1,824 research outputs found
Photometric reverberation mapping of 3C120
We present the results of a five month monitoring campaign of the local
active galactic nuclei (AGN) 3C120. Observations with a median sampling of two
days were conducted with the robotic 15cm telescope VYSOS-6 located near Cerro
Armazones in Chile. Broad band (B,V) and narrow band (NB) filters were used in
order to measure fluxes of the AGN and the H_beta broad line region (BLR)
emission line. The NB flux is constituted by about 50% continuum and 50% H_beta
emission line. To disentangle line and continuum flux, a synthetic H_beta light
curve was created by subtracting a scaled V-band light curve from the NB light
curve. Here we show that the H_beta emission line responds to continuum
variations with a rest frame lag of 23.6 +/- 1.69 days. We estimate a virial
mass of the central black hole M_BH = 57 +/- 27 * 10^6 solar masses, by
combining the obtained lag with the velocity dispersion of a single
contemporaneous spectrum. Using the flux variation gradient (FVG) method, we
determined the host galaxy subtracted rest frame 5100A luminosity at the time
of our monitoring campaign with an uncertainty of 10% (L_AGN = 6.94 +/- 0.71*
10^43 ergs^-1). Compared with recent spectroscopic reverberation results, 3C120
shifts in the R_BLR - L_AGN diagram remarkably close to the theoretically
expected relation of R-L^0.5. Our results demonstrate the performance of
photometric AGN reverberation mapping, in particular for efficiently
determining the BLR size and the AGN luminosityComment: 11 pages, 11 figures, Published in Astronomy and Astrophysic
Interoperability and Standards: The Way for Innovative Design in Networked Working Environments
Organised by: Cranfield UniversityIn today’s networked economy, strategic business partnerships and outsourcing has become the dominant
paradigm where companies focus on core competencies and skills, as creative design, manufacturing, or
selling. However, achieving seamless interoperability is an ongoing challenge these networks are facing,
due to their distributed and heterogeneous nature. Part of the solution relies on adoption of standards for
design and product data representation, but for sectors predominantly characterized by SMEs, such as the
furniture sector, implementations need to be tailored to reduce costs. This paper recommends a set of best
practices for the fast adoption of the ISO funStep standard modules and presents a framework that enables
the usage of visualization data as a way to reduce costs in manufacturing and electronic catalogue design.Mori Seiki – The Machine Tool Compan
Circumstellar Disks revealed by / Flux Variation Gradients
The variability of young stellar objects (YSO) changes their brightness and
color preventing a proper classification in traditional color-color and color
magnitude diagrams. We have explored the feasibility of the flux variation
gradient (FVG) method for YSOs, using and band monitoring data of the
star forming region RCW\,38 obtained at the University Observatory Bochum in
Chile. Simultaneous multi-epoch flux measurements follow a linear relation
for almost all YSOs with large variability
amplitude. The slope gives the mean color temperature of
the varying component. Because is hotter than the dust sublimation
temperature, we have tentatively assigned it to stellar variations. If the
gradient does not meet the origin of the flux-flux diagram, an additional non-
or less-varying component may be required. If the variability amplitude is
larger at the shorter wavelength, e.g. , this component is cooler
than the star (e.g. a circumstellar disk); vice versa, if , the
component is hotter like a scattering halo or even a companion star. We here
present examples of two YSOs, where the FVG implies the presence of a
circumstellar disk; this finding is consistent with additional data at and
. One YSO shows a clear -band excess in the color-color diagram,
while the significance of a -excess in the other YSO depends on the
measurement epoch. Disentangling the contributions of star and disk it turns
out that the two YSOs have huge variability amplitudes (\,mag). The
FVG analysis is a powerful complementary tool to analyze the varying
components of YSOs and worth further exploration of monitoring data at other
wavelengths.Comment: 5 pages, 5 figures, accepted for publication in Astronomy and
Astrophysic
Modelling photometric reverberation data -- a disk-like broad-line region and a potentially larger black hole mass for 3C120
We consider photometric reverberation mapping, where the nuclear continuum
variations are monitored via a broad-band filter and the echo of emission line
clouds of the broad line region (BLR) is measured with a suitable narrow-band
(NB) filter. We investigate how an incomplete emission-line coverage by the NB
filter influences the BLR size determination. This includes two basic cases: 1)
a symmetric cut of the blue and red part of the line wings, and 2) the filter
positioned asymmetrically to the line centre so that essentially a complete
half of the emission line is contained in the NB filter. Under the assumption
that the BLR size is dominated by circular Keplerian orbits, we find that
symmetric cutting of line wings may lead to overestimating the BLR size by less
than 5%. The case of asymmetric half-line coverage, similar as for our data of
the Seyfert 1 galaxy 3C120, yields the BLR size with a bias of less than 1%.
Our results suggest that any BLR size bias due to narrow-band line cut in
photometric reverberation mapping is small and in most cases negligible. We
used well sampled photometric reverberation mapping light curves with sharp
variation features in both the continuum and the Hbeta light curves to
determine the geometry type of the Hbeta BLR for 3C120. Modelling of the light
curve, under the assumption that the BLR is essentially virialised, argues
against a spherical geometry and favours a nearly face-on disk-like geometry
with inclination i = 10 +/- 4 deg and extension from 22 to 28 light days. The
low inclination may lead to a larger black hole mass than the derived when
using the average geometry scaling factor f=5.5. We discuss deviations of
Seyfert 1 galaxies from the M_BH - sigma relation.Comment: 9 pages, 11 figures, accepted for publication in Astronomy and
Astrophysic
Formación inicial de profesores de educación media de ciencia mediante la teoría de enseñanza y aprendizaje basada en modelos mentales
Este estudio describe cómo se aplica la Teoría de los Modelos Mentales en la formación inicial del profesor de Ciencias de enseñanza media en la Facultad de Educación de la Universidad de Concepción. Esta nueva modalidad de formación, se introdujo a partir del año 2004, en las asignaturas de Didáctica III y IV y en el desarrollo de la tesis de pregrado. Los sesenta estudiantes participantes de la experiencia generaron más de treinta planificaciones de unidades sobre diferentes temas científicos, en las que se utiliza la Teoría de los Modelos Mentales, y que han aplicado a alumnos de enseñanza media. Los dos estudios pilotos que midieron la efectividad de estas planificaciones, indican que el uso de esta perspectiva genera auspiciosos resultados en el aprendizaje de los estudiantes de enseñanza media y en la organización del quehacer en el aula del futuro docente
Modelling and analysing the relationship between innovation and the European Regulations on hazardous waste shipments
In Europe, there are different regulations regarding hazardous waste management with which European Union Member States must comply. On the one hand, Member States must meet the recovery targets that are set in the different waste Directives, and they have two options here: material recovery facilities in the country of origin, or recovery through the shipment of waste. In addition, EU Member States must comply with the regulations governing the shipment of hazardous waste (HW), that is, the Basel Convention and the European Regulation on the shipment of waste. Two main questions arise: where is hazardous waste sent, and why? We analyse the European regulation on the shipment of waste, and we consider the above questions by combining network analysis methodology, to examine which countries in the network can be grouped in HW-trading communities, and ANOVA technique to study how the groups created in the network behave in different contexts. These HW-trading communities can be assessed according to European Innovation Indicators, GDP, and other variables. The results allow us to understand the drivers behind the shipment of HW for recovery in Europe. First, this study provides a descriptive overview of the relationships between European countries, the way in which they cooperate and describes how each country is positioned in the joint network. Second, the study is able to identify the most relevant countries in the network. Third, the HW-trading communities are analysed to discover whether they behave differently from the other groups according to GDP and other variables, amongst which we have included the following Europe Innovation Indicators: innovation index, research systems, innovation friendly environment, or innovators. The results show that the Nordic countries are outstanding in the way in which their waste is managed with other countries and reveal a community that works both in the context of hazardous waste shipment and innovation
Dust reverberation-mapping of the Seyfert 1 galaxy WPVS48
Using robotic telescopes of the Universitatssternwarte Bochum near Cerro
Armazones in Chile, we monitored the z=0.0377 Seyfert 1 galaxy WPVS48 (2MASX
J09594263-3112581) in the optical (B and R) and near-infrared (NIR, J and Ks)
with a cadence of two days. The light curves show unprecedented variability
details. The NIR variation features of WPVS48 are consistent with the
corresponding optical variations, but the features appear sharper in the NIR
than in the optical, suggesting that the optical photons undergo multiple
scatterings. The J and Ks emission, tracing the hot (1600 K) dust echo, lags
the B and R variations by on average 64 +/- 4 days and 71 +/- 5 days,
respectively (restframe). WPVS48 lies on the known tau-M_V relationship.
However, the observed lag is about three times shorter than expected from the
dust sublimation radius r_sub inferred from the optical-UV luminosity, and
explanations for this common discrepancy are searched for. The sharp NIR echos
argue for a face-on torus geometry and allow us to put forward two potential
scenarios: 1) as previously proposed, in the equatorial plane of the accretion
disk the inner region of the torus is flattened and may come closer to the
accretion disk. 2) The dust torus with inner radius r_sub is geometrically and
optically thick, so that the observer only sees the facing rim of the torus
wall, which lies closer to the observer than the torus equatorial plane and
therefore leads to an observed foreshortened lag. Both scenarios are able to
explain the factor three discrepancy between tau and r_sub. Longer-wavelength
dust reverberation data might enable one to distinguish between the scenarios.Comment: 4 pages, 6 figures, Published in Astronomy and Astrophysic
Soft Ground Improved by Rigid Vertical Piles. Experimental and Numerical Study of Two Real Cases in France
Settlements remain the major concern during the construction and along the life of a roadway embankment built over soft soils. A foundation ground reinforced by a system of rigid piles is an effective solution; it reduces and homogenizes the surface settlements. Rigid piles reinforcement system has been strongly developed in France for the last fifteen years, however, confrontations of several design used methods highlighted important variations in results. This results in implementing a French National Research Project A.S.I.RI. (Grounds Improvement by Rigid Inclusions) gathering construction companies, engineering and design departments, universities and research centers. This project aims to propose guidelines for the design, and the construction of reinforced soils by rigid inclusions. After a short presentation of the technique, this article is devoted to two French case studies of ground improvement by rigid piles, the Senette’s street and the Ramp of Glain examples. In both cases a roadway embankment is intended to be supported by soft soil. The compressible soils are soft sandy clay from alluvial origin. The performance of the embankment supporting system is assessed based on monitoring data obtained from various instruments installed during construction including settlement cells, inclinometers, piezometers, total stress cells and Geodetect settlement strip. The study was made with finite differences and finite elements numerical tools. Some analytical methods are used. A confrontation between experimental, analytical and numerical results is then presented
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