Context. Diffusive shock acceleration (DSA) is the most promising mechanism that accelerates Galactic cosmic rays (CRs) in the shocks of supernova remnants (SNRs). It is based on particles scattering ...caused by turbulence ahead and behind the shock. The turbulence upstream is supposedly generated by the CRs, but this process is not well understood. The dominant mechanism may depend on the evolutionary state of the shock and can be studied via the CRs escaping upstream into the interstellar medium (ISM). Aims. Previous observations of the γ Cygni SNR showed a difference in morphology between GeV and TeV energies. Since this SNR has the right age and is at the evolutionary stage for a significant fraction of CRs to escape, our aim is to understand γ-ray emission in the vicinity of the γ Cygni SNR. Methods. We observed the region of the γ Cygni SNR with the MAGIC Imaging Atmospheric Cherenkov telescopes between 2015 May and 2017 September recording 87 h of good-quality data. Additionally, we analysed Fermi-LAT data to study the energy dependence of the morphology as well as the energy spectrum in the GeV to TeV range. The energy spectra and morphology were compared against theoretical predictions, which include a detailed derivation of the CR escape process and their γ-ray generation. Results. The MAGIC and Fermi-LAT data allowed us to identify three emission regions that can be associated with the SNR and that dominate at different energies. Our hadronic emission model accounts well for the morphology and energy spectrum of all source components. It constrains the time-dependence of the maximum energy of the CRs at the shock, the time-dependence of the level of turbulence, and the diffusion coefficient immediately outside the SNR shock. While in agreement with the standard picture of DSA, the time-dependence of the maximum energy was found to be steeper than predicted, and the level of turbulence was found to change over the lifetime of the SNR.
Our team at the INAF-Astronomical Observatory of Padova and the University of Padova is engaged in the design, construction and operations of instruments with very high time accuracy in the optical ...band for applications to High Time Resolution Astrophysics and Quantum Astronomy. Two instruments were built to perform photon counting with sub-nanosecond temporal accuracy, Aqueye+ and Iqueye. Aqueye+ is regularly mounted at the 1.8m Copernicus telescope in Asiago, while Iqueye was mounted at several 4m class telescopes around the world and is now attached through the Iqueye Fiber Interface at the 1.2m Galileo telescope in Asiago. They are used to perform coordinated high time resolution optical observations and, for the first time ever, experiments of optical intensity interferometry on a baseline of a few kilometers. I will report on recent technological developments and scientific results obtained within the framework of this project.
The Vela pulsar is among a number of pulsars which show detectable optical pulsations. We performed optical observations of this pulsar in January and December 2009 with the Iqueye instrument mounted ...at the ESO 3.5 m New Technology Telescope. Our aim was to perform phase fitting of the Iqueye data, and to measure the optical pulse profile of the Vela pulsar at high time resolution, its absolute phase and rotational period. We calculated for the first time an independent optical timing solution and obtained the most detailed optical pulse profile available to date. Iqueye detected a distinct narrow component on the top of one of the two main optical peaks, which was not resolved in previous observations, and a third statistically significant optical peak not aligned with the radio one. The quality of the Iqueye data allowed us to determine the relative time of arrival of the radio-optical-gamma-ray peaks with an accuracy of a fraction of a millisecond. We compare the shape of the Iqueye pulse profile with that observed in other energy bands and discuss its complex multi-wavelength structure.
Several types of Galactic sources, like magnetars, microquasars, novae or pulsar wind nebulae flares, display transient emission in the X-ray band. Some of these sources have also shown emission at ...MeV--GeV energies. However, none of these Galactic transients have ever been detected in the very-high-energy (VHE; E\(>\)100 GeV) regime by any Imaging Air Cherenkov Telescope (IACT). The Galactic Transient task force is a part of the Transient Working group of the Cherenkov Telescope Array (CTA) Consortium. The task force investigates the prospects of detecting the VHE counterpart of such sources, as well as their study following Target of Opportunity (ToO) observations. In this contribution, we will show some of the results of exploring the capabilities of CTA to detect and observe Galactic transients; we assume different array configurations and observing strategies.
A&A 670, A8 (2023) Context. Diffusive shock acceleration (DSA) is the most promising mechanism
to accelerate Galactic cosmic rays (CRs) in the shocks of supernova remnants
(SNRs). The turbulence ...upstream is supposedly generated by the CRs, but this
process is not well understood. The dominant mechanism may depend on the
evolutionary state of the shock and can be studied via the CRs escaping
upstream into the interstellar medium (ISM). Aims. Previous observations of the
$\gamma$-Cygni SNR showed a difference in morphology between GeV and TeV
energies. Since this SNR has the right age and is at the evolutionary stage for
a significant fraction of CRs to escape, we aim to understand $\gamma$-ray
emission in the vicinity of the $\gamma$-Cygni SNR. Methods. We observed the
region of the $\gamma$-Cygni SNR with the MAGIC Imaging Atmospheric Cherenkov
telescopes between May 2015 and September 2017 recording 87 h of good-quality
data. Additionally we analysed Fermi-LAT data to study the energy dependence of
the morphology as well as the energy spectrum in the GeV to TeV range. The
energy spectra and morphology were compared against theoretical predictions,
which include a detailed derivation of the CR escape process and their
$\gamma$-ray generation. Results. The MAGIC and Fermi-LAT data allowed us to
identify three emission regions, which can be associated with the SNR and
dominate at different energies. Our hadronic emission model accounts well for
the morphology and energy spectrum of all source components. It constrains the
time-dependence of the maximum energy of the CRs at the shock, the
time-dependence of the level of turbulence, and the diffusion coefficient
immediately outside the SNR shock. While in agreement with the standard picture
of DSA, the time-dependence of the maximum energy was found to be steeper than
predicted and the level of turbulence was found to change over the lifetime of
the SNR.
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► The geno- and cytotoxicity of gold nanoparticles in cancer and healthy cells were investigated. ► The reactive oxygen species (ROS) generation was evidenced for both cells. ► The ...healthy cells exhibit less sensitive to DNA damage than cancer cells. ► The nanoparticulate systems can be applied in cancer therapy with reduced side effects.
Engineered nanomaterials have been extensively applied as active materials for technological applications. Since the impact of these nanomaterials on health and environment remains undefined, research on their possible toxic effects has attracted considerable attention. It is known that in humans, for example, the primary site of gold nanoparticles (AuNps) accumulation is the liver. The latter has motivated research regarding the use of AuNps for cancer therapy, since specific organs can be target upon appropriate functionalization of specific nanoparticles. In this study, we investigate the geno and cytotoxicity of two types of AuNps against human hepatocellular carcinoma cells (HepG2) and peripheral blood mononuclear cells (PBMC) from healthy human volunteers. The cells were incubated in the presence of different concentrations of AuNps capped with either sodium citrate or polyamidoamine dendrimers (PAMAM). Our results suggest that both types of AuNps interact with HepG2 cells and PBMC and may exhibit in vitro geno and cytotoxicity even at very low concentrations. In addition, the PBMC were less sensitive to DNA damage toxicity effects than cancer HepG2 cells upon exposure to AuNps.
O mundo experimentou, em anos recentes, uma das situações mais difíceis no que tange à saúde, à convivência e às dinâmicas laborais e pessoais, o que trouxe à luz muitos desafios e também ...oportunidades únicas de aprendizagem. Em um contexto em que uma multidão foi hospitalizada, temas como hospitalidade, hotelaria hospitalar, acolhimento, alojamento e cuidado estiveram em evidência. Este trabalho examinou uma experiência de internação em área hospitalar dedicada ao cuidado de pacientes com suspeita de infecção pelo vírus SARS-CoV-2, em um hospital privado da cidade de São Paulo. Teve como objetivo investigar se as áreas de hospitalidade e de hotelaria hospitalar foram significativamente impactadas pelas novas dinâmicas relacionais postas pela pandemia e se, em função dessas dinâmicas, o conceito de hospitalidade e os procedimentos de hotelaria hospitalar foram fortalecidos nos profissionais dos hospitais, que passaram a encontrar na forma de acolhimento e cuidado do outro oportunidades para reconhecerem-se como agentes de hospitalidade. Buscou-se observar comportamentos e condutas profissionais, coletar informações, analisar os dados colhidos e, por indução, explicar como se desenrolou este processo de ajustamento pessoal. A pesquisa, qualitativa e interpretativa, teve coleta de dados por observação (participante e não-participante) e entrevistas informais em profundidade.
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