394 research outputs found
Transplantation of a Human Mammary Carcinoma Cell Line (BT 20) Into Nude Mice
Cell suspensions of a human mammary carcinoma cell line (BT 20), when injected subcutaneously into nude athymic mice (BALB/c Nu/Nu), produced tumor nodules at the injection site. Subsequent serial transplantations also gave rise to neoplastic nodules after latency periods averaging 3 weeks. The nodules displayed morphologic and functional characteristics comparable to those of the original tumor cells. Metastases, however, were not observed in any of the tumor-bearing mic
Anomalous circular polarization profiles in the He I 1083.0 nm multiplet from solar spicules
We report Stokes vector observations of solar spicules and a prominence in
the He I 1083 nm multiplet carried out with the Tenerife Infrared Polarimeter.
The observations show linear polarization profiles that are produced by
scattering processes in the presence of a magnetic field. After a careful data
reduction, we demonstrate the existence of extremely asymmetric Stokes V
profiles in the spicular material that we are able to model with two magnetic
components along the line of sight, and under the presence of atomic
orientation in the energy levels that give rise to the multiplet. We discuss
some possible scenarios that can generate the atomic orientation in spicules.
We stress the importance of spectropolarimetric observations across the limb to
distinguish such signals from observational artifacts.Comment: accepted for publication in Ap
On the Magnetic Field Strength of Active Region Filaments
We study the vector magnetic field of a filament observed over a compact
Active Region Neutral Line. Spectropolarimetric data acquired with TIP-II (VTT,
Tenerife, Spain) of the 10830 \AA spectral region provide full Stokes vectors
which were analyzed using three different methods: magnetograph analysis,
Milne-Eddington inversions and PCA-based atomic polarization inversions. The
inferred magnetic field strengths in the filament are of the order of 600 - 700
G by all these three methods. Longitudinal fields are found in the range of 100
- 200 G whereas the transverse components become dominant, with fields as large
as 500 - 600 G. We find strong transverse fields near the Neutral Line also at
photospheric levels. Our analysis indicates that strong (higher than 500 G, but
below kG) transverse magnetic fields are present in Active Region filaments.
This corresponds to the highest field strengths reliably measured in these
structures. The profiles of the Helium 10830 \AA lines observed in this Active
Region filament are dominated by the Zeeman effect.Comment: Accepted for publication in Astronomy and Astrophysics, 9 pages, 4
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Maximizing team synergy in AI-related interdisciplinary groups: an interdisciplinary-by-design iterative methodology
In this paper, we propose a methodology to maximize the benefits of interdisciplinary cooperation in AI research groups. Firstly, we build the case for the importance of interdisciplinarity in research groups as the best means to tackle the social implications brought about by AI systems, against the backdrop of the EU Commission proposal for an Artificial Intelligence Act. As we are an interdisciplinary group, we address the multi-faceted implications of the mass-scale diffusion of AI-driven technologies. The result of our exercise lead us to postulate the necessity of a behavioural theory that standardizes the interaction process of interdisciplinary groups. In light of this, we conduct a review of the existing approaches to interdisciplinary research on AI appliances, leading to the development of methodologies like ethics-by-design and value-sensitive design, evaluating their strengths and weaknesses. We then put forth an iterative process theory hinging on a narrative approach consisting of four phases: (i) definition of the hypothesis space, (ii) building-up of a common lexicon, (iii) scenario-building, (iv) interdisciplinary self-assessment. Finally, we identify the most relevant fields of application for such a methodology and discuss possible case studies
Factors related to women’s psychological distress during the covid-19 pandemic: Evidence from a two-wave longitudinal study
Background. A growing body of research has highlighted the negative effects of the COVID-19 pandemic on women’s mental health. Previous studies showed that women have higher levels of depression, anxiety and PTSD, and worse psychological adjustment than men, which also persisted after the earlier phase of the pandemic. This study aimed to evaluate changes in women’s psychological distress during the pandemic and to evaluate the factors that have a more significant impact in predicting women’s psychological distress. Methods. This two-wave longitudinal study (T1 = Italian first lockdown, and T2 = second phase, when the restrictive measures were eased) involved 893 women (Mage = 36.45, SD = 14.48). Participants provided demographic and health data as well as measures of psychological distress, emotion regulation processes, and ability to tolerate uncertainty. Results. No significant changes were found in women’s psychological distress between T1 and T2, i.e., during and after the first lockdown. Lower social stability status and higher maladaptive emotional coping predicted high psychological distress. Conclusions. Results showed that modifiable psychological variables play a central role in predicting distress and indicated that emotion regulation interventions might be helpful in increasing psychological resilience and mitigating the adverse impacts of the COVID-19 pandemic within the female population
Genetic analysis of human and swine influenza A viruses isolated in Northern Italy during 2010–2015
Summary Influenza A virus (IAV) infection in swine plays an important role in the ecology of influenza viruses. The emergence of new IAVs comes through different mechanisms, with the genetic reassortment of genes between influenza viruses, also originating from different species, being common. We performed a genetic analysis on 179 IAV isolates from humans (n. 75) and pigs (n. 104) collected in Northern Italy between 2010 and 2015, to monitor the genetic exchange between human and swine IAVs. No cases of human infection with swine strains were noticed, but direct infections of swine with H1N1pdm09 strains were detected. Moreover, we pointed out a continuous circulation of H1N1pdm09 strains in swine populations evidenced by the introduction of internal genes of this subtype. These events contribute to generating new viral variants—possibly endowed with pandemic potential—and emphasize the importance of continuous surveillance at both animal and human level
Estimation of solar prominence magnetic fields based on the reconstructed 3D trajectories of prominence knots
We present an estimation of the lower limits of local magnetic fields in
quiescent, activated, and active (surges) promineces, based on reconstructed
3-dimensional (3D) trajectories of individual prominence knots. The 3D
trajectories, velocities, tangential and centripetal accelerations of the knots
were reconstructed using observational data collected with a single
ground-based telescope equipped with a Multi-channel Subtractive Double Pass
imaging spectrograph. Lower limits of magnetic fields channeling observed
plasma flows were estimated under assumption of the equipartition principle.
Assuming approximate electron densities of the plasma n_e = 5*10^{11} cm^{-3}
in surges and n_e = 5*10^{10} cm^{-3} in quiescent/activated prominences, we
found that the magnetic fields channeling two observed surges range from 16 to
40 Gauss, while in quiescent and activated prominences they were less than 10
Gauss. Our results are consistent with previous detections of weak local
magnetic fields in the solar prominences.Comment: 14 pages, 12 figures, 1 tabl
An active region filament studied simultaneously in the chromosphere and photosphere: I - Magnetic structure
A thorough multiwavelength, multiheight study of the vector magnetic field in
a compact active region (AR) filament (NOAA10781) is presented. We suggest an
evolutionary scenario for this filament. Full Stokes vectors were acquired with
TIP-II in a spectral range which comprises the chromospheric He I 10830 A
multiplet and the photospheric Si I 10827 A line. An AR filament (that was
formed before our observing run) was detected in the He I absorption images on
2005 July 3rd. The chromospheric vector magnetic field in this portion of the
filament was strongly sheared whereas the photospheric field lines underneath
had an inverse polarity configuration. From July 3rd to July 5th, an opening
and closing of the polarities at either side of the polarity inversion line
(PIL) was recorded, resembling the recently discovered process of the sliding
door effect seen by Hinode. During this time, a newly created region that
contained pores and orphan penumbrae at the PIL was observed.On July 5th, a
normal polarity configuration was inferred from the chromospheric spectra,
while strongly sheared field lines aligned with the PIL were found in the
photosphere. In this same data set, the spine of the filament is also observed
in a different portion of the FOV and is clearly mapped by the Silicon line
core. The inferred vector magnetic fields of the filament suggest a flux rope
topology. Furthermore, the observations indicate that the filament is divided
in two parts, one which lies in the chromosphere and another one that stays
trapped in the photosphere. Therefore, only the top of the helical structure is
seen by the Helium lines. The pores and orphan penumbrae at the PIL appear to
be the photospheric counterpart of the extremely low-lying filament. We suggest
that orphan penumbrae are formed in very narrow PILs of compact ARs and are the
photospheric manifestation of flux ropes in the photosphere.Comment: Accepted for publication in Astronomy & Astrophysics, 16 pages, 13
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Polarimetric Diagnostics of Unresolved Chromospheric Magnetic Fields
For about a decade, spectro-polarimetry of HeI 10830 has been applied to the
magnetic diagnostics of the solar chromosphere. This resonance line is very
versatile, as it is visible both on disk and in off-limb structures, and it has
a good sensitivity to both the weak-field Hanle effect and the strong-field
Zeeman effect. Recent observations of an active-region filament showed that the
linear polarization was dominated by the transverse Zeeman effect, with very
little or no hint of scattering polarization. This is surprising, since the HeI
levels should be significantly polarized in a conventional scattering scenario.
To explain the observed level of atomic depolarization by collisional or
radiative processes, one must invoke plasma densities larger by several orders
of magnitude than currently known values for prominences. We show that such
depolarization can be explained quite naturally by the presence of an
unresolved, highly entangled magnetic field, which averages to give the ordered
field inferred from spectro-polarimetric data, over the typical temporal and
spatial scales of the observations. We present a modeling of the polarized HeI
10830 in this scenario, and discuss its implications for the magnetic
diagnostics of prominences and spicules, and for the general study of
unresolved magnetic field distributions in the solar atmosphere
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