Spatially resolved physical and chemical properties of the planetary nebula NGC 3242

Optical integral-field spectroscopy was used to investigate the planetary nebula NGC 3242. We analysed the main morphological components of this source, including its knots, but not the halo. In addition to revealing the properties ofthe physical and chemical nature of this nebula, we also provided reliable spatially resolved constraints that can be used for future photoionisation modelling of the nebula. The latter is ultimately necessary to obtain a fully self-consistent 3D picture of the physical and chemical properties of the object. The observations were obtained with the VIMOS instrument attached to VLT-UT3. Maps and values for specific morphological zones for the detected emission-lines were obtained and analysed with routines developed by the authors to derive physical and chemical conditions of the ionised gas in a 2D fashion. We obtained spatially resolved maps and mean values of the electron densities, temperatures, and chemical abundances, for specific morphological structures in NGC 3242. These results show the pixel-to-pixel variations of the the small- and large-scale structures of the source. These diagnostic maps provide information free from the biases introduced by traditional single long-slit observations. In general, our results are consistent with a uniform abundance distribution for the object, whether we look at abundance maps or integrated fluxes from specified morphological structures. The results indicate that special care should be taken with the calibration of the data and that only data with extremely good signal-to-noise ratio and spectral coverage should be used to ensure the detection of possible spatial variations.Comment: 11 pages, 8 figures accepted for publication in Astronomy & Astrophysic

Project risk management in an automotive company

The main purpose of this research project was to analyse the project risk management practices in an automotive company, in order to recommend appropriate improvements. Design/methodology/approach - The research methodology chosen to conduct the study was case study, since the research was carried out in a multinational company in the automotive industry, and data was collected through observation, document analysis and a questionnaire. Findings - Although the company has defined how to approach project risk management, it was found out that the reality experienced does not reflect what is proposed by the major references. The proposal for an approach to risk management, process by process, was well received and appreciated by the project team. Research limitations/implications - Due to the size of company, and also in some cases due to confidentiality reasons, it was not possible to obtain all the necessary data for a more accurate analysis. Additionally, due to the work routine, communication with colleagues was rarely immediate or fluid. It is also important to highlight the fact that project risk management is not an established practice within the organization. Originality/value - Risk management practices as other project management practices are context dependent and should be adapted to the situation. Other companies working with a similar context can benefit from this study and adopt similar procedures to improve their risk management practices.(undefined

Human dynamics revealed through Web analytics

When the World Wide Web was first conceived as a way to facilitate the sharing of scientific information at the CERN (European Center for Nuclear Research) few could have imagined the role it would come to play in the following decades. Since then, the increasing ubiquity of Internet access and the frequency with which people interact with it raise the possibility of using the Web to better observe, understand, and monitor several aspects of human social behavior. Web sites with large numbers of frequently returning users are ideal for this task. If these sites belong to companies or universities, their usage patterns can furnish information about the working habits of entire populations. In this work, we analyze the properly anonymized logs detailing the access history to Emory University's Web site. Emory is a medium size university located in Atlanta, Georgia. We find interesting structure in the activity patterns of the domain and study in a systematic way the main forces behind the dynamics of the traffic. In particular, we show that both linear preferential linking and priority based queuing are essential ingredients to understand the way users navigate the Web.Comment: 7 pages, 8 figure

Strong curvature singularities in quasispherical asymptotically de Sitter dust collapse

We study the occurrence, visibility, and curvature strength of singularities in dust-containing Szekeres spacetimes (which possess no Killing vectors) with a positive cosmological constant. We find that such singularities can be locally naked, Tipler strong, and develop from a non-zero-measure set of regular initial data. When examined along timelike geodesics, the singularity's curvature strength is found to be independent of the initial data.Comment: 16 pages, LaTeX, uses IOP package, 2 eps figures; accepted for publication in Class. Quantum Gra

Physicochemical and microstructural properties of composite edible film obtained by complex coacervation between chitosan and whey protein isolate

The aim of this work was to study the potential application of edible films obtained by complex coacervation promoted by the electrostatic interactions between positively charged chitosan (CH) 3% (w/w) and negatively charged whey protein isolate (WPI) 3% (w/w). Preliminary assays of turbidimetry were made in order to find the optimal CH-to-WPI mass ratio for the complex coacervation. The maximum turbidity was obtained in the CH:WPI mass ratio of 0.1:1 (w/w). The dispersions of CH/WPI (both at 3 % (w/w)), WPI 5 % (w/w) and CH 3% (w/w) were analyzed by Cryo-scanning electron microscopy (Cryo-SEM) and the micrograph of CH/WPI coacervate presented a more compact network structure than dispersions of individual biopolymers. The composite CH/WPI films were prepared, characterized and their performance and physicochemical properties were compared with those of CH or WPI films, in terms of water vapor permeability (WVP), mechanical properties, solubility, sorption isotherms, optical properties, scanning electron microscopy (SEM) imaging, Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Results revealed that the incorporation of small amounts of CH in the matrix of WPI led to form a composite film with higher tensile strength, lower deformation, malleability, flexibility, solubility and WVP in comparison to the mono-component WPI and CH films. The CH incorporation resulted in a decrease in equilibrium moisture content of the CH/WPI film and the Guggenheim-Anderson-de Boer (GAB) model of sorption data indicated isotherms of type II. All the films presented a homogeneous structure, color transparency, which is desired in food applications and packaging technology.This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2020 and UID/QUI/50006/2020 units; the work was also supported by BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte 2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

New mathematical framework for spherical gravitational collapse

A theorem, giving necessary and sufficient condition for naked singularity formation in spherically symmetric non static spacetimes under hypotheses of physical acceptability, is formulated and proved. The theorem relates existence of singular null geodesics to existence of regular curves which are super-solutions of the radial null geodesic equation, and allows us to treat all the known examples of naked singularities from a unified viewpoint. New examples are also found using this approach, and perspectives are discussed.Comment: 8 pages, LaTeX2