2,724 research outputs found
Vulnerability analysis in complex networks under a flood risk reduction point of view
The measurement and mapping of transportation network vulnerability to natural hazards constitute subjects of global interest for a sustainable development agenda and as means of adaptation to climate change. During a flood, some elements of a transportation network can be affected, causing the loss of lives. Furthermore, impacts include damage to vehicles, streets/roads, and other logistics services - sometimes with severe economic consequences. The Network Science approach may offer a valuable perspective considering one type of vulnerability related to network-type critical infrastructures: the topological vulnerability. The topological vulnerability index associated with an element is defined as reducing the network’s average efficiency due to removing the set of edges related to that element. In this paper, we present the results of a systematic literature overview and a case study applying the topological vulnerability index for the highways in Santa Catarina (Brazil). We produce a map considering that index and areas susceptible to urban floods and landslides. Risk knowledge, combining hazard and vulnerability, is the first pillar of an Early Warning System and represents an important tool for stakeholders of the transportation sector in a disaster risk reduction agenda.Peer Reviewe
Correlation between the granulosa cell layer and active caspase-3 expression in ovarian follicles of Tropidurus hispidus and T. semitaeniatus (Squamata, Tropiduridae): immunohistochemical approach
The greatest threats to terrestrial reptiles are urban development and habitat modification.
In this sense, a better understanding of folliculogenesis in these animals would be important to knowledge of reproductive biology. The aim of this study was to analyze the correlation between the thickness of the granulosa cell layer and the expression of the active caspase-3 protein in the previtellogenic and vitellogenic follicles of T. hispidus and T. semitaeniatus. Ovaries were used for histological (morphology and morphometry: thickness of granulosa layer) and immunohistochemical (active caspase-3 expression) analyses. The previtellogenic follicles of T. hispidus and T. semitaeniatus showed a thicker granulosa layer, with pyriform and small cells. The vitellogenic follicles had a monolayer of cuboid cells, and a thicker thecal layer. The thickness of the granulosa layer was significantly higher in the previtellogenic compared to the vitellogenic phase for both species. However, no differences were observed between the species.
Active caspase-3 was observed in the pyriform and intermediate cells in previtellogenesis of T. hispidus and T. semitaeniatus. Nevertheless, no immunostaining was observed in the vitellogenic phase in both species. In conclusion, this study shows that the thickness of the granulosa cell layer is higher in the previtellogenic follicles compared to the vitellogenic follicles in the two Tropidurus species. Pyriform and intermediate cells from previtellogenic follicles show high expression of the protein, indicating that remodeling of the epithelium is associated with apoptosis. Finally, our results provide a scientific basis for assisted reproductive techniques and conservation actions to the reptiles in the future.Las mayores amenazas para los reptiles terrestres son el desarrollo urbano y la modificación del hábitat. En este sentido, una mejor comprensión de la foliculogénesis en estos animales sería importante para el conocimiento de la biología reproductiva. El objetivo de este estudio fue analizar la correlación entre el grosor de la capa de células de la granulosa y la expresión de la proteína caspase-3 activa en los folículos previtelogénicos y vitelogénicos de T. hispidus y T. semitaeniatus. Los ovarios se usaron para análisis histológicos (morfología y morfometría: grosor de la capa de la granulosa) e inmunohistoquímicos (expresión activa de caspase-3). Los folículos previtelogénicos de T. hispidus y T. semitaeniatus mostraron una capa de granulosa más gruesa, con células piriformes y pequeñas. Los folículos vitelogénicos tenían una monocapa de células cuboides y una capa tecal más gruesa. El grosor de la capa de granulosa fue significativamente mayor en la fase previtelogénica en comparación con la fase vitelogénica para ambas especies. Sin embargo, no se observaron diferencias entre las especies. Se observó caspase-3 activa en las células piriformes e intermedias en previtelogénesis de T. hispidus y T. semitaeniatus. Sin embargo, no se observó inmunotinción en la fase vitelogénica en ambas especies. En conclusión, este estudio muestra que el grosor de la capa de células de la granulosa es mayor en los folículos previtelogénicos en comparación con los folículos vitelogénicos en las dos especies de Tropidurus. Las células piriformes e intermedias de folículos previtelogénicos muestran una alta expresión de la proteína, lo que indica que la remodelación del epitelio está asociada con la apoptosis. Finalmente, nuestros resultados proporcionan una base científica para técnicas de reproducción asistida y acciones de conservación para los reptiles en el futuro.Asociación Herpetológica Argentin
Theory of Functional Connections and Nelder-Mead optimization methods applied in satellite characterization
The growing population of man-made objects with the build up of
mega-constellations not only increases the potential danger to all space
vehicles and in-space infrastructures (including space observatories), but
above all poses a serious threat to astronomy and dark skies. Monitoring of
this population requires precise satellite characterization, which is is a
challenging task that involves analyzing observational data such as position,
velocity, and light curves using optimization methods. In this study, we
propose and analyze the application of two optimization procedures to determine
the parameters associated with the dynamics of a satellite: one based on the
Theory of Functional Connections (TFC) and another one based on the Nelder-Mead
heuristic optimization algorithm. The TFC performs linear functional
interpolation to embed the constraints of the problem into a functional. In
this paper, we propose to use this functional to analytically embed the
observational data of a satellite into its equations of dynamics. After that,
any solution will always satisfy the observational data. The second procedure
proposed in this research takes advantage of the Nealder-Mead algorithm, that
does not require the gradient of the objective function, as alternative
solution. The accuracy, efficiency, and dependency on the initial guess of each
method is investigated, analyzed, and compared for several dynamical models.
These methods can be used to obtain the physical parameters of a satellite from
available observational data and for space debris characterization contributing
to follow-up monitoring activities in space and astronomical observatories.Comment: Submitted to Acta Astronautic
Ionization and Fragmentation of a Global Warming Gas by EUV and X-Ray Photons
An experimental investigation of the processes leading tothe fragmentation of the singly ionized 1,1,1,2-tetrafluoroethane (HFC-134a, CH2FCF3) by EUV and soft X-rays is presented. HFC-134ais taken into consideration as the most convenient replacement for CFC-12 in refrigeration applications due to the fact that it has null ozone depletion factor. Dissociation of the singly ionized HFC-134amolecule was induced by valence, direct and indirect C 1s core photoionization or photoexcitation and the ionic fragments were detected in coincidence (PEPICO mode) with the ejected electrons without energy analysis. The singly ionized parent ion CF4CH2+can be detected even at photon energies above the C 1s threshold
Search for anomalous t t-bar production in the highly-boosted all-hadronic final state
A search is presented for a massive particle, generically referred to as a
Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are
sufficiently massive to produce highly Lorentz-boosted top quarks, which yield
collimated decay products that are partially or fully merged into single jets.
The analysis uses new methods to analyze jet substructure, providing
suppression of the non-top multijet backgrounds. The analysis is based on a
data sample of proton-proton collisions at a center-of-mass energy of 7 TeV,
corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits
in the range of 1 pb are set on the product of the production cross section and
branching fraction for a topcolor Z' modeled for several widths, as well as for
a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any
enhancement in t t-bar production beyond expectations of the standard model for
t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version
includes a minor typo correction that will be submitted as an erratu
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
Combined search for the quarks of a sequential fourth generation
Results are presented from a search for a fourth generation of quarks
produced singly or in pairs in a data set corresponding to an integrated
luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in
2011. A novel strategy has been developed for a combined search for quarks of
the up and down type in decay channels with at least one isolated muon or
electron. Limits on the mass of the fourth-generation quarks and the relevant
Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a
simple extension of the standard model with a sequential fourth generation of
fermions. The existence of mass-degenerate fourth-generation quarks with masses
below 685 GeV is excluded at 95% confidence level for minimal off-diagonal
mixing between the third- and the fourth-generation quarks. With a mass
difference of 25 GeV between the quark masses, the obtained limit on the masses
of the fourth-generation quarks shifts by about +/- 20 GeV. These results
significantly reduce the allowed parameter space for a fourth generation of
fermions.Comment: Replaced with published version. Added journal reference and DO
Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV
The t t-bar production cross section (sigma[t t-bar]) is measured in
proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS
experiment, corresponding to an integrated luminosity of 2.3 inverse
femtobarns. The measurement is performed in events with two leptons (electrons
or muons) in the final state, at least two jets identified as jets originating
from b quarks, and the presence of an imbalance in transverse momentum. The
measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/-
2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction
of the standard model.Comment: Replaced with published version. Included journal reference and DO
Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV
The production of b jets in association with a Z/gamma* boson is studied
using proton-proton collisions delivered by the LHC at a centre-of-mass energy
of 7 TeV and recorded by the CMS detector. The inclusive cross section for
Z/gamma* + b-jet production is measured in a sample corresponding to an
integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross
section with Z/gamma* to ll (where ll = ee or mu mu) for events with the
invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level
with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and
the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.)
+(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also
studied and found to be in agreement with the predictions made by the MadGraph
event generator with the parton shower and the hadronisation performed by
PYTHIA.Comment: Submitted to the Journal of High Energy Physic
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