353 research outputs found
The stellar halo of the Galaxy
Stellar halos may hold some of the best preserved fossils of the formation
history of galaxies. They are a natural product of the merging processes that
probably take place during the assembly of a galaxy, and hence may well be the
most ubiquitous component of galaxies, independently of their Hubble type. This
review focuses on our current understanding of the spatial structure, the
kinematics and chemistry of halo stars in the Milky Way. In recent years, we
have experienced a change in paradigm thanks to the discovery of large amounts
of substructure, especially in the outer halo. I discuss the implications of
the currently available observational constraints and fold them into several
possible formation scenarios. Unraveling the formation of the Galactic halo
will be possible in the near future through a combination of large wide field
photometric and spectroscopic surveys, and especially in the era of Gaia.Comment: 46 pages, 16 figures. References updated and some minor changes.
Full-resolution version available at
http://www.astro.rug.nl/~ahelmi/stellar-halo-review.pd
The sudden change phenomenon of quantum discord
Even if the parameters determining a system's state are varied smoothly, the
behavior of quantum correlations alike to quantum discord, and of its classical
counterparts, can be very peculiar, with the appearance of non-analyticities in
its rate of change. Here we review this sudden change phenomenon (SCP)
discussing some important points related to it: Its uncovering,
interpretations, and experimental verifications, its use in the context of the
emergence of the pointer basis in a quantum measurement process, its appearance
and universality under Markovian and non-Markovian dynamics, its theoretical
and experimental investigation in some other physical scenarios, and the
related phenomenon of double sudden change of trace distance discord. Several
open questions are identified, and we envisage that in answering them we will
gain significant further insight about the relation between the SCP and the
symmetry-geometric aspects of the quantum state space.Comment: Lectures on General Quantum Correlations and their Applications, F.
F. Fanchini, D. O. Soares Pinto, and G. Adesso (Eds.), Springer (2017), pp
309-33
Problems with Using the Normal Distribution – and Ways to Improve Quality and Efficiency of Data Analysis
Background: The Gaussian or normal distribution is the most established model to characterize quantitative variation of original data. Accordingly, data are summarized using the arithmetic mean and the standard deviation, by x 6 SD, or with the standard error of the mean, x 6 SEM. This, together with corresponding bars in graphical displays has become the standard to characterize variation. Methodology/Principal Findings: Here we question the adequacy of this characterization, and of the model. The published literature provides numerous examples for which such descriptions appear inappropriate because, based on the ‘‘95 % range check’’, their distributions are obviously skewed. In these cases, the symmetric characterization is a poor description and may trigger wrong conclusions. To solve the problem, it is enlightening to regard causes of variation. Multiplicative causes are by far more important than additive ones, in general, and benefit from a multiplicative (or log-) normal approach. Fortunately, quite similar to the normal, the log-normal distribution can now be handled easily and characterized at the level of the original data with the help of both, a new sign, x /, times-divide, and notation. Analogous to x 6 SD, it connects the multiplicative (or geometric) mean x * and the multiplicative standard deviation s * in the form x * x /s*, that is advantageous and recommended. Conclusions/Significance: The corresponding shift from the symmetric to the asymmetric view will substantially increas
Conservation of geosites as a tool to protect geoheritage: the inventory of Ceará Central Domain, Borborema Province - NE/Brazil
The Ceará Central Domain, in the northern Borborema Province/NE Brazil, encompasses important geological records (geosites) which allow understanding a relevant period of the Earth’s evolution, mainly associated to Neoproterozoic Brazilian/Pan-African Cycle and West Gondwana amalgamation, besides Neoarchean to Ordovician records. The presented geoheritage inventory aims to characterise the geosites with scienti c relevance of Ceará Central Domain. By applying a method for large areas, the nal selection resulted in eight geological frameworks represented by 52 geosites documented in a single database. This is the rst step for a geoconservation strategy based on systematic inventories, statutory protection, geoethical behaviour and awareness about scienti c, educational and/or cultural relevance of geosites.We specially thank all experts that helped us with
this inventory: Afonso Almeida, Carlos E.G. de
Araújo, César Veríssimo, Christiano Magini, Clóvis
Vaz Parente, Felipe G. Costa, Irani C. Mattos,
Neivaldo de Castro, Otaciel de Melo, Sebástian G.
Chiozza, Ticiano Santos and Stefano Zincone. We
are also thankful to Kátia Mansur, Ricardo Fraga
Pereira and anonymous reviewers for their valuable
contributions. PM is grateful to Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior
(CAPES) for PhD mobility scholarship PDSE
Program/Process n 88881.132168/2016-01info:eu-repo/semantics/publishedVersio
Portuguese validation of FACES-IV in adult children caregivers facing parental cancer
The purpose of the present study was to examine the psychometric properties
of the FACES-IV in Portuguese caregivers of cancer patients. In this cross-sectional study,
a sample of 214 adult children caregivers of cancer patients receiving chemotherapy,
completed FACES-IV, Family Communication Scale (FCS), Family Satisfaction Scale
(FSS), and Satisfaction with Social Support Scale (SSSS). Internal consistencies above .70
were found for all FACES-IV scales, except for Enmeshed and Rigid scales, as well as for
the FCS, FSS, and SSSS (except for Intimacy). Strong correlations between FACES-IV
and the validation scales FCS and FSS were found except for the Enmeshed and Rigid
scales. Confirmatory analysis yielded an acceptable model for the six theoretical subscales.
The discriminant analysis between problematic and non-problematic family systems
showed results similar to the original study. These findings suggest that FACES-IV is a
valid measure of family functioning in oncological family caregiving’s contexts.Acknowledgments This study was funded by a grant from the Portuguese Foundation for Science and
Technology (reference SFRH/BD/43275/2008)
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