Diffraction of X-Rays in Liquids: Effect of Temperature

Using an x-ray spectrometer similar to that used by G. W. Stewart, experiments are being carried out on the effect of varying temperature on liquid scattering, temperatures varying from room temperature to near the boiling points being used. To date, two liquids, cyclohexane (27°C and 83.5°C) and heptyl (heptylic) acid (28° C and 193° C) have been examined. Results and conclusions are as follows

Simulating Ability: Representing Skills in Games

Throughout the history of games, representing the abilities of the various agents acting on behalf of the players has been a central concern. With increasingly sophisticated games emerging, these simulations have become more realistic, but the underlying mechanisms are still, to a large extent, of an ad hoc nature. This paper proposes using a logistic model from psychometrics as a unified mechanism for task resolution in simulation-oriented games

Io: IUE observations of its atmosphere and the plasma torus

Two of the main components of the atmosphere of Io, neutral oxygen and sulfur, were detected with the IUE. Four observations yield brightnesses that are similar, regardless of whether the upstream or the downstream sides of the torus plasma flow around Io is observed. A simple model requires the emissions to be produced by the interaction of O and S columns in the exospheric range with 2 eV electrons. Cooling of the 5 eV torus electrons is required prior to their interaction with the atmosphere of Io. Inconsistencies in the characteristics of the spectra that cannot be accounted for in this model require further analysis with improved atomic data. The Io plasma torus was monitored with the IUE. The long-term stability of the warm torus is established. The observed brightnesses were analyzed using a model of the torus, and variations of less than 30 percent in the composition are observed, the quantitative results being model dependent

Understanding the Mechanism of Arsenic Mobilisation and Behaviour in Tailings Dams

This study was carried out on leaching of tailings at 30 ᵒC and 40 ᵒC. The mineralogical and chemical composition of the tailings material were determined by Quantitative X-Ray Diffractometry (QXRD) and Scanning Electron Microscopy combined with Energy Dispersive Spectroscopy (SEM-EDAX). The study revealed that the tailings contain sulphides (arsenopyrite and pyrite) which can leach to produce arsenic (As) and other ions in solution. The acid released during leaching depends on the temperature of leaching. More acid was produced at higher temperature (40 ᵒC) than lower temperature (30 ᵒC). It was established that arsenic precipitation from solution was higher at higher temperature (40 ᵒC) than lower temperature (30 ᵒC). Mimicking the study in a typical tailings environment, it could be proposed that As mobilisation will be enhanced at lower temperature (30 ᵒC) than at higher temperature (40 ᵒC). Keywords: Tailings, Leaching, Arsenopyrite, Heavy metals and Temperatur

Can we predict the duration of an interglacial?

Differences in the duration of interglacials have long been apparent in palaeoclimate records of the Late and Middle Pleistocene. However, a systematic evaluation of such differences has been hampered by the lack of a metric that can be applied consistently through time and by difficulties in separating the local from the global component in various proxies. This, in turn, means that a theoretical framework with predictive power for interglacial duration has remained elusive. Here we propose that the interval between the terminal oscillation of the bipolar seesaw and three thousand years (kyr) before its first major reactivation provides an estimate that approximates the length of the sea-level highstand, a measure of interglacial duration. We apply this concept to interglacials of the last 800 kyr by using a recently-constructed record of interhemispheric variability. The onset of interglacials occurs within 2 kyr of the boreal summer insolation maximum/precession minimum and is consistent with the canonical view of Milankovitch forcing pacing the broad timing of interglacials. Glacial inception always takes place when obliquity is decreasing and never after the obliquity minimum. The phasing of precession and obliquity appears to influence the persistence of interglacial conditions over one or two insolation peaks, leading to shorter (~ 13 kyr) and longer (~ 28 kyr) interglacials. Glacial inception occurs approximately 10 kyr after peak interglacial conditions in temperature and CO2, representing a characteristic timescale of interglacial decline. Second-order differences in duration may be a function of stochasticity in the climate system, or small variations in background climate state and the magnitude of feedbacks and mechanisms contributing to glacial inception, and as such, difficult to predict. On the other hand, the broad duration of an interglacial may be determined by the phasing of astronomical parameters and the history of insolation, rather than the instantaneous forcing strength at inception

The effect of homogenization at different pressures on the physical properties of an ice cream mixture and the resulting ice cream

The data presented in this bulletin were taken from a thesis submitted by the junior author in partial fulfillment of the requirements for the degree of Master of Arts in the Graduate School of the University of Missouri, 1927--P. [3].Includes bibliographical references (page 24)

Paleoclimatic reconstructions in western Canada from boreholetemperature logs: surface air temperature forcing and groundwater flow

International audienceModelling of surface temperature change effect on temperature vs.~depth and temperature-depth logs in Western Canada Sedimentary Basin show that SAT (surface air temperature) forcing is the main driving factor for the underground temperature changes diffusing with depth. It supports the validity of the basic hypothesis of borehole temperature paleoclimatology, namely that the ground surface temperature is systematically coupled with the air temperature in the longer term (decades, centuries). While the highest groundwater recharge rate used in the modelling suggests that for this extreme case some of the observed curvature in the profile, could be due to groundwater flow, it is more likely that the low recharge rates in this semi-arid region would have minimal impact. We conclude that surface temperature forcing is responsible for most of the observed anomalous temperature profile

Nonmigrating semidiurnal tide over the Arctic determined from TIMED Doppler Interferometer wind observations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94847/1/jgrd15899.pd

A Single Circumbinary Disk in the HD 98800 Quadruple System

We present sub-arcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8'' (38 AU), each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 microns show unequivocally that the optically fainter binary, HD 98800B, is the sole source of a comparatively large infrared excess upon which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 microns and longer, peaks at 25 microns, and has a best-fit black-body temperature of 150 K, indicating that most of the dust lies at distances greater than the orbital separation of the spectroscopic binary. We estimate the radial extent of the dust with a disk model that approximates radiation from the spectroscopic binary as a single source of equivalent luminosity. Given the data, the most-likely values of disk properties in the ranges considered are R_in = 5.0 +/- 2.5 AU, DeltaR = 13+/-8 AU, lambda_0 = 2(+4/-1.5) microns, gamma = 0+/-2.5, and sigma_total = 16+/-3 AU^2, where R_in is the inner radius, DeltaR is the radial extent of the disk, lambda_0 is the effective grain size, gamma is the radial power-law exponent of the optical depth, tau, and sigma_total is the total cross-section of the grains. The range of implied disk masses is 0.001--0.1 times that of the moon. These results show that, for a wide range of possible disk properties, a circumbinary disk is far more likely than a narrow ring.Comment: 11 page Latex manuscript with 3 postscript figures. Accepted for publication in Astrophysical Journal Letters. Postscript version of complete paper also available at http://www.hep.upenn.edu/PORG/web/papers/koerner00a.p

Experimental investigations related to ionospheric probing, Part 1 Final report

D region simulation by ultraviolet photoionization of nitric oxid