24,879 research outputs found
Chaos and a Resonance Mechanism for Structure Formation in Inflationary Models
We exhibit a resonance mechanism of amplification of density perturbations in
inflationary mo-dels, using a minimal set of ingredients (an effective
cosmological constant, a scalar field minimally coupled to the gravitational
field and matter), common to most models in the literature of inflation. This
mechanism is based on the structure of homoclinic cylinders, emanating from an
unstable periodic orbit in the neighborhood of a saddle-center critical point,
present in the phase space of the model. The cylindrical structure induces
oscillatory motions of the scales of the universe whenever the orbit visits the
neighborhood of the saddle-center, before the universe enters a period of
exponential expansion. The oscillations of the scale functions produce, by a
resonance mechanism, the amplification of a selected wave number spectrum of
density perturbations, and can explain the hierarchy of scales observed in the
actual universe. The transversal crossings of the homoclinic cylinders induce
chaos in the dynamics of the model, a fact intimately connected to the
resonance mechanism occuring immediately before the exit to inflation.Comment: 4 pages. This essay received an Honorable Mention from the Gravity
Research Foundation, 1998-Ed. To appear in Mod. Phys. Lett.
The mechanism for the electrooxidation of procarbazine pharmaceutical preparation in alkaline media and its mathematical description
The mechanism for the electrooxidation of procarbazine in alkaline media has been proposed. The process is realized completely on the electrode surface and is adsorption-controlled. The oscillatory behavior in this case is more probable, than for neutral media and may be caused by influences of electrochemical oxidation and salt dissolution from the electrode surface
ESO 603-G21: A strange polar-ring galaxy
We present the results of B, V, R surface photometry of ESO603-G21 - a galaxy
with a possible polar ring. The morphological and photometric features of this
galaxy are discussed. The central round object of the galaxy is rather red and
presents a nearly exponential surface brightness distribution. This central
structure is surrounded by a blue warped ring or disk. The totality of the
observed characteristics (optical and NIR colors, strong color gradients, HI
and H_2 content, FIR luminosity and star-formation rate, rotation-curve shape,
global mass-to-luminosity ratio, the agreement with the Tully-Fisher relation,
etc.) shows that ESO603-G21 is similar to late-type spiral galaxies. We suppose
that morphological peculiarities and the possible existence of two large-scale
kinematically-decoupled subsystems in ESO603-G21 can be explained as being a
result of dissipative merging of two spiral galaxies or as a consequence of a
companion accretion onto a pre-existing spiral host.Comment: 8 pages, Astron. Astrophys, accepte
Demonstration of new possibilities of multilayer technology on resistive microstrip/ microdot detectors
The first successful attempts to optimize the electric field in Resistive
Microstrip Gas Chamber and resistive microdot detectors using additional field
shaping strips located inside the detector substrate are describedComment: Presented at the RD-51 mmini week, CERN, June 201
Produção de suínos na fase de gestação em sistema de cama sobreposta.
bitstream/item/125843/1/Folder-Producao-Gestacao-cama-sobreposta-suinos.pdfFolder - PNMAI
Arranjo tecnológico no tratamento de dejetos de suínos e aves para a produção de fertilizante orgânico.
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