Understanding of the Mole Concept Achieved by Students in a Constructivist General Chemistry Course

The purpose of this research project was to study the conceptual understanding achieved in a general chemistry course based on a constructivist approach. A group of 28 students participated in repeated measures obtained by means of conceptual maps about the mole concept prepared three times during the course: at the beginning the course, immediately after the concept was studied, and after studying other related concepts. In addition, eight students selected from the group of 28 were interviewed. The interviews were carried out focusing on their conceptual maps. The analysis of the repeated measures indicated significant differences among the three times, especially between the first two. It was evidenced, therefore, that these students obtained a significantly higher level of understanding of the mole concept. The qualitative analysis carried out with students identified a broad range of responses that represent different levels of hierarchical organization, of progressive differentiation, and of formation of significant relations of the mole concept. Some recommendations offered are to develop and implement teaching methods that promote understanding of scientific concepts, and to prepare science professors and teachers to emphasize teaching for conceptual understanding

Multicriteria evaluation of novel technologies for organic micropollutants removal in advanced water reclamation schemes for indirect potable reuse

Postprint (author's final draft

Erupting Cataclysmic Variable Stars in the Nearest Globular Cluster, NGC 6397: Intermediate Polars?

NGC 6397 is the closest globular cluster, and hence the ideal place to search for faint stellar populations such as cataclysmic variables (CVs). HST and Chandra observers have identified nine certain and likely CVs in this nearby cluster, including several magnetic CV candidates. We have combined our recent UV imagery with archival HST images of NGC 6397 to search for new CV candidates and especially to look for dwarf nova-like eruptive events. We find remarkable and somewhat unexpected dwarf nova-like eruptions of the two well-known cataclysmic systems CV2 and CV3. These two objects have been claimed to be {\it magnetic} CVs, as indicated by their helium emission-line spectra. Magnetic fields in CVs are usually expected to prevent the disk instability that leads to dwarf nova eruptions. In fact, most field magnetic CVs are observed to not undergo eruptions. Our observations of the dwarf nova eruptions of CV2 and CV3 can be reconciled with these objects' HeII emission lines if both objects are infrequently-erupting intermediate polars, similar to EX Hya. If this is the case for most globular cluster CVs then we can reconcile the many X-ray and UV bright CV candidates seen by Chandra and HST with the very small numbers of erupting dwarf novae observed in cluster cores.Comment: 12 pages, 3 figures. Accepted for publication in The Astronomical Journal. Two additional authors adde

Medina: Improving cloud services trustworthiness through continuous audit-based certification

One of the reasons of the still limited adoption of Cloud Computing in the EU is the EU customers' perceived lack of security and transparency in this technology. Cloud service providers (CSPs) usually rely on security certifications as a mean to improve transparency and trustworthiness, however European CSPs still face multiple challenges for certifying their services (e.g., fragmentation in the certification market, and lack of mutual recognition). In this context, the EU Cybersecurity Act (EU CSA) proposes improving customer's trust in the European ICT market through a European certification scheme (EUCS). The proposed cloud security certification scheme conveys new technological challenges including the notion of automated monitoring for the whole supply chain, which needs to be solved in order to bring all the expected benefits to EU cloud providers and customers. In this context, MEDINA proposes a framework for supporting a continuous audit-based certification for CSPs based on EU CSA's scheme for cloud security certification. MEDINA will tackle challenges in areas like security validation/ testing, machine-readable certification language, cloud security performance, and audit evidence management. MEDINA will provide and empirically validate sustainable outcomes in order to benefit EU adopters.This work has been partially funded by the European project MEDINA (Horizon 2020 research and innovation Programme, under grant agreement no 952633)

Global noise studies for CMS Tracker upgrade

7 páginas, 6 figuras.-- Trabajo presentado al "Topical Workshop on Electronics for Particle Physics 2010 (TWEPP-10)" celebrado en Alemania.-- Open Access.-- et al.The characterization of the noise emissions of DC-DC converters at system level is critical to optimize the design of the detector and define rules for the integration strategy. This paper presents the impedance effects on the noise emissions of DC-DC converters at system level. Conducted and radiated noise emissions at the input and at the output from DC-DC converters have been simulated for different types of power network and FEE impedances. System aspects as granularity, stray capacitances of the system and different working conditions of the DC-DC converters are presented too. This study has been carried out using simulation models of noise emissions of DC-DC converters in the real scenario. The results of these studies show important recommendations and criteria to be applied to integrate the DC-DC converters and decrease the system noise level.C.R. wants to thank to US DOE, under contract DE-AC02-76SF00515, for the support of this work.Peer reviewe

Russia and "hybrid warfare"

In the aftermath of the Crimea annexation in March 2014, the idea of ‘hybrid warfare’ quickly gained prominence as a concept that could help to explain the success of Russian military operations in this conflict. Although the concept continues to enjoy widespread popularity in both scholarly and policy circles, its utility as an analytical tool is also heavily contested. This article adds to the literature critical of the ‘hybrid warfare’ concept. It argues that in addition to the fact that what is now described as a ‘hybrid’ approach to war is in fact nothing new, the problems pertaining to its utility for the study of contemporary Russia go deeper than this. ‘Hybrid warfare’ inadequately reflects the direction of Russian military modernisation and as such has led to a skewed understanding of Russian military capabilities. Moreover, the tendency to use ‘hybrid warfare’ not only to conceptualise developments in the Russian military, but in the country’s foreign policy in general, can lead to serious unintended consequences