781 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
On the sensitivity of HeI singlet lines to the FeIV model atom in O stars
Recent calculations and analyses of O star spectra have revealed
discrepancies between theory and observations, and between different
theoretical calculations, for the strength of optical HeI singlet
transitions.We investigate the source of these discrepancies. Using a non-LTE
radiative transfer code we have undertaken detailed test calculations for a
range of O star properties. Our principal test model has parameters similar to
those of the O9V star, 10 Lac. We show that the discrepancies arise from
uncertainties in the radiation field in the HeI resonance transition near
584Angs. The radiation field at 584Angs. is influenced by model assumptions,
such as the treatment of line-blanketing and the adopted turbulent velocity,
and by the FeIV atomic data. It isshown that two FeIV transitions near 584Angs
can have a substantial influence on the strength of the HeI singlet
transitions. Because of the difficulty of modeling the HeI singlet lines,
particularly in stars with solar metalicity, the HeI triplet lines should be
preferred in spectral analyses. These lines are much less sensitive to model
assumptions.Comment: 7 pages, 9 figures, accepted for publication in A&
PySubdiv 1.0: open-source geological modeling and reconstruction by non-manifold subdivision surfaces
Sealed geological models are commonly used as an input to process
simulations, for example, in hydrogeological or geomechanical studies.
Creating these meshes often requires tedious manual work, and it is
therefore difficult to adjust a once-created model. In this work, we
propose a flexible framework to create and interact with geological models
using explicit surface representations. The essence of the work lies in the
determination of the control mesh and the definition of semi-sharp-crease
values, which, in combination, enable the representation of complex
structural settings with a low number of control points. We achieve this
flexibility through the adaptation of recent algorithms from the field of
computer graphics to the specific requirements of geological modeling,
specifically the representation of non-manifold topologies and sharp
features. We combine the method with a particle swarm optimization (PSO)
approach to enable the automatic optimization of vertex position and crease
sharpness values. The result of this work is implemented in an open-source
software (PySubdiv) for reconstructing geological structures while resulting
in a model which is (1) sealed/watertight, (2) controllable with a control
mesh and (3) topologically similar to the input geological structure. Also,
the reconstructed model may include a lower number of vertices compared to
the input geological structure, which results in reducing the cost of
modeling and simulation. In addition to enabling a manual adjustment of
sealed geological models, the algorithm also provides a method for the
integration of explicit surface representations in inverse frameworks and
the consideration of uncertainties.</p
Absolute-Magnitude Distributions and Light Curves of Stripped-Envelope Supernovae
The absolute visual magnitudes of three Type IIb, 11 Type Ib and 13 Type Ic
supernovae (collectively known as stripped-envelope supernovae) are studied by
collecting data on the apparent magnitude, distance, and interstellar
extinction of each event. Weighted and unweighted mean absolute magnitudes of
the combined sample as well as various subsets of the sample are reported. The
limited sample size and the considerable uncertainties, especially those
associated with extinction in the host galaxies, prevent firm conclusions
regarding differences between the absolute magnitudes of supernovae of Type Ib
and Ic, and regarding the existence of separate groups of overluminous and
normal-luminosity stripped-envelope supernovae. The spectroscopic
characteristics of the events of the sample are considered. Three of the four
overluminous events are known to have had unusual spectra. Most but not all of
the normal luminosity events had typical spectra. Light curves of
stripped-envelope supernovae are collected and compared. Because SN 1994I in
M51 was very well observed it often is regarded as the prototypical Type Ic
supernova, but it has the fastest light curve in the sample. Light curves are
modeled by means of a simple analytical technique that, combined with a
constraint on E/M from spectroscopy, yields internally consistent values of
ejected mass, kinetic energy, and nickel mass.Comment: 39 pages, 14 figures, 7 tables; Accepted to A
The ACS Nearby Galaxy Survey Treasury VII. The NGC 4214 Starburst and the Effects of Star Formation History on Dwarf Morphology
We present deep Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2)
optical observations obtained as part of the ACS Nearby Galaxy Survey Treasury
(ANGST) as well as early release Wide Field Camera 3 (WFC3) ultra-violet and
infrared observations of the nearby dwarf starbursting galaxy NGC 4214. Our
data provide a detailed example of how covering such a broad range in
wavelength provides a powerful tool for constraining the physical properties of
stellar populations. The deepest data reach the ancient red clump at M_F814W
-0.2. All of the optical data reach the main sequence turnoff for stars younger
than ~300 Myr, and the blue He burning sequence for stars younger than 500 Myr.
The full CMD-fitting analysis shows that all three fields in our data set are
consistent with ~75% of the stellar mass being older than 8 Gyr, in spite of
showing a wide range in star formation rates at the present day. Thus, our
results suggest that the scale length of NGC 4214 has remained relatively
constant for many Gyr. As previously noted by others, we also find the galaxy
has recently ramped up production, consistent with its bright UV luminosity and
its population of UV-bright massive stars. In the central field we find UV
point sources with F336W magnitudes as bright as -9.9. These are as bright as
stars with masses of at least 52-56 M_sun and ages near 4 Myr in stellar
evolution models. Assuming a standard IMF, our CMD is well-fitted by an
increase in star formation rate beginning 100 Myr ago. The stellar populations
of this late-type dwarf are compared with those of NGC 404, an early-type dwarf
that is also the most massive galaxy in its local environment. The late-type
dwarf appears to have a similar high fraction of ancient stars, suggesting that
these dominant galaxies may form at early epochs even if they have low total
mass and very different present-day morphologies.Comment: 17 pages, 10 figures, accepted for publication in Ap
P2Y1 receptor inhibition rescues impaired synaptic plasticity and astroglial Ca2+-dependent activity in the epileptic hippocampus
Indexación ScopusEpilepsy is characterized by a progressive predisposition to suffer seizures due to neuronal hyperexcitability, and one of its most common co-morbidities is cognitive decline. In animal models of chronic epilepsy, such as kindling, electrically induced seizures impair long-term potentiation (LTP), deteriorating learning and memory performance. Astrocytes are known to actively modulate synaptic plasticity and neuronal excitability through Ca2+-dependent gliotransmitter release. It is unclear, however, if astroglial Ca2+ signaling could contribute to the development of synaptic plasticity alterations in the epileptic hippocampus. By employing electrophysiological tools and Ca2+ imaging, we found that glutamatergic CA3-CA1 synapses from kindled rats exhibit an impairment in theta burst (TBS) and high frequency stimulation (HFS)-induced LTP, which is accompanied by an increased probability of neurotransmitter release (Pr) and an abnormal pattern of astroglial Ca2+-dependent transients. Both the impairment in LTP and the Pr were reversed by inhibiting purinergic P2Y1 receptors (P2Y1R) with the specific antagonist MRS2179, which also restored the spontaneous and TBS-induced pattern of astroglial Ca2+-dependent signals. Two consecutive, spaced TBS protocols also failed to induce LTP in the kindled group, however, this impairment was reversed and a strong LTP was induced when the second TBS was applied in the presence of MRS2179, suggesting that the mechanisms underlying the alterations in TBS-induced LTP are likely associated with an aberrant modulation of the induction threshold for LTP. Altogether, these results indicate that P2Y1R inhibition rescues both the pattern of astroglial Ca2+-activity and the plastic properties of CA3-CA1 synapses in the epileptic hippocampus, suggesting that astrocytes might take part in the mechanisms that deteriorate synaptic plasticity and thus cause cognitive decline in epileptic patients. © 2020https://www-sciencedirect-com.recursosbiblioteca.unab.cl/science/article/pii/S0969996120304071?via%3Dihu
Adult Rat Bones Maintain Distinct Regionalized Expression of Markers Associated with Their Development
The incidence of limb bone fracture and subsequent morbidity and mortality due to excessive bone loss is increasing in the progressively ageing populations of both men and women. In contrast to bone loss in the weight-bearing limb, bone mass in the protective skull vault is maintained. One explanation for this could be anatomically diverse bone matrix characteristics generated by heterogeneous osteoblast populations. We have tested the hypothesis that adult bones demonstrate site-specific characteristics, and report differences at the organ, cell and transcriptome levels. Limb bones contain greater amounts of polysulphated glycosaminoglycan stained with Alcian Blue and have significantly higher osteocyte densities than skull bone. Site-specific patterns persist in cultured adult bone-derived cells both phenotypically (proliferation rate, response to estrogen and cell volumes), and at the level of specific gene expression (collagen triple helix repeat containing 1, reelin and ras-like and estrogen-regulated growth inhibitor). Based on genome-wide mRNA expression and cluster analysis, we demonstrate that bones and cultured adult bone-derived cells segregate according to site of derivation. We also find the differential expression of genes associated with embryological development (Skull: Zic, Dlx, Irx, Twist1 and Cart1; Limb: Hox, Shox2, and Tbx genes) in both adult bones and isolated adult bone-derived cells. Together, these site-specific differences support the view that, analogous to different muscle types (cardiac, smooth and skeletal), skull and limb bones represent separate classes of bone. We assign these differences, not to mode of primary ossification, but to the embryological cell lineage; the basis and implications of this division are discussed
Организация работ по ремонту и обслуживанию предпусковых подогревателей двигателей грузовых автомобилей в условиях ремонтной мастерской ООО «Сибтрейд»
В разделе объект и методы исследования выполнен аналитический обзор по теме работы и обоснован выбор темы выпускной работы бакалавра.
В разделе расчеты и аналитика представлены необходимые инженерные расчеты, связанные с организацией работ по ремонту и обслуживанию предпусковых жидкостных подогревателей грузовых автомобилей.
В разделе "Социальная ответственность" выявлены опасные и вредные факторы, а также мероприятия по их ликвидации.In the section of the object and methods of research, an analytical review of the topic of work was carried out and the choice of the topic of the bachelor's thesis was substantiated.
The calculations and analytics section presents the necessary engineering calculations related to the organization of work on the repair and maintenance of pre-launch liquid heaters of trucks.
n the section "Social responsibility" identified dangerous and harmful factors, as well as measures for their elimination
Science and Film-making
The essay reviews the literature, mostly historical, on the relationship between science and film-making, with a focus on the science documentary. It then discusses the circumstances of the emergence of the wildlife making-of documentary genre. The thesis examined here is that since the early days of cinema, film-making has evolved from being subordinate to science, to being an equal partner in the production of knowledge, controlled by non-scientists
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