Apparatus for aiding a pilot in avoiding a midair collision between aircraft

An apparatus for aiding a pilot in avoiding a midair collision between aircraft is described. A protected aircraft carries a transmitter, a transponder, a receiver, and a data processor; and an intruding cooperating aircraft carries a transponder. The transmitter of the protected aircraft continuously transmits a signal to the transponders of all intruding aircraft. The transponder of each of the intruding aircraft adds the altitude of the intruding aircraft to the signal and transmits it back to the receiver of the protected aircraft. The receiver selects only the signal from the most hazardous intruding aircraft and applies it to the data processor. From this selected signal the data processor determines the closing velocity between the protected and intruding aircraft, the range between the two aircraft, their altitude difference and the time to a possible collision

The NASA-Lewis/ERDA solar heating and cooling technology program

Plans by NASA to carry out a major role in a solar heating and cooling program are presented. This role would be to create and test the enabling technology for future solar heating, cooling, and combined heating/cooling systems. The major objectives of the project are to achieve reduction in solar energy system costs, while maintaining adequate performance, reliability, life, and maintenance characteristics. The project approach is discussed, and will be accomplished principally by contract with industry to develop advanced components and subsystems. Advanced hardware will be tested to establish 'technology readiness' both under controlled laboratory conditions and under real sun conditions

Phase modulating with odd and even finite power series of a modulating signal

Method and apparatus is presented for producing a phase-modulated waveform having a high degree of linearity between the modulating signal and the phase of the modulated carrier signal. Two signals representing finite odd and even power series transformations of the modulating signal are produced and multiplied with two quadrature components of the input carrier signal, respectively. One of the multiplied signals is subtracted from the other and the resulting signal is hard-limited to produce a phase-modulated output signal. The means for producing the two signals representing the odd and even power series of the modulating signal includes means for varying the coefficients of the two power series. By means of an existing computer program, the coefficients of the two power series are selected such that there is an extremely high degree of linearity between the modulating signal and the phase of the modulated carrier signal

Wide deviation phase modulator

Modulator produces phase-modulated waveform having high modulating linearity. Technique is inherently wideband with respect to carrier frequency and can operate over decade carrier frequency range without adjustments. Circuit performance is both mathematically predictable and highly reproducible

Cluster Galaxy Evolution from a New Sample of Galaxy Clusters at 0.3 < z < 0.9

(Abridged) We analyze photometry and spectroscopy of a sample of 63 clusters at 0.3<z<0.9 drawn from the Las Campanas Distant Cluster Survey to empirically constrain models of cluster galaxy evolution. Specifically, by combining data on our clusters with those from the literature we parametrize the redshift dependence of 1) M*_I in the observed frame; 2) the V-I color of the E/S0 red sequence in the observed frames; and 3) the I-K' color of the E/S0 red sequence in the observed frame. Using the peak surface brightness of the cluster detection, S, as a proxy for cluster mass, we find no correlation between S and M* or the location of the red envelope in V-I. We suggest that these observations can be explained with a model in which luminous early type galaxies (or more precisely, the progenitors of current day luminous early type galaxies) form the bulk of their stellar populations at high redshift (>~ 5) and in which many of these galaxies, if not all, accrete mass either in the form of evolved stellar populations or gas that causes only a short term episode of star formation at lower redshifts (1.5 < z < 2). Our data are too crude to reach conclusions regarding the evolutionary state of any particular cluster or to investigate whether the morphological evolution of galaxies matches the simple scenario we discuss, but the statistical nature of this study suggests that the observed evolutionary trends are universal in massive clusters.Comment: 35 pages, accepted for publication in Ap

The Shape of Cas A

Based on optical, IR and X-ray studies of Cas A, we propose a geometry for the remnant based on a "jet-induced" scenario with significant systematic departures from axial symmetry. In this model, the main jet axis is oriented in the direction of strong blue-shifted motion at an angle of 110 - 120 degrees East of North and about 40 - 50 degrees to the East of the line of sight. Normal to this axis would be an expanding torus as predicted by jet-induced models. In the proposed geometry, iron-peak elements in the main jet-like flow could appear "beyond" the portions of the remnant rich in silicon by projection effects, not the effect of mixing. In the context of the proposed geometry, the displacement of the compact object from the kinematic center of the remnant at a position angle of ~169 degrees can be accommodated if the motion of the compact object is near to, but slightly off from, the direction of the main "jet" axis by of order 30 degrees. In this model, the classical NE "jet," the SW "counter-jet" and other protrusions, particularly the "hole" in the North, are non-asymmetric flows approximately in the equatorial plane, e.g., out through the perimeter of the expanding torus, rather than being associated with the main jet. We explore the spoke-like flow in the equatorial plane in terms of Rayleigh-Taylor, Richtmyer-Meshkov and Kelvin-Helmholz instabilities and illustrate these instabilities with a jet-induced simulation.Comment: 25 pages, 4 figures. Accepted for publication in the Astrophysical Journa

Spatially Resolved Spectroscopy of the E+A Galaxies in the z=0.32 Cluster AC114

We present spatially resolved intermediate resolution spectroscopy of a sample of twelve E+A galaxies in the z=0.32 rich galaxy cluster AC 114, obtained with the FLAMES multi-integral field unit system on the European Southern Observatory's VLT. Previous integrated spectroscopy of all these galaxies by Couch & Sharples (1987) had shown them to have strong Balmer line absorption and an absence of [OII 3727] emission -- the defining characteristics of the``E+A'' spectral signature, indicative of an abrupt halt to a recent episode of quite vigorous star formation. We have used our spectral data to determine the radial variation in the strength of Hdelta absorption in these galaxies and hence map out the distribution of this recently formed stellar population. Such information provides important clues as to what physical event might have been responsible for this quite dramatic change in star formation activity in these galaxies' recent past. We find a diversity of behaviour amongst these galaxies in terms of the radial variation in Hdelta absorption: Four galaxies show little Hdelta absorption across their entire extent; it would appear they were misidentified as E+A galaxies in the earlier integrated spectroscopic studies. The remainder show strong Hdelta absorption, with a gradient that is either negative (Hdelta equivalent width decreasing with radius), flat, or positive. By comparing with numerical simulations we suggest that the first of these different types of radial behaviour provides evidence for a merger/interaction origin, whereas the latter two types of behaviour are more consistent with the truncation of star formation in normal disk galaxies. It would seem therefore that more than one physical mechanism is responsible for E+A formation in the same environment.Comment: 15 pages, 10 figures, accepted MNRA

Potential formation sites of super star clusters in ultra-luminous infrared galaxies

Recent observational results on high spatial resolution images of ultra-luminous infrared galaxies (ULIGs) have revealed very luminous, young, compact, and heavily obscured super star clusters in their central regions, suggested to be formed by gas-rich major mergers. By using stellar and gaseous numerical simulations of galaxy mergers, we firstly demonstrate that the central regions of ULIGs are the most promising formation sites of super star clusters owing to the rather high gaseous pressure of the interstellar medium. Based on simple analytical arguments, we secondly discuss the possibility that super star clusters in an ULIG can be efficiently transferred into the nuclear region owing to dynamical friction and consequently merge with one another to form a single compact stellar nucleus with a seed massive black hole. We thus suggest that multiple merging between super star clusters formed by nuclear starbursts in the central regions of ULIGs can result in the formation of massive black holes.Comment: 12 pages 4 figures, 2001, accepted by ApJ

Hepatic acute phase response protects the brain from focal inflammation during postnatal window of susceptibility

Perinatal inflammation is known to contribute to neurodevelopmental diseases. Animal models of perinatal inflammation have revealed that the inflammatory response within the brain is age dependent, but the regulators of this variation remain unclear. In the adult, the peripheral acute phase response (APR) is known to be pivotal in the downstream recruitment of leukocytes to the injured brain. The relationship between perinatal brain injury and the APR has not been established. Here, we generated focal inflammation in the brain using interleukin (IL)-1β at postnatal day (P)7, P14, P21 and P56 and studied both the central nervous system (CNS) and hepatic inflammatory responses at 4 h. We found that there is a significant window of susceptibility in mice at P14, when compared to mice at P7, P21 and P56. This was reflected in increased neutrophil recruitment to the CNS, as well as an increase in blood–brain barrier permeability. To investigate phenomena underlying this window of susceptibility, we performed a dose response of IL-1β. Whilst induction of endogenous IL-1β or intercellular adhesion molecule (ICAM)-1 in the brain and induction of a hepatic APR were dose dependent, the recruitment of neutrophils and associated blood–brain barrier breakdown was inversely proportional. Furthermore, in contrast to adult animals, an additional peripheral challenge (intravenous IL-1β) reduced the degree of CNS inflammation, rather than exacerbating it. Together these results suggest a unique window of susceptibility to CNS injury, meaning that suppressing systemic inflammation after brain injury may exacerbate the damage caused, in an age-dependent manner

An Investigation into the Beneficial Effects of Intentionally Exposing Oysters to Air During Their Normal Growing Season

This report describes a field experiment which was primarily intended to quantify the beneficial effects of intentionally exposing oysters to air during their growing period. Test samples were submerged in the water at different depths and the normal tidal activity uncovered the samples for differing percentages of the tide cycle. The amount of time each sample was in air was monitored by a specially designed electronic instrument and logged. The logged data was processed into graphical data showing the growth rate of the test subjects with respect to exposure. The occurrence of Polydora was also monitored during periodic inspections and correlated with the amount of air exposure. A secondary objective of the experiment was to evaluate external shell fowling