Radiological evaluation of building materials used in Malumfashi, Katsina state, using gamma-ray spectroscopy analysis

The activity concentrations of naturally occurring radionuclides (226Ra, 232Th and 40K) in building materials (sand, cement, blocks, granite, and paints) used in the construction of buildings in Malumfashi local Government area of Katsina state, Nigeria were determined by means of a gamma-ray spectrometry system using Sodium Iodide thallium activated (NaI(Tl)) detector in a low background configuration. The average activity concentrations for 226Ra, 232Th and 40K ranged from 17.07±4.98 to 50.72±6.74, 23.03±1.54 to 42.91±2.37 and 84.03±5.44 to 363.45±5.27 Bqkg-1 respectively. Except for block samples, all the samples mean activity concentrations were less than their respective world averages. The estimated absorbed gamma dose rate (D) ranged from 30.75±4.22 to 64.57±4.78 nGyh-1and the outdoor annual effective dose equivalent (AEDE) varied from 0.038±0.004 to 0.06±0.0051 mSvy-1; these values are below the worldwide effective dose of 0.07 mSvy-1. The values of radium equivalent activity (Raeq), the external hazard index (Hex) and the internal hazard index (Hin) for all the samples in the present work were lower than the accepted safety limit value of 370 Bqkg-1.Keywords: Radionuclide, hazard indices, gamma-ray spectrometry, building materials, Malumfash

Work Ethics and Productivity in Local Government System in Nigeria, Problems and Prospects

The main thrust of this paper is motivated by the desire to examine the implications of the negative work attitudes that is prevalent among the employees of the local government system in Nigeria. The paper argued that the Nigeria local government system is engulfed in Negative work tendencies characterized by such factors as corruption, lateness to duty, lack of dedication to duty, high level of insubordination, indiscipline, high level of absenteeism and dereliction of duty which hinders efficient service delivery and in turn brings about low productivity. This manifestation has produced a sense of exclusion that has sought expression in what has been considered to be widespread dissatisfaction and disaffection in the entire system. A framework for enhancing a positive work ethics among the employees of the Nigeria local government system were suggested in a bid to ensure enhanced productivity of the workforce.Keywords: Local government, work ethics, productivity, Attitudes

Public goods and decay in networks

We propose a simple behavioral model to analyze situations where (1) a group of agents repeatedly plays a public goods game within a network structure and (2) each agent only observes the past behavior of her neighbors, but is affected by the decisions of the whole group. The model assumes that agents are imperfect conditional cooperators, that they infer unobserved contributions assuming imperfect conditional cooperation by others, and that they have some degree of bounded rationality. We show that our model approximates quite accurately regularities derived from public goods game experiments

Detecting the Earliest Galaxies Through Two New Sources of 21cm Fluctuations

The first galaxies that formed at a redshift ~20-30 emitted continuum photons with energies between the Lyman-alpha and Lyman limit wavelengths of hydrogen, to which the neutral universe was transparent except at the Lyman-series resonances. As these photons redshifted or scattered into the Lyman-alpha resonance they coupled the spin temperature of the 21cm transition of hydrogen to the gas temperature, allowing it to deviate from the microwave background temperature. We show that the fluctuations in the radiation emitted by the first galaxies produced strong fluctuations in the 21cm flux before the Lyman-alpha coupling became saturated. The fluctuations were caused by biased inhomogeneities in the density of galaxies, along with Poisson fluctuations in the number of galaxies. Observing the power-spectra of these two sources would probe the number density of the earliest galaxies and the typical mass of their host dark matter halos. The enhanced amplitude of the 21cm fluctuations from the era of Lyman-alpha coupling improves considerably the practical prospects for their detection.Comment: 11 pages, 7 figures, ApJ, published. Normalization fixed in top panels of Figures 4-

A theory-based intervention delivered by an online social media platform to promote oral health among Iranian adolescents: a cluster randomized controlled trial

Objective: Based on the Health Action Process Approach, we tested the efficacy of a theory-based program using an online social media platform (Telegram) to promote good oral hygiene behaviour among Iranian adolescents. / Design: A three-arm randomized-controlled trial design was used, consisting of an adolescent only intervention group (A group; n = 253), an adolescent and mother intervention group (A + M group; n = 260), and a control group (n = 278). / Main outcome measures: Psychosocial variables, toothbrushing behaviour, Visual Plaque Index, and Community Periodontal Index. / Results: Increases in adolescent toothbrushing at the one- and six-month follow-ups in both intervention groups compared to the control group were observed. Adolescents in the A + M group showed significant greater improvements in their toothbrushing behaviour, Visual Plaque Index, and Community Periodontal Index scores than adolescents in the A group. Improvements to toothbrushing social cognitions were also observed. / Conclusions: Current results support the use of the theory-based program delivered by Telegram in improving good oral hygiene behaviour and oral health outcomes among Iranian adolescents. Involving mothers in an intervention can confer additional benefits for adolescent oral health

Galaxy Formation by Galactic Magnetic Fields

Galaxies exhibit a sequence of various morphological types, i.e., the Hubble sequence, and they are basically composed of spheroidal components (elliptical galaxies and bulges in spiral galaxies) and disks. It is known that spheroidal components are found only in relatively massive galaxies with M=10^{10-12} M_sun, and all stellar populations in them are very old, but there is no clear explanation for these facts. Here we present a speculative scenario for the origin of the Hubble sequence, in which magnetic fields ubiquitously seen in galaxies have played a crucial role. We first start from a strange observational fact that magnetic field strengths observed in spiral galaxies sharply concentrate at a few microgauss, for a wide range of galaxy luminosity and types. We then argue that this fact and the observed correlation between star formation activity and magnetic field strength in spiral galaxies suggest that spheroidal galaxies have formed by starbursts induced by strong magnetic fields. Then we show that this idea naturally leads to the formation of spheroidal systems only in massive and high-redshift objects in hierarchically clustering universe, giving a simple explanation for various observations.Comment: 7 pages including 2 figures. Accepted by ApJ Letter

Spider Haiku

The utilization of lightweight oil palm shell to produce high strength lightweight sustainable material has led many researchers towards its commercialization as structural concrete. However, the low tensile strength of Oil Palm Shell Concrete (OPSC) has hindered its development. This study aims to enhance the mechanical properties and flexural behaviours of OPSC by the addition of steel fibres of up to 3% by volume, to produce oil palm shell fibre-reinforced concrete (OPSFRC). The experimental results showed that the steel fibres significantly enhanced the mechanical properties of OPSFRC. The highest compressive strength, splitting tensile and flexural strengths of 55, 11.0 and 18.5 MPa, respectively, were achieved in the OPSFRC mix reinforced with 3% steel fibres. In addition, the flexural beam testing on OPSFRC beams with 3% steel fibres showed that the steel fibre reinforcement up to 3% produced notable increments in the moment capacity and crack resistance of OPSFRC beams, but accompanied by reduction in the ductility

Exact quantum dissipative dynamics under external time-dependent fields driving

Exact and nonperturbative quantum master equation can be constructed via the calculus on path integral. It results in hierarchical equations of motion for the reduced density operator. Involved are also a set of well--defined auxiliary density operators that resolve not just system--bath coupling strength but also memory. In this work, we scale these auxiliary operators individually to achieve a uniform error tolerance, as set by the reduced density operator. An efficient propagator is then proposed to the hierarchical Liouville--space dynamics of quantum dissipation. Numerically exact studies are carried out on the dephasing effect on population transfer in the simple stimulated Raman adiabatic passage scheme. We also make assessments on several perturbative theories for their applicabilities in the present system of study

The Near-Linear Regime of Gravitational Waves in Numerical Relativity

We report on a systematic study of the dynamics of gravitational waves in full 3D numerical relativity. We find that there exists an interesting regime in the parameter space of the wave configurations: a near-linear regime in which the amplitude of the wave is low enough that one expects the geometric deviation from flat spacetime to be negligible, but nevertheless where nonlinearities can excite unstable modes of the Einstein evolution equations causing the metric functions to evolve out of control. The implications of this for numerical relativity are discussed.Comment: 10 pages, 2 postscript figures, revised tex