Zafar Ali - Academia.edu (original) (raw)

Papers by Zafar Ali

Macromolecular rapid communications, Jan 19, 2015

Polymer microcavities with adjustable openings and surface roughness are fabricated on a large sc... more Polymer microcavities with adjustable openings and surface roughness are fabricated on a large scale via single-hole poly(glycidyl methacrylate) (PGMA) swelling seed particles. The size of openings of these microcavities can be adjusted by changing the amount of hydrophilic monomer, and the degree of surface roughness is easily regulated relying on the adjustment of the polarity of monomer. Furthermore, the morphology of PGMA/poly(styrene-methacrylic acid) (PGMA/P(S-MAA)) microparticles from microcavity to erythrocyte shape is controlled by the polarity of seed surface. From transmission electron microscopy images of PGMA/P(S-MAA) microparticles, a fresh polymer particle appears in the cavity. To confirm this phenomenon, thermal annealing process in dioxane/water solution is carried out. Considering the flexibility of polymers, the openings and closing of the prepared microparticles are regulated following the increase in volume ratio of dioxane/water. Ball-in-bowl-shaped PGMA/P(S-M...

In this report we present a framework for evaluating performance of scheduling preorchestrated mu... more In this report we present a framework for evaluating performance of scheduling preorchestrated multimedia information over broadband integrated networks. We propose a set of Quality Of Presentation (QOP) parameters which quantify the quality of multimedia presentation from user's point of view. The communication of mulltimedia data in a networked environment can affect the desired QOP parameters due to jitter delays in the network. We evaluate trade-offs between QOP parameters and the system resources including channel utilization and buffering at the destination. These trade-offs can be used to develope an optimal transmission schedule for multimedia information.

Proceedings of ICNP - 1994 International Conference on Network Protocols, 1994

Distributed Synchronization Protocols for Multimedia Services on Internet ... Zafar Ali, Miae Woo... more Distributed Synchronization Protocols for Multimedia Services on Internet ... Zafar Ali, Miae Woo and Arif Ghafoor Distributed Multimedia Systems Lab School of Electrical Engineering, Purdue University West Lafayette, Indiana 47907 ... In this paper we present a distributed ...

Asian Pacific journal of cancer prevention : APJCP, 2011

To determine the HER-2/neu status by chromogenic in situ hybridization (CISH) on tissue specimens... more To determine the HER-2/neu status by chromogenic in situ hybridization (CISH) on tissue specimens with a borderline (2+) immunohistochemistry (IHC) score in carcinoma breast by a descriptive, cross-sectional study in the Histopathology Department, Armed Forces Institute of Pathology (AFIP), Rawalpindi from Jun 2008 to Dec 2009. Tissue block specimens from 50 consecutive patients having HER-2/neu score of borderline (2+) on IHC assay were tested for HER-2/neu gene amplification by CISH. Mean and standard deviation were calculated for quantitative variables like age and HER-2/neu gene copy signal/clusters by using SPSS version 14. Frequencies and percentages were also calculated for qualitative variables like type of carcinoma and results of HER-2/neu by CISH (amplified/nonamplified). HER-2/neu gene amplification by CISH was found in 10 (20%) out of 50 patients with borderline (2+) IHC score. All CISH amplified cases belonged to invasive ductal carcinoma type. No significant correlati...

ABSTRACT A comprehensive investigation on the nonlinearities of transmission fiber affecting the ... more ABSTRACT A comprehensive investigation on the nonlinearities of transmission fiber affecting the synchronization of transmitters and receivers in eight channel dense wavelength division multiplexing (DWDM) chaotic communication system is presented. Very much like conventional DWDM systems, four wave mixing (FWM) and Raman effects are numerically found to be the two main limiting factors in DWDM chaos propagation also with latter being more dominant. The deterioration of chaos signal on eight wavelengths after propagation through fiber is measured by respective sync diagrams. A novel hybrid scheme based on polarization interleaving with unequal channel spacing is discovered here to offset the negative effects of both above limiting factors.

Optical Review, 2012

ABSTRACT

Nature genetics, 2014

Centrioles are essential for ciliogenesis. However, mutations in centriole biogenesis genes have ... more Centrioles are essential for ciliogenesis. However, mutations in centriole biogenesis genes have been reported in primary microcephaly and Seckel syndrome, disorders without the hallmark clinical features of ciliopathies. Here we identify mutations in the genes encoding PLK4 kinase, a master regulator of centriole duplication, and its substrate TUBGCP6 in individuals with microcephalic primordial dwarfism and additional congenital anomalies, including retinopathy, thereby extending the human phenotypic spectrum associated with centriole dysfunction. Furthermore, we establish that different levels of impaired PLK4 activity result in growth and cilia phenotypes, providing a mechanism by which microcephaly disorders can occur with or without ciliopathic features.

Optik - International Journal for Light and Electron Optics, 2011

Erbium doped fiber ring lasers (EDFRL) are being used to generate optical chaos for secure commun... more Erbium doped fiber ring lasers (EDFRL) are being used to generate optical chaos for secure communication by modulating the cavity loss/pump power or exploiting nonlinearities. The security level in chaotic communication depends on degree of chaos quantified by the Lyapunov exponent and its variability which is determined by the number of tuneable system parameters which were limited to five main parameters, i.e. modulation index, modulation frequency, pump power, cavity gain and loss. In this study we have increased the number of tuneable parameters using square, triangular and sum of harmonics waveforms. We have analysed the effect on degree of chaos of phase and duty cycle of square modulating signal with gradual addition of harmonics. For the given cavity parameters, the Lyapunov exponents can be increased by more than fifteen times using square wave modulating signal and a duty cycle of 60%. The electrical parameters identified make generation of new chaotic sequences more flexible in a field deployed EDFRL chaotic system.

Optik - International Journal for Light and Electron Optics, 2013

ABSTRACT It is discovered here that the chaos generated by loss modulation of EDFRL is varying wi... more ABSTRACT It is discovered here that the chaos generated by loss modulation of EDFRL is varying with the message amplitude, frequency and phase also in addition to the modulating signal and the loop parameters so much so that the output may even become non-chaotic at some points; a phenomenon not reported earlier in literature. This makes a detailed parametric trend analysis of message signal entering in EDFRL loop for given cavity parameters mandatory which is carried out in this article. The range of parameters is identified where EDFRL seizes to generate chaos for given modulating signal and loop parameters. It is found that once message frequency is equal to integer multiples or sub-multiples of the modulating frequency the output no more remains chaotic and becomes pulsed which compromises the security of the system. A solution to this problem is proposed and verified in this work by using a dual frequency loss modulating signal with the two frequencies being not an integer multiple of each other. The Lyapunov exponent (LE) spectrum is shown for the integral sub-multiples of both frequencies separately and chaos is verified to exist at all values.

Optik - International Journal for Light and Electron Optics, 2012

The level of security in a chaotic optical communication system depends upon the degree of chaos ... more The level of security in a chaotic optical communication system depends upon the degree of chaos which is measured by the value of positive Lyapunov Exponent (LE) spectrum. A comparative investigation to question the degree of chaos acquired in different schemes of Erbium Doped Fiber Ring Laser (EDFRL) and semiconductor laser is presented. The analysis based on the statistical average of various simulation results reveals that semiconductor laser with optoelectronic feedback produces highest degree of chaos as compared to EDFRL schemes. Furthermore, pulsed chaos is better than non-pulsed chaos in terms of unpredictability as dictated by the measure of LE.

Optical Engineering, 2010

The simulation and numerical analysis of erbium-doped fiber-ring lasers for generation and enhanc... more The simulation and numerical analysis of erbium-doped fiber-ring lasers for generation and enhancement of chaos is presented. The degree of chaos determines the level of security in chaotic optical communication systems. Various parameters such as pump power, ...

Neural Computing and Applications, 2010

Abstract In modern world of today where air traffic is continuously increasing and available spac... more Abstract In modern world of today where air traffic is continuously increasing and available space at the airports remains finite, there is a problem of safe docking of air-craft. The problem needs to be solved to ensure safe and smooth movement of aircraft, passengers and crew while ...

Indian Journal of Human Genetics, 2011

The present study was carried out to determine the prevalence of families having mental retardati... more The present study was carried out to determine the prevalence of families having mental retardation in Pakistani population. We enrolled seven mentally retarded (MR) families with two or more affected individuals. Family history was taken to minimize the chances of other abnormalities. Pedigrees were drawn using the Cyrillic software (version 2.1). The structure of pedigrees shows that all the marriages are consanguineous and the families have recessive mode of inheritance. All the families were studied by linkage analysis to mental retardation locus (MRT1)/gene PRSS12. Three STR markers (D4S191, D4S2392, and D4S3024) in vicinity of mental retardation (MR) locus (MRT1)/gene PRSS12 were amplified on all the sample of each family by PCR. The PCR products were then genotyped on non denaturing polyacrylamide gel electrophoresis (PAGE). The Haplotype were constructed to determine the pattern of inheritance and also to determine that a family was linked or unlinked to gene PRSS12. One out of the seven families was potentially linked to gene PRSS12, while the other six families remain unlinked.

Indian Journal of Human Genetics, 2012

Families with at least 2 or more individuals having hereditary hearing loss were enrolled from di... more Families with at least 2 or more individuals having hereditary hearing loss were enrolled from different areas of Khyber Pakhtoonkhwa, mainly from district Peshawar. Detailed history was taken from each family to minimize the presence of other abnormalities and environmental causes for deafness. Families were questioned about skin pigmentation, hair pigmentation, and problems relating to balance, vision, night blindness, thyroid, kidneys, heart, and infectious diseases like meningitis, antibiotic usage, injury, and typhoid. The pedigree structures were based upon interviews with multiple family members, and pedigrees of the enrolled families were drawn using Cyrillic program (version 2.1). All families showed recessive mode of inheritance. I studied 8 families of these 10. For linkage analyses, studies for DFNB1 locus, 3 STR markers (D13S175, D13S292, and D13S787) were genotyped using polyacrylamide gel electrophoresis (PAGE) and haplotypes were constructed to determined, linkage with DFNB1 locus. From a total of 8 families, a single family-10 showed linkage to DFNB1 locus.

IEICE Transactions on Information and Systems, 2006

Summary: The rapidly increasing bandwidth requirements of IP traffic mean that networks based on ... more Summary: The rapidly increasing bandwidth requirements of IP traffic mean that networks based on optical technologies in conjunction with IP routing technologies will provide the backbone of the next generation Internet. One of the major issues is how to construct an optical-...

IEICE Transactions on Communications, 2005

The bandwidth explosion ushered in by the popularity of the Internet has spurred the recent accel... more The bandwidth explosion ushered in by the popularity of the Internet has spurred the recent acceleration in the development and deployment of equipment supporting packet based broadband services. This coupled with the widespread deployment of WDM based Optical ...

IEICE Transactions on Communications, 2007

Summary: Implementing the fast-responding multi-layer service network (MLSN) functionality will a... more Summary: Implementing the fast-responding multi-layer service network (MLSN) functionality will allow the IP/MPLS service network logical topology and Optical Virtual Network topology to be reconfigured dynamically according to the traffic pattern on the network. Direct links ...

IEEE Journal on Selected Areas in Communications, 2000

In this paper, we consider the problem of multimedia synchronization in a Web environment. The wo... more In this paper, we consider the problem of multimedia synchronization in a Web environment. The workload generated by the multimedia server during a Web session exhibits variations that are quite different from the traffic fluctuation offered by a single media stream, e.g., a variable bit rate (VBR) video. We propose a set of parameters that can be used to characterize the workload generated by the multimedia server in a Web-type browsing environment. The workload characterization scheme is subsequently used in designing a server-based synchronization scheme. The problem of scheduling multimedia information to ensure media synchronization in a Web environment is identified as a multicriteria scheduling problem, which is NP-hard.

IEEE/ACM Transactions on Networking, 2000

In this paper we propose a scalable algorithm for connection admission control (CAC). The algorit... more In this paper we propose a scalable algorithm for connection admission control (CAC). The algorithm applies to a Multiprotocol Label Switching (MPLS) ATM switch with a FIFO buffer. The switch carries data from statistically independent variable bit rate (VBR) sources that asynchronously alternate between ON and OFF states with exponentially distributed periods. The sources may be heterogeneous both in terms of their statistical characteristics (peak cell rate, sustained cell rate, and burst size attributes) as well as their Quality of Service (QoS) requirements.