2,049 research outputs found
Susceptibility and Vulnerability to Landslides—Case Study: Basin of River Bengalas—City of Nova Friburgo—Brazil
Landslides have frequently occurred in last years, due to the disorderly grownth of the cities and the occupation of risk areas by the poor population, causing social, environmental and economic impacts. Urban areas in expansion move to geologically unstable areas and topographically inclined, such as the Basin of River Bengalas, located in the city of Nova Friburgo, mountainous region of the State of Rio de Janeiro, Brazil. This article aims to present the model developed and used to evaluate the susceptibility and vulnerability of the Basin of River Bengalas to landslides, which in January 2011, with the occurrence of heavy rains, caused landslides that impacted in the death of 429 people in city of Nova Friburgo. For the case study, several investigations have been made related to the areas of the basin, such as slope, soil conditions, lithology, land use and cover, vertical curvature, horizontal curvature, and precipitation data. With this study it was possible to understand how the natural and anthropics elements of the basin are related to the local dynamics of the disasters regarding to their interferences in the induction of landslides; evaluate the effectiveness of the guidelines of the Plano Diretor Participativo do Município de Nova Friburgo regarding the landslides; identify the susceptible and vulnerable basin areas to landslides and calculate the rates of susceptibility and vulnerability to landslides from new calculation model proposed
Constraining the period of the ringed secondary companion to the young star J1407 with photographic plates
Context. The 16 Myr old star 1SWASP J140747.93-394542.6 (V1400 Cen) underwent
a series of complex eclipses in May 2007, interpreted as the transit of a giant
Hill sphere filling debris ring system around a secondary companion, J1407b. No
other eclipses have since been detected, although other measurements have
constrained but not uniquely determined the orbital period of J1407b. Finding
another eclipse towards J1407 will help determine the orbital period of the
system, the geometry of the proposed ring system and enable planning of further
observations to characterize the material within these putative rings. Aims. We
carry out a search for other eclipses in photometric data of J1407 with the aim
of constraining the orbital period of J1407b. Methods. We present photometry
from archival photographic plates from the Harvard DASCH survey, and Bamberg
and Sonneberg Observatories, in order to place additional constraints on the
orbital period of J1407b by searching for other dimming and eclipse events.
Using a visual inspection of all 387 plates and a period-folding algorithm we
performed a search for other eclipses in these data sets. Results. We find no
other deep eclipses in the data spanning from 1890 to 1990, nor in recent
time-series photometry from 2012-2018. Conclusions. We rule out a large
fraction of putative orbital periods for J1407b from 5 to 20 years. These
limits are still marginally consistent with a large Hill sphere filling ring
system surrounding a brown dwarf companion in a bound elliptical orbit about
J1407. Issues with the stability of any rings combined with the lack of
detection of another eclipse, suggests that J1407b may not be bound to J1407.Comment: 8 pages, 3 tables, 4 figures, accepted for publication in A&A. LaTeX
files of the paper, scripts for the figures, and a minimal working FPA can be
found under https://github.com/robinmentel/Constraining-Period
Effects of spin-elastic interactions in frustrated Heisenberg antiferromagnets
The Heisenberg antiferromagnet on a compressible triangular lattice in the
spin- wave approximation is considered. It is shown that the interaction
between quantum fluctuations and elastic degrees of freedom stabilizes the low
symmetric L-phase with a collinear Neel magnetic ordering. Multi-stability in
the dependence of the on-site magnetization on an unaxial pressure is found.Comment: Revtex, 4 pages, 2 eps figure
Associated production of H^{\pm} and W^{\mp} in high-energy e+e- collisions in the Minimal Supersymmetric Standard Model
We study the associated production of the charged Higgs boson and W^{\pm}
gauge boson in high energy e+e- collisions in the Minimal Supersymmetric
Standard Model (MSSM). This associated production, which first arises at the
one loop level, offers the possibility of producing the charged Higgs boson at
the e+e- collider with mass more than half the center-of-mass energy, when the
charged Higgs pair production is kinematically forbidden. We present analytic
and numerical results for the cross section for e+e- --> W+ H- in the full
MSSM, taking into account the previously uncalculated contributions from
supersymmetric (SUSY) particles. We find that the contributions of the SUSY
particles enhance the cross section over most of SUSY parameter space,
especially when the SUSY particles are light, ~200 GeV. With favorable SUSY
parameters, at small tan beta, this process can yield more than ten
W^{\pm}H^{\mp} events for m_{H^{\pm}} <~ 350 GeV in 500 fb-1 at a 500 GeV e+e-
collider, or m_{H^{\pm}} <~ 600 GeV in 1000 fb-1 at a 1000 GeV collider. 80%
left-handed polarization of the e- beam improves these reaches to m_{H^{\pm}}
<~ 375 GeV and m_{H^{\pm}} <~ 670 GeV, respectively.Comment: v2: 21 pages, 9 figures, comments on Higgs search bounds and new
references added, and minor changes; v3: 23 pages, 11 figures, review of
literature moved from introduction to new Sec.5 and 2 plots added, references
added, typos corrected; v4: bug fixed in nu nubar H0 cross section (Fig.11),
version to appear in PR
Selberg Supertrace Formula for Super Riemann Surfaces III: Bordered Super Riemann Surfaces
This paper is the third in a sequel to develop a super-analogue of the
classical Selberg trace formula, the Selberg supertrace formula. It deals with
bordered super Riemann surfaces. The theory of bordered super Riemann surfaces
is outlined, and the corresponding Selberg supertrace formula is developed. The
analytic properties of the Selberg super zeta-functions on bordered super
Riemann surfaces are discussed, and super-determinants of Dirac-Laplace
operators on bordered super Riemann surfaces are calculated in terms of Selberg
super zeta-functions.Comment: 43 pages, amste
First Monte Carlo simulation study of Galeras volcano structure using muon tomography
\circledC Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). Muon radiography is based on the observation of the absorption of muons in matter, as the ordinary radiography does by using X-rays. The interaction of cosmic rays with the atmosphere produce Extensive Air Showers (EAS), which provide abundant source of muons. These particles can be used for various applications of muon radiography, in particular to study the internal structure of different volcanoes edifice. We will focus on Galeras volcano located 9 km from Pasto city (Colombia). In this work we present the first study of the muon lateral distribution at Pasto altitude (4276 m a.s.l.) and a preliminary simulation the volcanic cone using GEANT41. For the interaction of the cosmic rays with the atmosphere we have used CORSIKA 740042 software with an atmosphere tropical model and QGSJETII-043 as hadronic model for the high energies and GHEISHA2002d4 for low energies. The analysis considers two different primary particle (proton and iron), four zenith angles (0°, 30°, 45° and 60°) with energies values of 5, 10 and 100 TeV
Antimicrobial activity of Bursera morelensis ramírez essential oil
Background: Bursera morelensis, known as “Aceitillo”, is an endemic tree of Mexico. Infusions made from the bark of this species have been used for the treatment of skin infections and for their wound healing properties. In this work, we present the results of a phytochemical and antimicrobial investigation of the essential oil of B. morelensis.Materials and Methods: The essential oil was obtained by a steam distillation method and analyzed using GC-MS. The antibacterial and antifungal activities were evaluated.Results: GC-MS of the essential oil demonstrated the presence of 28 compounds. The principal compound of the essential oil was α-Phellandrene (32.69%). The essential oil had antibacterial activity against Gram positive and negative strains. The most sensitive strains were S. pneumoniae, V. cholerae (cc) and E. coli (MIC 0.125 mg/mL, MBC 0.25 mg/mL). The essential oil was bactericidal for V. cholera (cc). The essential oil inhibited all the filamentous fungi. F. monilifome (IC50 = 2.27 mg/mL) was the most sensitive fungal strain.Conclusions: This work provides evidence that confirms the antimicrobial activity of the B. morelensis essential oil and this is a scientific support about of traditional uses of this species.Keywords: Essential oil; Medicinal plants; Tehuacan-Cuicatlan Valley; Burseraceae; Burser
Melting and Dimensionality of the Vortex Lattice in Underdoped YBa2Cu3O6.60
Muon spin rotation measurements of the magnetic field distribution in the
vortex state of the oxygen deficient high-Tc superconductor YBa{2}Cu{3}O{6.60}
reveal a vortex-lattice melting transition at much lower temperature than that
in the fully oxygenated material. The transition is best described by a model
in which adjacent layers of ``pancake'' vortices decouple in the liquid phase.
Evidence is also found for a pinning-induced crossover from a solid 3D to
quasi-2D vortex lattice, similar to that observed in the highly anisotropic
superconductor Bi{2+x}Sr{2-x}CaCu{2}O{8+y}.Comment: 8 pages, 4 figures, 5 postscript file
Ultrasound attenuation in gap-anisotropic systems
Transverse ultrasound attenuation provides a weakly-coupled probe of momentum
current correlations in electronic systems. We develop a simple theory for the
interpretation of transverse ultrasound attenuation coefficients in systems
with nodal gap anisotropy. Applying this theory we show how ultrasound can
delineate between extended-s and d-wave scenarios for the cuprate
superconductors.Comment: Uuencode file: 4 pages (Revtex), 3 figures. Some references adde
Extreme Electron-Phonon Coupling in Boron-based Layered Superconductors
The phonon-mode decomposition of the electron-phonon coupling in the
MgB2-like system Li_{1-x}BC is explored using first principles calculations. It
is found that the high temperature superconductivity of such systems results
from extremely strong coupling to only ~2% of the phonon modes. Novel
characteristics of E_2g branches include (1) ``mode lambda'' values of 25 and
greater compared to a mean of for other modes, (2) a precipitous
Kohn anomaly, and (3) E_2g phonon linewidths within a factor of ~2 of the
frequency itself, indicating impending breakdown of linear electron-phonon
theory. This behavior in borne out by recent inelastic x-ray scattering studies
of MgB2 by Shukla et al.Comment: 4 two-column pages, 4 figures. Equations simplified. Figure 4
changed. Comparison with new data include
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