258 research outputs found
Representaciones en el plano de cambios de nivel en el espacio por escolares de 5 años: estudio de casos
En este poster presentamos diferentes simbolizaciones que utilizan escolares del aula de infantil de 5 años para representar en un plano cambios de nivel en el espacio tridimensional. En particular, basándonos en un enfoque contextualizado y globalizado de la matemática (Alsina, 2012; Berdonneau, 2008), se ha diseñado una actividad (Gonzato, Fernández y Godino, 2011) en la que los niños y niñas tienen que localizar un tesoro escondido en el centro escolar situado en un piso distinto al de su ubicación y representar individualmente en un plano el itinerario seguido para hallarlo
A new perspective on the submillimetre galaxy MM 18423+5938 at redshift 3.9296 from radio continuum imaging
The bright submillimetre (sub-mm) galaxy MM 18423+5938 at redshift 3.9296 has
been predicted from mid-infrared and millimetre photometry to have an
exceptionally large total infrared (IR) luminosity. We present new radio
imaging at 1.4 GHz with the Westerbork Synthesis Radio Telescope that is used
to determine a radio-derived total IR luminosity for MM 18423+5938 via the well
established radio-far-infrared correlation. The flux density is found to be
S_1.4 GHz = 217 +/- 37 \mu Jy, which corresponds to a rest-frame luminosity
density of L_1.4 GHz = 2.32 +/- 0.40 x 10^25 / u W / Hz, where u is the
magnification from a probable gravitational lens. The radio-derived total IR
luminosity and star-formation rate are L_8-1000 \mu m = 5.6^+4.1_-2.4 x 10^13 /
u L_sol and SFR = 9.4^+7.4_-4.9 x 10^3 / u M_sol / yr, respectively, which are
~9 times smaller than those previously reported. These differences are
attributed to the IR spectral energy distribution of MM 18423+5938 being poorly
constrained by the limited number of reliable photometric data that are
currently available, and from a previous misidentification of the object at 70
\mu m. Using the radio derived total IR luminosity as a constraint, the
temperature of the cold dust component is found to be T ~ 24^+7_-5 K for a dust
emissivity of \beta = 1.5 +/- 0.5. The radio-derived properties of this galaxy
are still large given the low excitation temperature implied by the CO emission
lines and the temperature of the cold dust. Therefore, we conclude that MM
18423+5938 is probably gravitationally lensed.Comment: 5 pages, 2 figures, 1 table, accepted for publication in MNRAS
Letter
Comparison of an X-ray selected sample of massive lensing clusters with the MareNostrum Universe LCDM simulation
A long-standing problem of strong lensing by galaxy clusters regards the
observed high rate of giant gravitational arcs as compared to the predictions
in the framework of the "standard" cosmological model. Recently, few other
inconsistencies between theoretical expectations and observations have been
claimed which regard the large size of the Einstein rings and the high
concentrations of few clusters with strong lensing features. All of these
problems consistently indicate that observed galaxy clusters may be
gravitational lenses stronger than expected. We use clusters extracted from the
MareNostrum Universe to build up mock catalogs of galaxy clusters selected
through their X-ray flux. We use these objects to estimate the probability
distributions of lensing cross sections, Einstein rings, and concentrations for
the sample of 12 MACS clusters at presented in Ebeling et al. (2007)
and discussed in Zitrin et al. (2010). We find that simulated clusters produce
less arcs than observed clusters do. The medians of the
distributions of the Einstein ring sizes differ by between
simulations and observations. We estimate that, due to cluster triaxiality and
orientation biases affecting the lenses with the largest cross sections, the
concentrations of the individual MACS clusters inferred from the lensing
analysis should be up to a factor of larger than expected from the
CDM model. The arc statistics, the Einstein ring, and the
concentration problems in strong lensing clusters are mitigated but not solved
on the basis of our analysis. Nevertheless, due to the lack of redshifts for
most of the multiple image systems used for modeling the MACS clusters, the
results of this work will need to be verified with additional data. The
upcoming CLASH program will provide an ideal sample for extending our
comparison (abridged).Comment: 11 pages, 9 figures, accepted for publication on A&
Detection of rhabdovirus viral RNA in oropharyngeal swabs and ectoparasites of spanish bats
Rhabdoviruses infect a variety of hosts, including mammals, birds, reptiles, fish, insects and plants. As bats are the natural host for most members of the genus Lyssavirus, the specificity of the amplification methods used for active surveillance is usually restricted to lyssaviruses. However, the presence of other rhabdoviruses in bats has also been reported. In order to broaden the scope of such methods, a new RT-PCR, able to detect a diverse range of rhabdoviruses, was designed. The method detected 81 of 86 different rhabdoviruses. In total, 1488 oropharyngeal bat swabs and 38 nycteribiid samples were analysed, and 17 unique rhabdovirus-related sequences were detected. Phylogenetic analysis suggested that those sequences detected in bats did not constitute a monophyletic group, even when originating from the same bat species. However, all of the sequences detected in nycteribiids and one sequence obtained from a bat did constitute a monophyletic group with Drosophila melanogaster sigma rhabdovirus. © 2013 Crown.Peer Reviewe
New Adenovirus Groups in Western Palaearctic Bats
In the context of long-term screening for viruses on Western Palaearctic bats, we tested for the presence of adenovirus 1392 oropharyngeal swabs and 325 stool samples taken from 27 bat species. Adenoviruses were detected in 12 species of the Vespertilionidae and the Rhinolophidae families. Fifty positive respiratory and 26 positive stool samples were studied. Phylogenetic analyses of partial hexon protein and partial DNA-dependent DNA polymerase genes indicate that all these bat adenoviruses belong to the genus Mastadenovirus but without constituting a monophyletic cluster. According to genetic identities, the new groups are distinct to the previously described Bat mastadenovirus A and B species and contribute with potentially new members. Our data support that diversity of bat mastadenovirus is host-dependent and increase the knowledge of potentially pathogenic virus from bats. Due to the active role of bats as viral reservoirs, the characterization of these viruses is relevant for Public Health.This project was financially supported by an agreement between the Public Health Department of the Spanish Ministry of Health and the Instituto de Salud Carlos III for the development of "Rabies Surveillance in Spain" and by projects SAF 2006-12784-C02-01, SAF 2006-12784-C02-02, SAF 2009-09172 and SAF2013-47194-P of the General Research Programme of the Spanish Ministry of Science and Education
Investigating Local Patterns of Mumps Virus Circulation, Using a Combination of Molecular Tools
Mumps is a vaccine-preventable disease caused by the mumps virus (MuV). However, MuV has re-emerged in many countries with high vaccine coverage. The World Health Organization (WHO) recommends molecular surveillance based on sequencing of the small hydrophobic (SH) gene. Additionally, the combined use of SH and non-coding regions (NCR) has been described in different studies, proving to be a useful complement marker to discriminate general patterns of circulation at national and international levels. The aim of this work is to test local-level usefulness of the combination of SH and MF-NCR sequencing in tracing hidden transmission clusters and chains during the last epidemic wave (2015-2020) in Spain. A database with 903 cases from the Autonomous Community of Madrid was generated by the integration of microbiological and epidemiological data. Of these, 453 representative cases were genotyped. Eight different SH variants and thirty-four SH haplotypes were detected. Local MuV circulation showed the same temporal pattern previously described at a national level. Only two of the thirteen previously identified outbreaks were caused by more than one variant/haplotype. Geographical representation of SH variants allowed the identification of several previously undetected clusters, which were analysed phylogenetically by the combination of SH and MF-NCR, in a total of 90 cases. MF-NCR was not able to improve the discrimination of geographical clusters based on SH sequencing, showing limited resolution for outbreak investigations.A.M.G. was funded by CIBER de Epidemiología y Salud Pública (CIBERESP), ISCIII. This work was supported by the “Instituto de Salud Carlos III” (PI15CIII/00023 and PI19ICIII/0041).S
Highly sensitive 56 Gbps NRZ O-band BiCMOS-silicon photonics receiver using a Ge/Si avalanche photodiode
A hybrid BiCMOS-Silicon Photonics receiver with a waveguide-coupled Ge/Si avalanche photodiode is demonstrated with OMA sensitivities of −14.4dBm for error-free operation at 50 Gbps and -18.6 dBm under the KP4-FEC limit at 56 Gbps NRZ-OOK
The stellar masses and specific star-formation rates of submillimetre galaxies
Establishing the stellar masses (M*), and hence specific star-formation rates
(sSFRs) of submillimetre galaxies (SMGs) is crucial for determining their role
in the cosmic galaxy/star formation. However, there is as yet no consensus over
the typical M* of SMGs. Specifically, even for the same set of SMGs, the
reported average M* have ranged over an order of magnitude, from ~5x10^10 Mo to
~5x10^11 Mo. Here we study how different methods of analysis can lead to such
widely varying results. We find that, contrary to recent claims in the
literature, potential contamination of IRAC 3-8 um photometry from hot dust
associated with an active nucleus is not the origin of the published
discrepancies in derived M*. Instead, we expose in detail how inferred M*
depends on assumptions made in the photometric fitting, and quantify the
individual and cumulative effects of different choices of initial mass
function, different brands of evolutionary synthesis models, and different
forms of assumed star-formation history. We review current observational
evidence for and against these alternatives as well as clues from the
hydrodynamical simulations, and conclude that, for the most justifiable choices
of these model inputs, the average M* of SMGs is ~2x10^11 Mo. We also confirm
that this number is perfectly reasonable in the light of the latest
measurements of their dynamical masses, and the evolving M* function of the
overall galaxy population. M* of this order imply that the average sSFR of SMGs
is comparable to that of other star-forming galaxies at z>2, at 2-3 Gyr^-1.
This supports the view that, while rare outliers may be found at any M*, most
SMGs simply form the top end of the main-sequence of star-forming galaxies at
these redshifts. Conversely, this argues strongly against the viewpoint that
SMGs are extreme pathological objects, of little relevance in the cosmic
history of star-formation.Comment: Accepted to A&A. 13 pages, 5 figures, 3 tables. Main changes: 1)
investigation that the main-sequence does not change the location as much as
SMGs when changing SFHs; 2) a new table added with all stellar mass estimates
for individual SMGs (machine-readable version in the source file). V3:
missing references adde
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