Department Of Physics
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The Department provides tutorial and/or research courses at undergraduate and postgraduate levels leading to the award of the degrees of Bachelor of Sciences (Honours) (B.Sc.), the Master of Science (M.Sc.), Master of Philosophy (M.Phil.) and Doctor of Philosophy (Ph.D.) in Physics respectively. Physics is one of the basic experimental physical sciences.
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Browsing Department Of Physics by Author "Adewale, A.O."
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- ItemOpen AccessHaematological effects of radiofrequency radiation from GSM base stations on four successive generations (F1 – F4) of albino mice, Mus Musculus.(Journal of Environmental and Occupational Science, 2012) Otitoloju, A.A.; Osunkalu, V.O.; Oduware, R.; Obe, I.A.; Adewale, A.O.The aim of the study is to evaluate the haematological effects of radiofrequency (RF) radiation from Global Systems for Mobile Communication (GSM) base stations on four successive generations of albino mice Mus musculus were evaluated. Methods: Each generation of mice were exposed to the RF radiation from birth till they reproduced and blood samples collected. After the mice had given birth to the young ones and weaned off, the parent group was sacrificed and 500µl of blood was obtained. Estimation of hemoglobin concentration, white blood cell count, platelet count, red blood cell count, lymphocyte, pack cell volume (PCV) and red cell indices were carried out using electronic coulter counter. Results: The level of radiofrequency radiation around the base station was found to range between 0.6129V/m to 1.695V/m. In the successive generations of mice, a pattern of pancytosis was observed and significant increases were observed in the Packed Cell Volume, White Blood Cell Count, Platelet Count and Red Blood Cell Count. Conclusion: In the successive generations of exposed mice, a pattern of pancytosis was observed, as well as, an increase in the haemopoetic process which caused significant effects on bone marrow stem cell proliferation of differentiation. The effects of chronic exposure to radiofrequency radiations on peripheral blood parameters is found to be sufficient to apply the precautionary principle to discourage the indiscriminate location of GSM base stations in areas where prolonged exposure to radiofrequency radiations are likely to occur.
- ItemOpen AccessIonospheric imaging in Africa(RADIO SCIENCE, 2013) Chartier, A.T.; Kinrade, J.; Mitchell, C.N.; Rose, J.A.R.; Jackson, D.R.; Cilliers, P.; Habarulema, J.; Katamzi, Z.; Mckinnell, L.; Matamba, T.; Opperman, B.; Ssessanga, N.; Giday, N.M.; Tyalimpi, V.; De Franceschi, G.; Romano, V.; Scotto, C.; Notarpietro, R.; Dovis, F.; Avenant, E.; Wonnacott, R.; Oyeyemi, E.O.; Mahrous, A.; Tsidu, G.M.; Lekamisy, H.; Olwendo, J.O.; Sibanda, P.; Gogie, T.K.; Rabiu, B.; De Jong, K.; Adewale, A.O.Accurate ionospheric specification is necessary for improving human activities such as radar detection, navigation, and Earth observation. This is of particular importance in Africa, where strong plasma density gradients exist due to the equatorial ionization anomaly. In this paper the accuracy of three-dimensional ionospheric images is assessed over a 2 week test period (2–16 December 2012). These images are produced using differential Global Positioning System (GPS) slant total electron content observations and a time-dependent tomography algorithm. The test period is selected to coincide with a period of increased GPS data availability from the African Geodetic Reference Frame (AFREF) project. A simulation approach that includes the addition of realistic errors is employed in order to provide a ground truth. Results show that the inclusion of observations from the AFREF archive significantly reduces ionospheric specification errors across the African sector, especially in regions that are poorly served by the permanent network of GPS receivers. The permanent network could be improved by adding extra sites and by reducing the number of service outages that affect the existing sites.
- ItemOpen AccessLevel of Radiofrequency (RF) Radiations from GSM Base Stations and its Biological Effects on Albino Mice, Mus musculus(Journal of Applied Sciences and Environmental Management, 2010) Otitoloju, A.A.; Osunkalu, V.O.; Obe, I.A.; Adewale, A.O.; Akinde, O.R.Levels of radiofrequency radiations around two global systems for mobile communication (GSM) base stations located in the vicinity of a residential quarter and workplace complex were measured. The effects of the radiofrequency radiations on albino mice placed in exposure cages and located around the base stations over a six months period were carried out. The levels of radiofrequency (RF) radiations around the base stations were found to be between 488.51mV/m to 625.49mV/m compared to 59 mV/m in control stations. The results of the weight change experiment showed that over the 180 days of observation, there was weight gain in the exposed and control mice groups. Statistical comparisons of mean weight changes between exposed mice and control mice showed that there were no significant (P>0.05) differences between the weight of the test animals. The hematological studies revealed an elevation of white blood cell (WBC) counts in mice exposed to RF radiations compared to control group. There was however no significant (P>0.05) difference between the red blood cell counts in the exposed and control mice. There was also no significant (P>0.05) difference in the hemoglobin and glucose levels in the blood of both exposed and control mice groups. The red blood cells in exposed mice were however found to contain a higher number of macrocytes, poikilocytes, polychromatic cells and fewer target cells than the control mice. Histological studies of the heart and kidney of exposed mice showed only slight tissues deformities in kidneys of exposed mice compared to control. The relevance of these findings in setting radiofrequency radiation exposure guidelines and the need for more studies with widely varying biological parameters is very necessary as Nigeria leaps further into the communication age.
- ItemOpen AccessLow solar activity variability and IRI 2007 predictability of equatorial Africa GPS TEC(Elsevier Ltd, 2011) Adewale, A.O.; E.O. Oyeyemi, E.O.; Cilliers, P.J.; McKinnell, L.A.; Adeloye, A.B.Diurnal, seasonal and latitudinal variations of Vertical Total Electron Content (VTEC) over the equatorial region of the African continent and a comparison with IRI-2007 derived TEC (IRI-TEC), using all three options (namely; NeQuick, IRI01-corr and IRI-2001), are presented in this paper. The variability and comparison are presented for 2009, a year of low solar activity, using data from thirteen Global Positioning System (GPS) receivers. VTEC values were grouped into four seasons namely March Equinox (February, March, April), June Solstice (May, June, July), September Equinox (August, September, October), and December Solstice (November, December, January). VTEC generally increases from 06h00 LT and reaches its maximum value at approximately 15h00–17h00 LT during all seasons and at all locations. The NeQuick and IRI01-corr options of the IRI model predict reasonably well the observed diurnal and seasonal variation patterns of VTEC values. However, the IRI-2001 option gave a relatively poor prediction when compared with the other options. The post-midnight and post-sunset deviations between modeled and observed VTEC could arise because NmF2 or the shape of the electron density profile, or both, are not well predicted by the model; hence some improvements are still required in order to obtain improved predictions of TEC over the equatorial region of the Africa sector.
- ItemOpen AccessPreliminary Study on the Induction of Sperm Head Abnormalities in Mice, Mus musculus, Exposed to Radiofrequency Radiations from Global System for Mobile Communication Base Stations.(Bull Environ Contam Toxicol, 2010) Otitoloju, A.A.; Obe, I.A.; Adewale, A.O.; Otubanjo, O.A.; Osunkalu, V.O.The exposure of male mice to radiofrequency radiations from mobile phone (GSM) base stations at a workplace complex and residential quarters caused 39.78 and 46.03%, respectively, in sperm head abnormalities compared to 2.13% in control group. Statistical analysis of sperm head abnormality score showed that there was a significant (p\0.05) difference in occurrence of sperm head abnormalities in test animals. The major abnormalities observed were knobbed hook, pin-head and bananashaped sperm head. The occurrence of the sperm head abnormalities was also found to be dose dependent. The implications of the observed increase occurrence of sperm head abnormalities on the reproductive health of humans living in close proximity to GSM base stations were discussed.
- ItemOpen AccessResponses of equatorial F region to different geomagnetic storms observed by GPS in the African sector(JOURNAL OF GEOPHYSICAL RESEARCH, 2011) Adewale, A.O.; Oyeyemi, E.O.; Adeloye, A.B.; Ngwira, C.M.; Athieno, R.This article presents the first results regarding the investigation of the response of the equatorial ionospheric F region in the African sector during geomagnetic storm periods between April 2000 and November 2007 using GPS‐derived vertical total electron content observed at Libreville, Gabon (0.35°N, 9.67°E, dip latitude −8.05°S). We performed a superposed epoch analysis of the storms by defining the start time of the epoch as the storm onset time. During geomagnetic storms, the altered electric fields contribute significantly to the occurrence of negative and positive ionospheric storm effects. Our results showed that the positive storm effects are more prevalent than the negative storm effects and generally last longer irrespective of storm onset times. Also, the positive storm effects are most pronounced in the daytime than in the premidnight and postmidnight periods.
- ItemOpen AccessSolar activity dependence of total electron content derived from GPS observations over Mbarara(Elsevier Ltd, 2012) Adewale, A.O.; Oyeyemi, E.O.; Olwendo, J.Vertical total electron content (VTEC) observed at Mbarara (geographic co-ordinates: 0.60oS, 30.74oE; geomagnetic coordinates: 10.22oS, 102.36oE), Uganda, for the period 2001–2009 have been used to study the diurnal, seasonal and solar activity variations. The daily values of the 10.7 cm radio flux (F10.7) and sunspot number (R) were used to represent Solar Extreme Ultraviolet Variability (EUV). VTEC is generally higher during high solar activity period for all the seasons and increases from 0600 h LT and reaches its maximum value within 1400 h–1500 h LT. All analysed linear and quadratic fits demonstrate positive VTEC-F10.7 and positive VTEC-R correlation, with all fits at 0000 h and 1400 h LT being significant with a confidence level of 95% when both linear and quadratic models are used. All the fits at 0600 h LT are insignificant with a confidence level of 95%. Generally, over Mbarara, quadratic fit shows that VTEC saturates during all seasons for F10.7 more than 200 units and R more than 150 units. The result of this study can be used to improve the International Reference Ionosphere (IRI) prediction of TEC around the equatorial region of the African sector.
- ItemOpen AccessStimulation of Haemopoetic Activity in Bone Marrow and Deformation of Red Blood Cells in Albino Mice, Mus musculus Exposed to Radiations from GSM Base Stations.(Sierra Leone Journal of Biomedical Research, 2010) Otitoloju, A.A.; Osunkalu, V.O.; Akogun, M.M.; Obe, I.A.; Adewale, A.O.; Akinde, O.R.The levels of radiofrequency radiations around two global systems for mobile communication (GSM) base stations located around a residential quarter and workplace complex were measured. The effects of the radiofrequency radiations on albino mice placed in exposure cages and located around the base stations over a six months period were investigated. The levels of radiofrequency (RF) radiations around the base stations were found to range between 383 mV/m to 730 mV/m compared to 59 mV/m in control stations. In the exposed mice, a pattern of pancytosis was observed and significant increases were observed in the Packed Cell Volume (PCV), White Cell Count (WBC), Platelet count (PLT) and Red Cell Count (RCC) throughout the period of exposure in both stations when compared with control values. No significant (p>0.05) differences were observed in these values when both stations were compared. After 90 days of exposure, marginal increases occurred in the mean cell volume of exposed mice at station 1 and 2 (53.1±3.6fl Vs 55.9±1.8fl and 57.9±0.25fl respectively), with the mean cell haemoglobin concentration showing significant reduction after 180 days of exposure at station 2 (27.9±2.4g/dl Vs 25.7±0.29g/dl; p<0.05). Marked anisopoikilocytosis and striking polychromasia were seen on peripheral films of exposed mice, with bone marrow showing increased cellularity. Exposure of the mice to radiofrequency radiations therefore resulted in cellular proliferation with subsequent stimulation of haemopoetic activity and probable increase in the utilisation of folate and iron resulting in increased mean cell volume (MCV) and reduction in mean cell haemoglobin concentration (MCHC). The fears of a possible biological effect of chronic human exposure to radiofrequency radiations may therefore be reasonable enough to justify the clamour for the reduction in the proliferation of GSM base stations across the country.
- ItemOpen AccessA study of L-band scintillations and total electron content at an equatorial station, Lagos, Nigeri(RADIO SCIENCE, 2012) Adewale, A.O.; Oyeyemi, E.O.; Adeloye, A.B.; Mitchell, C.N.; Rose, J.A.R.; Cilliers, P. J.In this paper we present the first results from measurements of scintillation and total electron content (TEC) from an equatorial station, Lagos (Latitude 6.5 N, Longitude 3.4 E, magnetic latitude 3.03 S), Nigeria, using a Novatel GSV4004B GPS ionospheric scintillation and TEC monitor. Details are presented for data collected between February 2010 and August 2010. The results show that the presence of some large scale depletions of TEC or plasma bubbles may be noted during the evening hours and that TEC depletions correspond to increased rate of change of TEC (ROT). This confirms that plasma bubbles are associated with large scale irregularities. It is also established that enhanced amplitude scintillation (S4) corresponds quite well with TEC depletions and increases in ROT. The diurnal and seasonal percentage occurrence for different levels of scintillation activity has peaks in the equinox months (March and April) at 23:00 LT
- ItemOpen AccessTEC derived from some GPS stations in Nigeria and comparison with the IRI and NeQuick models(Elsevier Ltd, 2014) Rabiu, A.B.; Adewale, A.O.; Abdulrahim, R.B.; Oyeyemi, E.O.Total electron content (TEC) measured simultaneously using Global Positioning System (GPS) ionospheric monitors installed at some locations in Nigeria during the year 2011 (Rz = 55.7) was used to study the diurnal, seasonal, and annual TEC variations. The TEC exhibits daytime maximum, seasonal variation and semiannual variations. Measured TEC were compared with those predicted by the improved versions of the International Reference Ionosphere (IRI) and NeQuick models. The models followed the diurnal and seasonal variation patterns of the observed values of TEC. However, IRI model produced better estimates of TEC than NeQuick at all locations.
- ItemOpen AccessVariability of foF2 in the African equatorial ionosphere(Elsevier Ltd, 2010) Adewale, A.O.; Akala, A.O.; Oyeyemi, E.O.; Somoye, E.O.; Adeloye, A.B.This paper presents the impact of diurnal, seasonal and solar activity effects on the variability of ionospheric foF2 in the African equatorial latitude. Three African ionospheric stations; Dakar (14.8°N, 17.4°W, dip: 11.4°N), Ouagadougou (12.4°N, 1.5°W, dip: 2.8°N) and Djibouti (11.5°N, 42.8°E, dip: 7.2°N) were considered for the investigation. The overall aim is to provide African inputs that will be of assistance at improving existing forecasting models. The diurnal analysis revealed that the ionospheric critical frequency (foF2) is more susceptible to variability during the night-time than the day-time, with two peaks in the range; 18–38% during post-sunset hours and 35– 55% during post-midnight hours. The seasonal and solar activity analyses showed a post-sunset September Equinox maximum and June Solstice maximum of foF2 variability in all the stations for all seasons. At all the stations, foF2 variability was high for low solar activity year. Overall, we concluded that equatorial foF2 variability increases with decreasing solar activity during night-time.