Open Access Macedonian Journal of Medical Sciences
BACKGROUND OF THE STUDY: Β-carotene, flavonoids and phenolic compounds found in methanol extracts... more BACKGROUND OF THE STUDY: Β-carotene, flavonoids and phenolic compounds found in methanol extracts of Moringa leaves and papaya fruit have high antioxidant activity so that they can be used for antiaging. The concentration of solvent is a factor that will affect the levels of active ingredients in methanol extract. This study aims to determine the effect of the concentration of the methanol solvent derived from the extraction of Moringa leaves and papaya fruit on the inhibitory activity of the elastase and hyaluronidase enzymes. AIM OF THE STUDY: Knowing the best extracts of methanol 50, 70, and 96% of Moringa leaf (Moringa oleifera) and papaya fruit (Carica papaya) as antiaging agents through inhibition of elastase and hyaluronidase enzymes. METHODOLOGY: In this study variations in the concentration of methanol 50%, 70%, and 96% were used for the extraction of Moringa leaves and papaya fruit. The extract was obtained by maceration method which was then tested for the inhibition of t...
Enterobius vermicularis (EV) is a pinworm which commonly resides in the lumen of the intestinal t... more Enterobius vermicularis (EV) is a pinworm which commonly resides in the lumen of the intestinal tract and lays eggs on the perianal skin. However, rarely the worm can infest various other sites in the body and cases with infestation of such ectopic sites have been reported in literature. Rare cases of mesenteric lymph node involvement have also been reported. We report a case in a young male who presented with signs and symptoms of acute appendicitis. During surgery, enlarged mesenteric lymph nodes were identified. Histological examination revealed adult worm in the appendiceal lumen. Histological examination of mesenteric lymph node revealed degenerated worm surrounded by caseating chronic granulomatous inflammation. We conclude that EV infestation should be considered in the differential diagnosis of enlarged mesenteric lymph node with chronic granulomatous inflammation, especially in young patients and when accompanying bowel tissue also reveal the helminth
High-grade neuroendocrine carcinoma (NEC) of the esophagus is an extremely aggressive and rare di... more High-grade neuroendocrine carcinoma (NEC) of the esophagus is an extremely aggressive and rare disease, which is still not well understood. In this case report, we discuss a 73-year-old male patient that presented with the sole complaint of dysphagia to solid foods. During our evaluation of the patient, a six-centimeter esophageal mass was found on esophagogastroduodenoscopy (EGD). A diagnosis of poorly differentiated (high-grade) non-small cell neuroendocrine carcinoma was made after a histological analysis and immunostaining. We attempted to highlight the diagnosis, evaluation process, and treatment options related to this entity. Our review of the literature revealed that further research is needed, focusing on neuroendocrine carcinomas of the esophagus and how this entity differs from some of the more well-known neuroendocrine neoplasms in terms of management.
Lecture Notes in Nanoscale Science and Technology, 2013
In this chapter, we analyze the polarization response of multi-layer quantum dot molecules (QDMs)... more In this chapter, we analyze the polarization response of multi-layer quantum dot molecules (QDMs) containing up to nine vertically stacked quantum dot layers by carrying out a systematic set of multi-million atom simulations. The atomistic modeling and simulations allow us to include correct symmetry properties in the calculations of the electronic and optical spectra: a factor critical to explain the experimental evidence. The values of the degree of polarization (DOP) calculated from our model based on the geometry parameters directly extracted from the experimental TEM images follow the trends of the recently published experimental data. We also present detailed physical insight of the fundamental underlying physics by examining strain profiles, band edges diagrams, and wave function plots. Multi-directional calculations of the DOP reveal a unique property of the InAs QDMs that the TE response in the plane perpendicular to the growth direction is highly anisotropic. Therefore we propose that a single value of the DOP is not sufficient to fully characterize the polarization response. We explain this anisotropy of the TE modes in terms of the orientation of the hole wave functions that align along the [\(\bar{1}10\)] direction. Our results provide a new insight that the isotropic polarization response measured in the experimental PL spectra is due to two factors: (i) TM[001] mode increases due to enhanced intermixing of HH and LH bands and (ii) TE[110] mode reduces significantly due to the hole wave function alignments along the [\(\bar{1}10\)] direction. This is in contrast to general notion that only an increase in the TM[001] mode is responsible for the isotropic polarization. We also present polarization response as a function of various geometry configurations of the quantum dot layers to provide a guide to experimentalists for the design of optical devices based on multi-layer QDMs.
Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association, Jan 11, 2015
Achilles tendons heal slower than other tissues, therefore requiring the developmnent of a strate... more Achilles tendons heal slower than other tissues, therefore requiring the developmnent of a strategy for accelerating the process. Vascular supply plays an important role in primary tendon healing, especially during the early healing phase. MicroRNA (miR)-210 has been reported as being crucial for angiogenesis, which is a key factor of tissue repair. We report herein that local injection of synthetic miR-210 into the injured Achilles tendon of a rat accelerated healing of the tendon. Achilles tendons were transected and repaired via the Kessler suture technique in Sprague-Dawley rats. Then, double stranded (ds) miR-210 was injected into the repaired sites. The control group was injected with non-functioned dsRNA. At 2, 6 and 12 weeks, histological evaluations were performed. At two and six weeks, mechanical testing and angiogenesis were evaluated. Gene expression analysis using real-time polymerase chain reaction (PCR) and immunohistochemistry were performed at two weeks. At two and ...
ABSTRACT This research proposed a multi-resolution based Lung parenchyma segmentation method to s... more ABSTRACT This research proposed a multi-resolution based Lung parenchyma segmentation method to segment the lung lobes at accuracy levels acceptable for clinical applications. The methodology incorporates statistical models together with multi-resolution analysis techniques in order to enhance the accuracy of the overall system. In this research, the image quality and accuracy of detecting the cancer affected area are the key factors. The assessment of image quality and improvements are depending on the enhancement stage where different techniques have been used. Mainly Gabor filter and Fourier Transforms have been used for image enhancement and Pixel Percentage and Mask Labeling techniques have been used for detecting the area of interest.
ABSTRACT The feasibility study of a newly proposed smart base isolation system employing magneto-... more ABSTRACT The feasibility study of a newly proposed smart base isolation system employing magneto-rheological elastomers(MREs) has been carried out. MREs belong to a class of smart materials whose elastic modulus or stiffness can be adjusted by varying the magnitude of the magnetic field. The base isolation systems are considered as one of the most effective devices for vibration mitigation of civil engineering structures such as bridges and buildings in the event of earthquakes. The proposed base isolation system strives to enhance the performance of the conventional base isolation system by improving the robustness of the system wide stiffness range controllable of MREs, which improves the adaptability and helps in better vibration control. To validate the effectiveness of the MRE-based isolation system, an extensive numerical simulation study has been performed using both single-story and five-story building structures employing base isolated devices under several historical earthquake excitations. The results show that the proposed system outperformed the conventional system in reducing the responses of the structure in all the seismic excitations considered in the study.
Electronic components, based on current semiconductor technologies and operating in radiation ric... more Electronic components, based on current semiconductor technologies and operating in radiation rich environments, suffer degradation of their performance as a result of radiation exposure. Silicon carbide (SiC) provides an alternate solution as a radiation hard material, because of its wide bandgap and higher atomic displacement energies, for devices intended for radiation environment applications. However, the radiation tolerance and reliability of SiC-based devices needs to be understood by testing devices under controlled radiation environments. These kinds of studies have been previously performed on diodes and MESFETs, but multilayer devices such as bipolar junction transistors (BJT) have not yet been studied. In this thesis, SiC material, BJTs fabricated from SiC, and various dielectrics for SiC passivation are studied by exposure to high energy ion beams with selected energies and fluences. The studies reveal that the implantation induced crystal damage in SiC material can be partly recovered at relatively low temperatures, for damage levels much lower than needed for amorphization. The implantation experiments performed on BJTs in the bulk of devices show that the degradation in device performance produced by low dose ion implantations can be recovered at 420 o C, however, higher doses produce more resistant damage. Ion induced damage at the interface of passivation layer and SiC in BJT has also been examined in this thesis. It is found that damaging of the interface by ionizing radiation reduces the current gain as well. However, for this type of damage, annealing at low temperatures further reduces the gain. Silicon dioxide (SiO 2) is today the dielectric material most often used for gate dielectric or passivation layers, also for SiC. However, in this thesis several alternate passivation materials are investigated, such as, AlN, Al 2 O 3 and Ta 2 O 5. These materials are deposited by atomic layer deposition (ALD) both as single layers and in stacks, combining several different layers. Al 2 O 3 is further investigated with respect to thermal stability and radiation hardness. It is observed that high temperature treatment of Al 2 O 3 can substantially improve the performance of the dielectric film. A radiation hardness study furthermore reveals that Al 2 O 3 is more resistant to ionizing radiation than currently used SiO 2 and it is a suitable candidate for devices in radiation rich applications.
We apply an easy and simple technique, the generalized approximation method (GAM) to investigate ... more We apply an easy and simple technique, the generalized approximation method (GAM) to investigate the temperature field associated with the Falkner-Skan boundary-layer problem. The nonlinear partial differential equations are transformed to nonlinear ordinary differential equations using the similarity transformations. An iterative scheme for the non-linear ordinary differential equations associated with the velocity and temperature profiles are developed via GAM. Numerical results for the dimensionless velocity and temperature profiles of the wedge flow are presented graphically for different values of the wedge angle and Prandtl number.
Archives of public health = Archives belges de santé publique, 2014
Childhood vaccination rates in Nigeria are among the lowest in the world and this affects morbidi... more Childhood vaccination rates in Nigeria are among the lowest in the world and this affects morbidity and mortality rates. A 2011 mixed methods study in two states in Nigeria examined coverage of measles vaccination and reasons for not vaccinating children. A household survey covered a stratified random cluster sample of 180 enumeration areas in Bauchi and Cross River States. Cluster-adjusted bivariate and then multivariate analysis examined associations between measles vaccination and potential determinants among children aged 12-23 months, including household socio-economic status, parental knowledge and attitudes about vaccination, and access to vaccination services. Focus groups of parents in the same sites subsequently discussed the survey findings and gave reasons for non-vaccination. A knowledge to action strategy shared findings with stakeholders, including state government, local governments and communities, to stimulate evidence-based actions to increase vaccination rates. I...
In this paper, we study a class of initial boundary value problem (IBVP) of the Kortewegde Vries ... more In this paper, we study a class of initial boundary value problem (IBVP) of the Kortewegde Vries equation posed on a finite interval with nonhomogeneous boundary conditions. The IBVP is known to be locally well-posed, but its global L 2 − a priori estimate is not available and therefore it is not clear whether its solutions exist globally or blow up in finite time. It is shown in this paper that the solutions exist globally as long as their initial value and the associated boundary data are small, and moreover, those solutions decay exponentially if their boundary data decay exponentially
In this paper, a balanced antenna for mobile handset applications with dualfrequency performance,... more In this paper, a balanced antenna for mobile handset applications with dualfrequency performance, covering the 2.4 GHz and the entire 5 GHz WLAN frequency bands, is investigated and discussed. The antenna is a thin-strip planar dipole with folded structure and a dual-arm on each monopole. For validation, the antenna prototype was fabricated and tested. The performance of this balanced antenna was verified and characterised in terms of the antenna return loss, radiation pattern, power gain and surface current distribution of the proposed antenna. The predicted and measured results show good agreement.
2011 Malaysian Conference in Software Engineering, 2011
Software Engineering (SE) discipline has come a long way since the 1968 NATO conference when the ... more Software Engineering (SE) discipline has come a long way since the 1968 NATO conference when the term SE was first used. Lot of work has been done for developing and revising SE curriculum and body of knowledge (e.g. SE 2004, GSwE2009, SWEBOK efforts). Different universities are developing and revising SE program and curricula at graduate and undergraduate levels all over
2009 2nd IEEE International Conference on Computer Science and Information Technology, 2009
Page 1. Enterprise Content Management (ECM): Needs, Challenges and Recommendations Muhammad Usman... more Page 1. Enterprise Content Management (ECM): Needs, Challenges and Recommendations Muhammad Usman Shaheed Zulfikar Ali Bhutto Institute of Science and Technologies, Islamabad, Pakistan muhammadusman1@yahoo.com ...
Semi-arid and dry sub-humid areas (especially in the tropics) are characterized by high inter-ann... more Semi-arid and dry sub-humid areas (especially in the tropics) are characterized by high inter-annual and intra-seasonal rainfall variability. Agriculture, which employs the bulk of the rapidly increasing populations, is largely rain-fed, low-input based and highly resource dependent. Recent spates of drought have, therefore, exacerbated the now-too-familiar specter of famine and starvation in these areas with glaring examples being the recurring episodes in sub-Saharan Africa since the great Sahel drought of 1969-1973. A great need for accurate and timely hazard forecast products in aid of agriculture thus exists. Several schemes are currently employed by various agencies around the globe in this direction. There does remain, however, a gap between product provision and user expectations. This paper examines this gap suggesting a five-point framework within which it can be addressed as an action agenda for the climate science community. The paper posits that changes are possible to existing methodologies (related to three of these points), which, within the context of current science, can greatly enhance the utility of forecast products for agriculture in marginal areas. The remaining two points have, however, been identified as requiring additional applied research and necessary pointers for addressing these issues are provided. First is the need for appropriate impact-related indicators for intra-seasonal and interannual rainfall variability that are easy to compute, amenable to forecasting and follow closely the experiences of farmers in marginal areas. The second is a consideration of appropriate forecast information formatting and communication medium that guarantee effective feedback between forecast producers and users. Specific examples of the status quo and of work currently underway are cited from southern Africa-a region currently attracting international attention as a result of recent droughts and the threat of famine.
Herein we report a synthesis of copper nanoparticles (Cu-NPs) in chitosan (Cts) media via a chemi... more Herein we report a synthesis of copper nanoparticles (Cu-NPs) in chitosan (Cts) media via a chemical reaction method. The nanoparticles were synthesized in an aqueous solution in the presence of Cts as stabilizer and CuSO 4 •5H 2 O precursor. The synthesis proceeded with addition of NaOH as pH moderator, ascorbic acid as antioxidant and hydrazine as the reducing agent. The characterization of the prepared NPs was done using ultraviolet-visible spectroscopy, which showed a 593 nm copper band. The Field Emission Scanning Electron Microscope (FESEM) images were also observed, and found to be in agreement with the UV-Vis result, confirming the formation of metallic Cu-NPs. The mean size of the Cu-NPs was estimated to be in the range of 35-75 nm using X-ray diffraction. XRD was also used in analysis of the crystal structure of the NPs. The interaction between the chitosan and the synthesized NPs was studied using Fourier transform infrared (FT-IR) spectroscopy, which showed the capping of the NPs by Cts.
It has been observed in laboratory experiments that when nonlinear dispersive waves are forced pe... more It has been observed in laboratory experiments that when nonlinear dispersive waves are forced periodically from one end of undisturbed stretch of the medium of propagation, the signal eventually becomes temporally periodic at each spatial point. The observation has been confirmed mathematically in the context of the damped Korteweg-de Vries (KdV) equation and the damped Benjamin-Bona-Mahony (BBM) equation. In this paper we intend to show the same results hold for the pure KdV equation (without the damping terms) posed on a finite domain. Consideration is given to the initial-boundary-value problem ut + ux + uux + uxxx = 0, u(x, 0) = φ(x), 0 < x < 1, t > 0, u(0, t) = h(t), u(1, t) = 0, ux(1, t) = 0, t > 0. (*) It is shown that if the boundary forcing h is periodic with small ampitude, then the small amplitude solution u of (*) becomes eventually time-periodic. Viewing (*) (without the initial condition) as an infinite-dimensional dynamical system in the Hilbert space L 2 (0, 1), we also demonstrate that for a given periodic boundary forcing with small amplitude, the system (*) admits a (locally) unique limit cycle, or forced oscillation, which is locally exponentially stable. A list of open problems are included for the interested readers to conduct further investigations.
International Journal of Antennas and Propagation, 2007
The design of an ultra-wideband microstrip patch antenna with a small coplanar capacitive feed st... more The design of an ultra-wideband microstrip patch antenna with a small coplanar capacitive feed strip is presented. The proposed rectangular patch antenna provides an impedance bandwidth of nearly 50%, and has stable radiation patterns for almost all frequencies in the operational band. Results presented here show that such wide bandwidths are also possible for triangular and semiellipse geometries with a similar feed arrangement. The proposed feed is a very small strip placed very close to the radiator on a substrate above the ground plane. Shape of the feed strip can also be different, so long as the area is not changed. Experimental results agree with the simulated results. Effects of key design parameters such as the air gap between the substrate and the ground plane, the distance between radiator patch and feed strip, and the dimensions of the feed strip on the input characteristics of the antenna have been investigated and discussed. As demonstrated here, the proposed antenna c...
Open Access Macedonian Journal of Medical Sciences
BACKGROUND OF THE STUDY: Β-carotene, flavonoids and phenolic compounds found in methanol extracts... more BACKGROUND OF THE STUDY: Β-carotene, flavonoids and phenolic compounds found in methanol extracts of Moringa leaves and papaya fruit have high antioxidant activity so that they can be used for antiaging. The concentration of solvent is a factor that will affect the levels of active ingredients in methanol extract. This study aims to determine the effect of the concentration of the methanol solvent derived from the extraction of Moringa leaves and papaya fruit on the inhibitory activity of the elastase and hyaluronidase enzymes. AIM OF THE STUDY: Knowing the best extracts of methanol 50, 70, and 96% of Moringa leaf (Moringa oleifera) and papaya fruit (Carica papaya) as antiaging agents through inhibition of elastase and hyaluronidase enzymes. METHODOLOGY: In this study variations in the concentration of methanol 50%, 70%, and 96% were used for the extraction of Moringa leaves and papaya fruit. The extract was obtained by maceration method which was then tested for the inhibition of t...
Enterobius vermicularis (EV) is a pinworm which commonly resides in the lumen of the intestinal t... more Enterobius vermicularis (EV) is a pinworm which commonly resides in the lumen of the intestinal tract and lays eggs on the perianal skin. However, rarely the worm can infest various other sites in the body and cases with infestation of such ectopic sites have been reported in literature. Rare cases of mesenteric lymph node involvement have also been reported. We report a case in a young male who presented with signs and symptoms of acute appendicitis. During surgery, enlarged mesenteric lymph nodes were identified. Histological examination revealed adult worm in the appendiceal lumen. Histological examination of mesenteric lymph node revealed degenerated worm surrounded by caseating chronic granulomatous inflammation. We conclude that EV infestation should be considered in the differential diagnosis of enlarged mesenteric lymph node with chronic granulomatous inflammation, especially in young patients and when accompanying bowel tissue also reveal the helminth
High-grade neuroendocrine carcinoma (NEC) of the esophagus is an extremely aggressive and rare di... more High-grade neuroendocrine carcinoma (NEC) of the esophagus is an extremely aggressive and rare disease, which is still not well understood. In this case report, we discuss a 73-year-old male patient that presented with the sole complaint of dysphagia to solid foods. During our evaluation of the patient, a six-centimeter esophageal mass was found on esophagogastroduodenoscopy (EGD). A diagnosis of poorly differentiated (high-grade) non-small cell neuroendocrine carcinoma was made after a histological analysis and immunostaining. We attempted to highlight the diagnosis, evaluation process, and treatment options related to this entity. Our review of the literature revealed that further research is needed, focusing on neuroendocrine carcinomas of the esophagus and how this entity differs from some of the more well-known neuroendocrine neoplasms in terms of management.
Lecture Notes in Nanoscale Science and Technology, 2013
In this chapter, we analyze the polarization response of multi-layer quantum dot molecules (QDMs)... more In this chapter, we analyze the polarization response of multi-layer quantum dot molecules (QDMs) containing up to nine vertically stacked quantum dot layers by carrying out a systematic set of multi-million atom simulations. The atomistic modeling and simulations allow us to include correct symmetry properties in the calculations of the electronic and optical spectra: a factor critical to explain the experimental evidence. The values of the degree of polarization (DOP) calculated from our model based on the geometry parameters directly extracted from the experimental TEM images follow the trends of the recently published experimental data. We also present detailed physical insight of the fundamental underlying physics by examining strain profiles, band edges diagrams, and wave function plots. Multi-directional calculations of the DOP reveal a unique property of the InAs QDMs that the TE response in the plane perpendicular to the growth direction is highly anisotropic. Therefore we propose that a single value of the DOP is not sufficient to fully characterize the polarization response. We explain this anisotropy of the TE modes in terms of the orientation of the hole wave functions that align along the [\(\bar{1}10\)] direction. Our results provide a new insight that the isotropic polarization response measured in the experimental PL spectra is due to two factors: (i) TM[001] mode increases due to enhanced intermixing of HH and LH bands and (ii) TE[110] mode reduces significantly due to the hole wave function alignments along the [\(\bar{1}10\)] direction. This is in contrast to general notion that only an increase in the TM[001] mode is responsible for the isotropic polarization. We also present polarization response as a function of various geometry configurations of the quantum dot layers to provide a guide to experimentalists for the design of optical devices based on multi-layer QDMs.
Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association, Jan 11, 2015
Achilles tendons heal slower than other tissues, therefore requiring the developmnent of a strate... more Achilles tendons heal slower than other tissues, therefore requiring the developmnent of a strategy for accelerating the process. Vascular supply plays an important role in primary tendon healing, especially during the early healing phase. MicroRNA (miR)-210 has been reported as being crucial for angiogenesis, which is a key factor of tissue repair. We report herein that local injection of synthetic miR-210 into the injured Achilles tendon of a rat accelerated healing of the tendon. Achilles tendons were transected and repaired via the Kessler suture technique in Sprague-Dawley rats. Then, double stranded (ds) miR-210 was injected into the repaired sites. The control group was injected with non-functioned dsRNA. At 2, 6 and 12 weeks, histological evaluations were performed. At two and six weeks, mechanical testing and angiogenesis were evaluated. Gene expression analysis using real-time polymerase chain reaction (PCR) and immunohistochemistry were performed at two weeks. At two and ...
ABSTRACT This research proposed a multi-resolution based Lung parenchyma segmentation method to s... more ABSTRACT This research proposed a multi-resolution based Lung parenchyma segmentation method to segment the lung lobes at accuracy levels acceptable for clinical applications. The methodology incorporates statistical models together with multi-resolution analysis techniques in order to enhance the accuracy of the overall system. In this research, the image quality and accuracy of detecting the cancer affected area are the key factors. The assessment of image quality and improvements are depending on the enhancement stage where different techniques have been used. Mainly Gabor filter and Fourier Transforms have been used for image enhancement and Pixel Percentage and Mask Labeling techniques have been used for detecting the area of interest.
ABSTRACT The feasibility study of a newly proposed smart base isolation system employing magneto-... more ABSTRACT The feasibility study of a newly proposed smart base isolation system employing magneto-rheological elastomers(MREs) has been carried out. MREs belong to a class of smart materials whose elastic modulus or stiffness can be adjusted by varying the magnitude of the magnetic field. The base isolation systems are considered as one of the most effective devices for vibration mitigation of civil engineering structures such as bridges and buildings in the event of earthquakes. The proposed base isolation system strives to enhance the performance of the conventional base isolation system by improving the robustness of the system wide stiffness range controllable of MREs, which improves the adaptability and helps in better vibration control. To validate the effectiveness of the MRE-based isolation system, an extensive numerical simulation study has been performed using both single-story and five-story building structures employing base isolated devices under several historical earthquake excitations. The results show that the proposed system outperformed the conventional system in reducing the responses of the structure in all the seismic excitations considered in the study.
Electronic components, based on current semiconductor technologies and operating in radiation ric... more Electronic components, based on current semiconductor technologies and operating in radiation rich environments, suffer degradation of their performance as a result of radiation exposure. Silicon carbide (SiC) provides an alternate solution as a radiation hard material, because of its wide bandgap and higher atomic displacement energies, for devices intended for radiation environment applications. However, the radiation tolerance and reliability of SiC-based devices needs to be understood by testing devices under controlled radiation environments. These kinds of studies have been previously performed on diodes and MESFETs, but multilayer devices such as bipolar junction transistors (BJT) have not yet been studied. In this thesis, SiC material, BJTs fabricated from SiC, and various dielectrics for SiC passivation are studied by exposure to high energy ion beams with selected energies and fluences. The studies reveal that the implantation induced crystal damage in SiC material can be partly recovered at relatively low temperatures, for damage levels much lower than needed for amorphization. The implantation experiments performed on BJTs in the bulk of devices show that the degradation in device performance produced by low dose ion implantations can be recovered at 420 o C, however, higher doses produce more resistant damage. Ion induced damage at the interface of passivation layer and SiC in BJT has also been examined in this thesis. It is found that damaging of the interface by ionizing radiation reduces the current gain as well. However, for this type of damage, annealing at low temperatures further reduces the gain. Silicon dioxide (SiO 2) is today the dielectric material most often used for gate dielectric or passivation layers, also for SiC. However, in this thesis several alternate passivation materials are investigated, such as, AlN, Al 2 O 3 and Ta 2 O 5. These materials are deposited by atomic layer deposition (ALD) both as single layers and in stacks, combining several different layers. Al 2 O 3 is further investigated with respect to thermal stability and radiation hardness. It is observed that high temperature treatment of Al 2 O 3 can substantially improve the performance of the dielectric film. A radiation hardness study furthermore reveals that Al 2 O 3 is more resistant to ionizing radiation than currently used SiO 2 and it is a suitable candidate for devices in radiation rich applications.
We apply an easy and simple technique, the generalized approximation method (GAM) to investigate ... more We apply an easy and simple technique, the generalized approximation method (GAM) to investigate the temperature field associated with the Falkner-Skan boundary-layer problem. The nonlinear partial differential equations are transformed to nonlinear ordinary differential equations using the similarity transformations. An iterative scheme for the non-linear ordinary differential equations associated with the velocity and temperature profiles are developed via GAM. Numerical results for the dimensionless velocity and temperature profiles of the wedge flow are presented graphically for different values of the wedge angle and Prandtl number.
Archives of public health = Archives belges de santé publique, 2014
Childhood vaccination rates in Nigeria are among the lowest in the world and this affects morbidi... more Childhood vaccination rates in Nigeria are among the lowest in the world and this affects morbidity and mortality rates. A 2011 mixed methods study in two states in Nigeria examined coverage of measles vaccination and reasons for not vaccinating children. A household survey covered a stratified random cluster sample of 180 enumeration areas in Bauchi and Cross River States. Cluster-adjusted bivariate and then multivariate analysis examined associations between measles vaccination and potential determinants among children aged 12-23 months, including household socio-economic status, parental knowledge and attitudes about vaccination, and access to vaccination services. Focus groups of parents in the same sites subsequently discussed the survey findings and gave reasons for non-vaccination. A knowledge to action strategy shared findings with stakeholders, including state government, local governments and communities, to stimulate evidence-based actions to increase vaccination rates. I...
In this paper, we study a class of initial boundary value problem (IBVP) of the Kortewegde Vries ... more In this paper, we study a class of initial boundary value problem (IBVP) of the Kortewegde Vries equation posed on a finite interval with nonhomogeneous boundary conditions. The IBVP is known to be locally well-posed, but its global L 2 − a priori estimate is not available and therefore it is not clear whether its solutions exist globally or blow up in finite time. It is shown in this paper that the solutions exist globally as long as their initial value and the associated boundary data are small, and moreover, those solutions decay exponentially if their boundary data decay exponentially
In this paper, a balanced antenna for mobile handset applications with dualfrequency performance,... more In this paper, a balanced antenna for mobile handset applications with dualfrequency performance, covering the 2.4 GHz and the entire 5 GHz WLAN frequency bands, is investigated and discussed. The antenna is a thin-strip planar dipole with folded structure and a dual-arm on each monopole. For validation, the antenna prototype was fabricated and tested. The performance of this balanced antenna was verified and characterised in terms of the antenna return loss, radiation pattern, power gain and surface current distribution of the proposed antenna. The predicted and measured results show good agreement.
2011 Malaysian Conference in Software Engineering, 2011
Software Engineering (SE) discipline has come a long way since the 1968 NATO conference when the ... more Software Engineering (SE) discipline has come a long way since the 1968 NATO conference when the term SE was first used. Lot of work has been done for developing and revising SE curriculum and body of knowledge (e.g. SE 2004, GSwE2009, SWEBOK efforts). Different universities are developing and revising SE program and curricula at graduate and undergraduate levels all over
2009 2nd IEEE International Conference on Computer Science and Information Technology, 2009
Page 1. Enterprise Content Management (ECM): Needs, Challenges and Recommendations Muhammad Usman... more Page 1. Enterprise Content Management (ECM): Needs, Challenges and Recommendations Muhammad Usman Shaheed Zulfikar Ali Bhutto Institute of Science and Technologies, Islamabad, Pakistan muhammadusman1@yahoo.com ...
Semi-arid and dry sub-humid areas (especially in the tropics) are characterized by high inter-ann... more Semi-arid and dry sub-humid areas (especially in the tropics) are characterized by high inter-annual and intra-seasonal rainfall variability. Agriculture, which employs the bulk of the rapidly increasing populations, is largely rain-fed, low-input based and highly resource dependent. Recent spates of drought have, therefore, exacerbated the now-too-familiar specter of famine and starvation in these areas with glaring examples being the recurring episodes in sub-Saharan Africa since the great Sahel drought of 1969-1973. A great need for accurate and timely hazard forecast products in aid of agriculture thus exists. Several schemes are currently employed by various agencies around the globe in this direction. There does remain, however, a gap between product provision and user expectations. This paper examines this gap suggesting a five-point framework within which it can be addressed as an action agenda for the climate science community. The paper posits that changes are possible to existing methodologies (related to three of these points), which, within the context of current science, can greatly enhance the utility of forecast products for agriculture in marginal areas. The remaining two points have, however, been identified as requiring additional applied research and necessary pointers for addressing these issues are provided. First is the need for appropriate impact-related indicators for intra-seasonal and interannual rainfall variability that are easy to compute, amenable to forecasting and follow closely the experiences of farmers in marginal areas. The second is a consideration of appropriate forecast information formatting and communication medium that guarantee effective feedback between forecast producers and users. Specific examples of the status quo and of work currently underway are cited from southern Africa-a region currently attracting international attention as a result of recent droughts and the threat of famine.
Herein we report a synthesis of copper nanoparticles (Cu-NPs) in chitosan (Cts) media via a chemi... more Herein we report a synthesis of copper nanoparticles (Cu-NPs) in chitosan (Cts) media via a chemical reaction method. The nanoparticles were synthesized in an aqueous solution in the presence of Cts as stabilizer and CuSO 4 •5H 2 O precursor. The synthesis proceeded with addition of NaOH as pH moderator, ascorbic acid as antioxidant and hydrazine as the reducing agent. The characterization of the prepared NPs was done using ultraviolet-visible spectroscopy, which showed a 593 nm copper band. The Field Emission Scanning Electron Microscope (FESEM) images were also observed, and found to be in agreement with the UV-Vis result, confirming the formation of metallic Cu-NPs. The mean size of the Cu-NPs was estimated to be in the range of 35-75 nm using X-ray diffraction. XRD was also used in analysis of the crystal structure of the NPs. The interaction between the chitosan and the synthesized NPs was studied using Fourier transform infrared (FT-IR) spectroscopy, which showed the capping of the NPs by Cts.
It has been observed in laboratory experiments that when nonlinear dispersive waves are forced pe... more It has been observed in laboratory experiments that when nonlinear dispersive waves are forced periodically from one end of undisturbed stretch of the medium of propagation, the signal eventually becomes temporally periodic at each spatial point. The observation has been confirmed mathematically in the context of the damped Korteweg-de Vries (KdV) equation and the damped Benjamin-Bona-Mahony (BBM) equation. In this paper we intend to show the same results hold for the pure KdV equation (without the damping terms) posed on a finite domain. Consideration is given to the initial-boundary-value problem ut + ux + uux + uxxx = 0, u(x, 0) = φ(x), 0 < x < 1, t > 0, u(0, t) = h(t), u(1, t) = 0, ux(1, t) = 0, t > 0. (*) It is shown that if the boundary forcing h is periodic with small ampitude, then the small amplitude solution u of (*) becomes eventually time-periodic. Viewing (*) (without the initial condition) as an infinite-dimensional dynamical system in the Hilbert space L 2 (0, 1), we also demonstrate that for a given periodic boundary forcing with small amplitude, the system (*) admits a (locally) unique limit cycle, or forced oscillation, which is locally exponentially stable. A list of open problems are included for the interested readers to conduct further investigations.
International Journal of Antennas and Propagation, 2007
The design of an ultra-wideband microstrip patch antenna with a small coplanar capacitive feed st... more The design of an ultra-wideband microstrip patch antenna with a small coplanar capacitive feed strip is presented. The proposed rectangular patch antenna provides an impedance bandwidth of nearly 50%, and has stable radiation patterns for almost all frequencies in the operational band. Results presented here show that such wide bandwidths are also possible for triangular and semiellipse geometries with a similar feed arrangement. The proposed feed is a very small strip placed very close to the radiator on a substrate above the ground plane. Shape of the feed strip can also be different, so long as the area is not changed. Experimental results agree with the simulated results. Effects of key design parameters such as the air gap between the substrate and the ground plane, the distance between radiator patch and feed strip, and the dimensions of the feed strip on the input characteristics of the antenna have been investigated and discussed. As demonstrated here, the proposed antenna c...
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Papers by Muhammad Usman