Papers by Mohd Shaban rizvi
2015 6th International Conference on Computing, Communication and Networking Technologies (ICCCNT), 2015
In today's world Built-In Test is the necessity for the designs of digital logic circuits. Ho... more In today's world Built-In Test is the necessity for the designs of digital logic circuits. However, providing solutions with such concept requires cumbersome and typical procedures of designs and because of this majority of the design go without incorporating the features of Built-In Test in the designs. The design procedures further aggravates if optimal design is needed. Hence, in view of this, an idea of a heuristic approach towards the designs of digital logic circuits in Built-In Test environment with optimal solution is proposed through this paper.
Physical Review Fluids, 2020
External forces, such as gravity, play significant role in the swimming properties of autonomous ... more External forces, such as gravity, play significant role in the swimming properties of autonomous biological microswimmers as well as artificial swimming robots. Here we have studied the influence of the external forces on the transport characteristics of the triangular bead-spring microswimmers. The microswimmer, formed by connecting three beads using three springs in an equilateral triangular arrangement, is capable of performing autonomous translational ("mover") and rotational ("rotor") motions. We show that for a mover triangle the application of a small external force results in the alignment of swimming direction with that of the external force, a phenomenon known as 'gravitaxis'. We demonstrate that this gravitactic nature of the active triangle is purely due to the hydrodynamic interaction among the beads. Under large external force, however, the gravitactic nature is lost. This transition from gravitactic to non-gravitactic motion of the microswimmer is characterized by a saddle node or pitchfork bifurcation where the strength of the critical external force scales linearly with the active force amplitude, f c e ∼ fa. However, for the rotor triangle only saddle node bifurcation is observed which results in a vanishing angular velocity as the strength of the external force is increased. The critical value of the external force for the rotor, however, scales as f c e ∼ f 2/3 a. These findings will provide insights into the the nature of biological swimming under gravity, especially the gravitactic microorganisms such as Chlamydomonas, as well as guiding the design of under water vehicles.
Physical Review E, 2018
We investigate analytically the transport characteristics of the triangular bead-spring microswim... more We investigate analytically the transport characteristics of the triangular bead-spring microswimmer and its dependence on the sizes of the beads as well as on the relative bead configurations. The microswimmer is composed of three beads connected by linear springs in an isosceles triangular arrangement. The bead at the apex of the isosceles triangle is taken to be of arbitrary size, while the other two beads are of equal and fixed size. This arrangement of the beads and springs undergoes autonomous propulsion thanks to the time-dependent active forces which act along the connecting springs. For small active force amplitudes we obtain an explicit expression for the average velocity of the microswimmer as a function of the shape of the isosceles triangle and the size of the central bead. This enables us to identify the conditions on the shape configuration and the relative bead sizes that yield the fastest motion. We find that the magnitude as well as the direction of motion critically depend on these parameters. In the limit where the central bead is large enough, the swimming direction becomes insensitive to the shape of the microswimmer. This limit is appropriate for modeling Chlamydomonas reinhardtii, an alga which moves with the help of its two flagella. Finally, we estimate the efficiency of the microswimmer and identify the model parameters that produce efficient swimming. These findings will help us understand the nature of biological swimming mechanisms and aid in the designing and tuning of rapid and efficient microswimmers capable of moving along arbitrary paths.
Physical Review Fluids, 2019
The transportation of the cargoes in biological cells is primarily driven by the motor proteins o... more The transportation of the cargoes in biological cells is primarily driven by the motor proteins on filamentous protein tracks. The stochastic nature of the motion of motor protein often leads to its spontaneous detachment from the track. Using the available experimental data, we demonstrate a tradeoff between the speed of the motor and its rate of spontaneous detachment from the track. Further, it is also shown that this speed-detachment relation follows a power law where its exponent dictates the nature of the motor protein processivity. We utilize this information to study the motion of motor protein on track using a random-walk model. We obtain the average distance travelled in fixed duration and average time required for covering a given distance by the motor protein. These analyses reveal non-monotonic dependence of the motor protein speed on its transport and, therefore, optimal motor speeds can be identified for the time and distance controlled conditions.
Physical review. E, 2018
The self-propelled microswimmers have recently attracted considerable attention as model systems ... more The self-propelled microswimmers have recently attracted considerable attention as model systems for biological cell migration as well as artificial micromachines. A simple and well-studied microswimmer model consists of three identical spherical beads joined by two springs in a linear fashion with active oscillatory forces being applied on the beads to generate self-propulsion. We have extended this linear microswimmer configuration to a triangular geometry where the three beads are connected by three identical springs in an equilateral triangular manner. The active forces acting on each spring can lead to autonomous steering motion; i.e., allowing the swimmer to move along arbitrary paths. We explore the microswimmer dynamics analytically and pinpoint its rich character depending on the nature of the active forces. The microswimmers can translate along a straight trajectory, rotate at a fixed location, as well as perform a simultaneous translation and rotation resulting in complex...
Evaluation of reliability is very important entity for the design and operation of systems. The s... more Evaluation of reliability is very important entity for the design and operation of systems. The safety, dependability, availability, Mean Time To Failure (MTTF), Mean Time Between Failure (MTBF), Mean Time To Repair (MTTR) and life cycle of the designed system can be judged from this reliability evaluation. For simple systems, the evaluation is straightforward. However, for complex systems, an algorithmic procedure is required. This paper presents an algorithmic procedure based on information matrices derived from graph theoretic approach. A simulation tool is developed that applies the algorithm to evaluate the reliability of complex systems.
Journal of the Mechanical Behavior of Biomedical Materials, 2014
The fibrous matrices are widely used as scaffolds for the regeneration of load-bearing tissues du... more The fibrous matrices are widely used as scaffolds for the regeneration of load-bearing tissues due to their structural and mechanical similarities with the fibrous components of the extracellular matrix. These scaffolds not only provide the appropriate microenvironment for the residing cells but also act as medium for the transmission of the mechanical stimuli, essential for the tissue regeneration, from macroscopic scale of the scaffolds to the microscopic scale of cells. The requirement of the mechanical loading for the tissue regeneration requires the fibrous scaffolds to be able to sustain the complex threedimensional mechanical loading conditions. In order to gain insight into the mechanical behavior of the fibrous matrices under large amount of elongation as well as shear, a statistical model has been formulated to study the macroscopic mechanical behavior of the electrospun fibrous matrix and the transmission of the mechanical stimuli from scaffolds to the cells via the constituting fibers. The study establishes the load-deformation relationships for the fibrous matrices for different structural parameters. It also quantifies the changes in the fiber arrangement and tension generated in the fibers with the deformation of the matrix. The model reveals that the tension generated in the fibers on matrix deformation is not homogeneous and hence the cells located in different regions of the fibrous scaffold might experience different mechanical stimuli. The mechanical response of fibrous matrices was also found to be dependent on the aspect ratio of the matrix. Therefore, the model establishes a structuremechanics interdependence of the fibrous matrices under large deformation, which can be utilized in identifying the appropriate structure and external mechanical loading conditions for the regeneration of load-bearing tissues.
Euroasian Journal of Hepato-Gastroenterology, 2012
Objective: To study the role of interleukin (IL)-12 and interferon (IFN)-γ in immunopathogenesis ... more Objective: To study the role of interleukin (IL)-12 and interferon (IFN)-γ in immunopathogenesis of hepatitis B virus (HBV) infection. Materials and methods: One hundred and fifty-seven patients with hepatitis B were screened by serological and molecular markers for HBV. Serum IL-12 and IFN-γ levels were estimated. Results: Among patients with acute HBV (AHB), the mean levels of IFN-γ (52.35 pg/ml) and IL-12 (57.12 pg/ml) were significantly higher in patients with nonnecrotizing inflammation (NNI) compared to those in patients with necrotizing inflammation (NI) (32.17 pg/ml and 42 pg/ml for IFN-γ and IL-12 respectively). In chronic HBV (CHB) with NI, IFN-γ levels were much higher than the same in AHB. However, no significant difference was found in IL-12 levels. IL-12 levels (25.76 pg/ml) were lower in NNI of CHB patients, while the levels of IL-12 were comparable between NI patients with AHB and CHB. Both IFN-γ and IL-12 were higher in hepatitis B e-antigen (HBeAg)-negative patients than HBeAg-positive patients.. Conclusion: Both IFN-γ and IL-12 appear to play a role in AHB and HBeAg negativity, however, further study will be required to get their precise role.
Journal of Theoretical Biology, 2012
During cytokinesis physical separation of cytoplasm into two daughter cells occurs. c Membrane ad... more During cytokinesis physical separation of cytoplasm into two daughter cells occurs. c Membrane addition and acto-myosin ring contraction are necessary for completion of cytokinesis. c Mechanisms of membrane addition and their consequences during cytokinesis are discussed. c The relationships between membrane addition and the membrane tension and ring force are obtained.
Acta Biomaterialia, 2012
Electrospun micro/nanofibrous biomaterials are widely used as extracellular matrix substitutes in... more Electrospun micro/nanofibrous biomaterials are widely used as extracellular matrix substitutes in tissue engineering applications because of their structural and mechanical properties. To explore the influence of microstructure on the mechanical behavior of fibrous material, a mathematical model of the fiber system was developed. The model describes the microstructural properties of a fibrous matrix using a probability density function, and enables study of their mechanical properties. The results from the mathematical model were validated by qualitative comparison with the experimental results of mechanical testing of polystyrene electrospun nanofibrous materials. The analyses show a trend of three-phase load-displacement behavior. Initially, as an increasing number of fibers are recruited for load bearing, the load-displacement curve has a 'J'-shaped toe region, which is followed by a nearly linear load-displacement curve, in which the number of load-bearing fibers remains nearly steady. Finally, there is a phase when the load-displacement curve descends, indicating failure of the material. The increase in flexibility of the fibrous material makes it stronger, but the randomness of fiber orientation makes the fibrous structure more flexible at the cost of lower strength. The measured mechanical properties of a fibrous matrix were also observed to be dependent on sample size. Therefore, the analyses establish a clear link between the structure and strength of fibrous materials for optimized design and fabrication of fibrous biomaterials with targeted use in tissue engineering, regenerative medicine and drug delivery. The model also establishes a need for standardization of experimental protocols for mechanical characterization of fibrous materials for consistency.
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Papers by Mohd Shaban rizvi