77 research outputs found
On static vs dynamic (switching of) operational policies in aircraft turnaround team allocation and management
Aircraft turnaround operations represent the fulcrum of airport operations. They include all services to be provided to an aircraft between two consecutive flights. These services are executed by human operators, often organised in teams, who employ some related equipment and vehicles (e.g. conveyor belts, trolleys and tugs for baggage loading/unloading and transportation). In this paper, we focus on the real-time management of turnaround operations, and assess the relative merits and limitations of so-called dispatching rules that originate from the manufacturing literature. More precisely, we focus on the real-time allocation, on the day of operation, of teams of ground handling operators to aircraft turnarounds. This is pursued from the viewpoint of third-party service providers. We employ simulation, in conjunction with deep reinforcement learning, and work on the case of a real airport and the entirety of its turnaround operations involving multiple service providers
The spectacular evolution of Supernova 1996al over 15 years: a low energy explosion of a stripped massive star in a highly structured environment
Spectrophotometry of SN 1996al carried out throughout 15 years is presented.
The early photometry suggests that SN 1996al is a Linear type-II supernova,
with an absolute peak of Mv ~ -18.2 mag. Early spectra present broad,
asymmetric Balmer emissions, with super-imposed narrow lines with P-Cygni
profile, and He I features with asymmetric, broad emission components. The
analysis of the line profiles shows that the H and He broad components form in
the same region of the ejecta. By day +142, the Halpha profile dramatically
changes: the narrow P-Cygni profile disappears, and the Halpha is fitted by
three emission components, that will be detected over the remaining 15 yrs of
the SN monitoring campaign. Instead, the He I emissions become progressively
narrower and symmetric. A sudden increase in flux of all He I lines is observed
between 300 and 600 days. Models show that the supernova luminosity is
sustained by the interaction of low mass (~1.15 Msun) ejecta, expelled in a low
kinetic energy (~ 1.6 x 10^50 erg) explosion, with highly asymmetric
circumstellar medium. The detection of Halpha emission in pre-explosion archive
images suggests that the progenitor was most likely a massive star (~25 Msun
ZAMS) that had lost a large fraction of its hydrogen envelope before explosion,
and was hence embedded in a H-rich cocoon. The low-mass ejecta and modest
kinetic energy of the explosion are explained with massive fallback of material
into the compact remnant, a 7-8 Msun black hole.Comment: 27 pages, 23 figures, Accepted for publication in MNRA
The binding landscape of a partially-selective isopeptidase inhibitor with potent pro-death activity, based on the bis(arylidene)cyclohexanone scaffold
Diaryldienone derivatives with accessible \u3b2-carbons show strong anti-neoplastic properties, related to their ability to make covalent adducts with free thiols by Michael addition, and low toxicity in vivo. Accumulation of poly- ubiquitylated proteins, activation of the unfolded protein response (UPR) and induction of cell death are universal hallmarks of their activities. These compounds have been characterized as inhibitors of isopeptidases, a family of cysteine-proteases, which de-conjugate ubiquitin and ubiquitin-like proteins from their targets. However, it is unclear whether they can also react with additional proteins. In this work, we utilized the biotin-conjugated diaryldienone- derivative named 2c, as a bait to purify novel cellular targets of these small molecules. Proteomic analyses have unveiled that, in addition to isopeptidases, these inhibitors can form stable covalent adducts with different intracellular proteins, thus potentially impacting on multiple functions of the cells, from cytoskeletal organization to metabolism. These widespread activities can explain the ability of diaryldienone derivatives to efficiently trigger different cell death pathways
The isopeptidase inhibitor 2cPE triggers proteotoxic stress and ATM activation in chronic lymphocytic leukemia cells
Relapse after treatment is a common and unresolved problem for patients suffering of the B-cell chronic lymphocytic leukemia (B-CLL). Here we investigated the ability of the isopeptidase inhibitor 2cPE to trigger apoptosis in leukemia cells in comparison with bortezomib, another inhibitor of the ubiquitin-proteasome system (UPS). Both inhibitors trigger apoptosis in CLL B cells and gene expression profiles studies denoted how a substantial part of genes up-regulated by these compounds are elements of adaptive responses, aimed to sustain cell survival. 2cPE treatment elicits the up-regulation of chaperones, proteasomal subunits and elements of the anti-oxidant response. Selective inhibition of these responses augments apoptosis in response to 2cPE treatment. We have also observed that the product of the ataxia telangiectasia mutated gene (ATM) is activated in 2cPE treated cells. Stimulation of ATM signaling is possibly dependent on the alteration of the redox homeostasis. Importantly ATM inhibition, mutations or down-modulation increase cell death in response to 2cPE. Overall this work suggests that 2cPE could offer new opportunities for the treatment of B-CLL
Projections of leaf turgor loss point shifts under future climate change scenarios
Predicting the consequences of climate change is of utmost importance to mitigate impacts on vulnerable ecosystems; plant hydraulic traits are particularly useful proxies for predicting functional disruptions potentially occurring in the near future. This study assessed the current and future regional patterns of leaf water potential at turgor loss point (Ψtlp) by measuring and projecting the Ψtlp of 166 vascular plant species (159 angiosperms and 7 gymnosperms) across a large climatic range spanning from alpine to Mediterranean areas in NE Italy. For angiosperms, random forest models predicted a consistent shift toward more negative values in low-elevation areas, while for gymnosperms the pattern was more variable, particularly in the alpine sector (i.e., Alps and Prealps). Simulations were also developed to evaluate the number of threatened species under two Ψtlp plasticity scenarios (low vs high plasticity), and it was found that in the worst-case scenario approximately 72% of the angiosperm species and 68% of gymnosperms within a location were at risk to exceed their physiological plasticity. The different responses to climate change by specific clades might produce reassembly in natural communities, undermining the resilience of natural ecosystems to climate change
Observations of Type Ia Supernova 2014J for Nearly 900 Days and Constraints on Its Progenitor System
We present extensive ground-based and ()
photometry of the highly reddened, very nearby type Ia supernova (SN Ia) 2014J
in M82, covering the phases from 9 days before to about 900 days after the
-band maximum. SN 2014J is similar to other normal SNe Ia near the maximum
light, but it shows flux excess in the band in the early nebular phase.
This excess flux emission can be due to light scattering by some structures of
circumstellar materials located at a few 10 cm, consistent with a single
degenerate progenitor system or a double degenerate progenitor system with mass
outflows in the final evolution or magnetically driven winds around the binary
system. At t+300 to +500 days past the -band maximum, the light
curve of SN 2014J shows a faster decline relative to the Ni decay. Such
a feature can be attributed to the significant weakening of the emission
features around [Fe III] 4700 and [Fe II] 5200 rather than
the positron escape as previously suggested. Analysis of the images taken
at t600 days confirms that the luminosity of SN 2014J maintains a flat
evolution at the very late phase. Fitting the late-time pseudo-bolometric light
curve with radioactive decay of Ni, Ni and Fe isotopes, we
obtain the mass ratio Ni/Ni as , which is
consistent with the corresponding value predicted from the 2D and 3D
delayed-detonation models. Combined with early-time analysis, we propose that
delayed-detonation through single degenerate scenario is most likely favored
for SN 2014J.Comment: 28 pages, 12 figures. Accepted for publication in Ap
Observations of the low-luminosity Type Iax supernova 2019gsc: a fainter clone of SN 2008ha?
We present optical photometric and spectroscopic observations of the faint-and-fast evolving Type Iax supernova (SN) 2019gsc, extending from the time of g-band maximum until about 50 d post-maximum, when the object faded to an apparent r-band magnitude m(r )= 22.48 +/- 0.11 mag. SN 2019gsc reached a peak luminosity of only M-g = -13.58 +/- 0.15 mag, and is characterized with a post-maximum decline rate Delta m(15)(g) = 1.08 +/- 0.14 mag. These light curve parameters are comparable to those measured for SN 2008ha of M-g = -13.89 +/- 0.14 mag at peak and Delta m(15)(g) =1.80 +/- 0.03 mag. The spectral features of SN 2019gsc also resemble those of SN 2008ha at similar phases. This includes both the extremely low ejecta velocity at maximum, similar to 3000 km s(-1) and at late-time (phase +54 d) strong forbidden iron and cobalt lines as well as both forbidden and permitted calcium features. Furthermore, akin to SN 2008ha, the bolometric light curve of SN 2019gsc is consistent with the production of approximate to 0.003 +/- 0.001 M-circle dot of Ni-56. The explosion parameters, M-ej approximate to 0.13 M-circle dot and E-k approximate to 12 x 10(48) erg, are also similar to those inferred for SN 2008ha. We estimate a subsolar oxygen abundance for the host galaxy of SN 2019gsc (12 + log(10)(O/H) =8.10 +/- 0.18 dex), consistent with the equally metal-poor environment of SN 2008ha. Altogether, our data set for SN 2019gsc indicates that this is a member of a small but growing group of extreme SN Iax that includes SN 2008ha and SN 2010ae
Observations of A Fast-Expanding and UV-Bright Type Ia Supernova SN 2013gs
In this paper, we present extensive optical and ultraviolet (UV) observations
of the type Ia supernova (SN Ia) 2013gs discovered during the Tsinghua-NAOC
Transient Survey. The photometric observations in the optical show that the
light curves of SN 2013gs is similar to that of normal SNe Ia, with an absolute
peak magnitude of = 19.25 0.15 mag and a post-maximum decline
rate m(B) = 1.00 0.05 mag. \emph{Gehrels Swift} UVOT
observations indicate that SN 2013gs shows unusually strong UV emission
(especially in the band) at around the maximum light (M
18.9 mag). The SN is characterized by relatively weak Fe~{\sc ii} {\sc iii}
absorptions at 5000{\AA} in the early spectra and a larger expansion
velocity ( 13,000 km s around the maximum light) than the
normal-velocity SNe Ia. We discuss the relation between the color and
some observables, including Si~{\sc ii} velocity, line strength of Si~{\sc ii}
6355, Fe~{\sc ii}/{\sc iii} lines and (B). Compared to
other fast-expanding SNe Ia, SN 2013gs exhibits Si and Fe absorption lines with
similar strength and bluer color. We briefly discussed the origin of
the observed UV dispersion of SNe Ia.Comment: 31 pages, 10 figures, accepted to publish in Ap
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