Contrast Adaptation in Subthreshold and Spiking Responses of Mammalian Y-Type Retinal Ganglion Cells

Retinal ganglion cells adapt their responses to the amplitude of fluctuations around the mean light level, or the contrast. But, in mammalian retina, it is not known whether adaptation arises exclusively at the level of synaptic inputs or whether there is also adaptation in the process of ganglion cell spike generation. Here, we made intracellular recordings from guinea pig Y-type ganglion cells and quantified changes in contrast sensitivity (gain) using a linear-nonlinear analysis. This analysis allowed us to measure adaptation in the presence of nonlinearities, such as the spike threshold, and to compare adaptation in subthreshold and spiking responses. At high contrast (0.30), relative to low contrast (0.10), gain reduced to 0.82 ± 0.016 (mean ± SEM) for the subthreshold response and to 0.61 ± 0.011 for the spiking response. Thus, there was an apparent reduction in gain between the subthreshold and spiking response of 0.74 ± 0.013. Control experiments suggested that the above effects could not be explained by an artifact of the intracellular recording conditions: extracellular recordings showed a gain change of 0.58 ± 0.022. For intracellular recordings, negative current reduced the spike output but did not affect the gain change in the subthreshold response: 0.80 ± 0.051. Thus, adaptation in the subthreshold response did not require spike-dependent conductances. We conclude that the contrast-dependent gain change in the spiking response can be explained by both a synaptic mechanism, as reflected by responses in the subthreshold potential, and an intrinsic mechanism in the ganglion cell related to spike generation

ADAPTING MODERN METHODS OF LECTURING IN NIGERIAN UNIVERSITIES: A CRITIQUE

Different disciplines have explored the concept of lecturing from different perspectives. However, adapting some modern methods of lecturing in Nigerian universities have not been systematically studied.   Therefore, this paper examines critically the modern   methods of lecturing in our modern days tertiary institutions in Nigeria.In agreement with other researches, this paper notes that there are many challenges facing the   methods of teaching in Nigerian Universities today. Triangulation method was used to gather information for this paper, and both primary and secondary   sources were used to obtain information for this article.  The findings of this paper show that the traditional lecture method will not lead to much educational achievements unless it is combined with interactive engagements with the students and prompt feedback from the tutorsThe paper recommends that if Government could live up to her   expectation by provision of basic amenities and   state-of-the-arts teaching facilities to the tertiary institutions, the phenomenon could be reduced. A concerted effort is therefore needed among all stake holders in the education sector for the task of promoting effective teaching in our tertiary institutions

Assessment of growth variables and regression models for the tree volume prediction of Azardirachta indica (a. Juss) at Warwade plantation, Dutse, Jigawa state, Nigeria

Savannah is well known with less diverse ecosystem. Tree growth dynamics is a major technique in quantifying the forest composition. However, there is need to determine community structure and model which is suitable for Azadiractha indica in arid land.Therefore, the experiment was carried out to assess the tree growth variables and regression models for tree volume prediction of Azadiractha indica in Warwade plantation. Four (4) plots of 25m x 25m were using random sampling technique at interval of 100m from each other. Tree growth variables such as: diameter at breast height (DBH), diameter at the base (Db) middle (Dm), top (Dt) and height were taken with aid of Spiegel relascope. Frequency of occurrence of all tree with diameter at breast height (DBH) ≥10cm were measured. Three regression models were developed which are exponential, Quadratic and Vapour pressure. A total of eighty-one (81) stems ha-1 of the species were identified and counted. The tree growth variables measure showed that Azadiractha indica plantation had total volume of 14126.59m3 per ha-1 and basal area was 339998.19m2. The range of 61-70cm of diameter class had the highest number of terms per hectare (33.33%). The models developed showed that exponential model volume was found to be more suitable and good fit for tree volume prediction in the context of the data used. Therefore, exponential model generated in this study is recommended for volume prediction at Warwade Forest Reserve, Dutse, and Jigawa State. Keywords: Growth Assessment, Regression Models, Tree Volume Prediction, Azardirachta indica and Warwade

Effects of Neem Aqueous Extract (Azadirachta indica) against Aphids and Aphid-borne Virus in Cowpea (Vigna unguiculata L. Walp)

Pests and diseases are among the major factors limiting plant growth and yields. Pests are known vectors of pathogens including viruses. Proper management of plant pests is an indirect means of controlling viral diseases in plants. This study aimed at comparing the potential of neem extract and a synthetic insecticide (lambda cyhalothrin) for the management of aphids and Cowpea aphid-borne mosaic virus (CABMV) in five different cowpea (Vigna unguiculata) genotypes and to determine the residual effects of the insecticide in the cowpea grains. The experimental field was laid out in randomized complete block design with three replicates. Treatments included; spraying of cowpea plots with aqueous neem extract and lambda cyhalothrin (LC) twice at foliage stage, once at flowering and podding stages. Control plots were left unsprayed. Data were obtained on growth and yields of cowpea genotypes as well as the pest and virus disease traits. Results of the Analysis of Variance (ANOVA) revealed that variations attributable to genotypes were significant (p ≤ 0.01) for cowpea yields and virus disease traits. Treatments applied influenced the occurrence of pests and virus diseases. Neem extract reduced aphid infestations and virus diseases as much as the insecticide. Ife BPC accumulated a very high level of LC (1.14 ppm) in its grain when compared with the maximum residue level (MRL) for lambda cyalothrin in cowpea seeds. The study concludes that the use of eco-friendly bio-pesticide such as neem aqueous extract is effective for the management of aphids and aphid-borne virus in cowpea fields. Keywords: Aphids; aqueous extract; cowpea; neem; pesticide; viru

Experimental Investigation of Lard and Tallow Oils Suitability in Turning Operation of Hypo-Eutectoid Steels

This research is aimed at evaluating the performance suitability of lard and tallow based cutting fluids as potential cutting fluids in turning of hypo-eutectoid steels using carbide cutting tool steels. This was achieved via investigation of the effect of those selected fluids on certain parameters like tool temperature, tool life, spindle power consumption, Work-piece under roughness and chip formations etc., as compared to the conventional mineral oil-based MCFs.Cooling and lubrication in machining are important in reducing the severity of the contact processes at the cutting tool-workpiece interface. Currently, there are wide scale evaluations of the use of metal working fluids (MWFs) in machining, so as to reduce the amount of lubricants in metal removing operations. The increasing awareness of the general public on the environment and health impact of mineral oil-based metal cutting fluids (MCFs) is forcing machine workshop operators to reduce their use as cutting fluids and in search for more environmental friendly animal oil-based cutting fluids. Based on this, commercially available animal oils are currently been exploited as potential oils for formulation of animal oil-based cutting fluids. It is therefore necessary to conduct machining trials to determine the suitability of these oils in metal cutting operations such as turning, drilling and milling etc. This study investigates the effect of the selected cutting fluids on certain machining parameters in turning operations of hypo-eutectoid steels using carbide cutting tool. The selected oils purchased from a local market in Ibadan, Nigeria were sieved to remove any foreign particles or dirt. The solution (water, additives, and base-oil) were mixed at an elevated temperature of 55oC in a proportion 5:1:2.The essence of the emulsifier (additive) was to prevent separation of water from oil. The steel samples obtained from a steel company in Nigeria after spectrochemical analysis, were machined on a variable speed center lathe under different machining parameters. Experimental results clearly showed that Conventional cutting fluid might be replaced with Non-conventional one like LOCFs and TOCFs as they give better performances. With slight modifications and deliberate but careful alterations in some of the components of such oils, better performing cutting fluids could be obtainedSelf-Sponsore

Molecular identification and genetic diversity study of the Iraqi truffles

The aim of this study is to investigate the molecular identification of the Iraqi truffles species and a better understanding of genetic diversity in the center of the truffles habitat. Thirty-two samples were collected from the Iraqi desert and local markets. Samples were chosen depending on the morphological diversity of the fruit body and sample collection area. Results of ITS region sequencing for the 32 samples showed two genuses Tirmania and Terfezia are the main dominant, 4 species of Tirmania pinoyi and 28 species of Terfezia claveryi. All species sequences were deposited in NCBI GenBank and all had accessions number. The neighbor-Joining method was used to generate a phylogenic tree to study the genetic diversity of the ITS sequences for the 32 Iraqi truffle samples. Results showed a high genetic diversity for the Iraqi truffles samples. The phylogenic study showed Iraqi truffles clustered with different groups as a clade with the reference sequences from other countries represent three continents Asia, Africa, and Europe. Also, we found in this study a unique cluster group for the Iraqi sequences for T. pinoyi and T. claveryi truffles cluster in one group and do not match with any reference sequences used in this study. This is a piece of strong evidence proofed the Iraqi habitat could be the origin of center diversity for the T. pinoyi and T. claveryi truffles

Use of Bamboo and Earth Materials in Construction for the Provision of Affordable Building Structures for Sustainable Development at Kuje Area Council, Abuja

The study was carried out on the use of bamboo and earth materials in building construction in provision of affordable housing at Kuje area council Abuja. The purpose of the study was to determine the status of the use of bamboo and earth materials in construction at Kuje area council Abuja, identifying the factors limiting the use of bamboo and earth materials in construction at Kuje area council Abuja, examine the strategies that will improve the use of bamboo and earth materials in construction at Kuje area council Abuja. Three research questions and three hypotheses were formulated to guide the study. A population of 80 respondents, comprising of 20 engineers and 60 craftsmen was used for the study. A structured questionnaire was developed by the researcher and was used as an instrument for data collection. The instrument was validated by three lecturers in the department of industrial and technology education, federal university of technology Minna. The data collected was analyzed using mean and standard deviation, while t-test statistic was used to test three hypotheses at 0.05level of significance. The findings of the study revealed that there are limitations in the use of bamboo for building construction in the Kuje Area Council. Based on the findings of the study, it was recommended that the use of bamboo and earth materials in building construction should be introduced as part of the curriculum for construction education at both undergraduate and postgraduate levels in order to sensitize the students to their potential uses and benefits. The government should employ a policy of adapting bamboo and earth materials that require minimal amounts of capital and foreign exchange and makes use of available raw materials and skills in small-scale operations and suggestion were also made for further research works

Growth performance of Clarias gariepinus fed compounded rations and maggots

ABSTRAC

EFFECT OF GROUNDNUT CAKE AND SOYA BEANS ON ENHANCED CITRIC ACID PRODUCTION FROM PAWPAW AND ORANGE PEEL BY MUTANTS OF ASPERGILLUS NIGER

This present study was concerned with the biosynthesis of citric acid (CA) with mutant strain of Aspergillus niger using pawpaw and orange peel as substrates by solid state fermentation process. The A. niger strain isolated from spoilt orange was identified, screened for CA production on Czapek-Dox Agar and subjected to mutation by ethidium bromide. The effect of carbon sources, nitrogen sources and substrates were also determined.  Among the mutant strains, A. niger PJ-02 A120 was found to be the best mutant that produced citric acid (65.00±0.58f) after 48 hours in Vogel’s medium. The effects of carbon sources (sucrose and glucose) on CA production from each substrate (orange and pawpaw peel) using mutant A. niger PJ-02 was determined and sucrose, the best carbon source was combined with two the nitrogen sources (groundnut cake and soyabeans) to determine the most suitable supplement for CA production. Groundnut cake enhances the production of citric acid while soyabeans was inhibitory. Citric acid was further produced in pawpaw peel and orange peel medium containing sucrose (5 %) groundnut cake (2 %), methanol (1.5 %) and the mutant strain. The orange peel substrates yielded 112.07g/kg of CA while 107.17g/kg was recorded for pawpaw peel when fermented for 5 days at 30°C. The Production of citric acid with mutant Aspergillus niger proved better with orange peel than pawpaw peel when optimized with alcohol.     &nbsp

ASSESSMENT OF SCARCITY OF WOODWORK ARTISAN IN BUILDING CONSTRUCTION IN KWARA STATE, NIGERIA

Woodwork artisanal scarcity is at an alarming rate in Nigeria and in Kwara state in particular. The reason being that most of the available woodwork artisans lack adequate skills demanded quality Building Construction. Generally, the issue of woodwork artisanal scarcity is not a current one as it dates as far back as the two World Wars. This study is on the causes of the observed scarcity of woodwork artisans in Nigeria and Kwara state in particular. The objectives of the study were to identify the factors increasing woodwork artisanal scarcity in Kwara state, its effect on Kwara state economy and the possible remedies. The study employed the use of descriptive survey design which involves the use of a structured questionnaire to collect data from 25 contractors and 35 woodwork artisans in carpentry and joinery. There was no sampling because the population is manageable, hence, the entire population was used. Mean ratings were used to answer research questions. The findings show that major factors causing the scarcity of woodwork artisans include; fluctuating payment, low remuneration, low motivation, lack of interest to take-up woodwork trade by youth, technological advancements in tools, equipment and working process. It also identified the effects of scarcity of woodwork artisan on Kwara state economy. Based on the finding of the study, it was recommended that the Carpentry and Joinery Union of Kwara state should encourage the welfare of its members in order to improve the issues raised by this study