Search results for "ISM [X-ray]"

The Company Clusters Power in Tourism Destinations: The Network Configuration and the Business Organisation

2022

Better and greater coordination and integration between companies are essential for tourist destination development processes improving competitiveness. Moreover, it is difficult to imagine that all companies can cooperate. In this way, we can imagine finding a group of companies that, for several reasons, decide to cooperate, creating some clusters as small groups. Companies with stable connections with other clusters or relevant companies could be relevant and central to Tourism Destination (TD) management. In this way, the knowledge of network articulation seems to be critical for TD management business dynamics. In most cases, the relationships are hidden and not formalised, increasing …

Insight into the Mechanism of Action of Marine Cytotoxic Thiazinoquinones

2017

The electrochemical response of four natural cytotoxic thiazinoquinones isolated from the Aplidium species was studied using conventional solution-phase and solid-state techniques, based on the voltammetry of immobilized particles methodology. The interaction with O-2 and electrochemically generated reactive oxygen species (ROS) was electrochemically monitored. At the same time, a molecular modeling study including density functional theory (DFT) calculations was performed in order to analyze the conformational and electronic properties of the natural thiazinoquinones, as well as those of their reduced intermediates. The obtained electrochemical and computational results were analyzed and c…

Constrains on mantle, slab and crustal contributions to major volatiles and noble gases along the Andean Volcanic Belt

2020

Über die frühen Werke von Carl Gotthard Graß in der Akademischen Bibliothek der Universität Lettlands, über die Freundschaft, Antiquarismus in der Ge…

2020

A Methanol Extract ofBrugmansia arboreaAffects the Reinforcing and Motor Effects of Morphine and Cocaine in Mice

2013

Previous reports have shown that several of the effects of morphine, including the development of tolerance and physical withdrawal symptoms, are reduced by extracts ofBrugmansia arborea(L.) Lagerheim (Solanaceae) (B. arborea). In the present study we evaluate the action of the methanol extract ofB. arborea(7.5–60 mg/kg) on the motor and reinforcing effects of morphine (20 and 40 mg/kg) and cocaine (25 mg/kg) using the conditioned place preference (CPP) procedure. At the doses employed,B. arboreadid not affect motor activity or induce any effect on CPP. The extract partially counteracted morphine-induced motor activity and completely blocked the CPP induced by 20 mg/kg morphine. On the othe…

A simulation of disagreement for control of rational cheating in peer review

2013

Understanding the peer review process could help research and shed light on the mechanisms that underlie crowdsourcing. In this paper, we present an agent-based model of peer review built on three entities - the paper, the scientist and the conference. The system is implemented on a BDI platform (Jason) that allows to define a rich model of scoring, evaluating and selecting papers for conferences. Then, we propose a programme committee update mechanism based on disagreement control that is able to remove reviewers applying a strategy aimed to prevent papers better than their own to be accepted (rational cheating). We analyze a homogeneous scenario, where all conferences aim to the same leve…

X-ray emission from stellar jets by collision against high-density molecular clouds: an application to HH 248

2015

We investigate the plausibility of detecting X-ray emission from a stellar jet that impacts against a dense molecular cloud. This scenario may be usual for classical T Tauri stars with jets in dense star-forming complexes. We first model the impact of a jet against a dense cloud by 2D axisymmetric hydrodynamic simulations, exploring different configurations of the ambient environment. Then, we compare our results with XMM-Newton observations of the Herbig-Haro object HH 248, where extended X-ray emission aligned with the optical knots is detected at the edge of the nearby IC 434 cloud. Our simulations show that a jet can produce plasma with temperatures up to 10 MK, consistent with producti…

Thermal emission, shock modification, and X-ray emitting ejecta in SN 1006

2009

Efficient particle acceleration can modify the structure of supernova remnants. In this context we present the results of the combined analysis of the XMM-Newton EPIC archive observations of SN 1006. We aim at describing the spatial distribution of the physical and chemical properties of the X-ray emitting plasma at the shock front. We investigate the contribution of thermal and non-thermal emission to the X-ray spectrum at the rim of the remnant to study how the acceleration processes affect the X-ray emitting plasma. We perform a spatially resolved spectral analysis on a set of regions covering the whole rim of the shell and we exploit the results of the spectral analysis to produce a cou…

X-ray emitting structures in the Vela SNR: ejecta anisotropies and progenitor stellar wind residuals

2021

The Vela supernova remnant (SNR) shows several ejecta fragments protruding beyond the forward shock (shrapnel). Recent studies have revealed high Si abundance in two shrapnel (A and G), located in opposite directions with respect to the SNR center. This suggests the possible existence of a Si-rich jet-counterjet structure. We analyzed an XMM-Newton observation of a bright clump, behind shrapnel G, which lies along the direction connecting A and G. The aim is to study the physical and chemical properties of this clump to ascertain whether it is part of this putative jet-like structure. We produced background-corrected and adaptively-smoothed count-rate images and median photon energy maps, a…

Stability analysis of relativistic jets from collapsars and its implications on the short-term variability of gamma-ray bursts

2002

We consider the transverse structure and stability properties of relativistic jets formed in the course of the collapse of a massive progenitor. Our numerical simulations show the presence of a strong shear in the bulk velocity of such jets. This shear can be responsible for a very rapid shear--driven instability that arises for any velocity profile. This conclusion has been confirmed both by numerical simulations and theoretical analysis. The instability leads to rapid fluctuations of the main hydrodynamical parameters (density, pressure, Lorentz factor, etc.). However, the perturbations of the density are effectively decoupled from those of the pressure because the beam of the jet is radi…