A Short Ion Path High Voltage Tube

A vacuum tube for the acceleration of charged particles is described. The total acceleration of the ions takes place in a distance of 18 inches although the total height of the tube is about 14 feet. It has been used at one million volts peak a.c. with target currents of 5 ma of electrons and 0.2 ma of positive ions

Living \u3cem\u3eMore Than\u3c/em\u3e Just Enough for the City: Persistence of High-Quality Vegetation in Natural Areas in an Urban Setting

Urban environments pose special challenges to flora, including altered disturbance regimes, habitat fragmentation, and increased opportunity for invasion by non-native species. In addition, urban natural area represents most people’s contact with nature, given the majority of the world’s population currently live in cities. We used coefficients of conservatism (C-values), a system that ranks species based on perceived fidelity to remnant native plant communities that retain ecological integrity, to quantify habitat quality of 14 sites covering 850 ha within the city of Indianapolis, Indiana, in the Midwestern United States. All sites contained significant natural area and were inventoried via intensive complete censuses throughout one or two growing seasons within the last 15 years. Mean C-values for five sites were high, especially when compared to values reported for the highest quality preserves in central Indiana. However, for most sites the difference in mean C-value with and without non-natives was rather high, meaning that natural quality is likely to have been compromised by the presence of non-natives. Sites receiving the highest levels of stewardship and those with the least public access via trails had the highest mean native C-values. A total of 34 invasive non-native species were found across all 14 sites. Most were woody species. Mean C-value over all sites was significantly negatively correlated with the number of non-natives present, especially those considered invasive. These results demonstrate for the Indianapolis area, and likely other urbanized Midwestern cities, remnant natural areas can retain high ecological value, especially if they receive regular environmental stewardship

Reinforced carbon-carbon oxidation behavior in convective and radiative environments

Reinforced carbon-carbon, which is used as thermal protection on the space shuttle orbiter wing leading edges and nose cap, was tested in both radiant and plasma arcjet heating test facilities. The test series was conducted at varying temperatures and pressures. Samples tested in the plasma arcjet facility had consistently higher mass loss than those samples tested in the radiant facility. A method using the mass loss data is suggested for predicting mission mass loss for specific locations on the Orbiter

Local Chemical Environments and the Phonon Partial Densities of States of 57Fe in 57Fe3Al

Inelastic nuclear resonant scattering spectra were measured on alloys of Fe3Al that were chemically disordered, partially ordered, and D03 ordered. The features in the phonon partial density of states of 57Fe were found to change systematically with chemical short-range order in the alloy. Changes in the phonon partial density of states were modeled successfully by assigning vibrational spectra to 57Fe atoms in different first-nearest-neighbor chemical environments

The Fading of Supernova Remnant Cassiopeia A from 38 MHz to 16.5 GHz from 1949 to 1999 with New Observations at 1405 MHz

We report 1405 MHz measurements of the flux density of the approximately 320 year old supernova remnant Cassiopeia A, relative to the flux density of Cygnus A, made between 1995 and 1999. When compared to measurements made between 1957 and 1976, we find that the rate at which Cassiopeia A has been fading at this and nearby frequencies has changed from approximately 0.9 % yr^-1 in the 1960s to approximately 0.6 - 0.7 % yr^-1 now. Furthermore, we have collected from the literature measurements of this fading rate at lower (38 - 300 MHz) and higher (7.8 - 16.5 GHz) frequencies. We show that the fading rate has dropped by a factor of approximately 3 over the past 50 years at the lower frequencies, while remaining relatively constant at the higher frequencies, which is in agreement with the findings of others. Our findings at 1405 MHz, in conjunction with a measurement of the fading rate at the nearby frequency of 927 MHz by Vinyajkin (1997), show an intermediate behavior at intermediate frequencies. We also find that Cassiopeia A, as of approximately 1990, was fading at about the same rate, approximately 0.6 - 0.7 % yr^-1, at all of these frequencies. Future measurements are required to determine whether the fading rate will continue to decrease at the lower frequencies, or whether Cassiopeia A will now fade at a relatively constant rate at all of these frequencies

Letters between W. V. Davis and William Kerr\u27s secretary

Letters concerning a course in carpentry at Utah Agricultural College

Recurrence interval analysis of high-frequency financial returns and its application to risk estimation

We investigate the probability distributions of the recurrence intervals $\tau$ between consecutive 1-min returns above a positive threshold $q>0$ or below a negative threshold $q<0$ of two indices and 20 individual stocks in China's stock market. The distributions of recurrence intervals for positive and negative thresholds are symmetric, and display power-law tails tested by three goodness-of-fit measures including the Kolmogorov-Smirnov (KS) statistic, the weighted KS statistic and the Cram\'er-von Mises criterion. Both long-term and shot-term memory effects are observed in the recurrence intervals for positive and negative thresholds $q$. We further apply the recurrence interval analysis to the risk estimation for the Chinese stock markets based on the probability $W_q(\Delta{t},t)$, Value-at-Risk (VaR) analysis and VaR analysis conditioned on preceding recurrence intervals.Comment: 17 pages, 10 figures, 1 tabl

Plasma arginine vasopressin concentrations in epileptics under monotherapy

Plasma arginine vasopressin concentrations were determined by radio-immunoassay in 112 adult epileptics who were taking carbamazepine, phenytoin, primidone, or sodium valproate in long-term monotherapy, and in 19 controls. No significant difference was found between the groups, but some epileptics taking carbamazepine and primidone showed low values. Serum concentrations of carbamazepine did not correlate with the concentrations of plasma arginine vasopressin. In conclusion, there was no evidence of a stimulating effect of chronic carbamazepine medication or a special inhibiting effect of phenytoin on the release of vasopressin arginine from the posterior pituitary