The preparation of ultra fine beryllium powder by the amalgam process Technical report

Beryllium powder production by electrolysis of beryllium chloride-sodium chloride molten eutectic mixtur

Selfie-engagement on social media: pathological narcissism, positive expectation, and body objectification – which is more influential?

The current use of social media platforms by active young users/creators of visual content provides an easy medium to achieve narcissistic goals of self-promotion and attention-seeking, and to socialize with self-objectification experiences. One of the most popular activities associated with social media use is selfie-sharing. Consequently, the global focus on online physical appearance approval could reinforce selfie-engagement as a specific body image-related behavior, potentially associated with selfie-marketing strategies for self-improvement, and problematic social media use. The present study evaluated the main direct effect of pathological narcissism, objectified body consciousness, and expectations toward selfies on young women’s and men’s selfie-engagement. A total of 570 young adults (66.8% females; mean age = 24.4 years, SD = 3.6) participated in an online survey study. Variables were assessed using the Pathological Narcissism Inventory (Fossati, Feeney, Pincus, Borroni, & Maffei, 2015), Objectified Body Consciousness Scale (Dakanalis et al., 2015), Selfie-expectancies Scale (Boursier & Manna, 2018), and a measure of selfie-engagement. Hierarchical regression analyses were performed on independent male and female subsamples. Results showed that body surveillance and positive selfie-expectancies are consistent selfie-behavior predictors, among both men (R2 = 0.227; p < .001) and women (R2 = 0.332; p < .001). Furthermore, findings confirm women’s involvement in appearance concerns and body-image related practices, even though men’s engagement in body-objectification deserve attention. The study provides novel findings in the field of self-objectification research as well as contributing to the ongoing debate concerning which psychological factors can be predictive of males' and females' selfie-engagement. The implications of these findings are also discussed in light of the debate on social media use and misuse

Objectified body consciousness, body image control in photos, and problematic social networking: the role of appearance control beliefs

At present, adolescents' photo-taking and photo-sharing on social media represent ubiquitous practices and objectified body consciousness (OBC) might offer a useful framework to explore online self-presentation and social networking site (SNS) use. Indeed, SNS might represent a highly accessible medium for socializing with self-objectification. However, the relationship between OBC components and problematic SNS use is still understudied. The present study evaluated the previously unexplored predictive role of appearance control beliefs on problematic SNS use, testing the mediating effect of body image control in photos (BICP) across male and female groups. A total of 693 adolescents (55% females; mean age 16 years) participated in the study. Results showed the negatively predictive role of appearance control beliefs on control over body image in photos. Moreover, BICP mediated the appearance control beliefs' negative effect on problematic SNS use in girls. The present study tested the unexplored effect of appearance control beliefs upon problematic SNS use, contributing to the OBC research field and the ongoing debate concerning predictive and protective factors in problematic SNS use

Hybrid functional calculations of the Al impurity in silica: Hole localization and electron paramagnetic resonance parameters

We performed first-principle calculations based on the supercell and cluster approaches to investigate the neutral Al impurity in smoky quartz. Electron paramagnetic resonance measurements suggest that the oxygens around the Al center undergo a polaronic distortion which localizes the hole being on one of the four oxygen atoms. We find that the screened exchange hybrid functional successfully describes this localization and improves on standard local density approaches or on hybrid functionals that do not include enough exact exchange such as B3LYP. We find a defect level at about 2.5 eV above the valence band maximum, corresponding to a localized hole in a O 2p orbital. The calculated values of the g tensor and the hyperfine splittings are in excellent agreement with experiment.Comment: 5 pages, 2 figures, 1 tabl

A teleparallel model for the neutrino

The main result of the paper is a new representation for the Weyl Lagrangian (massless Dirac Lagrangian). As the dynamical variable we use the coframe, i.e. an orthonormal tetrad of covector fields. We write down a simple Lagrangian - wedge product of axial torsion with a lightlike element of the coframe - and show that variation of the resulting action with respect to the coframe produces the Weyl equation. The advantage of our approach is that it does not require the use of spinors, Pauli matrices or covariant differentiation. The only geometric concepts we use are those of a metric, differential form, wedge product and exterior derivative. Our result assigns a variational meaning to the tetrad representation of the Weyl equation suggested by J.B.Griffiths and R.A.Newing.Comment: 4 pages, REVTe

Ultra-fine beryllium powder by amalgam process Progress report, period ending 31 Oct. 1966

Metallurgical evaluation of beryllium powdered metal, and electron microscope studies of agglomerate particle size

Test particle motion in a gravitational plane wave collision background

Test particle geodesic motion is analysed in detail for the background spacetimes of the degenerate Ferrari-Ibanez colliding gravitational wave solutions. Killing vectors have been used to reduce the equations of motion to a first order system of differential equations which have been integrated numerically. The associated constants of the motion have also been used to match the geodesics as they cross over the boundary between the single plane wave and interaction zones.Comment: 11 pages, 6 Postscript figure

A longitudinal study of adolescent Internet addiction: the role of conscientiousness and classroom hostility

Over the last decade, research on Internet Addiction (IA) has increased. However, almost all studies in this area are cross-sectional and do not examine the context in which internet use takes place. Therefore, a longitudinal study examined the role of conscientiousness (as a personality trait) and classroom hostility (as a contextual factor) in the development of IA. The participants comprised 648 adolescents and were assessed over a two-year period (while aged 16–18 years). A three-level hierarchical linear model was carried out on the data collected. Findings revealed that: (i) lower conscientiousness was associated with IA and this did not change over time; and (ii) although being in a more hostile classroom did not initially have a significant effect, it increased girls’ IA vulnerability over time and functioned protectively for boys. Results indicated that the contribution of individual and contextual IA factors may differ across genders and over time. More specifically, although the protective effect of conscientiousness appeared to hold, the over-time effect of classroom hostility increased the risk of IA for girls. These findings are discussed in relation to the psychological literature. The study’s limitations and implications are also discussed

The Biot-Savart operator and electrodynamics on subdomains of the three-sphere

We study steady-state magnetic fields in the geometric setting of positive curvature on subdomains of the three-dimensional sphere. By generalizing the Biot-Savart law to an integral operator BS acting on all vector fields, we show that electrodynamics in such a setting behaves rather similarly to Euclidean electrodynamics. For instance, for current J and magnetic field BS(J), we show that Maxwell's equations naturally hold. In all instances, the formulas we give are geometrically meaningful: they are preserved by orientation-preserving isometries of the three-sphere. This article describes several properties of BS: we show it is self-adjoint, bounded, and extends to a compact operator on a Hilbert space. For vector fields that act like currents, we prove the curl operator is a left inverse to BS; thus the Biot-Savart operator is important in the study of curl eigenvalues, with applications to energy-minimization problems in geometry and physics. We conclude with two examples, which indicate our bounds are typically within an order of magnitude of being sharp.Comment: 24 pages (was 28 pages) Revised to include a new introduction, a detailed example, and results about helicity; other changes for readabilit

P,T-Violating Nuclear Matrix Elements in the One-Meson Exchange Approximation

Expressions for the P,T-violating NN potentials are derived for $\pi$, $\rho$ and $\omega$ exchange. The nuclear matrix elements for $\rho$ and $\omega$ exchange are shown to be greatly suppressed, so that, under the assumption of comparable coupling constants, $\pi$ exchange would dominate by two orders of magnitude. The ratio of P,T-violating to P-violating matrix elements is found to remain approximately constant across the nuclear mass table, thus establishing the proportionality between time-reversal-violation and parity-violation matrix elements. The calculated values of this ratio suggest a need to obtain an accuracy of order $5 \times 10^{-4}$ for the ratio of the PT-violating to P-violating asymmetries in neutron transmission experiments in order to improve on the present limits on the isovector pion coupling constant.Comment: 17 pages, LaTeX, no figure