The Management of Gravitational Ulcer

1. The magnitude of the problem of gravitational ulcer is indicated. 2. A brief historical review of treatment methods is presented. 3. The normal venous circulation of the lower limb is described and the conditions which may lead to venous stasis reviewed. 4. A scheme of management based on attempts to restore the disordered haemodynamics is described and the technical considerations discussed. 5. A practical method of locating incompetent communicating veins is described. 6. Methods designed to assess the state of efficiency of the deep veins are described: no clinical or venographic test is accurate enough for practical use. 7. A follow up study of cases of puerperal white leg is presented. 8. A scheme of treatment is outlined and the results of its application to a series of 284 consecutive cases of gravitational ulcer presented. 9. A discussion of the views of others on various aspects of the problem is presented and the following conclusions noted: (1) Gravitational ulcer does not result from the presence of varicose veins alone, a phlebitic factor is a necessary precursor. (2) Gravitational ulcer may occur in the absence of superficial varices. (3) Superficial varicose veins never represent a useful collateral circulation after deep thrombosis. Indeed, in the majority of cases the varices precede the deep thrombosis. The elimination of reflux into and stasis in such superficial varices is always beneficial to the total venous economy of the limb. (4) Continued elastic support is essential to reduce the risk of recurrence from the continuing effects of deep vein insufficiency. (5) Skin grafting directly on to muscle or periosteum is a useful procedure in resistant cases. 10. The procedure of deep vein ligation is discussed and five cases briefly presented

Conceptual analysis of a lunar base transportation system

Important to the planning for a lunar base is the development of transportation requirements for the establishment and maintenance of that base. This was accomplished as part of a lunar base systems assessment study conducted by the NASA Langley Research Center in conjunction with the NASA Johnson Space Center. Lunar base parameters are presented using a baseline lunar facility concept and timeline of developmental phases. Masses for habitation and scientific modules, power systems, life support systems, and thermal control systems were generated, assuming space station technology as a starting point. The masses were manifested by grouping various systems into cargo missions and interspersing manned flights consistent with construction and base maintenance timelines. A computer program that sizes the orbital transfer vehicles (OTV's), lunar landers, lunar ascenders, and the manned capsules was developed. This program consists of an interative technique to solve the rocket equation successively for each velocity correction (delta V) in a mission. The delta V values reflect integrated trajectory values and include gravity losses. As the program computed fuel masses, it matched structural masses from General Dynamics' modular space-based OTV design. Variables in the study included the operation mode (i.e., expendable vs. reusable and single-stage vs. two-stage OTV's), cryogenic specific impulse, reflecting different levels of engine technology, and aerobraking vs. all-propulsive return to Earth orbit. The use of lunar-derived oxygen was also examined for its general impact. For each combination of factors, the low-Earth orbit (LEO) stack masses and Earth-to-orbit (ETO) lift requirements are summarized by individual mission and totaled for the developmental phase. In addition to these discrete data, trends in the variation of study parameters are presented

Searching for Earth-mass planets around α\alpha Centauri: precise radial velocities from contaminated spectra

This work is part of an ongoing project which aims to detect terrestrial planets in our neighbouring star system $\alpha$ Centauri using the Doppler method. Owing to the small angular separation between the two components of the $\alpha$ Cen AB binary system, the observations will to some extent be contaminated with light coming from the other star. We are accurately determining the amount of contamination for every observation by measuring the relative strengths of the H-$\alpha$ and NaD lines. Furthermore, we have developed a modified version of a well established Doppler code that is modelling the observations using two stellar templates simultaneously. With this method we can significantly reduce the scatter of the radial velocity measurements due to spectral cross-contamination and hence increase our chances of detecting the tiny signature caused by potential Earth-mass planets. After correcting for the contamination we achieve radial velocity precision of $\sim 2.5\,\mathrm{m\,s^{-1}}$ for a given night of observations. We have also applied this new Doppler code to four southern double-lined spectroscopic binary systems (HR159, HR913, HR7578, HD181958) and have successfully recovered radial velocities for both components simultaneously.Comment: accepted for publication in the International Journal of Astrobiology (published by Cambridge University Press); will appear in a revised form, subsequent to editorial input by Cambridge University Pres

Color Image Processing and Object Tracking System

This report describes a personal computer based system for automatic and semiautomatic tracking of objects on film or video tape, developed to meet the needs of the Microgravity Combustion and Fluids Science Research Programs at the NASA Lewis Research Center. The system consists of individual hardware components working under computer control to achieve a high degree of automation. The most important hardware components include 16-mm and 35-mm film transports, a high resolution digital camera mounted on a x-y-z micro-positioning stage, an S-VHS tapedeck, an Hi8 tapedeck, video laserdisk, and a framegrabber. All of the image input devices are remotely controlled by a computer. Software was developed to integrate the overall operation of the system including device frame incrementation, grabbing of image frames, image processing of the object's neighborhood, locating the position of the object being tracked, and storing the coordinates in a file. This process is performed repeatedly until the last frame is reached. Several different tracking methods are supported. To illustrate the process, two representative applications of the system are described. These applications represent typical uses of the system and include tracking the propagation of a flame front and tracking the movement of a liquid-gas interface with extremely poor visibility

Differential Susceptibility of Japanese Beetle, Oriental Beetle, and European Chafer (Coleoptera: Scarabaeidae) Larvae to Five Soil Insecticides

Efficacy of bendiocarb, chlorpyrifos, diazinon, ethoprop, and isofenphos was evaluated against last-instar larvae of European chafer, Rhizotrogus majalis (Razoumowsky), Japanese beetle, Popillia japonica Newman, and Oriental beetle, Anomala orientalis Waterhouse, by incorporating insecticides into soil at one-half New York State recommended rates in a laboratory bioassay. Mortality was assessed at 1, 2, 3, 4, and 5 wk. The experiment was repeated three times with white grubs collected at different times and from different locations in New York. White grub species differed significantly in their response to some of the insecticides; European chafer was generally least susceptible. Diazinon provided high mortality of Oriental beetle and European chafer grubs but very low mortality of Japanese beetles. Isofenphos provided generally low mortality of all three grub species, although the levels of mortality varied among species. Ethoprop provided uniform mortality of all three grub species. Results of these studies indicate the need to develop species-specific insecticide recommendations for the white grub complex

A comparison of blade tip timing data analysis methods

The experimental determination of the vibration characteristics of rotating engine blades is very important for fatigue failure considerations. One of the most promising techniques for measuring the frequency of blade vibrations is blade tip timing. In this paper, three vibration analysis methods were specifically formulated and applied to the tip timing problem for the first time, using data obtained from a simple mathematical blade tip timing simulation. The results from the methods were compared statistically in order to determine which of the techniques is more suitable. One of the methods, the global autoregressive instrumental variables approach, produced satisfactory results at realistic noise levels. However, all of the techniques produced biased results under certain circumstances