EMG-EMG Coherence Analysis of Elbow and Shoulder Muscles

Motor coordination can be described by the activation of a few intermuscular coordination patterns, or muscle synergies. Muscle synergy can be defined as a relatively fixed pattern of activation across a set of muscles. The neural mechanisms underlying muscle synergies remain to be fairly unknown. Through a muscle synergy study [13], co-activation in muscle pairs was discovered through a non-negative matrix factorization: NMF) analysis. In order to evaluate the same muscles under the frequency domain, coherence analysis: a correlational method) was used. Additionally, a comparison can be made to determine if the resulting muscle pairs overlap with the muscle pairs found through the synergy analysis. Using coherence analysis, it was evaluated whether muscle members co-activated within a muscle synergy are correlated in the frequency domain, suggesting a common fixed drive in the central nervous system

Design and Implementation Strategies for Peer-Led Team Learning in Organic Chemistry

Peer-Led Team Learning (PLTL), which initially began as an effort to improve undergraduate chemistry education, has shown the potential to improve learning among college students in all disciplines. The model applies the desired qualities of teamwork to learning. This project is aimed at designing and setting up a PLTL Workshop at Southern Adventist University (SAU). Nine students currently taking organic chemistry at SAU volunteered to participate in the project. In order to determine the effectiveness of the project, test scores were collected and analyzed for any apparent trends, and an end-of-semester survey was conducted. The results indicate that the program was a success

The Dynamics of Spacing and Timing of Births in Ghana

Studying the dynamics of timing and spacing of births is important for several reasons including an understanding of completed family size as well as maternal and child mortality differentials. Using the 1998 DHS data, this paper examines whether there are intrinsic socio-cultural factors that affect the duration of birth intervals in Ghana. The results suggest that while most socio-cultural differences are mediated through socio-economic and demographic factors, there is the persistence of ethnic-specific norms and practices that affect the timing of births. At all durations, Ewes and Mole- Dagbanis were consistently found to have longer intervals between successive births than Akans. This has been explained through to ethnic differences in unobservable norms and observable practices such as lineage patterns, duration of the period of post-partum sexual abstinence and amenorrhoea. Besides the socio-economic and socio-cultural factors, other consistently significant covariates were age at first birth, birth cohorts and the survival status of the index. Age at first marriage was found to associate only with the timing of the first two children

Lagged Effect of Childhood Mortality on Reproductive Behavior in Ghana and Kenya

This paper goes beyond the physiological impact of infant deaths on fertility by examining whether such deaths elicit an explicit, conscious and intentional fertility response in sub-Saharan Africa. The major research questions are: what are the long term implications of childhood mortality on reproductive behavior? Does the death of the first child, for instance, affect the risk of a higher order birth? These questions are examined using DHS data from Ghana and Kenya. At each parity, women with childhood mortality experience were found to have a higher number of subsequent than those without. Additionally, multivariate results suggest that infant deaths tend to have a long term impact on reproductive behaviour. The death of the first child in particular was found to associate with the risk of a higher order birth. This is probably because first births in most African cultures are deemed special and as such their death as infants has a long term effect on a woman’s reproductive behaviour. From a policy perspective, these finding suggest that improvement in child survival programs could significantly improve fertility through both the biological and behavioural effects

Fertility Response to Childhood Mortality in Sub-Saharan with Emphasis on Ghana and Kenya

Notwithstanding the extensive social scientific research, there are still unanswered questions regarding the persistence of high fertility in sub-Saharan Africa. Although fertility behaviour depends on multiplicity of factors, childhood mortality is regarded as an important determinant.However, while the theoretical pathways through which infant and child mortality affect fertility are well understood, the empirical evidence has been inconsistent. Thus, the unsettled nature of the link between childhood mortality and fertility was a major motivation for this study. Methodologically, the paper examines the usefulness of frailty models in exploring the childhood mortality-fertility relationships using DHS data from Ghana and Kenya. Invariably, women with prior infant deaths were found to have more subsequent births than those without mortality experience, suggesting both a physiological and behavioral response. While corroborating this finding, the multivariate results demonstrated that models without unobserved heterogeneity tended to produce biased estimates. Comparing Ghana and Kenya, there were significant differences in the effects of childhood mortality on subsequent births. At all parities, the fertility response to mortality was found to be larger in Ghana, perhaps suggesting a negative relationship between fertility response and the stage of fertility transition

A Retinal Circuit That Computes Object Motion

Certain ganglion cells in the retina respond sensitively to differential motion between the receptive field center and surround, as produced by an object moving over the background, but are strongly suppressed by global image motion, as produced by the observer's head or eye movements. We investigated the circuit basis for this object motion sensitive (OMS) response by recording intracellularly from all classes of retinal interneurons while simultaneously recording the spiking output of many ganglion cells. Fast, transient bipolar cells respond linearly to motion in the receptive field center. The synaptic output from their terminals is rectified and then pooled by the OMS ganglion cell. A type of polyaxonal amacrine cell is driven by motion in the surround, again via pooling of rectified inputs, but from a different set of bipolar cell terminals. By direct intracellular current injection, we found that these polyaxonal amacrine cells selectively suppress the synaptic input of OMS ganglion cells. A quantitative model of these circuit elements and their interactions explains how an important visual computation is accomplished by retinal neurons and synapses.Molecular and Cellular Biolog

A chirp spread spectrum modulation scheme for robust power line communication

This paper proposes the use of a LoRa like chirp spread spectrum physical layer as the basis for a new Power Line Communication modulation scheme suited for low-bandwidth communication. It is shown that robust communication can be established even in channels exhibiting extreme multipath interference, impulsive noise and low SNR (-40dB), with synchronisation requirements relaxed compared to conventional LoRa. ATP-EMTP simulations using frequency dependent line and transformer models, and simulations using artificial Rayleigh channels demonstrate the effectiveness of the new scheme in providing load data from LV feeders back to the MV primary substation. Our results demonstrate error-free communication at SNRs of -40dB, and can be further improved by trading-off data rate. We further present experimental results based on a Field Programmable Gate Array hardware implementation which match the simulated performance

A sub-μs accuracy GPS alternative using electrical transmission grids as precision timing networks

It is widely recognised that over-reliance on GNSS (e.g GPS) for time synchronisation represents an acute threat to modern society, and a diversity of alternatives are required to mitigate the threat of an outage. This paper proposes a GNSS alternative using time dissemination over national scale transmission or distribution networks. The method utilises the same frequency bandwidth and coupling technology as established power line carrier technology in conjunction with modern chirp Spread Spectrum modulation. The basis of the method is the transmission of a time synchronised chirp from a central substation, coupled into the aerial modes of the transmission line. During GNSS operation, all substations can estimate the time of flight by correlating the received chirp with a time-synchronised local copy. During GNSS outage, time sychronisation to the central substation is maintained by correcting for the precalculated time of flight. It is shown that recent advances in chirp spread spectrum allow for a computationally efficient algorithm with the capacity to compute hundreds of thousand of chirp correlations every second, facilitating timing accuracy which satisfies the majority of smart grid applications. ATP-EMTP simulations of the method on large transmission networks demonstrate sub-μs timing accuracy even in the presence of low SNR and impulsive noise. An FPGA prototype demonstrates experimentally sub-μs accuracy for time dissemination over a distance of 700 m. Averaging over time is shown to facilitate satisfactory performance down to -20dB, which could extend the range of the system to a national scale and a time dissemination network invulnerable to wireless spoofing and jamming attack vectors

The Belief in and Veneration of Ancestors in Akan Traditional Thought: Finding Values for Human Well-being

Traditional Africans' belief in and veneration of ancestors is an almost ubiquitous, long-held and widely known, for it is deeply entrenched in the African metaphysical worldview itself. This belief in and veneration of ancestors is characterised by strong moral undertone. This moral undertone involves an implicit indication that individual members of communities must live exemplary lives in accordance with the ethos of the community. Living according to the ethos is among the conditions for attaining the prestige of being elevated to an ancestor after one's death. The aim of this paper is to gain an understanding of the metaphysical and moral demands connected to ancestor veneration. With this understanding, the paper suggests values that can promote a better way for humans to coexist, and indicates a moral sense of the responsibility people should hold towards each other. The paper's focal aim is to expose what it considers to be the moral undertones or features associated with a belief in and veneration of ancestors, mainly from traditional Akan perspectives. The paper also considers how principles and values of Akan communitarianism can be espoused to promote human well-being. It is the position of the paper that the metaphysical and, especially, the moral underpinning of ancestor veneration in the traditional Akan society, can provide values that can serve as catalysts for the furtherance of human well-being