Showing papers by "University of Colorado Colorado Springs published in 1968"

Microwave Oscillator Noise Reduction by a Transmission Stabilizing Cavity

Abstract: The theory of cavity stabilization of a microwave oscillator is reviewed and the appropriate design equations presented. The theory is verified with data taken on three different types of microwave oscillators: 1) a 10-GHz reflex klystron (stabilization factor achieved-22; FM noise reduction-28 dB; typical FM noise level-0.008 Hz in a 1-Hz bandwidth); 2) a 9.7-GHz low-noise two-cavity klystron oscillator (stabilization factor achieved-10; FM noise reduction--21.7 dB; typical FM noise level-0.0007 Hz in a 1-Hz bandwidth); 3) a 10-GHZ avalanche transit time diode oscillator (stabilization factor estimated at 30; FM noise reduction-29.5 dB; typical FM noise level--0.5 Hz in a 1-Hz bandwidth). Stabilization of the avalanche transit time diode oscillator produced a significant reduction in AM noise for modulation frequencies larger than the bandwidth of the stabilizing cavity.

Dc operated positive ion accelerator and neutron generator having an externally available ground potential target

Abstract: Sealed neutron generator containing an isotope of hydrogen having an ion source, an accelerator and a target containing a substance which reacts with impinging ions to produce neutrons maintained at ground potential and located to be available at the exterior of the generator.

Preventive Periodontic Treatment Procedures: Results after one Year

Abstract: Results of the first year of treatment in a study being conducted at the US Air Force Academy, Colorado Springs, Colo are discussed.

The macrophage‐tubercle bacillus relationship and resistance to tuberculosis

Abstract: In most animals, including man, Mycobacterium tuberculosis and the host cell the macrophage exist in an extremely close relationship from the earliest onset of infection until the cure or death.of the animal. Other leukocytes participate in the reaction to the tuberculous infection but to an appreciably lesser degree. For example, polymorphonuclear leukocytes are quite capable of phagocytosis of tubercle bacilli and, as Vorwald’ showed, in the first few hours of experimental infection accumulate at the site of entry of the bacilli in significant numbers. This response is short-lived and within 24 hours, in most animals, the mononuclear phagocyte predominates at the site of initial infection.2 Vorwald’s studies were made after i.v. injection of bacilli and thus would apply only to hematogenous spread in natural infections. Examination of hourly cellular responses after airborne infections would be informative. It also is known that ingested tubercle bacilli inhibit the migration of polymorphonuclear leukocytes3 without otherwise injuring the c e k 4 The inhibition of such migration is in proportion to the virulence of the bacillus or to its “cord” factor.5 After a few days, the microphage does not again significantly participate in the host response to tubercle bacilli except at foci of softening of caseous material or, more commonly, at sites of acute tissue or cellular necrosis. Lymphocytes also appear at the site of most tuberculous infections but reach significant numbers only after two to three weeks. The accumulation of lymphocytes is almost certainly related to the development of cellular hypersensitivity. The relationship to resistance to the tubercle bacillus, if any, is still obscure. Peripheral blood lymphocytosis in human tuberculosis, however, is often associated with clinical improvement and the heaviest accumulation of lymphocytes in the tissues seems to be around those tuberculous foci which are contained rather than spreading, where bacilli are few and where necrosis is not acute. Lymphopenia of the blood and tissues, as induced by experimental total body irradiation, does not seem to reduce resistance to tuberculosis nor do diseases such as lymphatic leukemia, or some types of congenital agammaglobulinemia, predispose to tuberculosis. From onset to termination, however, the macrophage is a vigorous part of the host response to tuberculosis, noted by the monocytosis in the blood, by the continued phagocytosis of the bacilli by this cell, and by the continued formation by this cell of the epithelioid cells as well as giant cells of the tubercle. It may be also of importance to note some human “experiments” to illustrate the macrophage-tubercle bacillus relationship. In those human diseases where antibody production is impaired, bacterial infection is a persistent complication from the earliest stage of the disease until termination, but not infection by Mycobacterium tuberculo.ris. In Hodgkins disease, however, where the reticuloendothelial system (RES) is primarily affected but antibody production is normal, tuberculosis complicated from 15 to 30% of all cases when contact with active tuberculosis was common. It is now well recognized that the Hodgkins patient with an active disease loses both the ability to acquire hypersensitivity as well as previously acquired delayed hvpersensitivity. This does not necessarily indicate interdependence of resistance and hypersensitivity, but does reflect some loss of

Hybrid computer integration of partial differential equations by use of an assumed sum seperation of variables

Abstract: The majority of numerical solution methods for partial differential equations by either analog or digital methods involve some form of finite differences technique, integral transforms, or Monto-Carlo methods. On the other hand, the most common classical analytical approach is based on some form of separation of variables and series expansions. The motivation for the research presented in this paper was to investigate the possibility of using the classical separation of variables approach as a basis for an efficient computational algorithm. The method studied was developed with a hybrid computer implemention in mind due to the ease in on-line operation in engineering design applications although it could be used for digital computation also.