The measurement of ionospheric absorption using extraterrestrial radio waves

Introduction: The discovery by Jansky in 1932 of the presence of radio waves incident upon the earth from outer space has led to several new methods of studying the earth's upper atmosphere. This report describes the manner in which these extraterrestrial radio waves may be used to measure the radio absorption characteristics of the ionosphere. It opens with a brief discussion of the theory of ionospheric absorption; this is followed by a description of the basic principles involved in this new technique. Two different types of equipment which may be used for this type of absorption measurement are then discussed. The report concludes with a brief summary of three types of ionospheric absorption phenomena which have been studied at various latitudes with such equipments.Introduction – Section I Summary of Theory of Ionospheric Absorption – Section II Extraterrestrial Radio Waves and Ionospheric Absorption – Section III The Measurement of Ionospheric Absorption Using Extraterrestrial Radio Waves : With a simple receiver ; The continually self-calibrating system ; Some additional points – Section IV Some Experimental Observations of Ionospheric Absorption Using Extraterrestrial Radio Waves – BibliographyYe

Even circuits of prescribed clockwise parity

We show that a graph has an orientation under which every circuit of even length is clockwise odd if and only if the graph contains no subgraph which is, after the contraction of at most one circuit of odd length, an even subdivision of K_{2,3}. In fact we give a more general characterisation of graphs that have an orientation under which every even circuit has a prescribed clockwise parity. This problem was motivated by the study of Pfaffian graphs, which are the graphs that have an orientation under which every alternating circuit is clockwise odd. Their significance is that they are precisely the graphs to which Kasteleyn's powerful method for enumerating perfect matchings may be applied

Experiment Luxembourg

The earlier orbits and ephemerides for the Soviet satellites were not sufficiently accurate to be very useful in making observations in Alaska. Extrapolations from our own observations gave better predictions. This merely pointed out the fact that rough observations of meridian transits at high latitudes will give better values of the inclination of the orbit than precision observations at low latitudes. Hence, it was decided to observe visually the meridian transits estimating the altitude by noting the position with respect to the stars or using crude alidade measurements. The times of the earlier observations were observed on a watch or clock and the clock correction obtained from WWV. Later the times were determined with the aid of stop watches, taking time intervals from WWV signals. This rather meager program of optical observations of the Soviet satellites was undertaken to give supplementary data for use of the radio observations, and particularly to assist in the prediction of position of the satellite so that the 61-foot radar of Stanford Research Institute could be set accurately enough to observe it (the beam width at the half-power points is about 3°). This report contains primarily the visual observations made at the Geophysical Institute by various members of the staff, and a series of observations by Olaf Halverson at Nome, Alaska. In addition there is a short discussion of the geometry of the trajectory, the illumination of a circumpolar satellite, and a note on the evaluation of Brouwer's moment factors.The research reported In this document has been sponsored by the Geophysics Research Directorate of the Air Force Cambridge Research Center* Air Research and Development Command, under Contract AF 19(604)-3880.List of Figures -- Introduction -- Present knowledge of the electron densities and collision frequencies in the D region of the ionosphere. -- The theory of radio wave interaction. -- The outline of the planned experiment. -- Some comments about the planned experiment. Some comments about gyrointeraction. -- Conclusion -- Acknowledgements -- ReferencesYe

An approach to valuing ponds within farming systems for aquaculture

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Task A, Analysis of C-W Data, Final Report

The object of this investigation is to obtain additional information concerning the effects of aurora on high frequency radio signals which is essential to a complete understanding of new modes of propagation that have tactical and strategic applications.Signal Corps Contract No. DA-36-039-SC-71137 Department of the Army Project No. 3-99-03-022 Signal Corps Project No. 182BLIST OF FIGURES -- [SECTION I] PURPOSE -- [SECTION II] ABSTRACT -- [SECTION III] PUBLICATIONS. LECTURES, REPORTS AND CONFERENCES -- [SECTION IV] FACTUAL DATA : 1. Signal Outage Time on Short Paths and Blackouts Compared for Years of High and Low Solar Activity. ; 2. Study of Possible Relations between Transmission over Long Paths and Ionospheric,Magnetic and Solar Phenomena. ; 3. Study of Fluctuation Indices. ; 4. Effects of Ionospheric Absorption and Irregularities on 4 Mc/s Short Path Transmission. ; 5. F2 Region Parameters at College for the Period June 1941 Through December 1956. ; 6. Tables of Monthly Medians Signal Strength June 1949-December 1950 and January 1954-October 1955. -- [SECTION V] OVERALL CONCLUSIONS -- [SECTION VI] RECOMMENDATIONS -- [SECTION VII] PERSONNELYe

THE RELATION OF COAT COLOR TO THE SPONTANEOUS INCIDENCE OF MAMMARY TUMORS IN MICE

1. The material included in this paper consists of F1 and F2 virgin female mice derived from a cross between a strain high in mammary cancer incidence (dilute brown) and one relatively low in incidence of mammary cancer but relatively high in the incidence of various internal tumors (yellow). 2. In the F1 and F2 hybrid generations the yellow animals have a significantly lower incidence of mammary tumors than do the non-yellows. This is the first clear case of a difference in the incidence of spontaneous tumors in mice associated with a color difference. 3. Mammary tumors occur, however, significantly earlier in the yellow mice and are just as malignant as those appearing in the non-yellows. 4. The incidence of tumors other than mammary is not significantly different in the yellow and non-yellow hybrids. Such tumors, however, occur distinctly later in life than do the mammary tumors. This provides additional evidence that, in mice, mammary tumors cannot be considered to be the same biological phenomenon as are other types of tumor. 5. A study of the physiology of reproduction of yellow and non-yellow mice within the yellow stock suggests that the yellows pass through their reproductive cycle earlier than do the non-yellows. The duration of the cycle in the two forms is essentially equal. This fact would satisfactorily explain the earlier incidence of mammary tumors in yellow mice. 6. The lower incidence of mammary tumors in yellows as compared with non-yellows may be at least in part due to the same phenomenon. This would follow because the opportunity for mammary tissue in yellow mice of cancer age to be continuously affected by ovarian secretion would be less than in non-yellows. This would result in a higher percentage of yellows reaching an age at which stimuli from the ovary ceased before the mammary tissue had reached an age at which tumor formation is most frequent. 7. There is some evidence that, in this cross, dilute (dbdb) mice are less apt to form mammary tumors than are intensely pigmented animals. This point, however, needs further investigation before it can be considered to be established. 8. The facts recorded in this paper demonstrate that not all forms of tumor or all colors of mice can be lumped together in studying either the physiology or genetics of spontaneous tumor incidence

The role of dietary polyphenols in the moderation of the inflammatory response in early stage colorectal cancer

Current focus in colorectal cancer management is on reducing overall mortality by increasing the number of early stage cancers diagnosed and treated with curative intent. Despite the success of screening programmes in down-staging colorectal cancer, interval cancer rates are substantial and other strategies are desirable. Sporadic colorectal cancer is largely associated with lifestyle factors including diet. Polyphenols are phytochemicals ingested as part of a normal diet which are abundant in plant foods including fruits/berries and vegetables. These may exert their anti-carcinogenic effects via the modulation of inflammatory pathways. Key signal transduction pathways are fundamental to the association of inflammation and disease progression including those mediated by NF-κB and STAT, PI3K and COX. Our aim was to examine the evidence for the effect of dietary polyphenols intake on tumour and host inflammatory responses to determine if polyphenols may be effective as part of a dietary intervention. There is good epidemiological evidence of a reduction in colorectal cancer risk from case-control and cohort studies assessing polyphenol intake. It would be premature to suggest a major public health intervention to promote their consumption however, dietary change is safe and feasible, emphasising the need for further investigation of polyphenols and colorectal cancer risk

Technology and growth: an overview

Technology ; Economic development