Modelling bidirectional radiance measurements collected by the advanced solid-state array spectroradiometer over Oregon transect conifer forests

Thesis (M.A.)--Boston UniversityThe primary objective of this research is to test and validate a geometric-optical bidirectional reflectance canopy model developed by Li and Strahler, with respect to actual forest canopy reflectance measurments. This model treats forest canopies as scenes of discrete, three dimensional objects that are illuminated and viewed from different positions in the hemisphere. The shapes of the objects, their count densities and patterns of placement are the driving variables, and they condition the mixture of sunlit and shaded objects and background that is observed from a particular viewing direction, given a direction of illumination. This mixture, in turn, controls the brightness apparent to an observer or a radiometric instrument. The Advanced Solid-State Array Spectroradiometer (ASAS) is chosen to be the sensor having the ability of collecting measurements at various look angles and its imaged reflectance was used to validate the model. The modelled BRF's were compared to actual ASAS measured BRF's in sites with different canopy structures and densities. The comparision revealed execellent match between the modelled and measured reflectance, and great ability of the model in predicting the shape and magnitude of the BRDF, in almost all the sites investigated. It is concluded that the geometric optics approach provided a good way to model the bidirectional reflectance distribution function of natural vegetation canopies, that captures the most important features exhibited by bidirectional measurements of such canopies. Further modifications have been suggested that will improve the predicted BRF's, and yield better results. [TRUNCATED

The applications of neural network in mapping, modeling and change detection using remotely sensed data

Thesis (Ph.D.)--Boston UniversityAdvances in remote sensing and associated capabilities are expected to proceed in a number of ways in the era of the Earth Observing System (EOS). More complex multitemporal, multi-source data sets will become available, requiring more sophisticated analysis methods. This research explores the applications of artificial neural networks in land-cover mapping, forward and inverse canopy modeling and change detection. For land-cover mapping a multi-layer feed-forward neural network produced 89% classification accuracy using a single band of multi-angle data from the Advanced Solidstate Array Spectroradiometer (ASAS). The principal results include the following: directional radiance measurements contain much useful information for discrimination among land-cover classes; the combination of multi-angle and multi-spectral data improves the overall classification accuracy compared with a single multi-angle band; and neural networks can successfully learn class discrimination from directional data or multi-domain data. Forward canopy modeling shows that a multi-layer feed-forward neural network is able to predict the bidirectional reflectance distribution function (BRDF) of different canopy sites with 90% accuracy. Analysis of the signal captured by the network indicates that the canopy structural parameters, and illumination and viewing geometry, are essential for predicting the BRDF of vegetated surfaces. The inverse neural network model shows that the R2 between the network-predicted canopy parameters and the actual canopy parameters is 0.85 for canopy density and 0.75 for both the crown shape and the height parameters. [TRUNCATED

Liquid-Liquid Successive Fractionation of Stem Bark Alcoholic Extract from Acacia polyacantha: GC-MS Analysis and Antibacterial Activities.

Antimicrobial resistance is considered as one of the top problematic issues facing world health system. Fortunately, medicinal plants, considered as ongoing source of antimicrobial agents can resolve this health problem Acacia polyacantha tree (AL-Kakamout) is widely available in Sudan. It is one of the main sources of Gum Arabic and used traditionally for treating many bacterial diseases. This study aimed to analyze the fractions of hydro-ethanol extract of A. polyacantha stem bark obtained by liquid-liquid successive fractionation by GC-MS method and to determine the antibacterial activity of these fractions against two standard bacterial strains of Gram-positive bacteria Staphylococcus aureus (ATCC 25923) and Gram-negative bacteria Pseudomonas aeroginosa (ATCC 27853) by well diffusion technique. The powdered A. polyacantha stem bark was extracted by cold maceration using 70% Ethanol and successively fractionated to produce petroleum ether, butanol and aqueous fraction. The butanol fraction in which Cyclolanostanol acetate (28.29%), Dopamine, N,N-dimethyl-, dimethyl ether (21.94%), were dominating, was the most active against both bacterial strains. Petroleum ether fraction which is rich in Lupeol, trifluoroacetate (37.64%) and stigmasterol (13.05%) triterpenoids was found to be more active against P. aeroginosa and with less activity against S.aureus. While the remaining aqueous fraction where hordenine alkaloid (47.21%) and 3-O-Methyl-d-glucose (%30.46) were dominant components showed no activity against S.aureus and with low activity against P. aeroginosa. In conclusion, A.polyacantha bark extract fractions are rich in phytochemical compounds having antibacterial activity and highly recommended to be further investigated as potential antibacterial agents

Plojdy Analysis and Dna Content of Mutant Banana "Pisang Berangan" Using Flow Cytometry

Mutagens cause random changes in the nuclear DNA or cytoplasmic organelles, resulting in gene, chromosomal or genomic mutations and hence, create variability. In this study, flow cytometry (FCM) was used to determine ploidy levels and DNA content in gamma-irradiated variants of mutated Pisang Berangan (cv. Intan, AAA) - a local banana genotype. Induced variants such as short plant stature (stunted growth), late flowering plants (late maturity) and abnormalities in bunch characters were selected to study possible changes at the DNA level. The study showed that DNA content of mutated plants differed from non-irradiated control and that irradiation had the most effect at high doses (40 and 60 Gy). The increase of DNA content in 20 Gy and 30 Gy treated plants was not more than that of the control plants. The values of genomic DNA content of gamma-irradiation variants decreased as the dose of irradiation increased from 20 to 60 Gy, indicating that the high dose of gamma-irradiation had a significant effect on the genome of the plants. The analysis further showed that phenotypic variation due to mutagenesis was reflected in the DNA content of the plants. The results also showed that ploidy levels were not affected by gamma-irradiation even at high doses

The Perception of Stakeholders towards Services Provided By Primary Health Care in Khartoum State, Sudan

Background: Sudan is a signatory country to Alma Ata Declaration and Primary Health Care (PHC) had been established since 1979. Although a lot of improvement is claimed to be achieved in PHC, some of the areas might be still far below the expectations. The objective of this study was to investigate the perception of the PHC stakeholders in Khartoum State about the PHC services provided and the adequacy of facilities used.Materials and Methods: This is a cross-sectional descriptive study conducted in Khartoum State, Sudan, between June and October 2015. A structured questionnaire was administered to a sample of PHC stakeholders. A 3-point Likert scale was used to indicate the quality of the different services provided and the facilities present. SPSS version 20 was used for analysis to calculate relevant descriptive statistical parameters.Results: Vaccination and care for pregnant ladies were perceived by respondents as present and adequate (100% and 95%, respectively). The other services that are perceived as adequate include: child health care, health education, chronic illness, drugs availability and the referral system. In sanitation services and feedback about patients referred to hospitals, only 20% and 4% were satisfied, respectively.Conclusion: Most of the PHC services were perceived as adequate by the respondents from Khartoum State. The services and facilities that were perceived as inadequate include sanitation services, communicable diseases, the referral system and provision of dental services.Key words: primary health care (PHC), stakeholders

The effect of preheating of work on chatter during end milling of medium carbon steel performed on a Vertical Machining Center (VMC)

In the present work causes and after effects of chatter have been discussed and attempts have been made to control the occurrence of chatter during end milling operation conducted on a vertical machining center (VMC). Chatter has been treated as a resonance effect and preheating of the incoming work material layers using high frequency induction heating has been tried as a method of controlling chatter. It has been found that preheating results in substantial lowering down of acceleration amplitude of chatter in a wide range of cutting speed. This has facilitated low tool wear intensity, improved machined surface finish and low noise level during machining. Work material properties were practically unaffected due to low preheating temperature

Adaptive V2V routing with RSUs and gateway support to enhance network performance in VANET

In a VANET communication, link stability can neither be guaranteed nor make the established route link permanent due to the dynamic nature of the network. In V2V communication without the involvement of any infrastructural units like RSU access points or gateway, the probability of successful link establishment decreases when vehicle’s speed varies, red traffic light increases, cross-road increases and finally when the density of the running vehicles is sparse. To ensure route establishment and control route request broadcast in a sparse VANET with crossroad layout, RSUs are used in this paper for route discovery within one gateway zone when a next hop vehicle to relay the route request packet is unavailable. RSUs are static but the vehicles are dynamic in nature, so relying completely on RSU for forwarding data is not recommended because chances of link failure, link re-establishment, and handoff overhead will be high. So, in this paper, RSUs and Gateways are evoked for route discovery and data forwarding only when necessary. Moreover, a local route repair is attempted in this paper when the path length is high to reduce or avoid loss of buffered packets along the route and to maintain a more stable link with the help of RSUs

Structural Characterization and Physical Properties of Syzygium cumini Flowering Plant

ABSTRACT: In this study, the flowering plant of syzygium cumini was used. X-ray fluorescence (XRF) and X-ray diffraction (XRD) were used to investigate the structure of the leaves and barks of syzygium cumini. The XRD results were indicated that the structures of both leaves and bark were amorphous. The XRF results indicated that both leaves and barks contained Potassium (K), Calcium (Ca), (Ti), and Magnesium (Mn), Iron (Fe), Copper (Cu), Zinc (Zn), Zernike (As), Lead (Pb), Barium (Br), Strontium (Sr). The optical properties of syzygium cumini were carried out using Fourier Transformation infrared spectroscopy (FTIR) and Ultra violet spectroscopy (UV). The FTIR spectra showed a broad and strong absorption band in the range (685-1638) cm -1 , and these absorptions were assigned to the different stretching vibrations. The absorption for bark and leave was found to be 2.45 and 2.52 a u, while the wave length was found to be 277.4 and 277.5 nm, respectively. The energy band gap is calculated and found to be 5.017 and 4.67 eV, for bark and leave, respectively

A Comparison Between Students’ Performance In Multiple Choice and Modified Essay Questions in the MBBS Pediatrics Examination at the College of Medicine, King Khalid University, KSA

Objectives: To investigate the relation between the students' scores in MCQs and MEQs of the summative assessment in pediatrics at the College of medicine KKU. Introduction: Student assessment is the most difficult task in medicine since it is ultimately related to human life and safety. Assessment can take different types of formats with advantages and disadvantages and there is no single prescribed method of choice. Research Methods: This is a quantitative, observational retrospective study enrolling 50 students who completed the final MBBS examination in pediatrics in 2015.The medical students’ scores in MCQs and MEQs in the final MBBS pediatrics examination were collected and SPSS used for analysis. Results: 52% of the students scored A and B, 46% scored C and 2% scored D and nobody scored F. The mean percentage scores in MCQs, MEQs and the combined are75.03%, 79.99% and 76.68% respectively. The standard deviation (SD) for MCQs, MEQs and combined are 0.0753, 0.0763 and 0.0559 respectively.There are no significant differences in means and SD. The correlation (CR) between MCQs and MEQs is -1.73%. The CR between MCQs and MEQs for those who scored A and B is 7.38% which could indicate a weak but significant +ve CR (p value 0.017), (table3). For those who scored C inverse CR (-74.38%) was observed between MCQs and MEQs. Discussion: The main finding of this study was the weakly negative CR between students' performance on MCQs and MEQs. Good performance in MCQs is not necessary correlated with good performance in LEQs. This is not in agreement with Oyebola et al. and Moqattash et al findings, who reported positive CR in the performance of their students. The discrepancy observed in performance between MCQs and MEQs could be explained by the subjectivity and the difficulty in avoiding bias in setting and marking essay questions.   Key Words: multiple choice questions, Modified long essay questions, correlation