21,618 research outputs found
Evaluation of exercise-respiratory system modifications and preliminary respiratory-circulatory system integration scheme
The respiratory control system, functioning as an independent system, is presented with modifications of the exercise subroutine. These modifications illustrate an improved control of ventilation rates and arterial and compartmental gas tensions. A very elementary approach to describing the interactions of the respiratory and circulatory system is presented
Technique for producing bipolar and MOS field effect transistors on a single chip
Several cycles of photoetching, dopant deposition, and drive-in produce selectively-doped regions and semiconductor junctions within a single chip
Conceptual techniques for reducing parasitic current gain of lateral pnp transistors
Two techniques have been conceptually proposed as possible means of reducing parasitic beta in lateral p-n-p transistors. One method uses a degenerate substrate and high concentration P /plus/ guard-ring diffusion, another places the base contact at the center of an annular ring structure
Diffusion technique stabilizes resistor values
Reduction of the contact resistance stabilizes the values, over a broad temperature range, of resistors used in linear integrated circuits. This reduction is accomplished by p-plus diffusion under the alloyed aluminum contacts
Geometrically nonlinear analysis of the Apollo aft heat shield Final report, 1 Apr. 1966 - 15 Dec. 1966
Structural analysis of Apollo aft heat shield under water impact loading condition
A triangular thin shell finite element: Linear analysis
The formulation of the linear stiffness matrix for a doubly-curved triangular thin shell element, using a modified potential energy principle, is described. The strain energy component of the potential energy is expressed in terms of displacements and displacement gradients by use of consistent Koiter strain-displacement equations. The element inplane and normal displacement fields are approximated by complete cubic polynomials. The interelement displacement admissibility conditions are met in the global representation by imposition of constraint conditions on the interelement boundaries; the constraints represent the modification of the potential energy. Errors due to the nonzero strains under rigid body motion are shown to be of small importance for practical grid refinements through performance of extensive comparison analyses
Many-body Rabi oscillations of Rydberg excitation in small mesoscopic samples
We investigate the collective aspects of Rydberg excitation in ultracold
mesoscopic systems. Strong interactions between Rydberg atoms influence the
excitation process and impose correlations between excited atoms. The
manifestations of the collective behavior of Rydberg excitation are the
many-body Rabi oscillations, spatial correlations between atoms as well as the
fluctuations of the number of excited atoms. We study these phenomena in detail
by numerically solving the many-body Schr\"edinger equation.Comment: 8 pages, 5 figure
Nucler star formation in NGC 6240
We have made use of archival HST BVIJH photometry to constrain the nature of
the three discrete sources, A1, A2 and B1, identified in the double nucleus of
NGC 6240. STARBURST99 models have been fitted to the observed colours, under
the assumption, first, that these sources can be treated as star clusters (i.e.
single, instantaneous episodes of star formation), and subsequently as
star-forming regions (i.e. characterised by continuous star formation). For
both scenarios, we estimate ages as young as 4 million years, integrated masses
ranging between 7x10^6 Msun (B1) and 10^9 Msun (A1) and a rate of 1 supernova
per year, which, together with the stellar winds, sustains a galactic wind of
44 Msun/yr. In the case of continuous star formation, a star-formation rate has
been derived for A1 as high as 270 Msun/yr, similar to what is observed for
warm Ultraluminous Infrared Galaxies (ULIRGs) with a double nucleus. The A1
source is characterised by a mass density of about 1200 Msun/pc^3 which
resembles the CO molecular mass density measured in cold ULIRGs and the stellar
density determined in ``elliptical core'' galaxies. This, together with the
recent discovery of a supermassive binary black hole in the double nucleus of
NGC 6240, might indicate that the ongoing merger could shape the galaxy into a
core elliptical.Comment: 14 pages, 5 postscript figures, accepted by A&
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