412 research outputs found
Orbital angular momentum exchange in an optical parametric oscillator
We present a study of orbital angular momentum transfer from pump to
down-converted beams in a type-II Optical Parametric Oscillator. Cavity and
anisotropy effects are investigated and demostrated to play a central role in
the transverse mode dynamics. While the idler beam can oscillate in a
Laguerre-Gauss mode, the crystal birefringence induces an astigmatic effect in
the signal beam that prevents the resonance of such mode.Comment: 10 pages, 8 figures, regular articl
A Morphological-type dependence in the mu_0-log(h) plane of Spiral galaxy disks
We present observational evidence for a galaxy `Type' dependence to the
location of a spiral galaxy's disk parameters in the mu_0-log(h) (central disk
surface-brightness - disk scale-length) plane. With a sample of ~40 Low Surface
Brightness galaxies (both bulge- and disk-dominated) and ~80 High Surface
Brightness galaxies, the early-type disk galaxies (<=Sc) tend to define a
bright envelope in the mu_0-log(h) plane, while the late-type (>=Scd) spiral
galaxies have, in general, smaller and fainter disks. Below the defining
surface brightness threshold for a Low Surface Brightness galaxy (i.e. more
than 1 mag fainter than the 21.65 B-mag arcsec^(-2) Freeman value), the
early-type spiral galaxies have scale-lengths greater than 8-9 kpc, while the
late-type spiral galaxies have smaller scale-lengths. All galaxies have been
modelled with a seeing-convolved Sersic r^(1/n) bulge and exponential disk
model. We show that the trend of decreasing bulge shape parameter (n) with
increasing Hubble type and decreasing bulge-to-disk luminosity ratio, which has
been observed amongst the High Surface Brightness galaxies, extends to the Low
Surface Brightness galaxies, revealing a continuous range of structural
parameters.Comment: To be published in ApJ. Inc. three two-part figure
On the relation between circular velocity and central velocity dispersion in high and low surface brightness galaxies
In order to investigate the correlation between the circular velocity Vc and
the central velocity dispersion of the spheroidal component sigma_c, we
analyzed these quantities for a sample of 40 high surface brightness disc
galaxies (hereafter HSB), 8 giant low surface brightness spiral galaxies
(hereafter LSB), and 24 elliptical galaxies characterized by flat rotation
curves. We find that the Vc-sigma_c relation is descri ed by a linear law out
to velocity dispersions as low as sigma_c~50km/s, while in previous works a
power law was adopted for galaxies with sigma_c>80k/ms.
Elliptical galaxies with Vc based on dynamical models or directly derived
from the HI rotation curves follow the same relation as the HSB galaxies in the
Vc-sigma_c plane. On the contrary, the LSB galaxies follow a different
relation, since most of them show either higher Vc (or lower sigma_c) with
respect to the HSB galaxies. This argues against the relevance of baryon
collapse in the radial density profile of the dark matter haloes of LSB
galaxies. (abridged)Comment: 18 pages, 4 figures, ApJ in pres
Давньогрецький поліс в контексті соціально-політичних поглядів Платона та Аристотеля
У статті здійснено аналіз соціально-політичних засад розбудови грецького поліса в контексті поглядів Платона та Аристотеля.In this article accomplishes analyses of social and political bases of Greek polis development in the context of Platoon’s and Aristotle’s views
Identification of F-box only protein 7 as a negative regulator of NF-kappaB signalling.
The nuclear factor κB (NF-κB) signalling pathway controls important cellular events such as cell proliferation, differentiation, apoptosis and immune responses. Pathway activation occurs rapidly upon TNFα stimulation and is highly dependent on ubiquitination events. Using cytoplasmic to nuclear translocation of the NF-κB transcription factor family member p65 as a read-out, we screened a synthetic siRNA library targeting enzymes involved in ubiquitin conjugation and de-conjugation for modifiers of regulatory ubiquitination events in NF-κB signalling. We identified F-box protein only 7 (FBXO7), a component of Skp, Cullin, F-box (SCF)-ubiquitin ligase complexes, as a negative regulator of NF-κB signalling. F-box protein only 7 binds to, and mediates ubiquitin conjugation to cIAP1 and TRAF2, resulting in decreased RIP1 ubiquitination and lowered NF-κB signalling activity
The stellar disk thickness of LSB galaxies
We present surface photometry results for a sample of eleven edge-on galaxies
observed with the 6m telescope at the Special Astrophysical Observatory
(Russia). The photometric scale length, scale height, and central surface
brightness of the stellar disks of our sample galaxies are estimated. We show
that four galaxies in our sample, which are visually referred as objects of the
lowest surface brightness class in the Revised Flat Galaxies Catalog, have bona
fide low surface brightness (LSB) disks. We find from the comparison of
photometric scales that the stellar disks of LSB galaxies are thinner than
those of high surface brightness (HSB) ones. There is a clear correlation
between the central surface brightness of the stellar disk and its vertical to
radial scale ratio. The masses of spherical subsystems (dark halo + bulge) and
the dark halo masses are obtained for the sample galaxies based on the
thickness of their stellar disks. The LSB galaxies tend to harbor more massive
spherical subsystems than the HSB objects, whereas no systematic difference in
the dark halo masses between LSB and HSB galaxies is found. At the same time,
the inferred mass-to-luminosity ratio for the LSB disks appears to be
systematically higher than for HSB disks.Comment: 33 pages with 17 Postscript figures, uses aastex.cls, accepted by Ap
Optical vortices with starlight: Implications for ground-based stellar coronagraphy
Using an l = 1 blazed fork-hologram at the focal plane of the Asiago 122 cm
telescope, we obtained optical vortices from the stellar system Rasalgethi
(alpha Herculis) and from the single star Arcturus (alpha Bootis). We have
analyzed the structure of the optical vortices obtained from non-monochromatic
starlight under very poor seeing conditions using a fast CCD camera to obtain
speckle patterns and carry out the lucky imaging technique, alternative to
adaptive optics. With the insertion of a red filter and of a Lyot stop we
performed l = 1 optical vortex coronography the double star HD74010. The
results are in agreement with theory and numerical simulations. Our results
open the way to applications of optical vortices to ground based astronomical
observations, in particular for coronagraphy with l > 1 masks. No intrinsic
orbital angular momentum was detected in the starlight.Comment: 4 pages, 5 figures. Revised data analysi
Animación socio cultural en establecimiento carcelario masculino
Servicio Social ComunitarioEste trabajo contiene toda la información relevante acerca del contexto penitenciario, carcelario su historia y contexto poblacional, a su vez cuenta con una justificación, Marco teórico y empírico que sustentan porque la animación socio cultural es una metodología con enfoque comunitario pertinente para el trabajo con personas privadas de la libertad, finalmente se encuentran las conclusiones y anexos de todos los resultados obtenidos con el presente proyecto de grado.1. Resumen (Abstact, RAE)
2. Descripción de la problemática
3. Contexto Institucional, Geográfico, Poblacional
4. Descripción de la población
5. Justificación
6. Delimitación de la investigación
7. Objetivos
8. Marco Teórico
9. Marco Metodológico
10. Diseño Metodológico de la Intervención
11. Categorías de Análisis 12. Matriz Operativa del Proyecto
13. Conclusiones
14. Análisis de Procesos
15. Referencias
16. ApéndicesPregradoPsicólog
Low-Surface-Brightness Galaxies in the Sloan Digital Sky Survey. I. Search Method and Test Sample
In this paper we present results of a pilot study to use imaging data from
the Sloan Digital Sky Survey (SDSS) to search for low-surface-brightness (LSB)
galaxies. For our pilot study we use a test sample of 92 galaxies from the
catalog of Impey et al. (1996) distributed over 93 SDSS fields of the Early
Data Release (EDR). Many galaxies from the test sample are either LSB or dwarf
galaxies. To deal with the SDSS data most effectively a new photometry software
was created, which is described in this paper. We present the results of the
selection algorithms applied to these 93 EDR fields. Two galaxies from the
Impey et al. test sample are very likely artifacts, as confirmed by follow-up
imaging. With our algorithms, we were able to recover 87 of the 90 remaining
test sample galaxies, implying a detection rate of 96.5%. The three
missed galaxies fall too close to very bright stars or galaxies. In addition,
42 new galaxies with parameters similar to the test sample objects were found
in these EDR fields (i.e., 47% additional galaxies). We present the main
photometric parameters of all identified galaxies and carry out first
statistical comparisons. We tested the quality of our photometry by comparing
the magnitudes for our test sample galaxies and other bright galaxies with
values from the literature. All these tests yielded consistent results. We
briefly discuss a few unusual galaxies found in our pilot study, including an
LSB galaxy with a two-component disk and ten new giant LSB galaxies.Comment: 36 pages, 16 figures, accepted for publication by AJ, some figures
were bitmapped to reduce the siz
- …