1,797 research outputs found
Preserving Value in the Post-BAPCPA Era — An Empirical Study
Through the use of a multivariate regression model, this article studies the effect on debtor reorganization values of the shortened reorganization timeframe imposed by the Bankruptcy Abuse Prevention and Consumer Protection Act (“BAPCPA”). The study shows that BAPCPA is positively correlated at a statistically significant level with higher reorganization recoveries. This result is attributed to the increased proportion of prepackaged and prenegotiated bankruptcies observed in the post-2005 era, as these “fast-track” bankruptcy cases entail lower costs and better preserve the firm’s value
Aplicación de las Nuevas Tecnologías GPS-GPRS para el estudio del comportamiento y mejora de la producción de la raza de lidia
La dehesa es un ecosistema agroforestal único que aúna un óptimo rendimiento
económico con una menor incidencia en el medio. En la Península
Ibérica hay unas 500.000 hectáreas de dehesas concentradas en Andalucía,
Castilla y León, Extremadura, Castilla La Mancha y Madrid.
La raza de Lidia es, dentro de las razas autóctonas, por su rusticidad y
adaptación, una de las que mejor aprovechan y conservan la dehesa. Las
condiciones de cría en grandes fincas (400-500 hectáreas de media), el
espacio por cabeza (entre una y seis hectáreas por animal), la movilidad que
le da su menor tamaño con respecto a otras razas y su crecimiento en libertad
con mínima presencia humana la ha hecho indispensables para el mantenimiento
del ecosistema de la dehesa.
Con este trabajo pretendemos aplicar una tecnología innovadora como es
el GPS-GPRS a la monitorización de la etología del ganado de la raza de Lidia durante todos los periodos de su vida y especialmente en aquellos momentos
en los que el animal se ve sometido a diferentes prácticas de manejo.
Para ello, se implementará la tecnología de GPS que permite el posicionamiento
relativo de un objetivo mediante la captación de la señal de diferentes
satélites específicos, lo que proporcionará información precisa sobre: el
desplazamiento del ganado en un periodo determinado, las distancias recorridas,
el territorio pastoreado, las áreas más querenciosas, su ritmo circadiano,
las pautas de comportamiento, etc. Así mismo, el dispositivo incorporará
sensores de parámetros biológicos como la temperatura ó el ritmo
cardíaco, etc. La implementación de este sistema permitirá, a través del
posicionamiento, realizar la óptima gestión de los recursos pastables de la
dehesa, permitiendo ahorrar costes en alimentación, infraestructuras y personal,
y ofrecer, en un futuro cercano, una atractiva herramienta al ganadero
para realizar el control remoto de sus reses
Fine-structure diagnostics of neutral carbon toward HE 0515-4414
New high-resolution high signal-to-noise spectra of the damped Lyman
(DLA) system toward the quasi-stellar object HE 0515-4414 reveal
absorption lines of the multiplets 2 and 3 in \ion{C}{i}. The resonance lines
are seen in two components with total column densities of
and , respectively. The comparision of theoretical
calculations of the relative fine-structure population with the ratios of the
observed column densities suggests that the \ion{C}{i} absorbing medium is
either very dense or exposed to very intense UV radiation. The upper limit on
the local UV energy density is 100 times the galactic UV energy density, while
the upper limit on the \ion{H}{i} number density is 110 cm. The
excitation temperatures of the ground state fine-structure levels of
and K, respectively, are consistent with the temperature-redshift
relation predicted by the standard Friedmann cosmology. The cosmic microwave
background radiation (CMBR) is only a minor source of the observed
fine-structure excitation.Comment: 5 pages, 5 figures, uses A&A macro package, gzipped tar archive,
accepted by A&
Super-Solar Metallicity in Weak Mg II Absorption Systems at z ~ 1.7
Through photoionization modeling, constraints on the physical conditions of
three z ~ 1.7 single-cloud weak Mg II systems (W_r(2796) < 0.3A) are derived.
Constraints are provided by high resolution R = 45,000, high signal-to-noise
spectra of the three quasars HE0141-3932, HE0429-4091, and HE2243-6031 which we
have obtained from the ESO archive of VLT/UVES. Results are as follows:
(1) The single-cloud weak Mg II absorption in the three z ~ 1.7 systems is
produced by clouds with ionization parameters of -3.8 < logU < -2.0 and sizes
of 1-100 pc.
(2) In addition to the low-ionization phase Mg II clouds, all systems need an
additional 1-3 high-ionization phase C IV clouds within 100 km/s of the Mg II
component. The ionization parameters of the C IV phases range from -1.9 < logU
< -1.0, with sizes of tens of parsecs to kiloparsecs.
(3) Two of the three single-cloud weak Mg II absorbers have near-solar or
super-solar metallicities, if we assume a solar abundance pattern. Although
such large metallicities have been found for z < 1 weak Mg II absorbers, these
are the first high metallicities derived for such systems at higher redshifts.
(4) Two of the three weak Mg II systems also need additional low-metallicity,
broad Lya absorption lines, offset in velocity from the metal-line absorption,
in order to reproduce the full Lya profile.
(5) Metallicity in single-cloud weak Mg II systems are more than an order of
magnitude larger than those in Damped Lya systems at z ~ 1.7. In fact, there
appears to be a gradual decrease in metallicity with increasing N(HI), from
these, the most metal-rich Lya forest clouds, to Lyman limit systems, to
sub-DLAs, and finally to the DLAs.Comment: 25 pages, 7 figures, accepted by the Astrophysical Journa
Hubble Space Telescope Observations of Element Abundances in Low-redshift Damped Lyman-alpha Galaxies and Implications for the Global Metallicity-Redshift Relation
Most models of cosmic chemical evolution predict that the mass-weighted mean
interstellar metallicity of galaxies should rise with time from a low value
solar at to a nearly solar value at . In the
absence of any selection effects, the damped Lyman-alpha absorbers (DLAs) in
quasar spectra are expected to show such a rise in global metallicity. However,
it has been difficult to determine whether or not DLAs show this effect,
primarily because of the very small number of DLA metallicity measurements at
low redshifts. In an attempt to put tighter constraints on the low-redshift end
of the DLA metallicity-redshift relation, we have observed Zn II and Cr II
lines in four DLAs at , using the Space Telescope Imaging
Spectrograph (STIS) onboard the Hubble Space Telescope (HST). These
observations have provided the first constraints on Zn abundances in DLAs with
. In all the three DLAs for which our observations offer meaningful
constraints on the metallicity, the data suggest that the metallicities are
much lower than the solar value. These results are consistent with recent
imaging studies indicating that these DLAs may be associated with dwarf or low
surface brightness galaxies. We combine our results with higher redshift data
from the literature to estimate the global mean metallicity-redshift relation
for DLAs. We find that the global mean metallicity shows at most a slow
increase with decreasing redshift. ...(Please see the paper for the complete
abstract).Comment: 56 pages, including 13 figures. Accepted for publication in the
Astrophysical Journa
Elemental Abundances in Two High Column Density Damped Lyman Alpha Systems at z < 1.5
We present Keck/HIRES abundance measurements and metal-line kinematic
profiles of the damped Lyman alpha systems (DLAs) towards the quasars Q0933+733
(z_abs=1.479) and Q0948+433 (z_abs=1.233). These two DLAs have among the five
highest HI column densities at any redshift: N(HI)=4.2E21 cm^{-2}. The
metal-line data, presented here for the first time, reveal that these DLAs are
noteworthy for several other reasons as well. 1) The Q0933+733 DLA exhibits
simple kinematic structure with unusually narrow velocity widths as measured
from its unsaturated metal lines (delta v=16 km/s). At 2.6% solar, it has the
second lowest metallicity at z<2. 2) The Q0948+433 DLA has among the strongest
metal-line transitions of any known DLA. The saturated SiII1808 line implies a
high metallicity ([Si/H]> -1) and a significant alpha-enhancement. The strong
metal lines of this DLA have made possible the detection of TiII1910, CoII2012,
and MgI2026. 3) We find that the relative gas-phase abundances of both DLAs
follow the general trend seen at high redshift, e.g., enhanced Zn/Fe and Si/Fe,
and sub-solar Mn/Fe, indicating that there is little evolution in the
nucleosynthetic patterns of DLAs down to this epoch. 4) Their high HI column
densities imply that these DLAs dominate the column density-weighted cosmic
mean metallicity, , of the universe at z<1.5. Using the 15 DLAs with
measured metallicities in the redshift interval 0.4 =
-0.89^{+0.40}_{-0.33}, where the uncertainties are 95% confidence limits.Comment: 25 pages. Accepted for publication in the Astronomical Journa
The Role of Sub-damped Lyman-alpha Absorbers in the Cosmic Evolution of Metals
Observations of low mean metallicity of damped Lyman-alpha (DLA) quasar
absorbers at all redshifts studied appear to contradict the predictions for the
global mean interstellar metallicity in galaxies from cosmic chemical evolution
models. On the other hand, a number of metal-rich sub-DLA systems have been
identified recently, and the fraction of metal-rich sub-DLAs appears to be
considerably larger than that of metal-rich DLAs, especially at z < 1.5. In
view of this, here we investigate the evolution of metallicity in sub-DLAs. We
find that the mean Zn metallicity of the observed sub-DLAs may be higher than
that of the observed DLAs, especially at low redshifts, reaching a near-solar
level at z <~ 1. This trend does not appear to be an artifact of sample
selection, the use of Zn, the use of N_{HI}-weighting, or observational
sensitivity. While a bias against very low metallicity could be present in the
sub-DLA sample in some situations, this cannot explain the difference between
the DLA and sub-DLA metallicities at low z. The primary reason for the
difference between the DLAs and sub-DLAs appears to be the dearth of metal-rich
DLAs. We estimate the sub-DLA contribution to the total metal budget using
measures of their metallicity and comoving gas density. These calculations
suggest that at z <~ 1, the contribution of sub-DLAs to the total metal budget
may be several times that of DLAs. At higher redshifts also, there are
indications that the sub-DLAs may contribute significantly to the cosmic metal
budget.Comment: 9 pages, 2 figures, Accepted for Publication in the Astrophysical
Journa
Photoionized OVI absorbers toward the bright QSO HE 0515-4414
We report on detailed Monte Carlo inversion analysis of five OVI systems from
the spectrum of the bright quasar HE 0515-4414 (z_e = 1.71). The associated
system at z_a = 1.697 with the neutral hydrogen column density N(HI)= 4.4
10^{13} cm^{-2} shows pronounced absorption from highly ionized transitions of
CIII, CIV, NV, OVI, SiIV, and probably SVI. We found that only a power law type
ionizing spectrum (J_nu propto nu^{-1.5}) is consistent with the observed
sample of the line profiles, i.e. the system is definitely intrinsic. The
relative metal abundances give almost the solar pattern and the metallicity of
about 5 times solar. The system originates in a thin shell of the line-of-sight
thickness L <= 16 pc. Two OVI systems at z_a = 1.674 ([C/H] = -1.6) and 1.602
([O/H] = -1.1), arising in intervening halos, have linear sizes of L = 3-14 kpc
and 17 kpc, respectively. Absorption systems at z_a = 1.385 ([C/H] = -0.3, L =
1.7-2.5 kpc) and z_a = 1.667 ([C/H] = -0.5, L = 1 kpc) exhibit characteristics
very similar to that observed in metal-enriched high velocity clouds in the
Milky Way.These systems are probably embedded in extremely metal-poor halos
with [C/H] < -2.4 (z_a = 1.667) and [C/H] < -3.7 (z_a = 1.385). We also found
two additional extremely metal-poor Ly-alpha systems at z_a = 1.500 and 1.681
with, respectively, N(HI) = 1.7 10^{15} and 1.8 10^{15} cm^{-2} and [C/H] <
-4.0 and <-3.0, - an indication that the distribution of metals in the
metagalactic medium is utterly patchy. Our results show that the ionization
states in the analyzed OVI absorbers, ranging from z = 1.4 to 1.7, can be
maintained by photoionization only and that the fraction of the shock-heated
hot gas with temperature T > 10^5 K is negligible in these systems.Comment: 16 pages, including 11 PostScript figures. Accepted for publication
in A&
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