The potential for using remote sensing to quantify stress in and predict yield of sugarcane (Saccharum spp. hybrid)

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010

Marine propeller roughness penalties

PhD ThesisThe main objective of the project is to investigate the influence of surface roughness of marine propeller blades on propulsive power. The work has involved studies in the concept and practice of surface roughness measurement and characterisation as well as application of boundary layer theory for the analysis propeller-ship hull flow interaction of propeller flow and propellar-ship hull flow interaction. From extensive measurements of the surface topography of in-service propellers, a standard measurement procedure using different commercially available propeller-surveying instruments is described. A development of turbulent boundary layer procedures has been made to determine sufficiently accurately the increment of drag coefficient of propeller blade sections due to propeller blade surface roughness. The roughness function used for this integral boundary layer analysis is derived using, principally, Musker's experimental data. In addition, an experimental determination of the roughness function of a replicated propeller surface using a rotor apparatus has been carried out and described in detail. The turbulent boundary layer procedures require a knowledge of the surface variation of pressure over the propeller blade. For this purpose a program based on Riegels method has been used to give the velocity distribution for a given propeller section geometry. This is used with the boundary layer procedures for developing a complete program "PROFNESS" to calculate the increment of drag coefficient of the blade section. Results from different propellers analysed indicate that the power penalty is proportional to the relative blade roughness to the 1/3 power. An investigation has been made to compare the increment of frictional coefficient for a flat plate and propeller section profiles. It is shown that a "rough" flat plane calculation is quite adequate for such work.' The use of a flat plate analogue as a reference to calculate the skin friction resistance of both propeller and hull surfaces is considered. It is shown that the proposed solution of flat plate momentum integral equations provides a valid, simple and practical solution to the problem of predicting the hull and propeller roughness drag penalties. It also provides, particularly for ship hull resistance, a strong support for the ITTC Correlation Line, not only, and importantly, in regard to its slope, but also its level. For shipowners and operators who may not wish to access advanced computer programs, a simplified method has been proposed to calculate the propeller roughness penalties. There is a good agreement between the two simplified and detailed propeller analysis methods. The propeller roughness penalties, which can be obtained from either the simplified or the more rigorous method, can be related to the Rubert Propeller Comparator Gauges in order to quantify the benefits and justify the cost of the blade surface roughness. Analytical procedures have been included which can be used to calculate the combined effects on ship performance of propeller blade and ship hull surface roughnesses.Egyptian Government: 1983/84 & 1984/85 ORS Awards from the Vice-Chancellors and Principals of the Universities of the United Kingdom

The control of Foxp3+ regulatory T cell by interleukin-4 receptor alpha-mediated signaling

T regulatory (Treg) cells play a pivotal role in the maintenance of self-tolerance and immune homeostasis. Forkhead box P3 (Foxp3)+ Treg function is controlled by environmental cues of which cytokine-mediated signaling is a dominant component. Recently, Interleukin (IL)-4 has been shown to play an important role in determining the fate of Foxp3+ Tregs. In vivo, IL-4-mediated signaling via Interleukin-4 receptor alpha (IL4Rα) was convincingly shown to mediate Treg transdifferentiation into ex-Foxp3 Th2 or Th17 cells, suggesting a negative regulation of Foxp3+ Tregs by IL-4Rα-mediated signaling. Puzzlingly, however, IL-4-mediated signaling was also independently found to reinforce the Foxp3+ Tregs, counter-arguing for the positive regulation of Foxp3+ Tregs by IL-4Rα-mediated signaling. In the face of such a conundrum, the present work was set forth as an attempt to unambiguously and conclusively decipher the bases of the regulation of Foxp3+ Treg by IL-4Rα-mediated signaling using transgenic murine models. It was first noted that Foxp3+ Treg cells do express IL-4Rα under steady-state. Furthermore, in vitro, purified CD25+ Tregs were prompted to higher Foxp3 expression and increased survival upon stimulation with IL-4 arguing for a potentiating role of IL-4Rα mediated signaling on Foxp3+ Treg cells. To better address the need for the host Foxp3+ Treg cells to express IL-4Rα as observed, we generated Foxp3-specific IL-4Rα deficient mice where IL-4Rα is specifically deleted from Foxp3+ T cells in the whole organism. Even though naïve Foxp3cre IL-4Rα -/lox mice model at homeostasis did neither reveal any significant alteration of the cellular, tissular and phenotypic profile nor development of spontaneous inflammatory disorder when compared to wild-type mice, under S. mansoni infection impairment IL-4Rα-mediated signaling on Foxp3+ Tregs resulted in heightened activation marker expression and elevated T cell effector functions as indicated by increased cytokines production and greater T cell proliferation rate. This heightened immune responsiveness translated overall into an exacerbated parasitic egg-driven fibrogranulomatous inflammation in the liver and the gut of schistosomiasis-diseased Foxp3cre IL-4Rα-/lox mice. Furthermore, in another model of helminth infection with the parasitic nematode, Nippostrongylus brasiliensis, Foxp3cre IL-4Rα-/lox mice showed a higher level of mucus and exaggerated emphysematous pathology in the lungs. Interestingly, the impairment of IL-4Rα signaling within the Foxp3+ Treg population in Foxp3cre IL-4Rα-/lox mice led to a reduced recruitment of Foxp3+ Tregs and a diminished expression of Foxp3, and other associated Treg suppressive markers (i.e. IRF4 and Helios) during the course of these helminth infections. Taken together, our findings supported a role for IL-4Rα signaling in the positive regulation of Foxp3+ Tregs function and thus, the suppression of inflammatory responses during helminth infections. In conclusion, this work demonstrated a positive role for IL-4Rα mediated signaling in the biology of Foxp3+ Treg cells whereby the latter cells require IL-4Rα signaling to survive and maintain Foxp3 expression and suppressive functions so as to efficiently control tissue inflammatory responses during infection. The data presented do provide insights into the mechanisms of Foxp3+ Treg regulation that are highly relevant for the therapeutic control of inflammation during infectious diseases

Phone recognition using Restricted Boltzmann Machines

For decades, Hidden Markov Models (HMMs) have been the state-of-the-art technique for acoustic modeling despite their unrealistic independence assumptions and the very limited representational capacity of their hidden states. Conditional Restricted Boltzmann Machines (CRBMs) have recently proved to be very effective for modeling motion capture sequences and this paper investigates the application of this more powerful type of generative model to acoustic modeling. On the standard TIMIT corpus, one type of CRBM outperforms HMMs and is comparable with the best other methods, achieving a phone error rate (PER) of 26.7 % on the TIMIT core test set. Index Terms — phone recognition, restricted Boltzmann machines, distributed representations

Study of nasofrontal beak identification as a useful landmark in endoscopic frontal sinus surgery

Background: The nasal process of the frontal bone creates a bony thickening in the midline known as the nasofrontal beak (NFB). Surgery on the frontal sinuses can be safer when the NFB is used as a marker. Objective: To assess if identification of the nasofrontal beak during endoscopic frontal sinus surgery will add benefit to the identification of fontal sinus drainage pathway. Patients and Methods: From July 2020 to July 2021, At Zagazig University Hospitals, Otorhinolaryngology Department; trial included twelve patients with chronic frontal sinusitis who had been refractory to medical treatment for at least twelve weeks. All patients were scheduled for functional endoscopic sinus surgery. Results: The mean of distance from superior border of nasal beak to skull base in the right (Rt) side was 4.8 ± 2.9 and in the left (Lt) side was 5.4 ± 3.1. In terms of difficulty and distance, there was a significant negative association between the two variables; meaning that increasing distance would make the surgery easier. No recurrence of symptoms in Rt. side while in Lt. side recurrence occurs in only one case. Restenosis of frontal ostium didn’t occur in any case in Rt side or Lt side. No nasal adhesions in Rt side, but occurred in Lt side in only one case Conclusion: The frontonasal beak is one of these fixed anatomical bony landmarks as frontal sinus ostium is located at the anterior edge of the anterior recess. Preoperative imaging can anticipate the difficulties of frontal recess surgery by identifying it

Fabrication and Modification of Titania Nanotube Arrays for Harvesting Solar Energy and Drug Delivery Applications

The fast diminishing of fossil fuels in the near future, as well as the global warming caused by increasing greenhouse gases have motivated the urgent quest to develop advanced materials as cost-effective photoanodes for solar light harvesting and many other photocatalytic applications. Recently, titania nanotube arrays (TNTAs) fabricated by anodization process has attracted great interest due to their excellent properties such as: high surface area, vertically oriented, highly organized, one-dimensional, nanotubular structure, photoactivity, chemical stability and biocompatibility. This unique combination of excellent properties makes TNTAs an excellent photoanode for solar light harvesting. However, the relatively wide band gap energy of titania limits its photoactivity to the UV spectra which accounts only for 5 % of solar light spectra. The specific objectives of this thesis are to: First, fabricate reproducible well-organized, vertically-oriented TNTAs in different viscous electrolytes and optimize the fabrication parameters. Second, modify the TNTAs by doping nitrogen and carbon and study the effect of modification on optical properties and photoelectrochemical performance. And third, functionalizing the TNTAs surface by monodispersed magnetic ferrite nanoparticles for improved solar light harvesting and drug delivery application in cancer treatment. The effect of each fabrication parameter such as electric potential, pH, water content, anodization time and electrolyte composition was discussed. TNTAs were successfully fabricated in an inexpensive viscous electrolyte composed of 2 wt.% sodium carboxy methylcellulose (CMC). TNTAs were successfully fabricated on both sides of a Ti disc with total tube length of 9.5 µm with a unique structure composed of conducting Ti metal sandwiched between two semiconducting layers of TNTAs on each side with a new potential electronic and photocatalytic applications. A new, facile, low cost, environment-friendly and nanoarchitecture-safe method was introduced to fabricate N- and C-modified TiO2 nanotube arrays. Modified optical properties with narrow band gap energy, Eg, of 2.65 eV was obtained after annealing the modified TNTAs at 550°C. Modified TNTAs showed enhanced photoelectrochemical performance. Photoconversion efficiency (PCE) was increased from 4.35% for pristine (unmodified) TNTAs to 5.18% for modified TNTAs, an increase of 19%. Effect of nanotubes length of modified TNTAs on photoelectrochemical performance was also studied. Photocurrent density and PCE were increased by increasing nanotube length with a maximum PCE of 6.38% for nanotube length of 55 µm. This implies an excellent light penetration up to 55 µm depth into photoanode which is about 3.6 times higher than the maximum penetration depth (15 µm) in the nanoparticulate photoanode. This increasing pattern of photoconversion efficiency with increasing nanotubes length also implied a high charge separation rate and lower charge recombination rate. This high PCE value was attributed to: band gap reduction due to N- and C-modification of TNTAs surface, increased surface area of long TNTAs compared with short TNTAs, investigated in previous studies, and the excellent light penetration and harvesting properties. Ferrite NPs-encapsulated TNTAs were fabricated for the first time using a facile and efficient method. Ferrite nanoparticles of 13 ± 3 nm diameters were successfully distributed all over the top and inner surface of the nanotubes. UV-Vis reflectance spectra showed excellent visible light absorbance up to wave length of 660 nm (Eg = 1.88 eV). The prepared magnetic nanocomposite showed their potential capability to controlling the drug release of an anti-cancer drug (5-fluorouracil). The drug release of 5-fluorouracil by diffusion was sustained with controlled initial burst effect. The suitability of magnetic nanocomposite for cancer drug delivery was confirmed by in vitro cytotoxicity study

Stabilisation of clay subgrade soils using ground granulated blastfurnace slag

Roads constructed on expansive clays may be adversely affected by the behaviour of the clay. Expansive clays suffer volume change due to changes in moisture content which causes heaving, cracking and the break up of the road pavement. Stabilisation of these types of soil is necessary to suppress swelling and increase the strength of the soil and thus partially decrease the thickness of road pavement layers. The use of by-product materials for stabilisation has environmental and economic benefits. Ground granulated blastfurnace slag (GGBS), a by-product material in Egypt, and lime are used in the current work to stabilise samples of a clay soil similar to a typical Egyptian clay soil. This test soil comprises 80% River Aire soil and 20% calcium montmorillonite. The main objectives of this research were to investigate the effect of GGBS, with and without lime, on the engineering behaviour (plasticity characteristics, compaction, unconfined compressive strength (UCS) and swelling potential) of the test soil and to identify the reaction products of the stabilised materials to determine the mechanisms by which changes in engineering properties are obtained. In order to achieve these objectives, extensive laboratory investigations were carried out. Various mixes (up to 10% GGBS by dry weight of the test soil and up to 30% replacement by hydrated lime) were prepared and cured under two representative conditions {20°C with 90-100% relative humidity (CCI) and 35° C with 50-60% relative humidity (CC2)} for up to 12 months. Compaction and plasticity were measured soon after mixing, the swelling potential and UCS were measured after longer curing periods. Four analytical techniques {X ray diffraction, scanning electron microscopy, differential thermal analysis and nuclear magnetic resonance (NMR)} were used to identify the reaction products of the clay fraction of the test soil mixed with various amount of GGBS and lime. This pure clay test soil was used to ease identification of the reaction products. The investigations showed that generally the engineering properties (UCS, swelling, plasticity) improved with the addition of GGBS and with increasing curing period and temperature. The addition of lime resulted in a dramatic improvement within the test ranges covered in the programme. The maximum dry density, MDD, decreased and the optimum moisture content, OMC, increased with increasing GGBS and lime content. The major changes in the UCS and swelling behaviour are due to the formation of new cementitious materials. The analytical investigation confirmed two major reactions when GGBS and lime were added to the pure clay soil, hydration of GGBS activated by lime to produce calcium aluminosilicate hydrate gel (C-A-S-H) and hydrotalcite type phase, and the clay-lime reaction to produce calcium silicate hydrate (C-S-H), (C-A-H) and (C-A-S-H). The NMR test results revealed that the aluminosilicate chain length (EL), the aluminium: silicate (Al/Si) ratio and the amount of Si in the formed C-S-H significantly increased with an increase in the curing temperature and period, which indicates a more stable and well crystalline C-S-H. The results indicate that the use of GGBS alone, or preferably with lime, could have a significant effect on the behaviour of potentially swelling clays. Recommendations for further studies include a study of the effect of cyclic loading on the test soil. Also, site trials should be carried out to assess the suitability of using these materials in the field