Suitability of Unmanned Aerial Vehicles for Cadastral Surveys

Cadastral surveys in Ghana often employ well known surveying equipment such as Total Station andGNSSreceivers or a combination of both. These survey techniques are well-established and widely accepted. However, there are limitations in certain areas. In situations where difficult terrain and inaccessible areas and dense vegetation are encountered or when surveyor’s life may be at risk, Unmanned Aerial Vehicles (UAVs) could be used to overcome the limitations of these well-established survey instruments. This research used high resolution images from UAV (DJI Phantom 4) to survey plots within the University of Mines and Technology land area. Coordinates of the boundary points were extracted using Agisoft Photoscan.GNSSreceivers were also used to survey the land and the same boundary point coordinates obtained and compared. This enabled the establishment of accurate ground control points for georeferencing. The coordinates obtained from both UAV andGNSSSurveys were used to prepare cadastral plans and compared. The difference in Northings and Eastings from UAV andGNSSsurveys were +0.380 cmand +0.351 cmrespectively. These differences are well within tolerance of +/-0.9114 m(+/-3 ft) set by the Survey and Mapping Division (SMD) of the Lands Commission for cadastral plans production. This research therefore concludes that high resolution images from UAVs are suitable for cadastral surveying. Keywords: Unmanned Aerial Vehicles, Drones, Global Navigation Satellite Systems, Cadastral Survey

Comparative Analysis of Stockpile Volume Estimation using UAV and GPS Techniques

Mining operations involve the extraction of minerals of economic value from the earth. In surface mining operations, overburdens need to be stripped in other to reach the ore. Large volumes of waste as well as ore is stripped in the process. Various technologies have been used to aid in stockpile volume estimation. Notable among them are the Total Stations and Global Positioning Systems (GPS). However, labour, safety and time has challenged the use of these technologies. Unmanned Aerial Vehicle (UAV), commonly known as drone is an emerging technology for stockpile volume computations in the Mine. UAV technology for data collection is less labour intensive, safer and faster. Therefore, this study applied the UAV technology in an open pit to estimate stockpile volumes from a Mine. For the purpose of this study, GPS and UAV data were collected for measuring stockpile volumes of materials mined. The actual volumes of stockpiles A, B, C, D (Case 2), produced differences of 0.05% for A, 0.05% for B, 0.08% for C, 0.07% for D and 0.03% for A, -0.03% for B, 0.03% for C and 0.04% for D, for the GPS-based and the UAV-based techniques, respectively. The GPS-based technique generated moderate accuracies for volume estimation, but was time consuming and labour intensive, compared to the UAV-based technique; which was faster and less labour intensive. The UAV-based technique was the most accurate, safest and is capable of mapping large areas rapidly. It is therefore recommended that UAV survey be incorporated in stockpile volume estimation. Keywords: UAV, GPS, Stockpile, Mine, Total Station

Remote sensing for mapping wetland floods in Kafue Flats, Zambia

Monitoring huge and dynamic floodplains such as the Kafue Flats in Zambia is critical to its sustainable use. This requires among other things accurate, past and current geo-referenced flood maps. The aim of this study was, therefore, to use remotely sensed data to generate flood maps for Kafue Flats. Flood maps were created by classifying seven cloud-free Landsat images of selected months in 2001 and the areas flooded computed. Further spatial analyses were performed to integrate the flood maps to generate a multi-temporal flood map and to compute flood durations. The results indicate that 2001 was an extremely wet hydrological year with a maximum flooded area of 31%. Also, approximately 2% of study area remained flooded for six months while permanent open water bodies covered an area of approximately 4%. Statistical analysis showed that the flood extent is significantly related to water levels and discharge when water levels are high. Therefore, prediction equations were generated to estimate flood areas with respect to water flows. However, it has been revealed that rainfall within the flats has little influence on flooding. Rather, the most critical factor in controlling the flooding is water releases from the ltezhi-tezhi dam located upstream. This study has demonstrated that remote sensing is suitable for operational mapping and monitoring of tropical floodplains

Mapping the Effects of Anthropogenic Activities in the Catchment of Weija Reservoir using Remote Sensing Techniques

Man has contributed to land cover alteration since time-immemorial through clearing of land for residential, agriculture, recreational and industrial purposes. The emergence of adapting wild plants and animals for human use as well as industrialisation have also contributed to the alteration of land cover. Over the years, anthropogenic activities have had great impact on the Weija catchment. This study seeks to map the catchment and determine the impact of anthropogenic activities using Remote Sensing techniques. Observations and measurements were made on the field as well as classification of land cover using Landsat images of years 1991, 2003 and 2017. Results showed an increase in built-up areas by 18% from 1991 to 2017. Other classes such as shrubs increased due to decrease in dense vegetation. This study confirms the use of Remote Sensing as a valuable tool for detecting change in land cover and determining the impact of anthropogenic activities in the Weija Catchment. Keywords: Land Cover, GIS, Remote Sensing, Weija Catchment, Anthropogenic Activitie

Determination of the Interior Orientation Parameters of a Non-metric Digital Camera for Terrestrial Photogrammetric Applications

AbstractHigh cost of metric photogrammetric cameras has given rise to the utilisation of non-metric digital cameras to generate photogrammetric products in traditional close range or terrestrial photogrammetric applications. For precision photogrammetric applications, the internal metric characteristics of the camera, customarily known as the Interior Orientation Parameters, need to be determined and analysed. The derivation of these parameters is usually achieved by implementing a bundle adjustment with self-calibration procedure. The stability of the Interior Orientation Parameters is an issue in terms of accuracy in digital cameras since they are not built with photogrammetric applications in mind. This study utilised two photogrammetric software (i.e. Photo Modeler and Australis) to calibrate a non-metric digital camera to determine its Interior Orientation Parameters. The camera parameters were obtained using the two software and the Root Mean Square Errors (RMSE) calculated. It was observed that Australis gave a RMSE of 0.2435 and Photo Modeler gave 0.2335, implying that, the calibrated non-metric digital camera is suitable for high precision terrestrial photogrammetric projects. Keywords: Camera Calibration, Interior Orientation Parameters, Non-Metric Digital Camer

Early Detection of Illegal Settlements on Government Lands using UAV Technology - A Case Study

Illegal settlements (squatter settlements) have been a persisting problem in most developing countries and even some developed countries. This has led to the loss of huge sums of money, resources, time and energy. These illegal settlements serve as hide outs for most armed robbers, drug dealers, drug addicts, murderers, rapists, prostitutes and the like. Children born in these areas are not given proper care and education hence the cycle continuous. These squatters also pollute the environment through their activities. Some squatters on government lands and mining concessions indulge in illegal mining activities and illegal logging. Large portions of government lands are unguarded, as a result, most of these squatter settlements are very difficult to detect. Unmanned Aerial Vehicle (UAV) technology has improved tremendously over the past few years and has led to increase in the number of UAVs produced and are relatively affordable. The objective of this study was to detect illegal settlements in and around the University of Mines and Technology (UMaT) boundary and other government land using UAV technology. This study used high-resolution images acquired from UAV (Phantom 4 Pro) and Agisoft Metashape to align and optimise the images and generate point clouds, digital surface models, and orthophotos. Four illegal settlements were detected in this study. Three illegal settlements were detected in Part A and one in Part B of the study area. A combined area of 0.831 acres of land has been encroached upon by illegal settlers in the study area. UAV Technology is a useful tool to detect illegal settlements in their early stages in order to avoid such settlements developing into slums. This study, therefore, recommends the use of UAV Technology to aid early detection of illegal settlements

Retail Access is Associated with Multiple Tobacco Product Use among Adolescent

Background: Enforcement of retail access laws is essential to preventing adolescent tobacco use. A growing proportion of adolescent tobacco users report using two or more products. However, research has yet to explore the relationship between retail access and multiple tobacco product use. Methods: Data were obtained from the 2018 National Youth Tobacco Survey. Participants were 2,199 middle and high school tobacco users. Multivariate, multinomial logistic regression models were used to examine the relationship between tobacco retail access and past 30-day single, dual, and poly (three or more) tobacco product use. Covariates included sex, race/ethnicity, grade level, and tobacco marketing exposure. Results: Overall, 27.9% of adolescent tobacco users self-reported tobacco retail access. Further, 42.6% were single tobacco product users, 23.8% were dual tobacco product users, and 33.6% were poly tobacco product users. Retail access was associated with greater relative risk of being a dual (RRR: 1.78; 95% CI: 1.33 – 2.38) and poly tobacco product user (RRR: 2.25; 95% CI: 1.62 – 3.11), relative to a single tobacco product user, adjusting for covariates. Conclusion: Tobacco retail access was associated with greater risks of multiple tobacco product use among a nationally representative sample of adolescents. Descriptive findings reveal a gap in enforcement of tobacco age restrictions. Analytic findings suggest this gap in enforcement may be a contributing factor for multiple tobacco product use among adolescents

Histone Deacetylase Inhibitor Romidepsin Induces HIV Expression in CD4 T Cells from Patients on Suppressive Antiretroviral Therapy at Concentrations Achieved by Clinical Dosing

Persistent latent reservoir of replication-competent proviruses in memory CD4 T cells is a major obstacle to curing HIV infection. Pharmacological activation of HIV expression in latently infected cells is being explored as one of the strategies to deplete the latent HIV reservoir. In this study, we characterized the ability of romidepsin (RMD), a histone deacetylase inhibitor approved for the treatment of T-cell lymphomas, to activate the expression of latent HIV. In an in vitro T-cell model of HIV latency, RMD was the most potent inducer of HIV (EC50 = 4.5 nM) compared with vorinostat (VOR; EC50 = 3,950 nM) and other histone deacetylase (HDAC) inhibitors in clinical development including panobinostat (PNB; EC50 = 10 nM). The HIV induction potencies of RMD, VOR, and PNB paralleled their inhibitory activities against multiple human HDAC isoenzymes. In both resting and memory CD4 T cells isolated from HIV-infected patients on suppressive combination antiretroviral therapy (cART), a 4-hour exposure to 40 nM RMD induced a mean 6-fold increase in intracellular HIV RNA levels, whereas a 24-hour treatment with 1 μM VOR resulted in 2- to 3-fold increases. RMD-induced intracellular HIV RNA expression persisted for 48 hours and correlated with sustained inhibition of cell-associated HDAC activity. By comparison, the induction of HIV RNA by VOR and PNB was transient and diminished after 24 hours. RMD also increased levels of extracellular HIV RNA and virions from both memory and resting CD4 T-cell cultures. The activation of HIV expression was observed at RMD concentrations below the drug plasma levels achieved by doses used in patients treated for T-cell lymphomas. In conclusion, RMD induces HIV expression ex vivo at concentrations that can be achieved clinically, indicating that the drug may reactivate latent HIV in patients on suppressive cART

Expression profile of human Fc receptors in mucosal tissue: implications for antibody-dependent cellular effector functions targeting HIV-1 transmission

The majority of new Human Immunodeficiency Virus (HIV)-1 infections are acquired via sexual transmission at mucosal surfaces. Partial efficacy (31.2%) of the Thai RV144 HIV-1 vaccine trial has been correlated with Antibody-dependent Cellular Cytotoxicity (ADCC) mediated by non-neutralizing antibodies targeting the V1V2 region of the HIV-1 envelope. This has led to speculation that ADCC and other antibody-dependent cellular effector functions might provide an important defense against mucosal acquisition of HIV-1 infection. However, the ability of antibody-dependent cellular effector mechanisms to impact on early mucosal transmission events will depend on a variety of parameters including effector cell type, frequency, the class of Fc-Receptor (FcR) expressed, the number of FcR per cell and the glycoslyation pattern of the induced antibodies. In this study, we characterize and compare the frequency and phenotype of IgG (CD16 [FcγRIII], CD32 [FcγRII] and CD64 [FcγRI]) and IgA (CD89 [FcαR]) receptor expression on effector cells within male and female genital mucosal tissue, colorectal tissue and red blood cell-lysed whole blood. The frequency of FcR expression on CD14+ monocytic cells, myeloid dendritic cells and natural killer cells were similar across the three mucosal tissue compartments, but significantly lower when compared to the FcR expression profile of effector cells isolated from whole blood, with many cells negative for all FcRs. Of the three tissues tested, penile tissue had the highest percentage of FcR positive effector cells. Immunofluorescent staining was used to determine the location of CD14+, CD11c+ and CD56+ cells within the three mucosal tissues. We show that the majority of effector cells across the different mucosal locations reside within the subepithelial lamina propria. The potential implication of the observed FcR expression patterns on the effectiveness of FcR-dependent cellular effector functions to impact on the initial events in mucosal transmission and dissemination warrants further mechanistic studies