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Quantum two-photon laser in Kerr-like medium / Faisal Hamood Ahmed Mathkoor
Get PDFIn this thesis, we studied the Kerr nonlinearity effects on nonclassicality and statistics of the laser field besides the effects of detuning, injection rate, and intensity-dependent coupling (IDC). We developed a quantum theory of light generated from a two-photon laser (TPL) with nonlinear Kerr-like medium in a laser dissipative cavity. The full quantum mechanical approach with the density matrix of the particle-field system is used to derive the TPL master equation based on Scully-Lamb’s quantum theory of laser. Various dynamical operators of interest for the cavity field are calculated analytically and computed numerically. The sophisticated computational program was developed to obtain the numerical solution for the nonlinear density matrix equation where the exact solution is not possible. We obtained an approximate soluble form of the photon number distribution equation using reasonable assumptions. The assumptions are justified by making a comparison with the exact numerical results that show a good agreement for small fluctuations in the field. We studied the dynamics and effects of injection rate, two-photon detuning, the Kerr parameters, and IDC on mean photon number, entanglement criterion, second-order correlation functions 6¹2º , Mandel-& parameter, and photon number distribution. In the absence of IDC, we found that the field behaves nonclassically for a wide range of the selected parameters. The results show that the injection rate and detuning decrease the inter-mode correlation and change the field statistics from sub-Poissonian to super- Poissonian. However, the Kerr parameters change the field statistics from super-Poissonian to sub-Poissonian. This means that the Kerr parameters reduce the fluctuations in the mean photon number below the Poissonian classical limit, which is for photon number squeezed light. Moreover, Kerr parameters transform the detuning to become intensity-dependent and shift the field frequency through the effective detuning. In the presence of IDC, we found the effects of Kerr parameters and detuning are greatly suppressed, but the effects of the injection rate are enhanced. The nonlinearity of the Kerr effect results in a dramatic decrease in the mean photon number. However, the IDC rises mean photon numbers substantially. The generated photons have nonclassical properties that would last for a long time. Interestingly, statistics of the field are reversed and become super-Poissonian under the effects of Kerr parameters and sub-Poissonian under the injection rate, which is the opposite of the previous case of no IDC. The results show competition between the Kerr effect and both the two-photon detuning and the IDC with dominance in favor of the later. These competitions become important if we can exploit and control them to produce desirable nonclassical photons with acceptable photon number and photon number fluctuations that would be useful in certain applications in quantum metrology and quantum information
Synthesis and fabrication of trimetallic (Ru-Mn Co) catalyst supported on TiO2 and Ni(OH)2 thin films for photoelectrochemical applications / Ahmad Nazeer Che Mat
Get PDFAnatase supported heterogeneous photocatalyst consisting of RuO2, MnO2 and Co3O4 (1:13:13 ratio) was synthesized by precipitation method. The film of the prepared catalyst was fabricated by electrophoretic deposition technique in an aqueous solution of 0.1 mM ammonia and tested for photoelectrocatalytic (PEC) oxidation of methanol in 0.1M KOH under visible light irradiation. The as-prepared photocatalyst was characterized by FTIR, UV–Vis, XRD, Raman spectroscopy, FESEM/EDX, TEM, BET, XPS and TPR. The PEC study by cyclic voltammetry indicates that the oxidation of methanol to CO2 and H2O upon exposure to visible light occurs between 400 and 800 nm. The smaller value of the charge transfer resistance (Rct) of the RuO2-MnO2-Co3O4 supported anatase TiO2 electrode indicates a faster rate of charge transfer at the electrode-electrolyte interface compared to the TiO2 catalyst, which could be promising for direct methanol fuel cell application. Additionally, the trimetallic photocatalysts namely RuO2-MnO2-Co3O4 (1:13:13 ratio) supported anatase TiO2 also was tested for photoelectrochemical reduction of CO2 into formic acid in 0.2 M LiClO4 in aqueous and N,N-dimethylformamide (DMF) under visible light. The photocurrent density in aqueous medium is higher than DMF with the value of 12 μA/cm2 vs Ag/AgCl. The stable photocurrent from chronoamperometry revealing of good discernment of product where formic acid remains the major product in both aqueous and DMF medium. Furthermore, the photoelectrochemical reduction of CO2 in aqueous and N,N-dimethylformamide (DMF) was also investigated over spherical Ni(OH)2 photocatahode in 0.2 M LiClO4 prepared by hydrothermal method was investigated under visible light irradiation. The band gap of Ni(OH)2 obtained from UV-Vis spectroscopy was 1.8 eV which enabled efficient visible light absorption for the photoreaction. The porous spherical morphology of Ni(OH)2 allows deeper penetration of light onto the active sites for better photocatalytic performance. The photocurrent density in aqueous and DMF solution at 0.2 V (vs. Ag/AgCl) were 24 mA/cm2 and 5 mA/cm2, respectively. Acetaldehyde and methanol are the major products in aqueous solution, while formic acid and methanol were the major products in DMF, after 6 hours of photoelectrolysis. The products formation from the photoelectrochemical reduction of dissolved CO2 were 612 and 854 ppm in aqueous and DMF, respectively
Attitude towards patient undergraduate medical students in the University of Malaya / Jeevitha Rajasingam
Get PDFIn the last two decades, patient safety awareness has become one of the emerging themes. To prevent from doing harm to patients, safe medical practices should be implemented and followed strictly. Therefore, a basic understanding of human factor principles need to be instilled into all health care workers. Medical universities play a vital role in fostering patient safety attitudes of their students towards the importance of patient safety during their practise. However, the medical curricula still face challenges regarding the correct timing and appropriate methods of instruction in their understanding of their principles. Experiments have shown that patient safety classes in health care facilities are being developed, incorporated, and tested. In this study, the attitude towards patient safety among medical students in University of Malaya was studied. The end results of this study would help medical schools in introducing patient safety components to their curriculum.
This study was performed among undergraduate medical students in the University of Malaya. Attitudes toward Patient Safety Questionnaire III (APSQ-III) - a 30- items, 5-point Likert scale questionnaire, was used as the study instrument. Year 1 to Year 5 medical students were approached via an online questionnaire using Google form and administered to their email addresses.
It resulted in a positive attitude culture towards patient safety among the undergraduate medical students. By measurements, the attitude towards implementing team functioning was scored the highest (mean=4.37) and the male medical students had better attitude towards Error Reporting (mean=3.66) compared to the females. For Working hours, the scores (mean=4.03) among the Year 1 medical students was the lowest compared to all the other years.
Students had positive views of patient safety importance, some still felt that patient safety must be highlighted further in the medical curriculum. The World Health
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Organisation (WHO) has since established the Patient Safety Curriculum Guide to support health care organizations who incorporate values of patient protection by concentrating on operating a safety culture for all health care professionals and undergraduate medical students in an integrated manner. Hence more studies are needed to be focused in curriculum to enhance the attitude of students towards patient safety
Kodaly teachers’ perception on aural and Musicianship training in Malaysia / Low Siew Moon
Get PDFThis study investigated the perception of three experienced music teachers in Malaysia who apply Kodály method in their music teaching. A qualitative research approach was employed to investigate how aural and musicianship training in Kodály method being carried out in Malaysia. Narrative interviews were conducted for interviewees to share their teaching experiences using Kodály method. There are six core philosophies in Kodály method as follows: (1) Music literacyis the right for everyone, (2) The most authentic instrument is human voice, (3) Music education should start as young as possible, (4) Singing is the basis for all music, (5) Folk songs is the ‘musical mother tongue’, (6) Child-centered approach is vital (Casarow, 2015). This study aims to understand teacher’s training in Kodály teaching method in Malaysia. Kodály teacher and students have to prepare, present and practice when planning for music lesson. Perception of three music teachers in Malaysia who apply Kodály method in their music teaching were investigated. Data collected was analyzed and transcribed for discussion. In general, the result showed that Kodály method is a way of teaching that stimulates learners’ innate ability and can help to improve students’ aural ability and musicianship
Mathematical modelling of the tuberculosis epidemiology / Ayinla Ally Yeketi
Get PDFThis project analyses the tuberculosis (TB) epidemic mathematically using compartmental modelling approach. Three models are presented to discuss drug susceptible and multi-drug resistant TB. The first model presented has 4 compartments; susceptible, exposed, infectious and recovered. The relevance of the exposed class in managing TB is analysed and found to be useful in delaying the eventual onset of the infection. Compared to previous researches, our results significantly show that when efforts are made such that no infected individual bypasses the exposed class and progresses directly to the infectious, the TB epidemic is successfully combatted. Also, the model is used to show that reinfection has no significant relevance to TB incidence. The model is further extended to accommodate vaccination compartment. The vaccination compartment is included to understand the usefulness of a prophylactic vaccine in curbing the growth of TB epidemic. The intrinsic features to be considered in the formulation of the vaccine as well as the effective proportion of people to be vaccinated to achieve herd immunity are presented. A vaccine that would combat the infectivity rate of TB by half displays its potency in drastically reducing the TB incident rate. Placing the patient on good diets also gives a better result as discussed in the optimal control section. Furthermore, a model to analyse the relevance of quarantine in managing the incident rate of multi-drug resistant TB (MDR-TB) is formulated. The quarantine compartment is created to harbour individuals that develop MDR-TB. This shows its efficacy to help; monitor the recovery rate of individuals with MDR-TB, keep the MDRTB patients under watch regarding their medications, and as well prevent the MDR-TB patients from mingling with susceptible individuals. This model is shown to undergo backward bifurcation which gives a vital information on how to deal with the epidemic. In general, the equilibria points of all the 3 models are shown to be locally asymptotically stable whenever the basic reproduction number is less than unity
MAGEB2 antibody as potential diagnostic and predictive tool in the progression of oral cancer / Noratikah Awang Hasyim
Get PDFIntroduction: Oral squamous cell carcinoma (OSCC) represents more than 90% of all
oral cancer. Despite advances in diagnostic and therapeutic modalities, mortality and
morbidity rates have not improved in the last decade. Hence, alternative diagnostic and
therapeutic approaches are urgently needed. Cancer testes antigens (CTA) are proteins
that are expressed in various malignant tumours but its expression in normal tissue is
restricted to testes and occasionally placental trophoblast. Due to its exclusive presence
in different types of malignant tumors, and their ability to trigger immune responses,
CTA are considered promising biomarkers for cancer vaccines. A previous protein array
study reported that MAGEB2, a subset of CTA was significantly associated with better
prognosis in OSCC patients. Objectives: The objective of this study were to compare
the expressions of MAGEB2 antibody in the tissues of normal oral mucosa (NOM), oral
potentially malignant disorder (OPMD), and OSCC patient as well as to evaluate the
association of MAGEB2 antibody with socio-demographics and clinico-pathological
characteristics in OSCC patients, and lastly to determine the association of MAGEB2
expressions with overall survival in OSCC patients. Methods: Immunohistochemical
(IHC) staining with MAGEB2 antibody was performed on 10 NOM, 20 OPMD, and 57
OSCC tissues. Kruskal-Wallis test was used to compare MAGEB2 expression between
NOM, OPMD, and OSCC tissue. Diagnostic accuracy of MAGEB2 in distinguishing
NOM, OPMD, and OSCC tissue and prognostic accuracy of MAGEB2 with sociodemographic and clinico-pathologic characteristics were determined using receiver
operating characteristic (ROC) curve. Kaplan-Meier survival analysis was used to
determine the association between MAGEB2 expressions with overall survival (OS).
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Results: MAGEB2 expression was seen in 81% of OSCC tissue. The least MAGEB2
expression was observed in OPMD tissue. MAGEB2 expression was significantly
higher in OSCC compared to OPMD tissue (p = 0.014). However, there is no significant
difference between MAGEB2 expression in NOM Vs OSCC and NOM Vs OPMD
tissue. MAGEB2 was able to distinguish OSCC from OPMD tissue with diagnostic
accuracy of 61% sensitivity and 80% specificity. There is no significant correlation
between MAGEB2 protein expression with socio-demographic, clinico-pathologic
characteristics, and OS in OSCC patients. However, a trend of better overall survival in
tissues with high MAGEB2 expression was observed in this study.
Conclusions: MAGEB2 is a potential diagnostic biomarker in distinguishing OPMD
from OSCC tissues. However, there is no significant association between MAGEB2
expression with socio-demographic, clinico-pathological, and OS in OSCC patients. A
larger and equal number of sample size along with inclusion of various OPMD cases are
recommended for future stud
A microfluidic paper-based analytical device for early diagnosis and prognosis of acute myocardial infarction / Lim Wei Yin
Get PDFAcute myocardial infarction (AMI), also termed as heart attack, is often clinically screened by blood test through the measurement of cardiac biomarkers (i.e., troponin (T or I), creatine kinase (CK−MB) and myoglobin) and electrocardiography (ECG) changes which are presented to the hospital. However, the early diagnosis of AMI is challenging because the detection of biomarkers such as troponin (T or I) and CK−MB are only reliable at the intermediate and later stages (> 6 hours after chest pain onset), during myocardial injury and myocardial infarction. On the other hand, myoglobin often been used as early biomarker which is detectable within the first 3 hours of chest pain onset was found to be more specific to skeletal muscle injury rather than myocardial injury. To overcome these limitations, the detection of a new combination of cardiac biomarkers for early diagnosis and prognosis of AMI was demonstrated in this Ph.D. project. The uniqueness of this new combination of cardiac biomarkers detection was to allow an early diagnosis of the patient at risk, to provide immediate therapy and reduce mortality rate of AMI. Glycogen phosphorylase isoenzyme BB (GPBB) was detected as a potential early biomarker of ischemic myocardial injury (within the first 4 hours) while cTnT and CK−MB were detected as prognosis biomarkers of myocardial injury and myocardial infarction. The main objective of this Ph.D. project is to develop a sensitive, low-cost and disposable microfluidic paper-based device (μPAD) for simultaneous detection of multiple cardiac biomarkers utilising both colourimetric and Surface Enhanced Raman Scattering (SERS) detection techniques. The fabricated μPAD was designed with three reaction zones: G for GPBB; M for CK−MB and T for cTnT, which was connected to a central sample zone on a nitrocellulose membrane by wax-printing technique using a wax printer—Fuji Xerox ColorQube 8870. Three different colour nanoparticles (silver, gold urchin and gold) were used as detecting indicator for a particular target analyte. The colourimetric signal could be easily observed easily through the naked eye based on the appearance of the distinct colour. Whereas the SERS signals are measured by the peak characteristics of the respective Raman reporter molecules in SERS probe at the three respective reaction zones. On the other hand, smartphone-based camera and desktop scanner were used as a diagnostic tool in colourimetric quantification; whereas Renishaw InVia Raman Microscope was used in SERS. As for the obtained results, the colourimetric and SERS-based sandwich immunoassay performed on the μPAD showed good reproducibility (RSD approximately 10%), good intra- and inter-day precision (CV 10%–20%), consistent stability test results throughout the 28 days, and a strong correlation between these three developed diagnostic tools ─ smartphone–based camera (R2 = 0.96); desktop scanner (R2 = 0.94) and SERS (R2 = 0.97) with the laboratory Siemens Centaur XPT Immunoassay System (a laboratory method) used at University Malaya Medical Center (UMMC). Additionally, to omit the requirement of the calibration curve for quantitative measurement, partial least squares (PLS) models were designed to quantify the levels of cardiac biomarkers with the Raman spectral data, for GPBB assay with R2 = 0.94; CK-MB assay with R2 = 0.80; and cTnT assay with R2 = 0.86. This method allows for absolute quantitative measurement when the conventional calibration curve fails to provide accurate estimate of the cardiac biomarkers, especially at low and high concentration ranges. Overall, the present findings indicated the potential of μPAD platform as a point-of-care testing (POCT) device for early diagnosis and prognosis of AMI by using smartphone-based camera/desktop scanner and Raman spectroscopy as a diagnostic tool for colourimetric detection and SERS detection, respectively. Hence, this developed the μPAD with a new combination of cardiac biomarkers which potentially function as a POC device for prompt diagnosis by rapid exclusion of MI (quantified by using a calibration curve or a calibration- free predictive diagnostic model)
Detection of standing and sitting variations based on in-socket piezoelectric sensors for transfemoral amputees / Tawfik Yahya Mohammed Alnusairi
Get PDFA transfemoral prosthesis is required to assist amputees to perform activities of daily
living (ADL). The purely mechanical or passive prosthesis has some drawbacks such as
consumption of high metabolic energy and limitations in mimicking normal dynamics
and kinematics of gait pattern. In contrast, the active prosthesis offers better performance
and consumes less metabolic energy. However, recent active prosthesis uses surface
electromyography as its sensory system which requires massive preparation work, causes
sores to the patient by its electrodes and requires a lot of computation to extract
meaningful features. This thesis focuses on developing signal conditioning circuitry to
classify six different activities related to sit-to-stand of a transfemoral amputee using
piezoelectric sensors as an in-socket sensory system. Also, it determines the optimal
classifier by evaluating fifteen time-domain and frequency-domain features and selecting
effective feature sets, and it investigates the effects of window size on the classification
accuracy.
Fifteen piezoelectric film sensors were embedded in the inner socket wall adjacent to
the most active regions of the agonist and antagonist knee extensor and flexor muscles,
an i.e. region with the highest level of muscle contractions of the quadriceps and
hamstring. A male transfemoral amputee wore the instrumented socket and was instructed
to perform several sitting and standing variations using an armless chair. Data were
collected from the fifteen sensors and went through signal conditioning circuits. The
overlapped technique was used to segment the data using different window lengths.
Fifteen time-domain and frequency-domain features were extracted and new feature sets
were obtained based on the feature performance. Eight of the common pattern recognition
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multiclass classifiers were evaluated and compared. Regression analysis was used to
investigate the impact of the number of features and the window lengths on classifiers’
accuracies. The classification accuracy was first calculated using k-fold cross-validation
method, and 20% of data set was held out for testing the optimal classifier.
It was shown that the integration of the developed signal conditioning circuitry, the
experimental protocol, and the data collection method could generate a consistent and
distinguish signal pattern for each sit-to-stand and stand-to-sit related activity. The results
showed that 2-feature set consisting of the root mean square (RMS) and the number of
peaks achieved the highest classification accuracy with most of the classifiers. Also, it
showed that varying a segment length from 150 ms to 600 ms had no significant effects
on support vector machine (SVM) classifiers using the 2-feature set. SVM with cubic
kernel was suggested to be the optimal classifier, and a classification accuracy of 98.33
% was achieved using the test data set.
In conclusion, this work demonstrates the use of in-socket piezoelectric sensors to
classify activities of a transfemoral amputee using pattern recognition. Different
variations of sitting and standing activities were accurately classified using two timedomain
features and SVM with cubic kernel
Determining the severity of obstructive sleep apnea (OSA) by using numerical analysis / Ang Ming Lok
Get PDFComputational technologies and biomechanical theories have been applied to study upper airway mechanics in obstructive sleep apnea (OSA). In this study, the patient is selected from ENT Department, UMMC, diagnosed with mild to severe OSA. In addition, the patient underwent maxillomandibular advancement (MMA) surgical treatment. Therefore, 3-dimensional modeling software will be used to model the upper airway, based on patient specific geometrical characteristics obtained from medical imaging and computed tomography (CT). Hence, providing an accurate assessment of airflow characteristics. Computational fluid dynamics (CFD) analysis will be combined with upper airway geometries obtained before and after surgical to determine the effects on parameters, such as, pressure drop and turbulent kinetic energy. Moreover, Patient-specific airway geometries obtained from CT scans is used to determine treatment therapy for OSA syndrome. CFD is therefore an attractive method to model treatment outcome in OSA patient-specific airway geometry before implementation of treatment devices or performing surgery
Investigations of air-water multiphase flow in tubes: Computational fluid dynamics / Goo Wei Hong
Get PDFMixing is a very crucial process in many industries, such as food processing industry, minerals processing industry, petrochemicals and refining industry, pulp and paper industry, polymer industry, pharmaceuticals industry and many more. There are different types of mixing, such as liquid-gas mixing, liquid-liquid mixing, solid-liquid mixing and many more. The definition of multiphase flow is the simultaneous flow of materials with multiple thermodynamic phases. A lot of process industries require multiphase flows during operation. Bubbly flow is defined as the flow of liquids that contains dispersed gas bubbles. One of the main applications of multiphases flows and bubbly flows is static mixer. The experimental and simulation studies on multiphase flows, especially bubbly flows are not widely performed due to due to several constraints. Therefore, the focus of this research project is on investigating bubbly flow using Computational Fluid Dynamics (CFD) software. The three most common multiphase models in FLUENT are Volume of Fluid (VOF) model, Mixture model and Eulerian model. The two most common models under Eulerian multiphase model in simulating bubbly flow are Population Balance Model (PBM) and Interfacial Area Concentration (IAC) model. The PBM and IAC model are compared with an available case study from ANSYS in simulating bubbly flow in a 2D vertical bubble column reactor. It is found that the simulation results obtained using PBM compared to IAC model, such as air volume fraction contours, water velocity vectors, air bin 0 fraction contours, graphs of air bin 3 fraction versus X direction at the centre of the 2D vertical bubble column reactor, discrete size 3 fraction of air contours, Sauter mean diameter of air contours and Sauter mean diameter distribution of air histograms have higher similarity with the results from the case study, but there exist some differences between the results. Not only that, the bubbly
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flow in 2D horizontal pipe is studied by manipulating the ratio of air velocity to water velocity (AV/WV) using PBM. It is found that the air volume fraction in the 2D horizontal pipe decreases when the AV/WV ratio decreases from 1. It is found that the air bubbles migrate towards the top wall of the 2D horizontal pipe almost instantly when the ratio of AV/WV is higher than 1 due to the larger buoyancy force whereas the air bubbles tend to travel the furthest at the centre of the 2D horizontal pipe before migrating to the top wall when the ratio of AV/WV is 1. However, the distance the air bubbles travel at the centre of the 2D horizontal pipe reduces if the AV/WV ratio decreases from 1. Lastly, CFD simulation of air-water multiphase flow in 3D Kenics static mixer is performed using VOF multiphase model by manipulating the volume fraction of air at the inlet. It is found that the mixing characteristics of the 3D Kenics static mixer are almost similar for the different volume fractions of air at the air inlet. However, reversed flow of water occurs due to the pressure-outlet boundary conditions at the outlets