32,907 research outputs found
A new method for the determination of thin film porosity
Internal reflection spectroscopy may be used to determine presence of water in thin film pores. Presence of water in such pores is function of relative humidity and pore size. Thus, one can determine pore size by controlling humidity. Fluids with surface tension different from that of water can be used to detect pores
Dosimetry for radiobiological studies of the human hematopoietic system
A system for estimating individual bone marrow doses in therapeutic radiation exposures of leukemia patients was studied. These measurements are used to make dose response correlations and to study the effect of dose protraction on peripheral blood cell levels. Three irradiators designed to produce a uniform field of high energy gamma radiation for total body exposures of large animals and man are also used for radiobiological studies
Aphidophagous Coccinellids in Alfalfa, Small Grains, and Maize in Eastern South Dakota
In a 13-year study of aphidophagous coccinellids associated with alfalfa (Medicago sativa), maize (Zea mays), and small grain crops in eastern South Dakota, the following species were consistently associated with the crops: Hippodamia convergens, H. tredecimpunctata tibialis, H. parenthesis, Coleomegilla maculata lengi, Coccinella transversoguttata richardsoni, Cycloneda munda, and Adalia bipunctata. All species except A. bipunctata were associated with each of the three crops, while A. bipunctata occurred only in maize. Relative abundances of each species varied among crops and among years. Although only seven species were associated with the crops, additional species were captured on sticky traps stationed adjacent to sampled fields. The species diversity of immature coccinellids did not differ among crops but did differ among years. The diversity of adults differed among crops and years. The site from which samples were taken had no influence on the diversity of immatures or adults. Species relative abundances in alfalfa and small grains were more similar to each other than they were to relative abundances in maize
Wind tunnel tests of a zero length, slotted-lip engine air inlet for a fixed nacelle V/STOL aircraft
Zero length, slotted lip inlet performance and associated fan blade stresses were determined during model tests using a 20 inch diameter fan simulator in the NASA-LeRC 9 by 15 foot low speed wind tunnel. The model configuration variables consisted of inlet contraction ratio, slot width, circumferential extent of slot fillers, and length of a constant area section between the inlet throat and fan face. The inlet performance was dependent on slot gap width and relatively independent of inlet throat/fan face spacer length and slot flow blockage created by 90 degree slot fillers. Optimum performance was obtained at a slot gap width of 0.36 inch. The zero length, slotted lip inlet satisfied all critical low speed inlet operating requirements for fixed horizontal nacelles subsonic V/STOL aircraft
Stress corrosion cracking of titanium alloys: Studies of cracks in thin specimens; SCC of Ti-6Al-4V in chloride, iodide and fluoride solutions; stress corrosion cracking in molten salts; electrochemistry of freshly generated titanium surfaces
Electrochemistry of freshly generated titanium surfaces and stress corrosion cracking in aqueous solutions and in molten salt
Fundamental investigation of stress corrosion cracking
Two principle areas studied were stress corrosion crack growth rates of a titanium alloy in liquid environments containing halide ions and pitting corrosion of titanium in bromide solutions. Two initial assumptions were made, that the rate of propagation was controlled by a macroscopic solution parameter and that this parameter was viscosity. A series of solutions were prepared using lithium chloride as the solute and water, methanol, glycerin, formic acid, acetone, dimethyl sulphoxide, etc. As solvents, these solutions were prepared with a 5:1 solvent-solute ratio. Viscosity was varied by changing the temperature and it was found: (1) In all solvents the velocity of cracking was proportional to the reciprocal of the viscosity. (2) Each solvent gave a separate relationship, (3) The temperature dependence and numerical values for the apparent activation energy of cracking and viscosity were the same
Generalising the logistic map through the -product
We investigate a generalisation of the logistic map as (, )
where stands for a generalisation of the ordinary product, known as
-product [Borges, E.P. Physica A {\bf 340}, 95 (2004)]. The usual product,
and consequently the usual logistic map, is recovered in the limit ,
The tent map is also a particular case for . The
generalisation of this (and others) algebraic operator has been widely used
within nonextensive statistical mechanics context (see C. Tsallis, {\em
Introduction to Nonextensive Statistical Mechanics}, Springer, NY, 2009). We
focus the analysis for at the edge of chaos, particularly at the
first critical point , that depends on the value of . Bifurcation
diagrams, sensitivity to initial conditions, fractal dimension and rate of
entropy growth are evaluated at , and connections with
nonextensive statistical mechanics are explored.Comment: 12 pages, 23 figures, Dynamics Days South America. To be published in
Journal of Physics: Conference Series (JPCS - IOP
Longitudinal response functions of 3H and 3He
Trinucleon longitudinal response functions R_L(q,omega) are calculated for q
values up to 500 MeV/c. These are the first calculations beyond the threshold
region in which both three-nucleon (3N) and Coulomb forces are fully included.
We employ two realistic NN potentials (configuration space BonnA, AV18) and two
3N potentials (UrbanaIX, Tucson-Melbourne). Complete final state interactions
are taken into account via the Lorentz integral transform technique. We study
relativistic corrections arising from first order corrections to the nuclear
charge operator. In addition the reference frame dependence due to our
non-relativistic framework is investigated. For q less equal 350 MeV/c we find
a 3N force effect between 5 and 15 %, while the dependence on other theoretical
ingredients is small. At q greater equal 400 MeV/c relativistic corrections to
the charge operator and effects of frame dependence, especially for large
omega, become more important. In comparison with experimental data there is
generally a rather good agreement. Exceptions are the responses at excitation
energies close to threshold, where there exists a large discrepancy with
experiment at higher q. Concerning the effect of 3N forces there are a few
cases, in particular for the R_L of 3He, where one finds a much improved
agreement with experiment if 3N forces are included.Comment: 26 pages, 9 figure
- …