Southern Hemisphere meteor rates Final report

Diurnal variations of Southern Hemisphere meteor rat

Mass Loss Due to Sputtering and Thermal Processes in Meteoroid Ablation

Conventional meteoroid theory assumes that the dominant mode of ablation is by evaporation following intense heating during atmospheric flight. In this paper we consider the question of whether sputtering may provide an alternative disintegration process of some importance.For meteoroids in the mass range from 10^-3 to 10^-13 kg and covering a meteor velocity range from 11 to 71 km/s, we numerically modeled both thermal ablation and sputtering ablation during atmospheric flight. We considered three meteoroid models believed to be representative of asteroidal (3300 kg m^-3 mass density), cometary (1000 kg m^-3) and porous cometary (300 kg m^-3) meteoroid structures. Atmospheric profiles which considered the molecular compositions at different heights were used in the sputtering calculations. We find that while in many cases (particularly at low velocities and for relatively large meteoroid masses) sputtering contributes only a small amount of mass loss during atmospheric flight, in some cases sputtering is very important. For example, a 10^-10 kg porous meteoroid at 40 km/s will lose nearly 51% of its mass by sputtering, while a 10^-13 kg asteroidal meteoroid at 60 km/s will lose nearly 83% of its mass by sputtering. We argue that sputtering may explain the light production observed at very great heights in some Leonid meteors. The impact of this work will be most dramatic for very small meteoroids such as those observed with large aperture radars.Comment: in pdf form, 48 pgs incl figures and table

A study of the binary system, aniline-o-chlorophenol

When two organic liquids are missed the resulting physical properties of the solution nearly always differ from those calculated on the assumption of an additive relationship. The extent of these deviations varies widely with the nature of the liquids chosen, and where there is a large evolution of heat it is considered that molecular compound formation has occurred. Some binary mixtures of phenols with aromatic bases have been investigated by Bramley (1) and are of this type. Macleod (2) has derived an expression for the viscosity of a binary mixture which has undergone volume change and compound formation. The expression contains the factor Ma/Mc, where Mc is the calculated mean molecular weight of the constituents and Ma is the actual mean molecular weight after mixing. By using Bramley’s density and viscosity results Macleod has evaluated Ma/Mc for the binary system aniline – o-chlorophenol. Bramley has determined the freezing-poing curve for this system, showing the existence of an equimolecular compound, and so Macleod has been able to calculate the number of double molecules required to give the ratio Ma/Mc. He has also calculated the equilibrium constants for a number of temperatures; using the amount of compound formation found from the viscosity formula at the equimolecular percentage and assuming the law of mass action to hold. The object of this work is a determination of the heats of reaction of this mixture at several temperatures, enabling the equilibrium constants to be calculated directly. The comparison of these constants with those obtained by Macleod from viscosity data should afford a check on his equation for the viscosity of binary mixtures. The formula for the calculation of the heat of reaction from the temperature rise necessitated knowledge of the specific heat of the mixture. It was therefore necessary to determine the specific heat curves at definite temperatures. These results, besides being necessary for the heats of reaction, also enables the partial molal heat capacities to be calculated. Further, so investigation of the literature shows that there are at present several different theories as to the nature of the link in this of compound. As the various theories depend partly upon the refractive index, it was decided to measure this property for the mixture. This work, together with refractive index measurements in hydrated mixtures, forms the second part of the thesis

Architectural Design: Charlton Pools Competition Project (1998)

Exhibited in Marvels: Architecture Unbuil

In vivo confocal microscopy of corneal nerves: an ocular biomarker for peripheral and cardiac autonomic neuropathy

PURPOSE. We investigated the relationship between corneal subbasal nerve (SBN) plexus density, corneal sensitivity, and peripheral and cardiac autonomic neuropathy in patients with type 1 diabetes mellitus. METHODS. We recruited 53 patients with type 1 diabetes mellitus and 40 normal control participants. Corneal in vivo confocal microscopy (IVCM) and sensitivity testing were performed on one eye of each subject. Autonomic function testing was done and an overall neuropathy score obtained from a combination of a symptomatic neuropathy score, clinical assessment, biothesiometry, and nerve conduction tests. RESULTS. The corneal SBN density (P < 0.001) and corneal sensitivity (P < 0.001) were significantly lower in subjects with diabetes compared to controls. A modest negative correlation between total neuropathy score and SBN density was observed (r ¼ À0.33, P ¼ 0.01). A negative correlation between corneal sensitivity and expiration/inspiration component of the autonomic nerve analysis (ANS-EI) also was noted (r ¼ À0.36, P ¼ 0.008). Corneal SBN density was abnormal in 50% of diabetic subjects classified as ''Normal'' by the clinical and electrophysiological based tests of total neuropathy score. CONCLUSIONS. The correlation of corneal SBN density with total neuropathy score suggests that reduced corneal nerve density reflects peripheral neuropathy in diabetes. Corneal SBN changes precede other clinical and electrophysiology tests of neuropathy supporting a possible role for corneal IVCM and corneal sensitivity testing as surrogate markers in the assessment of diabetic peripheral and cardiac autonomic neuropathy