Cold fronts in galaxy clusters

Cold fronts have been observed in a large number of galaxy clusters. Understanding their nature and origin is of primary importance for the investigation of the internal dynamics of clusters. To gain insight on the nature of these features, we carry out a statistical investigation of their occurrence in a sample of galaxy clusters observed with XMM-Newton and we correlate their presence with different cluster properties. We have selected a sample of 45 clusters starting from the B55 flux limited sample by Edge et al. (1990) and performed a systematic search of cold fronts. We find that a large fraction of clusters host at least one cold front. Cold fronts are easily detected in all systems that are manifestly undergoing a merger event in the plane of the sky while the presence of such features in the remaining clusters is related to the presence of a steep entropy gradient, in agreement with theoretical expectations. Assuming that cold fronts in cool core clusters are triggered by minor merger events, we estimate a minimum of 1/3 merging events per halo per Gyr.Comment: Accepted for publication in Astronomy & Astrophysics. Version with full resolution figures available at: http://www.iasf-milano.inaf.it/~simona/pub/coldfronts/ghizzardi.pd

Molecular and cellular processes of the innate immune response in insects: investigation on the immune modulation induced by entomopathogenic nematodes

Aim of this project was to investigate relationships between Rhynchophorus ferrugineus or Galleria mellonella and the entomopathogenic nematode Steinernema carpocapsae. In particular, the work was focused on the immune response of the insect host either in na\uefve larvae or in larvae infected with entomoparasites. We analyzed different immunological processes: the activity and modulation of prophenoloxidase-phenoloxidase (proPO) system, the cell-mediated encapsulation, the antimicrobial peptides (AMPs) inducible response and finally the phagocytosis activity of the host hemocytes. Furthermore, we investigated the immune depressive and immune evasive strategies of the parasite. Our results indicated that R. ferrugineus has an efficient immune system; however, in the early phase of infection, the presence of S. carpocapsae induces a strong inhibition of the host proPO system. In addition, the parasite does not seem to be susceptible to the encapsulation by host hemocytes; the parasite mimetic properties seem to be related to the structure of its body surface. S. carpocapsae, before the release of its symbiotic bacteria (X. nematophila), depresses and elude the host immune defenses, with the aim to create a favorable environment for its symbionts responsible of the septicemic death of the insect host. Besides, our results have demonstrated that X. nematophila is able to inhibit the synthesis and the activity of antimicrobial peptides. X .nematophila elude the recognition by hemocytes since it is not engulfed by the host cells. It is evident that the nematode and its symbiotic bacteria cooperate to elude and inhibit immune responses of the insect host. This study provides data that can help to a better understand of the relationships between parasites and their hosts

Molecular and cellular processes of the innate immune response in insects: investigation on the immune modulation induced by entomopathogenic nematodes

Aim of this project was to investigate relationships between Rhynchophorus ferrugineus or Galleria mellonella and the entomopathogenic nematode Steinernema carpocapsae. In particular, the work was focused on the immune response of the insect host either in naïve larvae or in larvae infected with entomoparasites. We analyzed different immunological processes: the activity and modulation of prophenoloxidase-phenoloxidase (proPO) system, the cell-mediated encapsulation, the antimicrobial peptides (AMPs) inducible response and finally the phagocytosis activity of the host hemocytes. Furthermore, we investigated the immune depressive and immune evasive strategies of the parasite. Our results indicated that R. ferrugineus has an efficient immune system; however, in the early phase of infection, the presence of S. carpocapsae induces a strong inhibition of the host proPO system. In addition, the parasite does not seem to be susceptible to the encapsulation by host hemocytes; the parasite mimetic properties seem to be related to the structure of its body surface. S. carpocapsae, before the release of its symbiotic bacteria (X. nematophila), depresses and elude the host immune defenses, with the aim to create a favorable environment for its symbionts responsible of the septicemic death of the insect host. Besides, our results have demonstrated that X. nematophila is able to inhibit the synthesis and the activity of antimicrobial peptides. X .nematophila elude the recognition by hemocytes since it is not engulfed by the host cells. It is evident that the nematode and its symbiotic bacteria cooperate to elude and inhibit immune responses of the insect host. This study provides data that can help to a better understand of the relationships between parasites and their hosts

Polyhydroxyalkanoate as a slow-release carbon source for in situ bioremediation of contaminated aquifers: from laboratory investigation to pilot-scale testing in the field

A pilot-scale study aiming to evaluate the potential use of poly-3-hydroxy-butyrate (PHB) as an electron donor source for in situ bioremediation of chlorinated hydrocarbons in groundwater was conducted. Compared with commercially available electron donors, PHB offers a restricted fermentation pathway (i.e., through acetic acid and molecular hydrogen) by avoiding the formation of any residual carbon that could potentially spoil groundwater quality. The pilot study was carried out at an industrial site in Italy, heavily contaminated by different chlorinated aliphatic hydrocarbons (CAHs). Prior to field testing, PHB was experimentally verified as a suitable electron donor for biological reductive dechlorination processes at the investigated site by microcosm studies carried out on site aquifer material and measuring the quantitative transformation of detected CAHs to ethene. Owing to the complex geological characteristics of the aquifer, the use of a groundwater circulation well (GCW) was identified as a potential strategy to enable effective delivery and distribution of electron donors in less permeable layers and to mobilise contaminants. A 3-screened, 30-m-deep GCW coupled with an external treatment unit was installed at the site. The effect of PHB fermentation products on the in situ reductive dechlorination processes were evaluated by quantitative real-time polymerase chain reaction (qPCR). The results from the first 4 months of operation clearly demonstrated that the PHB fermentation products were effectively delivered to the aquifer and positively influenced the biological dechlorination activity. Indeed, an increased abundance of Dehalococcoides mccartyi (up to 6.6 fold) and reduced CAH concentrations at the installed monitoring wells were observed

A systematic analysis of the XMM-Newton background: III. Impact of the magnetospheric environment

A detailed characterization of the particle induced background is fundamental for many of the scientific objectives of the Athena X-ray telescope, thus an adequate knowledge of the background that will be encountered by Athena is desirable. Current X-ray telescopes have shown that the intensity of the particle induced background can be highly variable. Different regions of the magnetosphere can have very different environmental conditions, which can, in principle, differently affect the particle induced background detected by the instruments. We present results concerning the influence of the magnetospheric environment on the background detected by EPIC instrument onboard XMM-Newton through the estimate of the variation of the in-Field-of-View background excess along the XMM-Newton orbit. An important contribution to the XMM background, which may affect the Athena background as well, comes from soft proton flares. Along with the flaring component a low-intensity component is also present. We find that both show modest variations in the different magnetozones and that the soft proton component shows a strong trend with the distance from Earth.Comment: To appear in Experimental Astronomy. Presented at AHEAD Background Workshop, 28-30 November 2016. Rome, Ital

A Systematic Analysis of the XMM-Newton Background: I. Dataset and Extraction Procedures

XMM-Newton is the direct precursor of the future ESA ATHENA mission. A study of its particle-induced background provides therefore significant insight for the ATHENA mission design. We make use of about 12 years of data, products from the third XMM-Newton catalog as well as FP7 EXTraS project to avoid celestial sources contamination and to disentangle the different components of the XMM-Newton particle-induced background. Within the ESA R&D AREMBES collaboration, we built new analysis pipelines to study the different components of this background: this covers time behavior as well as spectral and spatial characteristics.Comment: To appear in Experimental Astronomy, presented at AHEAD Background Workshop, 28-30 November 2016, Rome, Italy. 12 pages, 6 figure

La grandiosa rosa di pietra. Analisi litologica del rosone del Duomo di Modena

L'analisi litologica del rosone del Duomo di Modena ha permesso di identificare 5 diversi litotipi: Arenaria della Formazione di Pantano, Arenaria di Scabiazza, Pietra di Aurisina varietà granitello, Rosso Ammonitico e Marmo Proconnesio.Lo studio del rosone ha dimostrato come il Duomo sia l’unico monumento modenese in cui si sia utilizzata pietra locale. Nel contesto della Cattedrale la rosa si contraddistingue in quanto non presenta reimpiego di materiali antichi, come testimoniato nelle fasi precedenti, e nemmeno di Rosso Ammonitico veronese, litotipo principale utilizzato dai Campionesi. L’arenaria impiegata nel rivestimento lapideo esterno si è rivelata del tutto inadeguata, come dimostrato sulla Ghirlandina dalle sostituzioni col Rosso Ammonitico effettuate a partire dal XVI secolo. La pratica del restauro dei materiali degradati è stata affrontata diversamente nel corso dei secoli, e progressivamente si è giunti alla consapevolezza del rispetto dei materiali. Solo alla fine del ‘800, quando vennero condotti i risanamenti sulla Cattedrale, la cultura del restauro impose di impiegare lo stesso materiale nel ricostruire gli elementi danneggiati dal tempo. Una nuova attenzione, specchio della sensibilità artistica del momento storico, ha permesso di conservare questo unicum all’interno del panorama architettonico modenese

Bioelectrochemical hydrogen production with hydrogenophilic dechlorinating bacteria as electrocatalytic agents

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The "Oil-Spill Snorkel": an innovative bioelectrochemical approach to accelerate hydrocarbons biodegradation in marine sediments

This study presents the proof-of-concept of the "Oil-Spill Snorkel": a novel bioelectrochemical approach to stimulate the oxidative biodegradation of petroleum hydrocarbons in sediments. The "Oil-Spill Snorkel" consists of a single conductive material (the snorkel) positioned suitably to create an electrochemical connection between the anoxic zone (the contaminated sediment) and the oxic zone (the overlying O-2-containing water). The segment of the electrode buried within the sediment plays a role of anode, accepting electrons deriving from the oxidation of contaminants. Electrons flow through the snorkel up to the part exposed to the aerobic environment (the cathode), where they reduce oxygen to form water. Here we report the results of lab-scale microcosms setup with marine sediments and spiked with crude oil. Microcosms containing one or three graphite snorkels and controls (snorkel-free and autoclaved) were monitored for over 400 days. Collectively, the results of this study confirmed that the snorkels accelerate oxidative reactions taking place within the sediment, as documented by a significant 1.7-fold increase (p = 0.023, two-tailed t-test) in the cumulative oxygen uptake and 1.4-fold increase (p = 0.040) in the cumulative CO2 evolution in the microcosms containing three snorkels compared to snorkel-free controls. Accordingly, the initial rate of total petroleum hydrocarbons (TPH) degradation was also substantially enhanced. Indeed, while after 200 days of incubation a negligible degradation of TPH was noticed in snorkel-free controls, a significant reduction of 12 1% (p = 0.004) and 21 1% (p = 0.001) was observed in microcosms containing one and three snorkels, respectively. Although, the "Oil-Spill Snorkel" potentially represents a groundbreaking alternative to more expensive remediation options, further research efforts are needed to clarify factors and conditions affecting the snorkel-driven biodegradation processes and to identify suitable configurations for field applications