1,458 research outputs found
Students Flow in Private Universities in Nigeria: A Markov Chain Modelling Approach
The emergence of Private Universities in Nigeria is expected to help the flow and progression of students. Hence, this paper applies Markov Chain modelling to flows of students. The population of the study includes all students undertaking four-year programmes at a private University. The Faculty of Social and Management Sciences is chosen as a convenience sample. This Faculty has six departments for which secondary data are available for 2004/2005 to 2013/2014 sessions. Available data were analysed using the Matlab software. The results revealed that the probability of a student repeating a grade year influences the expected length of time of stay in the programme. Also, the study found that the average time a student spent at each level of the programme ranged from 1.14 to 1.43 sessions; the expected time it took a student to reach the wastage or graduation absorbing states ranged from a minimum of 1.4714 sessions (in 400 level) to a maximum of 4.7463 sessions (in 100 level). Furthermore, the probability of a student reaching a wastage absorbing state continuously decreased in all Departments and ranged from a maximum of 0.43 (in 100 level) to a minimum of 0.01 (in 400 level). A reverse trend in the probability of reaching a wastage absorbing state was however exhibited for the probability of a student reaching a graduating absorbing state. Finally, for the students sampled, the wastage ratio varied from 1.49 to 3.87, while the coefficient of efficiency was between 25.84 and 67.32.We concluded that Sociology and Anthropology Department has the highest level of efficiency of students progression in the Faculty. Keywords: markov processes, absorption states, dropout rates, private universities, transition states
Evaluating the role of bacterial diversity in supporting soil ecosystem functions under anthropogenic stress
Ecosystem functions and services are under threat from anthropogenic global change at a planetary scale. Microorganisms are the dominant drivers of nearly all ecosystem functions and therefore ecosystem-scale responses are dependent on responses of resident microbial communities. However, the specific characteristics of microbial communities that contribute to ecosystem stability under anthropogenic stress are unknown. We evaluated bacterial drivers of ecosystem stability by generating wide experimental gradients of bacterial diversity in soils, applying stress to the soils, and measuring responses of several microbial-mediated ecosystem processes, including C and N cycling rates and soil enzyme activities. Some processes (e.g., C mineralization) exhibited positive correlations with bacterial diversity and losses of diversity resulted in reduced stability of nearly all processes. However, comprehensive evaluation of all potential bacterial drivers of the processes revealed that bacterial α diversity per se was never among the most important predictors of ecosystem functions. Instead, key predictors included total microbial biomass, 16S gene abundance, bacterial ASV membership, and abundances of specific prokaryotic taxa and functional groups (e.g., nitrifying taxa). These results suggest that bacterial α diversity may be a useful indicator of soil ecosystem function and stability, but that other characteristics of bacterial communities are stronger statistical predictors of ecosystem function and better reflect the biological mechanisms by which microbial communities influence ecosystems. Overall, our results provide insight into the role of microorganisms in supporting ecosystem function and stability by identifying specific characteristics of bacterial communities that are critical for understanding and predicting ecosystem responses to global change
Scorpion toxin peptide action at the ion channel subunit level
This review categorizes functionally validated actions of defined scorpion toxin (SCTX) neuropeptides across ion channel subclasses, highlighting key trends in this rapidly evolving field. Scorpion envenomation is a common event in many tropical and subtropical countries, with neuropharmacological actions, particularly autonomic nervous system modulation, causing significant mortality. The primary active agents within scorpion venoms are a diverse group of small neuropeptides that elicit specific potent actions across a wide range of ion channel classes. The identification and functional characterisation of these SCTX peptides has tremendous potential for development of novel pharmaceuticals that advance knowledge of ion channels and establish lead compounds for treatment of excitable tissue disorders. This review delineates the unique specificities of 320 individual SCTX peptides that collectively act on 41 ion channel subclasses. Thus the SCTX research field has significant translational implications for pathophysiology spanning neurotransmission, neurohumoral signalling, sensori-motor systems and excitation-contraction coupling
Molecular basis for the hormonal regulation of the tyrosine aminotransferase and tryptophane oxygenase genes
Restoration of degraded forest reserves in Ghana
Deforestation in Ghana has led to a forest loss of almost 20% from 9,924,000 ha in 1990 to 7,986,000 ha today. To restore degraded lands, Forest Landscape Restoration has become a critical approach globally. This study was conducted in Ghana focusing on the examples of two forest landscape restoration projects in the Pamu Berekum Forest Reserve: 10-year-old mixed-stands of two to four native tree species and an exotic species stands, including Triplochiton scleroxylon, Terminalia ivorensis, Ceiba pentandra, Nauclea diderrichii and Cedrela odorata at Pamu Berekum 1 and 4-year-old Tectona grandis and 2-year-old Gmelina arborea monoculture stands at Pamu Berekum 2. Estimates of productivity in the restored forests are described, as well as the effects of the restoration on provision of ecosystem service and benefits obtained by local communities. Stand productivity was assessed as mean annual increment of diameter and height, biomass production, and standing volume. For ecosystem services, carbon stocks were calculated for the restored forests; other ecological benefits, as well as financial benefits, were obtained through interviews with fringe communities. The results indicate that FLR can be implemented successfully using different models provided that local communities are involved during the planning and implementation of interventions. When all stands were projected to 10 years, results show higher productivity in T. grandis (331.77 m3 ha-1) and G. arborea stands (1,785.99 m3ha-1) compared to mixed stand (160.41 m3 ha-1). The Gmelina arborea stand was more productive and had higher carbon stocks (1,350.10 Mg ha-1) relative to the T. grandis stand (159.89 Mg ha-1). Both restoration projects were found to deliver important benefits and ecosystem services at the local and national levels, including direct and indirect benefits. The results provide an example for forest/environmental managers on how FLR might be implemented to create multiple benefits at different levels from local communities to the national level. Thus, these results may be useful for guiding successful restoration activities within the context of the ongoing global Forest Landscape Restoration efforts
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Method for the prediction of the hydriding thermodynamics of ternary PD-based alloys.
A method has been developed to calculate the hydriding thermodynamics of ternary Pd-X-Y systems, where X and Y are substitutional alloying elements, by using the properties of the binary Pd-X and Pd-Y systems. Experimental data was collected on the Pd-Rh-Co system to test the validity of this method. Hydrogen pressure-composition isotherms of several binary Pd-Rh and Pd-Co alloys and Pd-Rh-Co ternary alloys were measured to determine the thermodynamics of hydrogen absorption, hydride formation and decomposition, and hydrogen capacity. Good agreement between the calculated and measured values for the ternary Pd-Rh-Co system, in the dilute alloying regime (< 10 at.% total alloying additions), was obtained using our method. Examining literature results on other ternary Pd-X-Y systems checked the universality of this method. Again, the method succeeds in predicting the hydriding thermodynamics for both lattice contracted and lattice expanded alloy systems, Pd-Ni-Rh and Pd-Ag-Y respectively
Death receptor 3 (TNFRSF25) increases mineral apposition by osteoblasts and region specific new bone formation in the axial skeleton of male DBA/1 mice
Fraser L. Collins and this work were funded by an Arthritis Research UK PhD studentship (Grant Code: 18598) awarded to Anwen S. Williams, Eddie C. Y. Wang, and Michael D. Stone. Eddie C. Y. Wang was additionally funded by MRC Project Grant G0901119. Funding for open access was kindly provided by Cardiff University.Peer reviewedPublisher PD
IRVE-3 Post-Flight Reconstruction
The Inflatable Re-entry Vehicle Experiment 3 (IRVE-3) was conducted from the NASA Wallops Flight Facility on July 23, 2012. Launched on a Black Brant XI sounding rocket, the IRVE-3 research vehicle achieved an apogee of 469 km, deployed and inflated a Hypersonic Inflatable Aerodynamic Decelerator (HIAD), re-entered the Earth's atmosphere at Mach 10 and achieved a peak deceleration of 20 g's before descending to splashdown roughly 20 minutes after launch. This paper presents the filtering methodology and results associated with the development of the Best Estimated Trajectory of the IRVE-3 flight test. The reconstructed trajectory is compared against project requirements and pre-flight predictions of entry state, aerodynamics, HIAD flexibility, and attitude control system performance
Coronary arteriographic findings in black patients and risk markers for coronary artery disease
Coronary arteriographic results are reported in 1535 black patients: 751 men (mean age 57 +/- 11) and 784 women (mean age 59 +/- 11). Among the black men 19%, 15%, 21%, and 4% had single-, double-, and triple-vessel and left main disease, respectively. Among the black women there were 12%, 10%, 15%, and 3% with similar involvement. Logistic regression models showed that most of the recognized risk factors were positively correlated with significant (at least one artery with >/= 50% stenosis) coronary disease, but a history of hypertension was not a significant independent predictor in either sex. ECG evidence of previous infarction increased the odds of detecting significant coronary disease by the greatest amount when controlling for other significant risk markers in women. In men both previous infarction and atypical pain (negative) were equally important. This study confirms but does not explain previous reports that have revealed less than expected angiographic evidence of significant coronary artery disease in black compared with white persons
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