongue) among adult Chinese, Malay and Indian Singaporeans selected to represent both genders and a wide range of ages/educational levels. Subjects rated using 0–10 visual analogue scales (VAS): (1) EID, (2) acceptability of 8 descriptors for death, and (3) appropriateness of "pits" and "all-worst" as descriptors for the worst possible health state. Subjects also valued 3 health states using VAS followed by time trade-off (TTO). The influence of sociocultural variables on EID and these descriptors was studied using univariable analyses and multiple linear regression (MLR). The influence of EID on VAS/TTO utilities with adjustment for sociocultural variables was assessed using MLR. RESULTS Subjects (n = 63, 35% Chinese, 32% Malay, median age 44 years) were generally comfortable with discussing death (median EID: 8.0). Only education significantly influenced EID (p = 0.045). EID correlated weakly with VAS/TTO scores (range: VAS: -0.23 to 0.07; TTO: -0.14 to 0.11). All subjects felt "passed away", "departed" and "deceased" were most acceptable (median acceptability: 8.0) while "sudden death" and "immediate death" were least acceptable (median acceptability: 5.0). Subjects clearly preferred "all-worst" to "pits" (63% vs. 19%, p < 0.001). CONCLUSION Singaporeans were generally comfortable with discussing death and had clear preferences for several descriptors of death and for "all-worst". EID is unlikely to influence health preference measurement in health valuation studies

Canonical Distribution Law and KCl: Sm2+ Fluorescence: The C2v Paradox

A combination of critical experiments has been carried out in order to elucidate the recent conclusions of Bradbury and Wong, who attributed all the dominant KCl: Sm2+ fluorescence lines to the nearest-neighbor C2v(1,1,0)Sm2+−K+ vacancy site. In an extensive investigation into the radiationless quenching, characteristic lifetimes, excitation spectra, and Zeeman polarization of KCl: Sm2+ fluorescence lines, all the prominent lines are unequivocally attributed to a distribution of three different Sm2+ - K+ vacancy sites. In addition, 18 weak lines are shown to originate from dimeric cluster and O2− compensated sites. The paradoxical C2v interpretations of Bradbury and Wong are shown to be based on incorrect premises, inadequate experimentation, and confusion in the identity of samples with different dopant concentrations

Crystalline ionic solutions

Systems of crystalline ionic solutions containing impurity cations and associated compensation defects are described. Interactions between aliovalent ions and compensation defects give rise to configuration partition functions which predict a distribution in ion-defect pair separation distances at low temperatures. At elevated temperatures such ion-defect pairs dissociate, and the concept of pair formation more appropriately gives way to the concept of pair correlation functions. The relative sizes of the aliovalent ion and the host ion which it replaces are seen to exert a pronounced effect on pair distribution. Salient features of the theory are applied to the KCl: Sr2+, NaCl: Mn2+, NaCl: Sr2+, LiCl: Mn2+ and (alkaline-earth halide): (rareearth)3+ systems. While the high-temperature treatment lends itself to comparisons with the Debye-Hückel theory for electrolytes, the low-temperature pair distribution theory is shown to be valid chiefly because of the specific nature of the crystalline ionic solutions