Preparation and characterization of Bi26–2xMn2xMo10O69-d and Bi26.4Mn0.6Mo10–2yMe2yO69-d(Me = V, Fe) solid solutions

Received: 06.06.2017; accepted: 23.06.2017; published: 14.07.2017.Single phase samples of bismuth molybdate, Bi26Mo10O69, doped with Mn on the bismuth sublattice and V, Fe on the molybdenum sublattice were found to crystallize in the triclinic Bi26Mo10O69 structure at low doping levels and in the monoclinic Bi26Mo10O69 structure - at higher dopant concentration. The assumption that all Mn ions have an oxidation state of +2 was confirmed by means of magnetic measurement results analysis using Curie-Weiss law. Conductivity was investigated using impedance spectroscopy. The conductivity of Bi26.4Mn0.6Mo9.6Fe0.4O69-d was 1.2*10-2 S*cm-1 at 973 K and 2.2*10-4 S*cm-1 at 623 K, and the conductivity of Bi26.4Mn0.6Mo9.2V0.8O69-d was 2.2*10-3 S*cm-1 at 973 K and 2.2*10-5 S*cm-1 at 623 K

Critical Phenomena in Neutron Stars I: Linearly Unstable Nonrotating Models

We consider the evolution in full general relativity of a family of linearly unstable isolated spherical neutron stars under the effects of very small, perturbations as induced by the truncation error. Using a simple ideal-fluid equation of state we find that this system exhibits a type-I critical behaviour, thus confirming the conclusions reached by Liebling et al. [1] for rotating magnetized stars. Exploiting the relative simplicity of our system, we are able carry out a more in-depth study providing solid evidences of the criticality of this phenomenon and also to give a simple interpretation of the putative critical solution as a spherical solution with the unstable mode being the fundamental F-mode. Hence for any choice of the polytropic constant, the critical solution will distinguish the set of subcritical models migrating to the stable branch of the models of equilibrium from the set of subcritical models collapsing to a black hole. Finally, we study how the dynamics changes when the numerically perturbation is replaced by a finite-size, resolution independent velocity perturbation and show that in such cases a nearly-critical solution can be changed into either a sub or supercritical. The work reported here also lays the basis for the analysis carried in a companion paper, where the critical behaviour in the the head-on collision of two neutron stars is instead considered [2].Comment: 15 pages, 9 figure

Multi-Wavelength Variability of the Synchrotron Self-Compton Model for Blazar Emission

Motivated by recent reports of strongly correlated radio and X-ray variability in 3C279 (Grandi, etal 1995), we have computed the relative amplitudes of variations in the synchrotron flux at $\nu$ and the self-Compton X-ray flux at 1 keV ($R(\nu)$) for a homogeneous sphere of relativistic electrons orbiting in a tangled magnetic field. Relative to synchrotron self-Compton scattering without induced Compton scattering, stimulated scattering reduces the amplitude of $R(\nu)$ by as much as an order of magnitude when \tau_T \gtwid 1. When $\tau_T$ varies in a fixed magnetic field, $R_{\tau}$ increases monotonically from 0.01 at $\nu_o$, the self-absorption turnover frequency, to $0.5$ at $100 \nu_o$. The relative amplitudes of the correlated fluctuations in the radio-mm and X-ray fluxes from 3C279 are consistent with the synchrotron self-Compton model if $\tau_T$ varies in a fixed magnetic field and induced Compton scattering is the dominant source of radio opacity. The variation amplitudes are are too small to be produced by the passage of a shock through the synchrotron emission region unless the magnetic field is perpendicular to the shock front.Comment: 21 pages, 4 fig

BOLLOCKS!! Designing pervasive games that play with the social rules of built environments

We propose that pervasive games designed with mechanics that are specifically in opposition with, or disruptive of, social rules of the environment in which they are played, have unique potential to provide interesting, provocative experiences for players. We explore this concept through the design and evaluation of an experimental game prototype, Shhh!, inspired by the juvenile game Bollocks, and implemented on Android mobile devices, which challenges players to make loud noises in libraries. Six participants played the game before engaging in semi-structured interviews, explored through inductive thematic analysis. Results suggest that the game provoked in players a heightened awareness of social rules, as well as a complex social dilemma of whether or not to act. We conclude by presenting a model for designing games that play with the social, as well as physical, rules of the environments in which they are set

Magnetic Structures of Some Multiferroics

We studied crystal and magnetic structures of some composite and single-phase multiferroics: (x)MFe2O4 + (1-x)BaTiO3, Ni3-yCoyV2O8, and Bi0.9Ba0.1Fe0.9Ti0.1O3. Composite multiferroics (x)MFe2O4 + (1-x)BaTiO3 with x = (0.2; 0.3; 0.4) and M = (Ni, Co) have ferrimagnetic structure, which is described by the propagation vector k = 0. Oxides Ni3-yCoyV2O8 with y = (0.1; 0.3; 0.5) possess a modulated magnetic structure, described by the vector k = (δ, 0, 0), where δ = 0.283 and 0.348 at 7.4 K for y = 0.1 and 0.5, respectively. In the Bi0.9Ba0.1Fe0.9Ti0.1O3 multiferroic a magnetic order is destroyed at 600 K and the Fe-ion magnetic moment decreases from µ = 3.46(5) μB at 300 K to zero at 600 K

Dyadic Synchrony and Responsiveness in the First Year: Associations with Autism Risk

In the first year of life, the ability to engage in sustained synchronous interactions develops as infants learn to match social partner behaviors and sequentially regulate their behaviors in response to others. Difficulties developing competence in these early social building blocks can impact later language skills, joint attention, and emotion regulation. For children at elevated risk for autism spectrum disorder (ASD), early dyadic synchrony and responsiveness difficulties may be indicative of emerging ASD and/or developmental concerns. As part of a prospective developmental monitoring study, infant siblings of children with ASD (high-risk group n = 104) or typical development (low-risk group n = 71), and their mothers completed a standardized play task when infants were 6, 9, and/or 12 months of age. These interactions were coded for the frequency and duration of infant and mother gaze, positive affect, and vocalizations, respectively. Using these codes, theory-driven composites were created to index dyadic synchrony and infant/maternal responsiveness. Multilevel models revealed significant risk group differences in dyadic synchrony and infant responsiveness by 12 months of age. In addition, high-risk infants with higher dyadic synchrony and infant responsiveness at 12 months received significantly higher receptive and expressive language scores at 36 months. The findings of the present study highlight that promoting dyadic synchrony and responsiveness may aid in advancing optimal development in children at elevated risk for autism. Lay Summary: In families raising children with an autism spectrum disorder (ASD), younger siblings are at elevated risks for social communication difficulties. The present study explored whether social-communication differences were evident during a parent–child play task at 6, 9, and 12 months of age. For infant siblings of children with ASD, social differences during play were observed by 12 months of age and may inform ongoing monitoring and intervention efforts

Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts.

The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes

Estimating the Number of Male Sex Workers with the Capture- Re-capture Technique in Nigeria

Estimating the size of populations most affected by HIV such as men who have sex with men (MSM) though crucial for structuring responses to the epidemic presents significant challenges, especially in a developing  society. Using capture-recapture methodology, the size of MSM-SW in  Nigeria was estimated in three major cities (Lagos, Kano and Port Harcourt) between July and December 2009. Following interviews with key informants, locations and times when MSM-SW were available to male clients were  mapped and designated as “hotspots”. Counts were conducted on two  consecutive weekends. Population estimates were computed using a  standardized Lincoln formula. Fifty-six hotspots were identified in Kano, 38 in Lagos and 42 in Port Harcourt. On a given weekend night, Port Harcourt had the largest estimated population of MSM sex workers, 723 (95%CI:  594-892) followed by Lagos state with 620 (95%CI: 517-724) and Kano  state with 353 (95%CI: 332-373). This study documents a large  population of MSM-SW in 3 Nigerian cities where higher HIV prevalence  among MSM compared to the general population has been documented. Research and programming are needed to better understand and address the health vulnerabilities that MSM-SW and their clients face. Afr J Reprod Health 2013 (Special Edition); 17[4]: 83-89).Keywords: Male sex worker, Capture-recapture, size estimation,   population estimates, Men who have sex with men, Nigeria, Lagos, Kano, Port Harcourt

An Open Community-Driven Model For Sustainable Research Software: Sustainable Research Software Institute

Research software plays a crucial role in advancing scientific knowledge, but ensuring its sustainability, maintainability, and long-term viability is an ongoing challenge. To address these concerns, the Sustainable Research Software Institute (SRSI) Model presents a comprehensive framework designed to promote sustainable practices in the research software community. This white paper provides an in-depth overview of the SRSI Model, outlining its objectives, services, funding mechanisms, collaborations, and the significant potential impact it could have on the research software community. It explores the wide range of services offered, diverse funding sources, extensive collaboration opportunities, and the transformative influence of the SRSI Model on the research software landscapeComment: 13 pages, 1 figur