63,857 research outputs found
mRNA of bovine tissue inhibitor of metalloproteinase: Sequence and expression in bovine ovarian tissue
Simulation of associative learning with the replaced elements model
Associative learning theories can be categorised according to whether they treat the representation of stimulus compounds in an elemental or configural manner. Since it is clear that a simple elemental approach to stimulus representation is inadequate there have been several attempts to produce more elaborate elemental models. One recent approach, the Replaced Elements Model (Wagner, 2003), reproduces many results that have until recently been uniquely predicted by Pearce’s Configural Theory (Pearce, 1994). Although it is possible to simulate the Replaced Elements Model using “standard” simulation programs the generation of the correct stimulus representation is complex. The current paper describes a method for simulation of the Replaced Elements Model and presents the results of two example simulations that show differential predictions of Replaced Elements and Pearce’s Configural Theor
AGN Feedback Compared: Jets versus Radiation
Feedback by Active Galactic Nuclei is often divided into quasar and radio
mode, powered by radiation or radio jets, respectively. Both are fundamental in
galaxy evolution, especially in late-type galaxies, as shown by cosmological
simulations and observations of jet-ISM interactions in these systems. We
compare AGN feedback by radiation and by collimated jets through a suite of
simulations, in which a central AGN interacts with a clumpy, fractal galactic
disc. We test AGN of and erg/s, considering jets
perpendicular or parallel to the disc. Mechanical jets drive the more powerful
outflows, exhibiting stronger mass and momentum coupling with the dense gas,
while radiation heats and rarifies the gas more. Radiation and perpendicular
jets evolve to be quite similar in outflow properties and effect on the cold
ISM, while inclined jets interact more efficiently with all the disc gas,
removing the densest in Myr, and thereby reducing the amount of
cold gas available for star formation. All simulations show small-scale inflows
of M/yr, which can easily reach down to the Bondi radius of
the central supermassive black hole (especially for radiation and perpendicular
jets), implying that AGN modulate their own duty cycle in a feedback/feeding
cycle.Comment: 21 pages, 15 figures, 2 table
The effect of elevated temperature exposure on the fracture toughness of solid wood and structural wood composites
This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://www.springer.com/life+sciences/forestry/journal/226.Fracture toughness of wood and wood composites has traditionally been characterized by a stress intensity factor, an initiation strain energy release rate (G[subscript init]) or a total energy to fracture (G[subscript f]). These parameters provide incomplete fracture characterization for these materials because the toughness changes as the crack propagates. Thus for materials such as wood, oriented strand board (OSB), plywood and laminated veneer lumber (LVL), it is essential to characterize the fracture properties during crack propagation by measuring a full crack resistant or R curve. This study used energy methods during crack propagation to measure full R curves and then compared the fracture properties of wood and various wood-based composites such as, OSB, LVL and plywood. The effect of exposure to elevated temperature on fracture properties of these materials was also studied. The steady state energy release rate (G[subscript SS]) of wood was lower than that of wood composites such as LVL, plywood and OSB. The resin in wood composites provides them with a higher fracture toughness compared to solid lumber. Depending upon the internal structure of the material the mode of failure also varied. With exposure to elevated temperatures, G[subscript SS] for all materials decreased while the failure mode remained the same. The scatter associated with conventional bond strength tests, such as internal bond (IB) and bond classification tests, renders any statistical comparison using those tests difficult. In contrast, fracture tests with R curve analysis may provide an improved tool for characterization of bond quality in wood composites
Radiation from a charged particle-in-flight from a laminated medium to vacuum
The radiation from a charged particle-in-flight from a semi-infinite
laminated medium to vacuum and back,- from vacuum to the laminated medium, has
been investigated. Expressions for the spectral-angular distribution of
radiation energy in vacuum (at large distances from the boundary of laminated
medium) were obtained for both the cases with no limitations on the amplitude
and variation profile of the laminated medium permittivity. The results of
appropriate numerical calculations are presented and possible applications of
the obtained results are discussed.Comment: 8 pages, 6 figures, contribution to Proceedings of International
Symposium RREPS-2009, 07-11 September, 2009, Zvenigorod, Russi
Epitaxial growth of deposited amorphous layer by laser annealing
We demonstrate that a single short pulse of laser irradiation of appropriate energy is capable of recrystallizing in open air an amorphous Si layer deposited on a (100) single-crystal substrate into an epitaxial layer. The laser pulse annealing technique is shown to overcome the interfacial oxide obstacle which usually leads to polycrystalline formation in normal thermal annealing
The evidence of quasi-free positronium state in GiPS-AMOC spectra of glycerol
We present the results of processing of Age-Momentum Correlation (AMOC)
spectra that were measured for glycerol by the Gamma-induced positron
spectroscopy (GiPS) facility. Our research has shown that the shape of
experimental s(t) curve cannot be explained without introduction of the
intermediate state of positronium (Ps), called quasi-free Ps. This state yields
the wide Doppler line near zero lifetimes. We discuss the possible properties
of this intermediate Ps state from the viewpoint of developed model. The amount
of annihilation events produced by quasi-free Ps is estimated to be less than
5% of total annihilations. In the proposed model, quasi-free Ps serves as a
precursor for trapped Ps of para- and ortho-states
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