3,042 research outputs found

    Evaluation of QSAR and ligand enzyme docking for the identification of ABCB1 substrates

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    P-glycoprotein (P-gp) is an efflux pump that belongs to ATP-binding cassette (ABC) transporter family embedded in the membrane bilayer. P-gp is a polyspecific protein that has demonstrated its function as a transporter of hydrophobic drugs as well as transporting lipids, steroids and metabolic products. Its role in multidrug resistance (MDR) and pharmacokinetic profile of clinically important drug molecules has been widely recognised. In this study, QSAR and enzyme-ligand docking methods were explored in order to classify substrates and non-substrates of P-glycoprotein. A set of 123 compounds designated as substrates (54) or non-substrates (69) by Matsson et al., 2009 was used for the investigation. For QSAR studies, molecular descriptors were calculated using ACD labs/LogD Suite and MOE (CCG Inc.). P-glycoprotein structures available in the Protein data bank were used for docking studies and determination of binding scores using MOE software. Binding sites were defined using co-crystallised ligand structures. Three classification algorithms which included classification and regression trees, boosted trees and support vector machine were examined. Models were developed using a training set of 98 compounds and were validated using the remaining compounds as the external test set. A model generated using BT was identified as the best of three models, with a prediction accuracy of 88%, Mathews correlation coefficient of 0.77 and Youden’s J index of 0.80 for the test set. Inclusion of various docking scores for different binding sites improved the models only marginally

    Effect of genotypes on soyabean seed quality development under West African Rainfed conditions

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    Effect of genotypes on soyabean seed quality development was monitored under rainfed conditions at Abeokuta between July and November, 1997. A consistent increase in rate of normal germination and seedling emergence occurred among early harvests. Greatest germination rate was detected in seeds harvested around physiological (functional) and harvest (full) maturity stages. Seedling emergence was significantly influenced by seed harvest date in all soyabean entries. Germination and emergence increased as soyaben seed development progressed and was greatest for seeds harvested between R7 and R8 in all soyabean cultivars. Enforced desiccation to 10% moisture content promoted germination of seeds harvested around physiological maturity stages. The onset of desiccation tolerance fell between physiological and harvest maturity stages in all the six soyabean cultivars. The rapid decline in seedling emergence of artifically dried seeds at 50d after mtff as against 60d after mtff for normal laboratory gemination indicated that seedlots of initial good germination may not necessarily produce high seedling emergence under good seeding condition due to differences in genotypes. Association of seed characters such as seed size, seed weight, germinability and emergence ability is essential in soyabean breeding to facilitate selection of genotypes with good seed quality, thereby reducing elaborate storage and screening methods

    Beyond locutionary denotations: exploring trust between practitioners and policy

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    This study reports the findings of a research on the trust relationship between practitioners in the Skills for Life (SfL) area and the policy that informs their practice. The exploration of this relationship was premised on an extended notion of trust relationship which draws from the Speech Act theory of Austin (1962; Searle 1969; Kissine 2008), leading to the claim that the existence of different layers of imports in textual analysis makes it possible for a trust relationship to exist between the human/physical and the non human/non physical. The study found that the majority of practitioners in the SfL field trust policy to deliver its inherent policy only to a limited extent. Amongst others, the study identified the impact of the perlocutionary import of policy text on practitioners as a viable reason for this limited level of trust. Such perlocutionary imports, it also found, have adverse impact on practitioners who are considered to have drawn from previous experience to mediate the import of contemporary policies

    The impact of active workstations on workplace productivity and performance: a systematic review

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    Active workstations have been recommended for reducing sedentary behavior in the workplace. It is important to understand if the use of these workstations has an impact on worker productivity. The aim of this systematic review was to examine the effect of active workstations on workplace productivity and performance. A total of 3303 articles were initially identified by a systematic search and seven articles met eligibility criteria for inclusion. A quality appraisal was conducted to assess risk of bias, confounding, internal and external validity, and reporting. Most of the studies reported cognitive performance as opposed to productivity. Five studies assessed cognitive performance during use of an active workstation, usually in a single session. Sit-stand desks had no detrimental effect on performance, however, some studies with treadmill and cycling workstations identified potential decreases in performance. Many of the studies lacked the power required to achieve statistical significance. Three studies assessed workplace productivity after prolonged use of an active workstation for between 12 and 52 weeks. These studies reported no significant effect on productivity. Active workstations do not appear to decrease workplace performance

    Conservation and Biodiversity Erosion in Ondo State, Nigeria: (2). Assessing Botanicals Used in the Storage of Farm Produce in Akure region

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    Semi-structured questionnaire matrix was used to identify plant species used for storage purposes in five communities situated within 5kilometre radius from Akure, the Ondo State capital, south-western Nigeria. A total of 32 botanical species were found to be commonly used in the preservation of farm produce in the study area. The leaves constituted the major part of the botanical that were widely utilised while the major farm produce common in the study area were kola nuts and bitter kola The descriptions of the indigenous knowledge of the various methods of application of the botanicals were identified and documented. Only nine of the botanicals were cultivated abundantly in the study area. The household farm, forest and common area constituted the major primary sources of the storage botanicals. Strategies that could ensure the continuous supply of the storage botanicals were proposed

    Aerosol Optical Depth Trends over Different Regions of Nigeria: Thirteen Years Analysis

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    Recurrent challenges of the theoretical estimation of aerosol optical thickness (AOT) are traceable to bogus assumption in its mathematical model. The objective of this paper is to propound a model that could describe the aerosol distribution sizes per time. The physics of the salient properties of aerosol within the Stokes regime was discussed. The mathematical model was applied to six locations within 335 ˟ 230 Km2 area of a selected portion of south-west, Nigeria. Though the climatic change is evident via thirteen years ground data set assimilation, the sensitivity of the proposed model was proven to increase by 0.1%. The research affirmed the use of some parameters (e.g. minimum temperature, cloud cover, relative humidity and rainfall) to estimate aerosol optical thickness and by extension the aerosol distribution size over an area

    A time-frequency analysis of the Canadian macroeconomy and the yield curve

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    We use wavelet analysis to study the relationship between the yield curve and macroeconomic indicators in Canada. We rely on the Nelson-Siegel approach to model the zero coupon yield curve, and use the Kalman lter to estimate its time-varying factors: the level, the slope and the curvature. Apart from the bidirectional yield-macro relation, the paper broadens the existing literature by exploring the link between the monetary policy and the yield curve.COMPETE 2020, Portugal 2020, FEDER, FCTinfo:eu-repo/semantics/publishedVersio

    Energy Efficiency in Building: Case of Buildings at the University of Ibadan, Nigeria

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    Nigeria today faces serious challenge in providing adequate energy to meet the needs of her citizenry. Efforts are currently geared towards generation of more energy to ease the problem. While these efforts are commendable, it is equally desirable to explore ways to minimize consumption of generated energy. The objective of this work is to investigate the effect of building orientation on energy demand in buildings. This paper considered the use of standard design considerations, fundamental cooling load equations and the guidelines stipulated by the American Society of Heating, Cooling and Air conditioning Engineers (ASHRAE). The study takes the designs of three buildings within the University of Ibadan, Nigeria into consideration with the view to harness the energy saving potentials through building orientation and selection of efficient cooling equipment. The results obtained were 155.34, 224.75, 86.35 kW and 163.60, 232.04 and 90.64 kW for the three lecture envelopes including the Faculty of Science, CBN and the Department of Chemistry lecture theatres using the North-South and East-West building orientations respectively. Increase in energy demand of 7.96, 7.29 and 4.29 kW was thus obtained with the East-West building orientation over North-South. Energy efficiency is thus guaranteed with North-South building orientatio

    Parametric retrieval model for estimating aerosol size distribution via the AERONET, LAGOS station

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    The size characteristics of atmospheric aerosol over the tropical region of Lagos, Southern Nigeria were investigated using two years of continuous spectral aerosol optical depth measurements via the AERONET station for four major bands i.e. blue, green, red and infrared. Lagos lies within the latitude of 6.465�N and longitude of 3.406�E. Few systems of dispersion model was derived upon specified conditions to solve challenges on aerosols size distribution within the Stokes regime. The dispersion model was adopted to derive an aerosol size distribution (ASD) model which is in perfect agreement with existing model. The parametric nature of the formulated ASD model shows the independence of each band to determine the ASD over an area. The turbulence flow of particulates over the area was analyzed using the unified number (Un). A comparative study via the aid of the Davis automatic weather station was carried out on the Reynolds number, Knudsen number and the Unified number. The Reynolds and Unified number were more accurate to describe the atmospheric fields of the location. The aerosols loading trend in January to March (JFM) and August to October (ASO) shows a yearly 15% retention of aerosols in the atmosphere. The effect of the yearly aerosol retention can be seen to partly influence the aerosol loadings between October and February.The size characteristics of atmospheric aerosol over the tropical region of Lagos, Southern Nigeria were investigated using two years of continuous spectral aerosol optical depth measurements via the AERONET station for four major bands i.e. blue, green, red and infrared. Lagos lies within the latitude of 6.465�N and longitude of 3.406�E. Few systems of dispersion model was derived upon specified conditions to solve challenges on aerosols size distribution within the Stokes regime. The dispersion model was adopted to derive an aerosol size distribution (ASD) model which is in perfect agreement with existing model. The parametric nature of the formulated ASD model shows the independence of each band to determine the ASD over an area. The turbulence flow of particulates over the area was analyzed using the unified number (Un). A comparative study via the aid of the Davis automatic weather station was carried out on the Reynolds number, Knudsen number and the Unified number. The Reynolds and Unified number were more accurate to describe the atmospheric fields of the location. The aerosols loading trend in January to March (JFM) and August to October (ASO) shows a yearly 15% retention of aerosols in the atmosphere. The effect of the yearly aerosol retention can be seen to partly influence the aerosol loadings between October and February

    Lifelong behavioral and neuropathological consequences of repetitive mild traumatic brain injury

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    Objective: Exposure to repetitive concussion, or mild traumatic brain injury (mTBI), has been linked with increased risk of long-term neurodegenerative changes, specifically chronic traumatic encephalopathy (CTE). To date, preclinical studies largely have focused on the immediate aftermath of mTBI, with no literature on the lifelong consequences of mTBI in these models. This study provides the first account of lifelong neurobehavioral and histological consequences of repetitive mTBI providing unique insight into the constellation of evolving and ongoing pathologies with late survival. Methods: Male C57BL/6J mice (aged 2–3 months) were exposed to either single or repetitive mild TBI or sham procedure. Thereafter, animals were monitored and assessed at 24 months post last injury for measures of motor coordination, learning deficits, cognitive function, and anxiety-like behavior prior to euthanasia and preparation of the brains for detailed neuropathological and protein biochemical studies. Results: At 24 months survival animals exposed to r-mTBI showed clear evidence of learning and working memory impairment with a lack of spatial memory and vestibule-motor vestibulomotor deficits compared to sham animals. Associated with these late behavioral deficits there was evidence of ongoing axonal degeneration and neuroinflammation in subcortical white matter tracts. Notably, these changes were also observed after a single mTBI, albeit to a lesser degree than repetitive mTBI. Interpretation: In this context, our current data demonstrate, for the first time, that rather than an acute, time limited event, mild TBI can precipitate a lifelong degenerative process. These data therefore suggest that successful treatment strategies should consider both the acute and chronic nature of mTBI
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