Gain variations as induced by the diffuse night sky background: the ASTRI-Horn experience

ASTRI-Horn is the prototype of the nine telescopes that form the ASTRI Mini-Array, under construction at the Teide Observatory in Spain, devoted to observe the sky above 10 TeV. It adopts an innovative optical design based on a dual-mirror Schwarzschild-Couder configuration, and the camera, composed by a matrix of monolithic multipixel silicon photomultipliers (SiPMs) is managed by ad-hoc tailored front-end electronics based on a peak-detector operation mode. During the Crab Nebula campaign in 2018-2019, ASTRI-Horn was affected by gain variations induced by high levels of night sky background. This paper reports the work performed to detect and quantify the effects of these gain variations in shower images. The analysis requested the use of simultaneous observations of the night sky background flux in the wavelength band 300-650 nm performed with the auxiliary instrument UVscope, a calibrated multi-anode photomultiplier working in single counting mode. As results, a maximum gain reduction of 15% was obtained, in agreement with the value previously computed from the variance of the background level in each image. This ASTRI-Horn gain reduction was caused by current limitation of the voltage supply. The analysis presented in this paper provides a method to evaluate possible variations in the nominal response of SiPMs when scientific observations are performed in the presence of high night sky background as in dark or gray conditions.Comment: 14 pages, 8 figures -- Submitted to Journal of Instrumentation (JINST) peer review on 10 November 202

Muon calibration of the ASTRI-Horn telescope: preliminary results

Astri-Horn is a Small-Sized Telescope (SST) for very-high energy gamma-ray astronomy installed in Italy at the INAF "M.C. Fracastoro" observing station (Mt. Etna, Sicily). The ASTRI-Horn telescope is characterized by a dual-mirror optical system and a curved focal surface covered by SiPM sensors managed by a innovative fast front-end electronics. Dedicated studies were performed to verify the feasibility of the calibration through muons on the relatively small size of the primary mirror (~4 m diameter), as in the case of larger Cherenkov telescopes. A number of tests were performed using simulations of the atmospheric showers with the CORSIKA package and of the telescope response with a dedicated simulator. In this contribution we present a preliminary analysis of muon events detected by ASTRI-Horn during the regular scientific data taking performed in December 2018 and March 2019. These muon events validate the results obtained with the simulations and definitively confirm the feasibility of calibrating the ASTRI-Horn SST telescope with muons.Comment: Proceedings of the 36th International Cosmic Ray Conference, Madison, Wisconsin, USA, 24 July-1 August 201

The Software Architecture and development approach for the ASTRI Mini-Array gamma-ray air-Cherenkov experiment at the Observatorio del Teide

The ASTRI Mini-Array is an international collaboration led by the Italian National Institute for Astrophysics (INAF) and devoted to the imaging of atmospheric Cherenkov light for very-high gamma-ray astronomy. The project is deploying an array of 9 telescopes sensitive above 1 TeV. In this contribution, we present the architecture of the software that covers the entire life cycle of the observatory, from scheduling to remote operations and data dissemination. The high-speed networking connection available between the observatory site, at the Canary Islands, and the Data Center in Rome allows for ready data availability for stereo triggering and data processing

The methodological approach for the generation of human dendritic cells from monocytes affects the maturation state of the resultant dendritic cells

Dendritic cells (DCs) are effective as antigen-presenting cells in the immune system and are present at two functional stages depending on their maturation state. For experimental investigation of this concept, CD14(+) monocytes from blood are isolated and cultured to generate in vitro the DCs needed for functional analysis. For positive selection of CD14(+) monocytes we compared two immunomagnetic bead technologies: MACS Separation, created by Miltenyi Biotec, and EasySep Selection, created by StemCell Technologies. The monocytes provided dendritic cells for their functional analysis. Lipopolysaccharide was added to cultured DCs to induce maturation. Although both systems generated DCs from the positively selected CD14(+) cells, there were certain differences between them. Morphological, phenotypic, and functional analysis showed that MACS-selection provided DCs that have typical features corresponding to day 6 or 7 of maturation. EasySep-DCs exist in a partially-mature state from day 6 onward, even without the addition of a maturation stimulus. The reason behind this partial maturation is possibly based on the dextran-coated beads that are associated with the EasySep product. Both methods provide pure and viable DCs, but we would recommend using the MACS system for obtaining DCs suitable for functional studies

Stimuli responsive gels based on interpenetrating network of chitosan and poly(vinyl pyrrolidone)

summary:We take some well-known inequalities for Green functions relative to Laplace's equation, and prove not only analogues of them relative to the heat equation, but generalizations of those analogues to the heat potentials of nonnegative measures on an arbitrary open set $E$ whose supports are compact polar subsets of $E$. We then use the special case where the measure associated to the potential has point support, in the following situation. Given a nonnegative supertemperature on an open set $E$, we prove a formula for the associated Riesz measure of any point of $E$ in terms of a limit inferior of the quotient of the supertemperature and the Green function for $E$ with a pole at that point

Root extracts of three species of Echinacea affect the maturation state of monocyte-generated human dendritic cells

Our study aims at investigating the effects of Echinacea phytocompounds on monocyte derived-dendritic cell (DC) generation, maturation and biological activity. Phenotypical evaluation, endocytic capacity and the dosage of culture surnatant cytokine are performed on immature and mature DCs, treated or not with E. purpurea, E. pallida, E. angustifolia root extracts (100-150-200 μg/mL). Our results demonstrate that Echinacea extracts don’t affect DC generation, while they interfere with their maturation (shown as a reduced expression of CD40, CD80, CD83 and HLA-DR antigens). Moreover, they seem to reduce the endocytic activity and the production of IL-10. No significant differences among the extracts belonging to the three analysed species have been noticed.Introduction. Echinacea represents a perennial plant indigenous to North America, but also cultured in Europe since a lot of years 1. Ten species belong to this genus 2, but only three species show pharmacological properties: E. angustifolia, E. pallida, E. purpurea 3.Up to date, formulations with Echinacea extracts are usually used for their immunomodulatory, antiiflammatory, antiviral and antioxidant activities, even if the mechanism of the action of their component has not yet been investigated.The goal of our study is to investigate the mechanism of action by which Echinacea phytocompounds have an immunoenhancing activity, focusing on the effects of these extracts on dendritic cell (DC) generation, maturation and biological activity. DCs are the most important antigen-presenting cells: they check both the first phase and the maintenance of adaptative immune responses and the induction of tolerance 4-7.Materials and Methods. DCs are in vitro generated from CD14+ circling monocytes, obtained from mononuclear cells of healthy donors, through an immunomagnetic system (Miltenyi Biotec, Germany). Monocytes are cultured in RPMI 1640 medium, added with fetal bovine serum, L-glutamine, streptomycin and penicillin and supplemented with growth factors (GM-CSF and IL-4) 5, in presence or absence of total root extract of the three specie of Echinacea (E. purpurea, E. pallida, E. angustifolia). These extracts are tested at a concentration of 100, 150 and 200 μg/mL. After 6 days of incubation, LPS is added to the culture for further 24 hours, in order to induce maturation. Then, morphological and phenotypical analysis are performed respectively by cytospin, May-Grunwald Giemsa staining and cytometric assays. The markers used are CD14 antigen, present on monocytes surface, but not on DC surface, CD40 and CD80 costimulatory molecules, HLA class II (HLA-DR) antigen and CD83 antigen, expressed by mature DCs 8.Functional studies on DCs generated in presence of Echinacea include cytometric analysis of endocytotic activity mediated by mannose receptor, using the dextran FITC-conjugated as an antigen, and the dosage of culture surnatant cytokines (IL-6, IL-1, IL-10, IL-12, TNF-α, TGF-β) through an enzyme immunoassay.Results and Discussion. Echinacea phytocompounds don’t compromise DC generation from monocytes (loss of CD14 expression on cells surface).Neverthless, total extracts interfere with the maturation, as the reduced expression of CD83 antigen shows if compared to the control. Moreover, in presence of Echinacea, a reduced expression (both as percentage and mean) of the CD80 and HLA-DR is observed, if compared to the control; as far the CD40 antigen is concerned, its percentage remains unchanged, while the mean decreases in presence of the extracts, compared to the control. No significant differences of cell phenotype among the different concentrations used, nor among the extracts belonging to the three analysed species, is noticed (Fig. 1).When on the 6th day we perform endocytosis assay, in presence of total root extract of Echinacea we observe no differences compared with the control: the cells show a marked phagocytic activity. On the contrary, on the 7th day, the cells treated with E. purpurea keep a more intense activity if compared to the control, even if slightly inferior to that one shown at the immature stage (Fig. 2).Cytokine dosage is carried out on the 7th day. In the sample treated with Echinacea we remark an increase in the release of IL-1 and a decrease in the concentration of IL-10, compared with the control. We notice no relevant differences between the three species we used (Fig. 3).Conclusions. Our study deserves further investigation. In fact, as far as the various and reported pharmacological properties is concerned, up to date the immunomodulatory activity is only partially elucidated. Analysing the literature and our data it seems fundamental to understand which are the compounds responsible of the pharmacological activity of the plant and the mechanism of action by which it is realized. For these reasons, we are going to study the activity of lipophilic and hydrophilic fractions of Echinacea extracts on DCs, but also evaluing the effects of separate active principals on these cells. It could be interesting to identify a possible fraction or species mainly responsible of the observed effects