Size distribution of nano particles from residential fixed-bed coal combustion

Abstract: Particle size distribution (PSD) from domestic coal combustion is an important parameter as it affects air quality, climate modelling, and health. There is limited information in the literature on particle size distribution from residential fixed-bed coal combustion processes. This study aimed to investigate the influence of coal combustion phases (ignition, flaming, and coking) on PSD of fine and ultrafine particles. Fine particle emissions from combustion of D-grade type coal (Ø 40 – 60 mm), in a lab-fabricated coal brazier (imbaula), were monitored using a NanoScan Scanning Mobility Particle Sizer (SMPS). Experiments were carried out using the reduced smoke top-lit updraft method, colloquially known as the Basa njengo Magogo (BnM) method. Particles from the top-lit updraft (TLUD) showed an ultrafine geometric mean diameter centred at approximately 110 nm for the ignition phase, 55 nm for the pyrolysis/ flaming phase, and 33 nm for the transition phase. The particle mode diameter rapidly increased during the ignition phase (145 nm) and gradually decreased during the flaming phase (35 nm) and the transition phase (31 nm)

All-Optical Switching with Transverse Optical Patterns

We demonstrate an all-optical switch that operates at ultra-low-light levels and exhibits several features necessary for use in optical switching networks. An input switching beam, wavelength $\lambda$, with an energy density of $10^{-2}$ photons per optical cross section [$\sigma=\lambda^2/(2\pi)$] changes the orientation of a two-spot pattern generated via parametric instability in warm rubidium vapor. The instability is induced with less than 1 mW of total pump power and generates several $\mu$Ws of output light. The switch is cascadable: the device output is capable of driving multiple inputs, and exhibits transistor-like signal-level restoration with both saturated and intermediate response regimes. Additionally, the system requires an input power proportional to the inverse of the response time, which suggests thermal dissipation does not necessarily limit the practicality of optical logic devices

Identification of Outflows and Candidate Dual Active Galactic Nuclei in SDSS Quasars at z=0.8-1.6

We present a sample of 131 quasars from the Sloan Digital Sky Survey at redshifts 0.8<z<1.6 with double peaks in either of the high-ionization narrow emission lines [NeV]3426 or [NeIII]3869. These sources were selected with the intention of identifying high-redshift analogs of the z<0.8 active galactic nuclei (AGN) with double-peaked [OIII]5007 lines, which might represent AGN outflows or dual AGN. Lines of high-ionization potential are believed to originate in the inner, highly photoionized portion of the narrow line region (NLR), and we exploit this assumption to investigate the possible kinematic origins of the double-peaked lines. For comparison, we measure the [NeV]3426 and [NeIII]3869 double peaks in low-redshift (z<0.8) [OIII]-selected sources. We find that [NeV]3426 and [NeIII]3869 show a correlation between line-splitting and line-width similar to that of [OIII]5007 in other studies; and the velocity-splittings are correlated with the quasar Eddington ratio. These results suggest an outflow origin for at least a subset of the double-peaks, allowing us to study the high-ionization gas kinematics around quasars. However, we find that a non-neligible fraction of our sample show no evidence for an ionization stratification. For these sources, the outflow scenario is less compelling, leaving the dual AGN scenario as a viable possibility. Finally, we find that our sample shows an anti-correlation between the velocity-offset ratio and luminosity ratio of the components, which is a potential dynamical argument for the presence of dual AGN. Therefore, this study serves as a first attempt at extending the selection of candidate dual AGN to higher redshifts.Comment: 19 pages, 12 figures, accepted for publication in The Astrophysical Journa

Translational regulation contributes to the elevated CO2 response in two Solanum species.

Understanding the impact of elevated CO2 (eCO2 ) in global agriculture is important given climate change projections. Breeding climate-resilient crops depends on genetic variation within naturally varying populations. The effect of genetic variation in response to eCO2 is poorly understood, especially in crop species. We describe the different ways in which Solanum lycopersicum and its wild relative S.&nbsp;pennellii respond to eCO2 , from cell anatomy, to the transcriptome, and metabolome. We further validate the importance of translational regulation as a potential mechanism for plants to adaptively respond to rising levels of atmospheric CO2

Dissecting social interaction:Dual-fMRI reveals patterns of interpersonal brain-behavior relationships that dissociate among dimensions of social exchange

During social interactions, each individual’s actions are simultaneously a consequence of and an antecedent to their interaction partner’s behavior. Capturing online the brain processes underlying such mutual dependency requires simultaneous measurements of all interactants’ brains during real-world exchange (‘hyperscanning’). This demands a precise characterization of the type of interaction under investigation, however, and analytical techniques capable of capturing interpersonal dependencies. We adapted an interactive task capable of dissociating between two dimensions of interdependent social exchange: goal structure (cooperation vs competition) and interaction structure [concurrent (CN) vs turn-based]. Performing dual-functional magnetic resonance imaging hyperscanning on pairs of individuals interacting on this task, and modeling brain responses in both interactants as systematic reactions to their partner’s behavior, we investigated interpersonal brain-behavior dependencies (iBBDs) during each dimension. This revealed patterns of iBBDs that differentiated among exchanges; in players supporting the actions of another, greater brain responses to the co-player’s actions were expressed in regions implicated in social cognition, such as the medial prefrontal cortex, precuneus and temporal cortices. Stronger iBBD during CN competitive exchanges was observed in brain systems involved in movement planning and updating, however, such as the supplementary motor area. This demonstrates the potential for hyperscanning to elucidate neural processes underlying different forms of social exchange

Effects of an E-Learning Module on Students’ Attitudes in an Electronics Class

Research has shown that students exhibit negative attitudes towards Electronics especially when they are taught using the conventional method. This is in addition to poor instructional methods that do not promote individualization of instruction or make learning interesting. The purpose of this study was to design an e-learning module in “Transistors” – a topic in the Electronics course - and determine its effects on students’ attitudes in Kenyan Polytechnics. The Solomon-three quasi-experimental, non-equivalent control group research design was used for the study. A sample consisting of 103 first year Electronic Engineering students from three Polytechnics were randomly assigned to three groups; one experimental, E and two controls; C1 and C2. A self-administered Students’ Attitude Questionnaire (SAQ) with a calculated Cronbach-alpha reliability coefficient of 0.88 was used for data collection. The data was analysed using t-tests and the analysis of covariance (ANCOVA) statistical test at an alpha level of significance of 0.05. The results of the t-test revealed that the differences in gain from pre-test to post-test between groups E and C1 were significant in favour of group E. Further results using ANCOVA revealed that there were statistically significant differences in post-test scores for students’ attitudes between groups E and C2 in favour of group E. This showed that the presence of a pre-test had a significant effect on students’ attitude towards the topic being taught irrespective of whether they were taught using the e-learning module or the conventional method. The findings of the study shall be useful to Electronics students and lecturers, curriculum developers, e-learning practitioners and educational policy makers in Kenya. Keywords: e-learning, conventional method, attitudes, electronics, transistors, studen