The Internet and youth engagement: An exploration of how youth spend their time online and its relation to civic involvement

A study was conducted to investigate the relationship between Internet use and civic involvement in youth. Participants consisted of 378 youth between the ages of 16 and 25 from across Canada. Participants completed an online questionnaire consisting of a measure called the Youth Inventory of Involvement, designed to assess civic involvement in youth. Brief measures of introversion/extraversion and depression were also completed. Participants then completed questions designed to assess the amount of time they spend online in an average week, as well as for what they use the Internet. Results indicate that there may be a non-linear relationship between amount of time spent online and involvement, with individuals at the extremes in terms of very low or very high Internet use showing lower levels of involvement than more moderate users. Different types of Internet users were identified and also differed in involvement. Contrary to some previous research a link between Internet use and depression was found. This study provides important evidence that a link between Internet use and involvement in youth does in fact exist and also identifies specific types of online activities that were found to be related to both involvement and psychological well-being

Palaeogeographical patterns in late Ordovician bryozoan morphology as proxies for temperature

Several studies have revealed temperature-related patterns in recent bryozoans, both in the chemical composition of the skeleton and in the morphological characters of the colonies, but comparable studies on Palaeozoic bryozoans are lacking. In this paper a statistical analysis of the morphological differences is undertaken between congeneric species of some Ordovician bryozoans from warm- and cold-water settings. For this study ten eurythermic cosmopolitan bryozoan genera from the Upper Ordovician were selected from the Mediterranean, Avalonia, Baltic and Laurentia-Siberian provinces. These genera are: Ceramopora and Ceramoporella (Cystoporata); Diplotrypa, Eridotrypa, Hallopora, Heterotrypa, Monticulipora and Trematopora (Trepostomata); Graptodictya (Cryptostomata); and Kukersella (Cyclostomata). The study involved 154 samples belonging to 104 different species. Twenty-eight morphological characters were measured, although only 21 were used in the final statistical analysis. Univariate (t, F, Kolmogorov-Smirnov and Mann-Whitney tests), multivariate discriminant and multivariate ordination (Principal Coordinates, Principal Components, Correspondence, and Detrended Correspondence) analyses were performed on the data. For the univariate and multivariate discriminant analyses, the total set of samples was divided a priori into cold- and warm-water subsets based on palaeolatitude: samples from the Mediterranean province were attributed to the cold-water subset, whereas samples from Avalonia, Baltic and the Laurentian-Siberian provinces were included in the warm-water subset. For the multivariate ordination analysis no a priori grouping by water temperature was imposed, and the aim of these analyses was to test whether different samples were correctly arranged along a water temperature gradient. The univariate statistical analysis showed that there are clear morphological differences between cold- and warm-water species in six of the ten Late Ordovician bryozoan genera analysed in this study, although these differences are only evident for some of the characters used, and only when the analysis is performed on individual genera. The best characters to differentiate species by water temperature are those related to the size of the zooidal polymorphs, especially the diameters of the autozooecia, mesozooecia and exilazooecia. With the exception of one genus (Trematopora), cold-water species have larger zooids. The discriminant analysis was able to classify correctly as warm- or cold-water 100% of the samples for two genera, slightly below 95% for two other genera, and between 67% and 90% for the remaining six genera. Finally, the multivariate ordination analysis was able to separate species by palaeogeographical province in some genera, but these provinces were not correctly arranged along a palaeolatitudinal gradient using any of the methods used

Interpreting granulite facies events through rare earth element partitioning arrays

The use of rare earth element (REE) partition coefficients is an increasingly common tool in metamorphic studies, linking the growth or modification of accessory mineral geochronometers to the bulk silicate mineral assemblage. The most commonly used mineral pair for the study of high-grade metamorphic rocks is zircon and garnet. The link from U–Pb ages provided by zircon to the P–T information recorded by garnet can be interpreted in relation to experimental data. The simplistic approach of taking the average REE abundances for zircon and garnet and comparing them directly to experimentally derived partition coefficients is imperfect, in that it cannot represent the complexity of a natural rock system. This study describes a method that uses all the zircon analyses from a sample, and compares them to different garnet compositions in the same rock. Using the most important REE values, it is possible to define zircon–garnet equilibrium using an array rather than an average. The array plot describes partitioning between zircon and garnet using DYb and DYb/DGd as the defining features of the relationship. This approach provides far more sensitivity to mineral reactions and diffusional processes, enabling a more detailed interpretation of metamorphic history of the sample

When is rotational angiography superior to conventional single-plane angiography for planning coronary angioplasty?

Objectives: To investigate the value of rotational coronary angiography (RoCA) in the context of percutaneous coronary intervention (PCI) planning. Background: As a diagnostic tool, RoCA is associated with decreased patient irradiation and contrast use compared with conventional coronary angiography (CA) and provides superior appreciation of three-dimensional anatomy. However, its value in PCI remains unknown. Methods: We studied stable coronary artery disease assessment and PCI planning by interventional cardiologists. Patients underwent either RoCA or conventional CA pre-PCI for planning. These were compared with the referral CA (all conventional) in terms of quantitative lesion assessment and operator confidence. An independent panel reanalyzed all parameters. Results: Six operators performed 127 procedures (60 RoCA, 60 conventional CA, and 7 crossed-over) and assessed 212 lesions. RoCA was associated with a reduction in the number of lesions judged to involve a bifurcation (23 vs. 30 lesions, P < 0.05) and a reduction in the assessment of vessel caliber (2.8 vs. 3.0 mm, P < 0.05). RoCA improved confidence assessing lesion length (P = 0.01), percentage stenosis (P = 0.02), tortuosity (P < 0.04), and proximity to a bifurcation (P = 0.03), particularly in left coronary artery cases. X-ray dose, contrast agent volume, and procedure duration were not significantly different. Conclusions: Compared with conventional CA, RoCA augments quantitative lesion assessment, enhances confidence in the assessment of coronary artery disease and the precise details of the proposed procedure, but does not affect X-ray dose, contrast agent volume, or procedure duration. © 2015 Wiley Periodicals, Inc

The Neoarchaean Uyea Gneiss Complex, Shetland: an onshore fragment of the Rae Craton on the European Plate

A tract of amphibolite facies granitic gneisses and metagabbros in northern Shetland, U.K., is here named the Uyea Gneiss Complex. Zircon U–Pb dating indicates emplacement of the igneous protoliths of the complex c. 2746–2726 Ma, at a later time than most of the Archaean protoliths of the Lewisian Gneiss Complex of mainland Scotland. Calc-alkaline geochemistry of the Uyea Gneiss Complex indicates arc-affinity and a strong genetic kinship among the mafic and felsic components. Zircon Hf compositions suggest an enriched mantle source and limited interaction with older crust during emplacement. Ductile fabrics developed soon after emplacement, with zircon rims at c. 2710 Ma, but there was little further deformation until Caledonian reworking east of the Uyea Shear Zone. There is no evidence for the Palaeoproterozoic reworking that dominates large tracts of the Lewisian Gneiss Complex and of the Nagssugtoqidian Orogen of East Greenland. The more northerly location of the Uyea Gneiss Complex and extensive offshore basement of similar age implies that, prior to the opening of the North Atlantic Ocean, these rocks were contiguous with the Archaean Rae Craton

The evolution of cooperation and altruism--a general framework and a classification of models.

One of the enduring puzzles in biology and the social sciences is the origin and persistence of intraspecific cooperation and altruism in humans and other species. Hundreds of theoretical models have been proposed and there is much confusion about the relationship between these models. To clarify the situation, we developed a synthetic conceptual framework that delineates the conditions necessary for the evolution of altruism and cooperation. We show that at least one of the four following conditions needs to be fulfilled: direct benefits to the focal individual performing a cooperative act; direct or indirect information allowing a better than random guess about whether a given individual will behave cooperatively in repeated reciprocal interactions; preferential interactions between related individuals; and genetic correlation between genes coding for altruism and phenotypic traits that can be identified. When one or more of these conditions are met, altruism or cooperation can evolve if the cost-to-benefit ratio of altruistic and cooperative acts is greater than a threshold value. The cost-to-benefit ratio can be altered by coercion, punishment and policing which therefore act as mechanisms facilitating the evolution of altruism and cooperation. All the models proposed so far are explicitly or implicitly built on these general principles, allowing us to classify them into four general categories

A Kinematical Approach to Conformal Cosmology

We present an alternative cosmology based on conformal gravity, as originally introduced by H. Weyl and recently revisited by P. Mannheim and D. Kazanas. Unlike past similar attempts our approach is a purely kinematical application of the conformal symmetry to the Universe, through a critical reanalysis of fundamental astrophysical observations, such as the cosmological redshift and others. As a result of this novel approach we obtain a closed-form expression for the cosmic scale factor R(t) and a revised interpretation of the space-time coordinates usually employed in cosmology. New fundamental cosmological parameters are introduced and evaluated. This emerging new cosmology does not seem to possess any of the controversial features of the current standard model, such as the presence of dark matter, dark energy or of a cosmological constant, the existence of the horizon problem or of an inflationary phase. Comparing our results with current conformal cosmologies in the literature, we note that our kinematic cosmology is equivalent to conformal gravity with a cosmological constant at late (or early) cosmological times. The cosmic scale factor and the evolution of the Universe are described in terms of several dimensionless quantities, among which a new cosmological variable delta emerges as a natural cosmic time. The mathematical connections between all these quantities are described in details and a relationship is established with the original kinematic cosmology by L. Infeld and A. Schild. The mathematical foundations of our kinematical conformal cosmology will need to be checked against current astrophysical experimental data, before this new model can become a viable alternative to the standard theory.Comment: Improved version, with minor changes. 58 pages, including 7 figures and one table. Accepted for publication in General Relativity and Gravitation (GERG

First-principles Calculation of the Formation Energy in MgO-CaO Solid Solutions

The electronic structure and total energy were calculated for ordered and disordered MgO-CaO solid solutions within the multiple scattering theory in real space and the local density approximation. Based on the dependence of the total energy on the unit cell volume the equilibrium lattice parameter and formation energy were determined for different solution compositions. The formation energy of the solid solutions is found to be positive that is in agreement with the experimental phase diagram, which shows a miscibility gap.Comment: 11 pages, 3 figure