Kapil Bajaj - Academia.edu (original) (raw)

Papers by Kapil Bajaj

Meckel’s diverticulum can manifest with various complications such as obstruction, intussusceptio... more Meckel’s diverticulum can manifest with various complications such as obstruction, intussusception, inflammation or diverticulitis, perforation, haemorrhage and fistula, and commonly manifests in children. Adult intussusception due to inverted Meckel’s diverticulum is an uncommon aetiology of intestinal obstruction but should be suspected in individuals. Imaging such as contrast-enhanced computed tomography aids in the diagnosis but it is not confirmatory to diagnose inverted Meckel’s diverticulum as a leading point. Resection of the intussusception segment is the definitive treatment. We present the case of a young man who presented in emergency with complaints of intestinal obstruction and ileo-ileal intussusception was the aetiology of for the same diagnosed on contrast-enhanced computed tomography of the abdomen. On exploration we discovered an inverted Meckel’s diverticulum to be the leading point for intussusception.

International Journal of Engineering Research and Applications, 2014

Masdar City is an archeology project in Abu Dhabi, in the United Arab Emirates. Its core is a pla... more Masdar City is an archeology project in Abu Dhabi, in the United Arab Emirates. Its core is a planned city, which is being built by Masdar, a subsidiary of Mubadala Development Company, with the majority of seed capital provided by the government of Abu Dhabi. Designed by the British architectural firm Foster and Partners and engineering and environmental consultancy Mott MacDonald, the city will rely entirely on solar energy and other renewable energy sources, with a zero waste ecology. It initially aimed to be a sustainable zero-carbon carfree city. . This article is a case study about “Masdar City,” a planned carbon-neutral town in Abu Dhabi. The article describes the key characteristics of Masdar City.

Medical Journal Armed Forces India, 2021

Background: Primary physicians have a very important role in identifying early breast cancer, as ... more Background: Primary physicians have a very important role in identifying early breast cancer, as well as promotion of awareness about breast cancer to general public. However, there is insufficient data about the knowledge of doctors, who have just finished their basic medical training, on breast cancer. Methods: All the postgraduate residents who had joined within the last 3 months, irrespective of the department, were invited to take part in the study. After explaining the aims of the study telephonically, consent was taken through online signatures and the participants were asked to fill online proformas. Descriptive statistics were used, and chi-square test was used to compare groups. P value of less than 0.05 was considered as significant. Results: A total of 106 participants took part in the study. Only 63 (59.4%) participants had satisfactory knowledge about the warning signs of breast cancer. Apart from question of ideal frequency of breast examination, which was answered by 59 (55.7%) participants, the rest of the questions were answered correctly by less than 50% of participants. On the questions on risk factors, 102 (96.5%) of the participants were assessed to have adequate knowledge. Overall only 51 (48.1%) participants were assessed to have satisfactory knowledge about warning signs, screening and risk factors related to breast cancer. Conclusions: The awareness about warning signs, risk factors and screening practices of breast cancer in newly joined residents was less than satisfactory. To improve this level of awareness, significant steps are needed at the level of undergraduate teaching.

Physical Review B, 1992

We report the observation of a magnetic-field-dependent excitonic photoluminescence linewidth in ... more We report the observation of a magnetic-field-dependent excitonic photoluminescence linewidth in Ino.4sGao. s2P semiconductor alloys (lattice matched to GaAs). The measurements were made at 1.4 K and the magnetic field ranged between 0 and 13.6 T. The photoluminescence peak energies ranged between 1.976 and 1.995 eV while the full width at half maximum linewidths varied from 4.3 to 6.0

Business Today, Aug 12, 2007

Studies in health technology and informatics, 2008

The effectiveness of simulation-based training has been accepted with great success in many field... more The effectiveness of simulation-based training has been accepted with great success in many fields including medicine. Most of the simulation research and development in medicine has focused on surgery. There has been some development of hardware based biomechanical models of sections of human anatomy, such as pelvic exam simulators. More recently, with the advances in haptics technology, software and hardware based simulators are being developed for the previously ignored area of palpatory diagnosis. The Virtual Haptic Back (VHB) is a simulator based on virtual reality and haptics that is currently being used to train medical students in palpatory diagnosis. This study examined the effect of repeating the training on the VHB.

We present results of Rayleigh-Bénard convection experiments using acetone with a Prandtl number ... more We present results of Rayleigh-Bénard convection experiments using acetone with a Prandtl number sigma approximately equal to 4 and 0<= ε ≡ Delta T/Delta Tc - 1 0 within a short time produced small-amplitude random convective flow patterns which grew from fluctuations just above onset. These patterns were similar to early stages of several computer simulations using random initial conditions

We present experimental and theoretical results for Rayleigh-Bénard convection with rotation abou... more We present experimental and theoretical results for Rayleigh-Bénard convection with rotation about a vertical axis in a binary gas mixture with Prandtl number sigma = 0.174 and dimensionless rotation rates 17 alt Omega alt 150 in a cylindrical cell. The critical Rayleigh numbers R_c(Omega) agree well with linear stability analysis. The bifurcation to rolls is found to be subcritical, as

For a homeotropically aligned nematic liquid crystal in a vertical magnetic field and heated from... more For a homeotropically aligned nematic liquid crystal in a vertical magnetic field and heated from below, it was predicted^1 that the bifurcation from conduction to convection is a subcritical Hopf bifurcation. Using 4-n-pentyl-4'-cyanobiphenyl (5CB) at a mean temperature of 25.6^oC in a cylindrical cell of aspect ratio (radius/height) Gamma=10.6, we observed travelling and standing waves during the transient from conduction

Measurements by others(See, e.g., X. Wu and A. Libchaber, Phys. Rev. A 45), 842 (1992); and J.J. ... more Measurements by others(See, e.g., X. Wu and A. Libchaber, Phys. Rev. A 45), 842 (1992); and J.J. Niemela, L. Skrbek, K.R. Sreenivasan, and R.J. Donnelly, preprint. of the Nusselt number N as a function of the Rayleigh number R, when fitted to N = N0 R ^ beta, yielded beta in the range 0.28 to 0.31. Theoretical values based on

Onset voltages Vc of electroconvection in a nematic liquid crystal (NLC) cell were measured as a ... more Onset voltages Vc of electroconvection in a nematic liquid crystal (NLC) cell were measured as a function of the drive frequency omega/ 2 pi. The cell (from E.H.C Co, Ltd Japan) had a nominal spacing of 25 mum and planar alignment. It was filled with the NLC Merck phase IV (N4). The NLC was doped with 0.1% by weight of

Physical Review E, 1997

We present experimental results for pattern formation in Rayleigh-Bénard convection of a fluid wi... more We present experimental results for pattern formation in Rayleigh-Bénard convection of a fluid with a Prandtl number σ ≃ 4. We find that the spiraldefect-chaos (SDC) attractor which exists for σ ≃ 1 has become unstable. Gradually increasing the temperature difference ∆T from below to well above its critical value ∆T c no longer leads to SDC. A sudden jump of ∆T from below to above ∆T c causes convection to grow from thermal fluctuations and does yield SDC. However, the SDC is a transient; it coarsens and forms a single cell-filling spiral which then drifts toward the cell wall and disappears.

Physica B: Condensed Matter, 1994

A system of classical dipoles free to rotate in a plane and fixed on an N×N square lattice (N= 16... more A system of classical dipoles free to rotate in a plane and fixed on an N×N square lattice (N= 16,24,32) has been studied by Spin Dynamics computer simulations as a function of Pd=J/kBT (J is dipole-dipole interaction energy, ks is Boltzmann constant and T is the system temperature). The measured spin-wave dispersion curves for Fd > 20 agree with the analytic values at Fd= ~ except for the infinite wavelength Goldstone mode. The high frequency modes soften as Fd is decreased. A long-lived rotational mode has been found in which dipoles at alternate lattice sites rotate continuously in opposite directions.

Physical Review E, 2002

We present experimental results for pattern formation in Rayleigh-Bénard convection with modulate... more We present experimental results for pattern formation in Rayleigh-Bénard convection with modulated rotation about a vertical axis. The dimensionless rotation rate ⍀ was varied as ⍀ m ϭ⍀͓1ϩ␦ cos(⍀t)͔ ͑time is scaled by the vertical viscous diffusion time of the cell͒. We used a cylindrical cell of aspect ratio ͑radius/ height͒ ⌫ϭ11.8 and varied ⍀, ␦, , and ⑀ϵR/R c (⍀)Ϫ1 (R is the Rayleigh number͒. The fluid was water with a Prandtl number of 4.5. Sufficiently far above onset even a small ␦տ0.02 stabilized a concentric-roll ͑target͒ pattern. Multiarmed spirals were observed close to onset. The rolls of the target patterns traveled radially inward independent of the sense of rotation. The radial speed v was nearly independent of ⑀ for fixed ⍀, ␦, and. However, v increased with any one of ⍀, ␦, and when all the other parameters were held fixed.

Physical Review E, 2002

This paper reviews results from and future prospects for experimental studies of Rayleigh-Bénard ... more This paper reviews results from and future prospects for experimental studies of Rayleigh-Bénard convection with rotation about a vertical axis. At dimensionless rotation rates 0 ≤ Ω ≤ 20 and for Prandtl numbers σ 1, Küppers-Lortz-unstable patterns offered a unique opportunity to study spatio-temporal chaos immediately above a supercritical bifurcation where weakly-nonlinear theories in the form of Ginzburg-Landau (GL) or Swift-Hohenberg (SH) equations can be expected to be valid. However, the dependence of the time and length scales of the chaotic state on ≡ ∆T /∆T c −1 was found to be different from the expected dependence based on the structure of GL equations. For Ω > ∼ 70 and 0.7 < ∼ σ < ∼ 5 patterns were found to be cellular near onset with local four-fold coordination. They differ from the theoretically expected Küppers-Lortz-unstable state. Stable as well as intermittent defect-free rotating square lattices exist in this parameter range. Smaller Prandtl numbers (0.16 < ∼ σ < ∼ 0.7) can only be reached in mixtures of gases. These fluids are expected to offer rich future opportunities for the study of a line of tricritical bifurcations, of supercritical Hopf bifurcations to standing waves, of a line of codimension-two points, and of a codimension-three point.

Physical Review E, 1998

By analyzing large-aspect-ratio spiral-defect-chaos (SDC) convection images, we show that the Kar... more By analyzing large-aspect-ratio spiral-defect-chaos (SDC) convection images, we show that the Karhunen-Loève decomposition (KLD) scales extensively for subsystem-sizes larger than 4d (d is the fluid depth), which strongly suggests that SDC is extensively chaotic. From this extensive scaling, the intensive length ξ KLD is computed and found to have a different dependence on the Rayleigh number than the two-point correlation length ξ 2. Local computations of ξ KLD reveal a substantial spatial nonuniformity of SDC that extends over radii 18d < r < 45d in a Γ = 109 aspect-ratio cell.

Physical Review E, 1999

We report free-surface instabilities in a deep bed of fine granular material of irregular shape u... more We report free-surface instabilities in a deep bed of fine granular material of irregular shape under vertical vibrations. At low frequency of vibration, the conical heap due to convective flow becomes unstable above a critical amplitude of vibration and acquires an azimuthal dependence which makes the heap surface corrugated. At even higher amplitude, the heap is no longer stable and splits into small heaps on a hexagonal lattice. At high frequency, we observe standing waves ͑stripes͒ at the same frequency as the driving one. The main mechanism of these instabilities can be traced back to the presence of the surrounding gas, since they vanish under vacuum conditions. ͓S1063-651X͑99͒07605-9͔

Physical Review E, 1995

Competition between subharmonically generated equilateral triangles and regular hexagons is obser... more Competition between subharmonically generated equilateral triangles and regular hexagons is observed in the Faraday experiment with viscous fluids subjected to a sinusoidal forcing. For kinematic viscosities around 17 cm /s, all spatially regular patternsstripes, squares, hexagons, and triangles can be parametrically excited in the same fiuid depending on the forcing amplitude and frequency. Close to this value of viscosity, hexagonal and square patterns coexist showing a bicritical point.

Review of Scientific Instruments, 1992

A procedure for performing synchronous detection of signals using a digital voltmeter (DVM) , bey... more A procedure for performing synchronous detection of signals using a digital voltmeter (DVM) , beyond the frequency limit set by a straightforward consideration of the sampling theorem and the conversion time of the DVM, is presented. This is achieved by using an independent ...

Meckel’s diverticulum can manifest with various complications such as obstruction, intussusceptio... more Meckel’s diverticulum can manifest with various complications such as obstruction, intussusception, inflammation or diverticulitis, perforation, haemorrhage and fistula, and commonly manifests in children. Adult intussusception due to inverted Meckel’s diverticulum is an uncommon aetiology of intestinal obstruction but should be suspected in individuals. Imaging such as contrast-enhanced computed tomography aids in the diagnosis but it is not confirmatory to diagnose inverted Meckel’s diverticulum as a leading point. Resection of the intussusception segment is the definitive treatment. We present the case of a young man who presented in emergency with complaints of intestinal obstruction and ileo-ileal intussusception was the aetiology of for the same diagnosed on contrast-enhanced computed tomography of the abdomen. On exploration we discovered an inverted Meckel’s diverticulum to be the leading point for intussusception.

International Journal of Engineering Research and Applications, 2014

Masdar City is an archeology project in Abu Dhabi, in the United Arab Emirates. Its core is a pla... more Masdar City is an archeology project in Abu Dhabi, in the United Arab Emirates. Its core is a planned city, which is being built by Masdar, a subsidiary of Mubadala Development Company, with the majority of seed capital provided by the government of Abu Dhabi. Designed by the British architectural firm Foster and Partners and engineering and environmental consultancy Mott MacDonald, the city will rely entirely on solar energy and other renewable energy sources, with a zero waste ecology. It initially aimed to be a sustainable zero-carbon carfree city. . This article is a case study about “Masdar City,” a planned carbon-neutral town in Abu Dhabi. The article describes the key characteristics of Masdar City.

Medical Journal Armed Forces India, 2021

Background: Primary physicians have a very important role in identifying early breast cancer, as ... more Background: Primary physicians have a very important role in identifying early breast cancer, as well as promotion of awareness about breast cancer to general public. However, there is insufficient data about the knowledge of doctors, who have just finished their basic medical training, on breast cancer. Methods: All the postgraduate residents who had joined within the last 3 months, irrespective of the department, were invited to take part in the study. After explaining the aims of the study telephonically, consent was taken through online signatures and the participants were asked to fill online proformas. Descriptive statistics were used, and chi-square test was used to compare groups. P value of less than 0.05 was considered as significant. Results: A total of 106 participants took part in the study. Only 63 (59.4%) participants had satisfactory knowledge about the warning signs of breast cancer. Apart from question of ideal frequency of breast examination, which was answered by 59 (55.7%) participants, the rest of the questions were answered correctly by less than 50% of participants. On the questions on risk factors, 102 (96.5%) of the participants were assessed to have adequate knowledge. Overall only 51 (48.1%) participants were assessed to have satisfactory knowledge about warning signs, screening and risk factors related to breast cancer. Conclusions: The awareness about warning signs, risk factors and screening practices of breast cancer in newly joined residents was less than satisfactory. To improve this level of awareness, significant steps are needed at the level of undergraduate teaching.

Physical Review B, 1992

We report the observation of a magnetic-field-dependent excitonic photoluminescence linewidth in ... more We report the observation of a magnetic-field-dependent excitonic photoluminescence linewidth in Ino.4sGao. s2P semiconductor alloys (lattice matched to GaAs). The measurements were made at 1.4 K and the magnetic field ranged between 0 and 13.6 T. The photoluminescence peak energies ranged between 1.976 and 1.995 eV while the full width at half maximum linewidths varied from 4.3 to 6.0

Business Today, Aug 12, 2007

Studies in health technology and informatics, 2008

The effectiveness of simulation-based training has been accepted with great success in many field... more The effectiveness of simulation-based training has been accepted with great success in many fields including medicine. Most of the simulation research and development in medicine has focused on surgery. There has been some development of hardware based biomechanical models of sections of human anatomy, such as pelvic exam simulators. More recently, with the advances in haptics technology, software and hardware based simulators are being developed for the previously ignored area of palpatory diagnosis. The Virtual Haptic Back (VHB) is a simulator based on virtual reality and haptics that is currently being used to train medical students in palpatory diagnosis. This study examined the effect of repeating the training on the VHB.

We present results of Rayleigh-Bénard convection experiments using acetone with a Prandtl number ... more We present results of Rayleigh-Bénard convection experiments using acetone with a Prandtl number sigma approximately equal to 4 and 0<= ε ≡ Delta T/Delta Tc - 1 0 within a short time produced small-amplitude random convective flow patterns which grew from fluctuations just above onset. These patterns were similar to early stages of several computer simulations using random initial conditions

We present experimental and theoretical results for Rayleigh-Bénard convection with rotation abou... more We present experimental and theoretical results for Rayleigh-Bénard convection with rotation about a vertical axis in a binary gas mixture with Prandtl number sigma = 0.174 and dimensionless rotation rates 17 alt Omega alt 150 in a cylindrical cell. The critical Rayleigh numbers R_c(Omega) agree well with linear stability analysis. The bifurcation to rolls is found to be subcritical, as

For a homeotropically aligned nematic liquid crystal in a vertical magnetic field and heated from... more For a homeotropically aligned nematic liquid crystal in a vertical magnetic field and heated from below, it was predicted^1 that the bifurcation from conduction to convection is a subcritical Hopf bifurcation. Using 4-n-pentyl-4'-cyanobiphenyl (5CB) at a mean temperature of 25.6^oC in a cylindrical cell of aspect ratio (radius/height) Gamma=10.6, we observed travelling and standing waves during the transient from conduction

Measurements by others(See, e.g., X. Wu and A. Libchaber, Phys. Rev. A 45), 842 (1992); and J.J. ... more Measurements by others(See, e.g., X. Wu and A. Libchaber, Phys. Rev. A 45), 842 (1992); and J.J. Niemela, L. Skrbek, K.R. Sreenivasan, and R.J. Donnelly, preprint. of the Nusselt number N as a function of the Rayleigh number R, when fitted to N = N0 R ^ beta, yielded beta in the range 0.28 to 0.31. Theoretical values based on

Onset voltages Vc of electroconvection in a nematic liquid crystal (NLC) cell were measured as a ... more Onset voltages Vc of electroconvection in a nematic liquid crystal (NLC) cell were measured as a function of the drive frequency omega/ 2 pi. The cell (from E.H.C Co, Ltd Japan) had a nominal spacing of 25 mum and planar alignment. It was filled with the NLC Merck phase IV (N4). The NLC was doped with 0.1% by weight of

Physical Review E, 1997

We present experimental results for pattern formation in Rayleigh-Bénard convection of a fluid wi... more We present experimental results for pattern formation in Rayleigh-Bénard convection of a fluid with a Prandtl number σ ≃ 4. We find that the spiraldefect-chaos (SDC) attractor which exists for σ ≃ 1 has become unstable. Gradually increasing the temperature difference ∆T from below to well above its critical value ∆T c no longer leads to SDC. A sudden jump of ∆T from below to above ∆T c causes convection to grow from thermal fluctuations and does yield SDC. However, the SDC is a transient; it coarsens and forms a single cell-filling spiral which then drifts toward the cell wall and disappears.

Physica B: Condensed Matter, 1994

A system of classical dipoles free to rotate in a plane and fixed on an N×N square lattice (N= 16... more A system of classical dipoles free to rotate in a plane and fixed on an N×N square lattice (N= 16,24,32) has been studied by Spin Dynamics computer simulations as a function of Pd=J/kBT (J is dipole-dipole interaction energy, ks is Boltzmann constant and T is the system temperature). The measured spin-wave dispersion curves for Fd > 20 agree with the analytic values at Fd= ~ except for the infinite wavelength Goldstone mode. The high frequency modes soften as Fd is decreased. A long-lived rotational mode has been found in which dipoles at alternate lattice sites rotate continuously in opposite directions.

Physical Review E, 2002

We present experimental results for pattern formation in Rayleigh-Bénard convection with modulate... more We present experimental results for pattern formation in Rayleigh-Bénard convection with modulated rotation about a vertical axis. The dimensionless rotation rate ⍀ was varied as ⍀ m ϭ⍀͓1ϩ␦ cos(⍀t)͔ ͑time is scaled by the vertical viscous diffusion time of the cell͒. We used a cylindrical cell of aspect ratio ͑radius/ height͒ ⌫ϭ11.8 and varied ⍀, ␦, , and ⑀ϵR/R c (⍀)Ϫ1 (R is the Rayleigh number͒. The fluid was water with a Prandtl number of 4.5. Sufficiently far above onset even a small ␦տ0.02 stabilized a concentric-roll ͑target͒ pattern. Multiarmed spirals were observed close to onset. The rolls of the target patterns traveled radially inward independent of the sense of rotation. The radial speed v was nearly independent of ⑀ for fixed ⍀, ␦, and. However, v increased with any one of ⍀, ␦, and when all the other parameters were held fixed.

Physical Review E, 2002

This paper reviews results from and future prospects for experimental studies of Rayleigh-Bénard ... more This paper reviews results from and future prospects for experimental studies of Rayleigh-Bénard convection with rotation about a vertical axis. At dimensionless rotation rates 0 ≤ Ω ≤ 20 and for Prandtl numbers σ 1, Küppers-Lortz-unstable patterns offered a unique opportunity to study spatio-temporal chaos immediately above a supercritical bifurcation where weakly-nonlinear theories in the form of Ginzburg-Landau (GL) or Swift-Hohenberg (SH) equations can be expected to be valid. However, the dependence of the time and length scales of the chaotic state on ≡ ∆T /∆T c −1 was found to be different from the expected dependence based on the structure of GL equations. For Ω > ∼ 70 and 0.7 < ∼ σ < ∼ 5 patterns were found to be cellular near onset with local four-fold coordination. They differ from the theoretically expected Küppers-Lortz-unstable state. Stable as well as intermittent defect-free rotating square lattices exist in this parameter range. Smaller Prandtl numbers (0.16 < ∼ σ < ∼ 0.7) can only be reached in mixtures of gases. These fluids are expected to offer rich future opportunities for the study of a line of tricritical bifurcations, of supercritical Hopf bifurcations to standing waves, of a line of codimension-two points, and of a codimension-three point.

Physical Review E, 1998

By analyzing large-aspect-ratio spiral-defect-chaos (SDC) convection images, we show that the Kar... more By analyzing large-aspect-ratio spiral-defect-chaos (SDC) convection images, we show that the Karhunen-Loève decomposition (KLD) scales extensively for subsystem-sizes larger than 4d (d is the fluid depth), which strongly suggests that SDC is extensively chaotic. From this extensive scaling, the intensive length ξ KLD is computed and found to have a different dependence on the Rayleigh number than the two-point correlation length ξ 2. Local computations of ξ KLD reveal a substantial spatial nonuniformity of SDC that extends over radii 18d < r < 45d in a Γ = 109 aspect-ratio cell.

Physical Review E, 1999

We report free-surface instabilities in a deep bed of fine granular material of irregular shape u... more We report free-surface instabilities in a deep bed of fine granular material of irregular shape under vertical vibrations. At low frequency of vibration, the conical heap due to convective flow becomes unstable above a critical amplitude of vibration and acquires an azimuthal dependence which makes the heap surface corrugated. At even higher amplitude, the heap is no longer stable and splits into small heaps on a hexagonal lattice. At high frequency, we observe standing waves ͑stripes͒ at the same frequency as the driving one. The main mechanism of these instabilities can be traced back to the presence of the surrounding gas, since they vanish under vacuum conditions. ͓S1063-651X͑99͒07605-9͔

Physical Review E, 1995

Competition between subharmonically generated equilateral triangles and regular hexagons is obser... more Competition between subharmonically generated equilateral triangles and regular hexagons is observed in the Faraday experiment with viscous fluids subjected to a sinusoidal forcing. For kinematic viscosities around 17 cm /s, all spatially regular patternsstripes, squares, hexagons, and triangles can be parametrically excited in the same fiuid depending on the forcing amplitude and frequency. Close to this value of viscosity, hexagonal and square patterns coexist showing a bicritical point.

Review of Scientific Instruments, 1992

A procedure for performing synchronous detection of signals using a digital voltmeter (DVM) , bey... more A procedure for performing synchronous detection of signals using a digital voltmeter (DVM) , beyond the frequency limit set by a straightforward consideration of the sampling theorem and the conversion time of the DVM, is presented. This is achieved by using an independent ...