Introduction: Primary osteoarthritis knee has been associated with multiple variables reported to... more Introduction: Primary osteoarthritis knee has been associated with multiple variables reported to affect the disease process in different ways. Age, Sex and BMI are among the few which have been characterized to be etiologically related to the osteoarthritis knee. Various scoring systems have been implicated in depicting the severity such as VAS, WOMAC and Lequesne scoring system. Their role has been studied in different studies.Material and methods: Study was conducted in Deptt. of Orthopedic Surgery, CSMMU, Lucknow between 2006 and 2008. Patients of primary osteoarthritis knee were included in the study. All the variables were analyzed and severity was characterized as per VAS, WOMAC and Lequesne scoring system. Xray was done and radiological staging was done as per Kellgren Lawrence scoring system.Observation and Results: 120 patients were enrolled between 2006 and 2008 out of which 46 (38.3%) were males and rest 61.7% were females. Maximum number of patients were in BMI range of >25-71 cases(59.17%). Mean VAS score was 6.8+/-.78 with maximum number presenting in 6 rating. Mean WOMAC pain score was 9.2+/-.08 and mean Lequesne pain score was 2.48+/-.06. Maximum number of cases presented with a VAS score of >5-118 cases(98.33%). 67.5% of cases presented in KL grade 3 followed by 25.83% in KL grade 2 and rest in grade 4. The 'p' values of VAS score, WOMAC score, Lequesne score were found to be 0.6127, 0.0477, 0.6943 respectively. Conclusion: Osteoarthritis Knee is associated significantly with age. Maximum number of patients present in KL grade 3 of the disease and WOMAC scoring system is the best predictor of severity of the disease.
We present theoretical and experimental analysis of an interferometric measurement of the in-situ... more We present theoretical and experimental analysis of an interferometric measurement of the in-situ phase drop across and current flow through a rotating barrier in a toroidal Bose-Einstein condensate (BEC). This experiment is the atomic analog of the rf-superconducting quantum interference device (SQUID). The phase drop is extracted from a spiral-shaped density profile created by the spatial interference of the expanding toroidal BEC and a reference BEC after release from all trapping potentials. We characterize the interferometer when it contains a single particle, which is initially in a coherent superposition of a torus and reference state, as well as when it contains a manybody state in the mean-field approximation. The single-particle picture is sufficient to explain the origin of the spirals, to relate the phase-drop across the barrier to the geometry of a spiral, and to bound the expansion times for which the in-situ phase can be accurately determined. Mean-field estimates and numerical simulations show that the inter-atomic interactions shorten the expansion time scales compared to the single-particle case. Finally, we compare the mean-field simulations with our experimental data and confirm that the interferometer indeed accurately measures the in-situ phase drop.
IEEE International Conference on Computational Photography (ICCP), 2013
Given a stack of registered images acquired using a range of focus settings (focal stack images),... more Given a stack of registered images acquired using a range of focus settings (focal stack images), we propose a new focus measure to identify the most focused image. Although, most of the paper is concerned with the new focus measure, for evaluation purposes, we will present it in the context of an application to generating omnifocus images. An omnifocus image is the composite image in which each pixel is selected form the frame in the stack in which it appears to be in best focus. Conventional focus measures usually maximize some measure of image gradient in a window. They tend to fail when one of the edges of the window lies near the boundary of an intensity edge, or the pixel is near other complex edge patterns. This leads to the misidentification of the focused frame and formation of artifacts in omnifocused image. Our proposed measure does not attempt to identify the focused frame by calculating the degree of defocus, like the gradient based methods. Rather, it hypothesizes that a specific frame is in focus and then validates or rejects this hypothesis by recreating the defocused frames in the vicinity, and comparing them with the observed defocused frames. This forward generative process leads to correct focus frame selection in regions where typical measures fail.This is because the conventional measures try to identify the focused frame from its distorted version which is the result of a complex convolution process. This involves a backward estimation for a many-to-one transformation. On the other hand, the generation of defocused frames from a hypothesized focused frame is more accurate since it involves applying an operator in the forward direction. We analytically show that under ideal imaging conditions, the proposed focus measure is unimodal in nature. This makes the search for the best focused image unambiguous. We evaluate our focus measure by generating omnifocus images from real focal stack images, and show that it performs better than all the existing focus measures.
We describe novel methods of computing sharp shadows and depth estimates of objects immersed in h... more We describe novel methods of computing sharp shadows and depth estimates of objects immersed in highly scattering media using multi-scale structured transmissive illumination, such as modified Hadamard tiles.
Indian journal of maternal and child health : official publication of Indian Maternal and Child Health Association
The incidence of neonatal respiratory distress (RD) ranges from 2.2% to 7.6% in developed countri... more The incidence of neonatal respiratory distress (RD) ranges from 2.2% to 7.6% in developed countries and from 0.7% to 8.3% in India. A study conducted in Pondicherry, India, found the incidence of neonatal RD to be 6.7%. The leading cause of neonatal RD is transient tachypnea (50-60% of RD cases) followed by infections (pneumonia, sepsis, or meningitis), meconium aspiration, and hyaline membrane disease (HMD). Significant predictors of neonatal RD include prematurity, malpresentation, abnormal delivery, premature rupture of membranes, fetal distress, multiple pregnancy, male sex, and low apgar score at birth. The case fatality rate for RD in India is 30-40%. In the Pondicherry study, it was 19%. Case fatality is highest for newborns with HMD (20-40% in developed countries and 50-75% in India). It ranges from 14.3% to 30.37% for meconium aspiration-related RD deaths. RD incidence and subsequent infant mortality can be reduced by improved prenatal care, early detection and referral of high risk pregnancies, closer links between referral hospitals and health centers, close monitoring of labor to detect fetal distress, and early intervention when indicated. In cases of RD, adequate and immediate resuscitation, oxygen supplementation, maintenance of optimal temperature, and time referral if RD lasts beyond two hours will reduce mortality. In cases of HMD and meconium aspiration, adequate ventilatory support and surfactant therapy will reduce mortality.
2009 Workshop on Applications of Computer Vision (WACV), 2009
This paper is about a vision-based system that automatically monitors intermodal freight trains f... more This paper is about a vision-based system that automatically monitors intermodal freight trains for the quality of how the loads (containers) are placed along the train. An accurate and robust algorithm to segment the foreground of containers in videos of the moving train is indispensable for this purpose. Given a video of a moving train consisting of containers of different types, this paper presents a method exploiting the information in both frequency and spatial domains to segment these containers. This method can accurately segment all types of containers under a variety of background conditions, e.g illumination variations and moving clouds, in the train videos shot by a fixed camera. The accuracy and robustness of the proposed method are substantiated through a large number of experiments on real data of train videos.
2013 IEEE International Conference on Image Processing, 2013
We propose a new motion-based background removal technique which along with panoramic mosaicing f... more We propose a new motion-based background removal technique which along with panoramic mosaicing forms the core of a vision system we have developed for analyzing the loading efficiency of intermodal freight trains. This analysis is critical for estimating the aerodynamic drag caused by air gaps present between loads in freight trains. The novelty of our background removal technique lies in using conventional motion estimates to design a cost function which can handle challenging texture-less background regions, e.g. clear blue sky. Supplemented with domain knowledge, we have built a system which has outperformed some recent background removal methods applied to our problem. We also build an orthographic mosaic of the freight train allowing identification of load types and gap lengths between them. The complete system has been installed near Sibley, Missouri, US and processes about 20-30 (5-10 GB/train video data depending on train length) trains per day with high accuracy.
Increased use of composites in aerospace and defense application induces the search for heat resi... more Increased use of composites in aerospace and defense application induces the search for heat resistant material. In present study silica reinforced epoxy functionally graded material using quartz fabric is prepared with different thickness. The gradation in silica : epoxy matrix is maintained with one side pure epoxy to opposite side pure silica. Thermal and mechanical behaviour of the composites were studied. It was found that the temperature gradient of 350°C to 950°C could be maintained for 2 to 5 min if the thickness of insulating silica layer is increased from 0.5 mm to 16 mm. Mechanical properties such as flexural modulus and strength of FGM composites were also evaluated. Strength and modulus decreased with increase of insulating layer.
Computer simulations have become a widely used and powerful tool to study the behaviour of many-p... more Computer simulations have become a widely used and powerful tool to study the behaviour of many-particle and many-interaction systems and processes such as nucleic acid dynamics, drug-DNA interactions, enzymatic processes, membrane, antibiotics. The increased reliability of computational techniques has made possible to plane a bottom-up approach in drug design, i.e. designing molecules with improved properties starting from the knowledge of the molecular mechanisms. However, the in silico techniques have to face the fact that the number of degrees of freedom involved in biological systems is very large while the time scale of several biological processes is not accessible to standard simulations. Algorithms and methods have been developed and are still under construction to bridge these gaps. Here we review the activities of our group focussed on the timescale bottleneck and, in particular, on the use of the metadynamics scheme that allows the investigation of rare events in reasonable computer time without reducing the accuracy of the calculation. In particular, we have devoted particular attention to the characterization at microscopic level of translocation of antibiotics through membrane pores, aiming at the identification of structural and dynamical features helpful for a rational drug design.
2008 Fourth International Conference on Wireless Communication and Sensor Networks, 2008
Abstract Space diversity technique is an attractive solution for improving quality in wireless li... more Abstract Space diversity technique is an attractive solution for improving quality in wireless links. The objectives of this paper are to investigate the impact of bit error rate on the number of users and the SNR for space time block coded MIMO Rayleigh fading channels. ...
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 2007
Intermodal (IM) trains are typically the fastest freight trains operated in North America. The ae... more Intermodal (IM) trains are typically the fastest freight trains operated in North America. The aerodynamic characteristics of many of these trains are often relatively poor resulting in high fuel consumption. However, considerable variation in fuel efficiency is possible depending on how the loads are placed on railcars in the train. Consequently, substantial potential fuel savings are possible if more attention is paid to the loading configuration of trains. A wayside machine vision (MV) system was developed to automatically scan passing IM trains and assess their aerodynamic efficiency. MV algorithms are used to analyse these images, detect and measure gaps between loads. In order to make use of the data, a scoring system was developed based on two attributes - the aerodynamic coefficient and slot efficiency. The aerodynamic coefficient is calculated using the Aerodynamic Subroutine of the train energy model. Slot efficiency represents the difference between the actual and ideal l...
In the present paper, we report the compensation effect on photoconductivity of thin films of Se7... more In the present paper, we report the compensation effect on photoconductivity of thin films of Se70Te30−xCdx (x = 2, 4, 6) alloys for high field conduction. Steady state photoconductivity measurements have been made in thin films for different electric fields. The photoconduction was found to be ohmic at low fields and Poole-Frenkel type at high fields. Meyer-Neldel rule (MN rule) for the pre-exponential factor (σ ph)0 and activation energy (ΔE ph) of photoconduction in thin films of Se70Te30−xCdx is observed in the present study.
In the present article, a relation is being developed to study the pressure dependence of sound v... more In the present article, a relation is being developed to study the pressure dependence of sound velocity of water at different temperature. The computed results are found out to be in excellent agreement with the experimental data. However, it is shown that the sound velocity of water exhibits anomalous behaviour in the temperature range of 273.98–289.01 K.
By using high-magnetic fields (up to 60 T), we observe compelling evidence of the integer quantum... more By using high-magnetic fields (up to 60 T), we observe compelling evidence of the integer quantum Hall effect in trilayer graphene. The magnetotransport fingerprints are similar to those of the graphene monolayer, except for the absence of a plateau at a filling factor of ¼ 2. At a very low filling factor, the Hall resistance vanishes due to the presence of mixed electron and hole carriers induced by disorder. The measured Hall resistivity plateaus are well reproduced theoretically, using a self-consistent Hartree calculations of the Landau levels and assuming an ABC stacking order of the three layers.
We report the generation of complex toroidal nanoscale vortices in nanochannel flows, through the... more We report the generation of complex toroidal nanoscale vortices in nanochannel flows, through the employment of patterned surface patches with contrasting wettability characteristics. Through extensive molecular-dynamics simulations, we further delineate that complicated interactions between the wettability gradient-driven vortex structures and surface roughness-influenced flow features may give rise to interesting patterns in the flow field. We also establish the orientation specificities of these nanoscale vortices, and demonstrate that the surface roughness effects may potentially act to alter the flow rotationalities realized out of modulated surface patterning effects to a considerable extent, which may have interesting consequences toward designing nanoscale mixing elements.
Working on a true molecular level is essential for advances in the field of molecular electronics... more Working on a true molecular level is essential for advances in the field of molecular electronics. Techniques have to be perfected and new approaches have to be developed in order to characterize the properties of a single molecule. In this work we report temperature-dependent transport studies of a single octanethiol molecule trapped between the apex of a scanning tunneling microscope tip and a substrate. At each temperature the molecule is brought into contact by decreasing the gap between tip and substrate in a controlled way. At a positive sample bias the molecule jumps into contact upon approaching the substrate by 0.16 ± 0.01 nm with respect to a fixed reference point defined by a sample bias of +1.5 V and a tunneling current of 0.5 nA. The conductance of octanethiol is temperature independent, demonstrating that either tunneling or ballistic transport is the main transport mechanism.
We study the ground-state properties of two-dimensional quantum-dot helium in zero external magne... more We study the ground-state properties of two-dimensional quantum-dot helium in zero external magnetic field (a system of two interacting electrons in a two-dimensional parabolic confinement potential) by using perturbation and variational theory. We introduce a family of ground-state trial wave functions with one, two, and three variational parameters. We compare the perturbation and variational energies with numerically exact diagonalization results and earlier unrestricted Hartree-Fock studies. We find that the three-parameter variational wave function is an excellent representation of the true ground state and argue on how to generalize such a wave function for larger quantum dots with arbitrary numbers of electrons.
We report the first unambiguous observation of a fractional quantum Hall state in the Landau leve... more We report the first unambiguous observation of a fractional quantum Hall state in the Landau level of a two-dimensional hole sample at the filling factor ν = 8/3. We identified this state by a quantized Hall resistance and an activated temperature dependence of the longitudinal resistance and found an energy gap of 40 mK. To our surprize the particle-hole conjugate state at filling factor ν = 7/3 in our sample does not develop down to 6.9 mK. This observation is contrary to that in electron samples in which the 7/3 state is typically more stable than the 8/3 state. We present evidence that the asymmetry between the 7/3 and 8/3 states in our hole sample is due to Landau level mixing.
ABSTRACT Soft lithography in 2-dimensional (2-D) was developed for polymer MEMS applications abou... more ABSTRACT Soft lithography in 2-dimensional (2-D) was developed for polymer MEMS applications about two decades back. The technique was highly useful for replication of microstructure molds using a soft polymeric material called PDMS (polydimethylsiloxane). From its inception the process has been widely applied to microfluidics, biochips, hybrid biomedical microdevices etc. However, it was limited to only surface microstructures and 3-Dimensional (3-D) soft lithography although performed by some research groups involved some very precise and expensive techniques like stereolithography etc. The exploration of soft lithography in three dimensions by using a replication technique with copper wires with micron size diameters was performed by our group relatively recently (Singh et al. in International conference on MEMS, IIT Madras, Chennai, 2009). In this work we have used the 3-D replication and molding technique to develop concentric solenoid patterns around micro-channels in the bulk of PDMS. The solenoidal paths of various pitches ranging from 0.4 to 1.2 mm have been replicated in PDMS using an innovatively designed fixture. The solenoids have been structurally characterized using an inverted fluorescence microscope (Nikon 80i) for dimensional parameters like pitch, length etc. Further, the solenoidal path designs have been simulated, optimized and fabricated around a central channel of 80 μ diameter and we have observed the repeatability of this fabrication process multiple times. The purpose of this architecture is to initiate valving action wherein fluid movement in the central channel can be restricted by filling the surrounding solenoidal track with compressed air at high pressure so that it can squeeze the centrally located micro-channel carrying the liquid. This valving structure may find a lot of applications in lab on chip devices, PCR biochips, biomedical micro-devices etc.
This study aimed to determine the skeletal effects of total ethanolic extract (TEE) and its butan... more This study aimed to determine the skeletal effects of total ethanolic extract (TEE) and its butanolic fraction (BF) from the stem-bark of Ulmus wallichiana, which is rich in C-glycosylated flavonoids, in growing rats (for peak bone [PB] achievement) and in ovariectomized (OVx) rats (for menopausal bone loss). TEE (750 mg kg(-1) d(-1)) and BF (50 mg kg(-1) d(-1)) were given orally for 10 weeks to weaning female Sprague-Dawley rats and for 12 weeks to adult OVx rats of the same strain, respectively. In studies with OVx rats, sham operated + vehicle, OVx + 17beta-estradiol, and OVx + vehicle groups served as various controls. Bone mineral density (BMD), biomechanical strength, bone histology, formations of osteoprogenitor cells, osteoid formation, and bone turnover/resorption markers were studied. Bioactive marker compounds in TEE and BF were analyzed by high-performance liquid chromatography. One-way analysis of variance was used to test significance of effects. In growing rats, both TEE and BF increased BMD, bone strength, and bone formation rate, suggesting higher PB achievement. OVx rats treated with either TEE or BF exhibited increased BMD at various anatomical positions and improved bone strength and trabecular architecture compared with the OVx + vehicle group. Serum osteocalcin and urinary type 1 collagen degradation product levels in OVx rats treated with either TEE or BF were significantly lower than those of the OVx + vehicle group. Neither TEE nor BF exhibited uterine estrogenicity. Analysis of marker compounds revealed significant enrichment of two bioactive markers in BF over TEE. Derived from U wallichiana, BF at much a lower dose than TEE was effective in PB achievement and prevention of OVx-induced bone loss.
Introduction: Primary osteoarthritis knee has been associated with multiple variables reported to... more Introduction: Primary osteoarthritis knee has been associated with multiple variables reported to affect the disease process in different ways. Age, Sex and BMI are among the few which have been characterized to be etiologically related to the osteoarthritis knee. Various scoring systems have been implicated in depicting the severity such as VAS, WOMAC and Lequesne scoring system. Their role has been studied in different studies.Material and methods: Study was conducted in Deptt. of Orthopedic Surgery, CSMMU, Lucknow between 2006 and 2008. Patients of primary osteoarthritis knee were included in the study. All the variables were analyzed and severity was characterized as per VAS, WOMAC and Lequesne scoring system. Xray was done and radiological staging was done as per Kellgren Lawrence scoring system.Observation and Results: 120 patients were enrolled between 2006 and 2008 out of which 46 (38.3%) were males and rest 61.7% were females. Maximum number of patients were in BMI range of >25-71 cases(59.17%). Mean VAS score was 6.8+/-.78 with maximum number presenting in 6 rating. Mean WOMAC pain score was 9.2+/-.08 and mean Lequesne pain score was 2.48+/-.06. Maximum number of cases presented with a VAS score of >5-118 cases(98.33%). 67.5% of cases presented in KL grade 3 followed by 25.83% in KL grade 2 and rest in grade 4. The 'p' values of VAS score, WOMAC score, Lequesne score were found to be 0.6127, 0.0477, 0.6943 respectively. Conclusion: Osteoarthritis Knee is associated significantly with age. Maximum number of patients present in KL grade 3 of the disease and WOMAC scoring system is the best predictor of severity of the disease.
We present theoretical and experimental analysis of an interferometric measurement of the in-situ... more We present theoretical and experimental analysis of an interferometric measurement of the in-situ phase drop across and current flow through a rotating barrier in a toroidal Bose-Einstein condensate (BEC). This experiment is the atomic analog of the rf-superconducting quantum interference device (SQUID). The phase drop is extracted from a spiral-shaped density profile created by the spatial interference of the expanding toroidal BEC and a reference BEC after release from all trapping potentials. We characterize the interferometer when it contains a single particle, which is initially in a coherent superposition of a torus and reference state, as well as when it contains a manybody state in the mean-field approximation. The single-particle picture is sufficient to explain the origin of the spirals, to relate the phase-drop across the barrier to the geometry of a spiral, and to bound the expansion times for which the in-situ phase can be accurately determined. Mean-field estimates and numerical simulations show that the inter-atomic interactions shorten the expansion time scales compared to the single-particle case. Finally, we compare the mean-field simulations with our experimental data and confirm that the interferometer indeed accurately measures the in-situ phase drop.
IEEE International Conference on Computational Photography (ICCP), 2013
Given a stack of registered images acquired using a range of focus settings (focal stack images),... more Given a stack of registered images acquired using a range of focus settings (focal stack images), we propose a new focus measure to identify the most focused image. Although, most of the paper is concerned with the new focus measure, for evaluation purposes, we will present it in the context of an application to generating omnifocus images. An omnifocus image is the composite image in which each pixel is selected form the frame in the stack in which it appears to be in best focus. Conventional focus measures usually maximize some measure of image gradient in a window. They tend to fail when one of the edges of the window lies near the boundary of an intensity edge, or the pixel is near other complex edge patterns. This leads to the misidentification of the focused frame and formation of artifacts in omnifocused image. Our proposed measure does not attempt to identify the focused frame by calculating the degree of defocus, like the gradient based methods. Rather, it hypothesizes that a specific frame is in focus and then validates or rejects this hypothesis by recreating the defocused frames in the vicinity, and comparing them with the observed defocused frames. This forward generative process leads to correct focus frame selection in regions where typical measures fail.This is because the conventional measures try to identify the focused frame from its distorted version which is the result of a complex convolution process. This involves a backward estimation for a many-to-one transformation. On the other hand, the generation of defocused frames from a hypothesized focused frame is more accurate since it involves applying an operator in the forward direction. We analytically show that under ideal imaging conditions, the proposed focus measure is unimodal in nature. This makes the search for the best focused image unambiguous. We evaluate our focus measure by generating omnifocus images from real focal stack images, and show that it performs better than all the existing focus measures.
We describe novel methods of computing sharp shadows and depth estimates of objects immersed in h... more We describe novel methods of computing sharp shadows and depth estimates of objects immersed in highly scattering media using multi-scale structured transmissive illumination, such as modified Hadamard tiles.
Indian journal of maternal and child health : official publication of Indian Maternal and Child Health Association
The incidence of neonatal respiratory distress (RD) ranges from 2.2% to 7.6% in developed countri... more The incidence of neonatal respiratory distress (RD) ranges from 2.2% to 7.6% in developed countries and from 0.7% to 8.3% in India. A study conducted in Pondicherry, India, found the incidence of neonatal RD to be 6.7%. The leading cause of neonatal RD is transient tachypnea (50-60% of RD cases) followed by infections (pneumonia, sepsis, or meningitis), meconium aspiration, and hyaline membrane disease (HMD). Significant predictors of neonatal RD include prematurity, malpresentation, abnormal delivery, premature rupture of membranes, fetal distress, multiple pregnancy, male sex, and low apgar score at birth. The case fatality rate for RD in India is 30-40%. In the Pondicherry study, it was 19%. Case fatality is highest for newborns with HMD (20-40% in developed countries and 50-75% in India). It ranges from 14.3% to 30.37% for meconium aspiration-related RD deaths. RD incidence and subsequent infant mortality can be reduced by improved prenatal care, early detection and referral of high risk pregnancies, closer links between referral hospitals and health centers, close monitoring of labor to detect fetal distress, and early intervention when indicated. In cases of RD, adequate and immediate resuscitation, oxygen supplementation, maintenance of optimal temperature, and time referral if RD lasts beyond two hours will reduce mortality. In cases of HMD and meconium aspiration, adequate ventilatory support and surfactant therapy will reduce mortality.
2009 Workshop on Applications of Computer Vision (WACV), 2009
This paper is about a vision-based system that automatically monitors intermodal freight trains f... more This paper is about a vision-based system that automatically monitors intermodal freight trains for the quality of how the loads (containers) are placed along the train. An accurate and robust algorithm to segment the foreground of containers in videos of the moving train is indispensable for this purpose. Given a video of a moving train consisting of containers of different types, this paper presents a method exploiting the information in both frequency and spatial domains to segment these containers. This method can accurately segment all types of containers under a variety of background conditions, e.g illumination variations and moving clouds, in the train videos shot by a fixed camera. The accuracy and robustness of the proposed method are substantiated through a large number of experiments on real data of train videos.
2013 IEEE International Conference on Image Processing, 2013
We propose a new motion-based background removal technique which along with panoramic mosaicing f... more We propose a new motion-based background removal technique which along with panoramic mosaicing forms the core of a vision system we have developed for analyzing the loading efficiency of intermodal freight trains. This analysis is critical for estimating the aerodynamic drag caused by air gaps present between loads in freight trains. The novelty of our background removal technique lies in using conventional motion estimates to design a cost function which can handle challenging texture-less background regions, e.g. clear blue sky. Supplemented with domain knowledge, we have built a system which has outperformed some recent background removal methods applied to our problem. We also build an orthographic mosaic of the freight train allowing identification of load types and gap lengths between them. The complete system has been installed near Sibley, Missouri, US and processes about 20-30 (5-10 GB/train video data depending on train length) trains per day with high accuracy.
Increased use of composites in aerospace and defense application induces the search for heat resi... more Increased use of composites in aerospace and defense application induces the search for heat resistant material. In present study silica reinforced epoxy functionally graded material using quartz fabric is prepared with different thickness. The gradation in silica : epoxy matrix is maintained with one side pure epoxy to opposite side pure silica. Thermal and mechanical behaviour of the composites were studied. It was found that the temperature gradient of 350°C to 950°C could be maintained for 2 to 5 min if the thickness of insulating silica layer is increased from 0.5 mm to 16 mm. Mechanical properties such as flexural modulus and strength of FGM composites were also evaluated. Strength and modulus decreased with increase of insulating layer.
Computer simulations have become a widely used and powerful tool to study the behaviour of many-p... more Computer simulations have become a widely used and powerful tool to study the behaviour of many-particle and many-interaction systems and processes such as nucleic acid dynamics, drug-DNA interactions, enzymatic processes, membrane, antibiotics. The increased reliability of computational techniques has made possible to plane a bottom-up approach in drug design, i.e. designing molecules with improved properties starting from the knowledge of the molecular mechanisms. However, the in silico techniques have to face the fact that the number of degrees of freedom involved in biological systems is very large while the time scale of several biological processes is not accessible to standard simulations. Algorithms and methods have been developed and are still under construction to bridge these gaps. Here we review the activities of our group focussed on the timescale bottleneck and, in particular, on the use of the metadynamics scheme that allows the investigation of rare events in reasonable computer time without reducing the accuracy of the calculation. In particular, we have devoted particular attention to the characterization at microscopic level of translocation of antibiotics through membrane pores, aiming at the identification of structural and dynamical features helpful for a rational drug design.
2008 Fourth International Conference on Wireless Communication and Sensor Networks, 2008
Abstract Space diversity technique is an attractive solution for improving quality in wireless li... more Abstract Space diversity technique is an attractive solution for improving quality in wireless links. The objectives of this paper are to investigate the impact of bit error rate on the number of users and the SNR for space time block coded MIMO Rayleigh fading channels. ...
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 2007
Intermodal (IM) trains are typically the fastest freight trains operated in North America. The ae... more Intermodal (IM) trains are typically the fastest freight trains operated in North America. The aerodynamic characteristics of many of these trains are often relatively poor resulting in high fuel consumption. However, considerable variation in fuel efficiency is possible depending on how the loads are placed on railcars in the train. Consequently, substantial potential fuel savings are possible if more attention is paid to the loading configuration of trains. A wayside machine vision (MV) system was developed to automatically scan passing IM trains and assess their aerodynamic efficiency. MV algorithms are used to analyse these images, detect and measure gaps between loads. In order to make use of the data, a scoring system was developed based on two attributes - the aerodynamic coefficient and slot efficiency. The aerodynamic coefficient is calculated using the Aerodynamic Subroutine of the train energy model. Slot efficiency represents the difference between the actual and ideal l...
In the present paper, we report the compensation effect on photoconductivity of thin films of Se7... more In the present paper, we report the compensation effect on photoconductivity of thin films of Se70Te30−xCdx (x = 2, 4, 6) alloys for high field conduction. Steady state photoconductivity measurements have been made in thin films for different electric fields. The photoconduction was found to be ohmic at low fields and Poole-Frenkel type at high fields. Meyer-Neldel rule (MN rule) for the pre-exponential factor (σ ph)0 and activation energy (ΔE ph) of photoconduction in thin films of Se70Te30−xCdx is observed in the present study.
In the present article, a relation is being developed to study the pressure dependence of sound v... more In the present article, a relation is being developed to study the pressure dependence of sound velocity of water at different temperature. The computed results are found out to be in excellent agreement with the experimental data. However, it is shown that the sound velocity of water exhibits anomalous behaviour in the temperature range of 273.98–289.01 K.
By using high-magnetic fields (up to 60 T), we observe compelling evidence of the integer quantum... more By using high-magnetic fields (up to 60 T), we observe compelling evidence of the integer quantum Hall effect in trilayer graphene. The magnetotransport fingerprints are similar to those of the graphene monolayer, except for the absence of a plateau at a filling factor of ¼ 2. At a very low filling factor, the Hall resistance vanishes due to the presence of mixed electron and hole carriers induced by disorder. The measured Hall resistivity plateaus are well reproduced theoretically, using a self-consistent Hartree calculations of the Landau levels and assuming an ABC stacking order of the three layers.
We report the generation of complex toroidal nanoscale vortices in nanochannel flows, through the... more We report the generation of complex toroidal nanoscale vortices in nanochannel flows, through the employment of patterned surface patches with contrasting wettability characteristics. Through extensive molecular-dynamics simulations, we further delineate that complicated interactions between the wettability gradient-driven vortex structures and surface roughness-influenced flow features may give rise to interesting patterns in the flow field. We also establish the orientation specificities of these nanoscale vortices, and demonstrate that the surface roughness effects may potentially act to alter the flow rotationalities realized out of modulated surface patterning effects to a considerable extent, which may have interesting consequences toward designing nanoscale mixing elements.
Working on a true molecular level is essential for advances in the field of molecular electronics... more Working on a true molecular level is essential for advances in the field of molecular electronics. Techniques have to be perfected and new approaches have to be developed in order to characterize the properties of a single molecule. In this work we report temperature-dependent transport studies of a single octanethiol molecule trapped between the apex of a scanning tunneling microscope tip and a substrate. At each temperature the molecule is brought into contact by decreasing the gap between tip and substrate in a controlled way. At a positive sample bias the molecule jumps into contact upon approaching the substrate by 0.16 ± 0.01 nm with respect to a fixed reference point defined by a sample bias of +1.5 V and a tunneling current of 0.5 nA. The conductance of octanethiol is temperature independent, demonstrating that either tunneling or ballistic transport is the main transport mechanism.
We study the ground-state properties of two-dimensional quantum-dot helium in zero external magne... more We study the ground-state properties of two-dimensional quantum-dot helium in zero external magnetic field (a system of two interacting electrons in a two-dimensional parabolic confinement potential) by using perturbation and variational theory. We introduce a family of ground-state trial wave functions with one, two, and three variational parameters. We compare the perturbation and variational energies with numerically exact diagonalization results and earlier unrestricted Hartree-Fock studies. We find that the three-parameter variational wave function is an excellent representation of the true ground state and argue on how to generalize such a wave function for larger quantum dots with arbitrary numbers of electrons.
We report the first unambiguous observation of a fractional quantum Hall state in the Landau leve... more We report the first unambiguous observation of a fractional quantum Hall state in the Landau level of a two-dimensional hole sample at the filling factor ν = 8/3. We identified this state by a quantized Hall resistance and an activated temperature dependence of the longitudinal resistance and found an energy gap of 40 mK. To our surprize the particle-hole conjugate state at filling factor ν = 7/3 in our sample does not develop down to 6.9 mK. This observation is contrary to that in electron samples in which the 7/3 state is typically more stable than the 8/3 state. We present evidence that the asymmetry between the 7/3 and 8/3 states in our hole sample is due to Landau level mixing.
ABSTRACT Soft lithography in 2-dimensional (2-D) was developed for polymer MEMS applications abou... more ABSTRACT Soft lithography in 2-dimensional (2-D) was developed for polymer MEMS applications about two decades back. The technique was highly useful for replication of microstructure molds using a soft polymeric material called PDMS (polydimethylsiloxane). From its inception the process has been widely applied to microfluidics, biochips, hybrid biomedical microdevices etc. However, it was limited to only surface microstructures and 3-Dimensional (3-D) soft lithography although performed by some research groups involved some very precise and expensive techniques like stereolithography etc. The exploration of soft lithography in three dimensions by using a replication technique with copper wires with micron size diameters was performed by our group relatively recently (Singh et al. in International conference on MEMS, IIT Madras, Chennai, 2009). In this work we have used the 3-D replication and molding technique to develop concentric solenoid patterns around micro-channels in the bulk of PDMS. The solenoidal paths of various pitches ranging from 0.4 to 1.2 mm have been replicated in PDMS using an innovatively designed fixture. The solenoids have been structurally characterized using an inverted fluorescence microscope (Nikon 80i) for dimensional parameters like pitch, length etc. Further, the solenoidal path designs have been simulated, optimized and fabricated around a central channel of 80 μ diameter and we have observed the repeatability of this fabrication process multiple times. The purpose of this architecture is to initiate valving action wherein fluid movement in the central channel can be restricted by filling the surrounding solenoidal track with compressed air at high pressure so that it can squeeze the centrally located micro-channel carrying the liquid. This valving structure may find a lot of applications in lab on chip devices, PCR biochips, biomedical micro-devices etc.
This study aimed to determine the skeletal effects of total ethanolic extract (TEE) and its butan... more This study aimed to determine the skeletal effects of total ethanolic extract (TEE) and its butanolic fraction (BF) from the stem-bark of Ulmus wallichiana, which is rich in C-glycosylated flavonoids, in growing rats (for peak bone [PB] achievement) and in ovariectomized (OVx) rats (for menopausal bone loss). TEE (750 mg kg(-1) d(-1)) and BF (50 mg kg(-1) d(-1)) were given orally for 10 weeks to weaning female Sprague-Dawley rats and for 12 weeks to adult OVx rats of the same strain, respectively. In studies with OVx rats, sham operated + vehicle, OVx + 17beta-estradiol, and OVx + vehicle groups served as various controls. Bone mineral density (BMD), biomechanical strength, bone histology, formations of osteoprogenitor cells, osteoid formation, and bone turnover/resorption markers were studied. Bioactive marker compounds in TEE and BF were analyzed by high-performance liquid chromatography. One-way analysis of variance was used to test significance of effects. In growing rats, both TEE and BF increased BMD, bone strength, and bone formation rate, suggesting higher PB achievement. OVx rats treated with either TEE or BF exhibited increased BMD at various anatomical positions and improved bone strength and trabecular architecture compared with the OVx + vehicle group. Serum osteocalcin and urinary type 1 collagen degradation product levels in OVx rats treated with either TEE or BF were significantly lower than those of the OVx + vehicle group. Neither TEE nor BF exhibited uterine estrogenicity. Analysis of marker compounds revealed significant enrichment of two bioactive markers in BF over TEE. Derived from U wallichiana, BF at much a lower dose than TEE was effective in PB achievement and prevention of OVx-induced bone loss.
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Papers by Avinash Kumar