6,728 research outputs found
ID5.17: New LearnWeb tool v.0.3 evaluation outcomes
Mazzetti, A., & Perez, M. (2009). ID5.17: New LearnWeb tool v.0.3 evaluation outcomes: TENCompetence.This document describes the evaluation of the new version of LearnWeb2.0, called: LearnWeb v.0.3 and KRService v.0.3. After a brief introduction, the evaluation methodology is described, both in terms of functionality tests and of quality tests. Then the loadability tests are described along with the usability aspects. A summary of the functionality follows, with the final recommendations for future versions.
This document is an internal deliverable of WP5. It deals with the evaluation of the software LearnWeb2.0 v.0.3The work on this publication has been sponsored by the TENCompetence Integrated Project that is funded by the European Commission's 6th Framework Programme, priority IST/Technology Enhanced Learning. Contract 027087 [http://www.tencompetence.org
Molecular gas and nuclear activity in early-type galaxies: any link with radio-loudness?
Aims. We want to study the amount of molecular gas in a sample of nearby
early-type galaxies (ETGs) which host low-luminosity Active Galactic Nuclei
(AGN). We look for possible differences between the radio-loud (RL) and
radio-quiet (RQ) AGN. Methods. We observed the CO(1-0) and CO(2-1) spectral
lines with the IRAM 30m and NRO 45m telescopes for eight galaxies. They belong
to a large sample of 37 local ETGs which host both RQ and RL AGN. We gather
data from the literature for the entire sample. Results. We report the new
detection of CO(1-0) emission in four galaxies (UGC0968, UGC5617, UGC6946, and
UGC8355) and CO(2-1) emission in two of them (UGC0968 and UGC5617). The
CO(2-1)/CO(1-0) ratio in these sources is . Considering both the
new observations and the literature, the detection rate of CO in our sample is
55 9%, with no statistically significant difference between the hosts of
RL and RQ AGNs. For all the detected galaxies we converted the CO luminosities
into the molecular masses, , that range from 10 to 10
M, without any statistically significant differences between RL and
RQ galaxies. This suggests that the amount of molecular gas does not likely set
the radio-loudness of the AGN. Furthermore, despite the low statistical
significance, the presence of a weak trend between the H mass with
various tracers of nuclear activity (mainly [O III] emission line nuclear
power) cannot be excluded.Comment: Accepted for publication on A&A, 9 pages, 5 figure
Probing an ultralight QCD axion with electromagnetic quadratic interaction
The axion-gluon coupling is the defining feature of the QCD axion. This
feature induces additional and qualitatively different interactions of the
axion with standard model particles -- quadratic couplings. Previously,
hadronic quadratic couplings have been studied and experimental implications
have been explored especially in the context of atomic spectroscopy and
interferometry. We investigate additional quadratic couplings to the
electromagnetic field and electron mass. These electromagnetic quadratic
couplings are generated at the loop level from threshold corrections and are
expected to be present in the absence of fine-tuning. While they are generally
loop-suppressed compared to the hadronic ones, they open up new ways to search
for the QCD axion, for instance via optical atomic clocks. Moreover, due to the
velocity spread of the dark matter field, the quadratic nature of the coupling
leads to low-frequency fluctuations in any detector setup. These distinctive
low-frequency fluctuations offer a way to search for heavier axions. We provide
an analytic expression for the power spectral density of this low-frequency
background and briefly discuss experimental strategies for a low-frequency
background search.Comment: 13 pages, 4 figure
Performance and reliability comparison of 1T-1R RRAM arrays with amorphous and polycrystalline HfO2
In this work, a comparison between 1T-1R RRAM 4kbits arrays manufactured either with amorphous or polycrystalline HfO2 in terms of performance, reliability, Set/Reset operations energy requirements, intra-cell and inter-cell variability during 10k Set/Reset cycles is reported. Polycrystalline array shows higher current ratio, lower switching voltages, lower power consumption, minor endurance degradation and higher overall yield than amorphous array. The drawbacks are represented by the higher Forming voltage, the larger read current distribution after Forming and the higher Reset voltage dispersion
ULYSSES: Universal LeptogeneSiS Equation Solver
ULYSSES is a python package that calculates the baryon asymmetry produced
from leptogenesis in the context of a type-I seesaw mechanism. The code solves
the semi-classical Boltzmann equations for points in the model parameter space
as specified by the user. We provide a selection of predefined Boltzmann
equations as well as a plugin mechanism for externally provided models of
leptogenesis. Furthermore, the ULYSSES code provides tools for
multi-dimensional parameter space exploration. The emphasis of the code is on
user flexibility and rapid evaluation. It is publicly available at
https://github.com/earlyuniverse/ulyssesComment: 20 pages, 2 figures, 4 table
Nuclear spirals as feeding channels to the Supermassive Black Hole: the case of the galaxy NGC 6951
We report the discovery of gas streaming motions along nuclear spiral arms
towards the LINER nucleus of the galaxy NGC 6951. The observations, obtained
using the GMOS integral field spectrograph on the Gemini North telescope,
yielded maps of the flux distributions and gas kinematics in the Halpha,
[NII]6584 and [SII]6717,31 emission lines of the inner 7x5 arcsec^2 of the
galaxy. This region includes a circumnuclear star-forming ring with radius
500pc, a nuclear spiral inside the ring and the LINER nucleus. The kinematics
of the ionized gas is dominated by rotation, but subtraction of a kinematic
model of a rotating exponential disk reveals deviations from circular rotation
within the nuclear ring which can be attributed to (1) streaming motions along
the nuclear spiral arms and (2) a bipolar outflow which seems to be associated
to a nuclear jet. On the basis of the observed streaming velocities and
geometry of the spiral arms we estimate a mass inflow rate of ionized gas of
3x10^(-4) Msun/yr, which is of the order of the accretion rate necessary to
power the LINER nucleus of NGC 6951. Similar streaming motions towards the
nucleus of another galaxy with LINER nucleus -- NGC 1097 -- have been reported
by our group in a previous paper. Taken together, these results support a
scenario in which nuclear spirals are channels through which matter is
transferred from galactic scales to the nuclear region to feed the supermassive
black hole.Comment: 25 pages, 6 eps figures, accepted for publication in Ap
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