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Search Results: 1 - 10 of 340 matches for " Gambhir Ranjit "
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Cold atoms as a coolant for levitated optomechanical systems
Gambhir Ranjit,Cris Montoya,Andrew A. Geraci
Physics , 2014, DOI: 10.1103/PhysRevA.91.013416
Abstract: Optically trapped dielectric objects are well suited for reaching the quantum regime of their center of mass motion in an ultra-high vacuum environment. We show that ground state cooling of an optically trapped nanosphere is achievable when starting at room temperature, by sympathetic cooling of a cold atomic gas optically coupled to the nanoparticle. Unlike cavity cooling in the resolved sideband limit, this system requires only a modest cavity finesse and it allows the cooling to be turned off, permitting subsequent observation of strongly-coupled dynamics between the atoms and sphere. Nanospheres cooled to their quantum ground state could have applications in quantum information science or in precision sensing.
Frequency Modulation Spectroscopy at High Modulation Depth in an Indium Atomic Beam
Nathan A. Schine,Gambhir Ranjit,Protik K. Majumder
Physics , 2013,
Abstract: We present a detailed analysis of an application of frequency modulation (FM) spectroscopy in the high modulation depth limit. We have recently completed and reported a measurement of the Stark shift in the indium $5p_{1/2}\rightarrow 6s_{1/2}$ 410 nm transition using this spectroscopy method [Ranjit, et al. Phys. Rev. A 87, 032506 (2013)]. FM spectroscopy proved essential to resolve spectroscopic features in an atomic beam where the optical depth was $\sim 10^{-3}$. A dual-modulation scheme is described which ensures truly background-free FM signals even in the low-density limit. Lock-in detection of the FM signal was accomplished using both the fundamental (1f) and second-harmonic (2f) modulation frequencies. A derivation of both the 1f and 2f signal line shapes in the high-modulation-depth limit is presented. These line shapes form the basis for quantitative fits to a wide variety of experimental FM spectra.
Attonewton force detection using microspheres in a dual-beam optical trap in high vacuum
Gambhir Ranjit,David P. Atherton,Jordan H. Stutz,Mark Cunningham,Andrew A. Geraci
Physics , 2015, DOI: 10.1103/PhysRevA.91.051805
Abstract: We describe the implementation of laser-cooled silica microspheres as force sensors in a dual-beam optical dipole trap in high vacuum. Using this system we have demonstrated trap lifetimes exceeding several days, attonewton force detection capability, and wide tunability in trapping and cooling parameters. Measurements have been performed with charged and neutral beads to calibrate the sensitivity of the detector. This work establishes the suitability of dual beam optical dipole traps for precision force measurement in high vacuum with long averaging times, and enables future applications including the study of gravitational inverse square law violations at short range, Casimir forces, acceleration sensing, and quantum opto-mechanics.
Geo-Social Profile Matching Algorithm for Dynamic Interests in Ad-Hoc Social Network  [PDF]
Nagender Aneja, Sapna Gambhir
Social Networking (SN) , 2014, DOI: 10.4236/sn.2014.35029
Abstract: Among mobile users, ad-hoc social network (ASN) is becoming a popular platform to connect and share their interests anytime anywhere. Many researchers and computer scientists investigated ASN architecture, implementation, user experience, and different profile matching algorithms to provide better user experience in ad-hoc social network. We emphasize that strength of an ad-hoc social network depends on a good profile-matching algorithm that provides meaningful friend suggestions in proximity. Keeping browsing history is a good way to determine user’s interest, however, interests change with location. This paper presents a novel profile-matching algorithm for automatically building a user profile based on dynamic GPS (Global Positing System) location and browsing history of users. Building user profile based on GPS location of a user provides benefits to ASN users as this profile represents user’s dynamic interests that keep changing with location e.g. office, home, or some other location. Proposed profile-matching algorithm maintains multiple local profiles based on location of mobile device.
Review of Turn around Point Long Period Fiber Gratings  [PDF]
Monika Gambhir, Shilpi Gupta
Journal of Sensor Technology (JST) , 2015, DOI: 10.4236/jst.2015.54009
Abstract: Long period fiber gratings are emerging as a potential candidate in the list of surrounding refractive index optical fiber sensors. Their sensitivity can be enhanced greatly if the grating period, fiber dimensions and surrounding refractive index are optimized in a way to operate at a point called turn around point on phase matching curves of these gratings. Turn around point LPFGs are well known for their ultrahigh sensitivity to external parameters. Potential of operating LPFG at or near turn around point has been investigated by many researchers in various applications including physical parameter sensing, adulteration detection, radiation dose, etc. Since TAP LPFGs are in investigation phase therefore a lot of rigorous & efficient work in finding techniques for optimizing their potential as sensor in chemical, biochemical, structural health monitoring is still to be carried out. A brief review of work carried out in this domain till now is presented here and key findings from literature review are highlighted.
Accordion Manoeuvre with Ilizarov Frame over Nail in Situ in a Case of Infected Non-Union of Femur: Discussion on Strategies: A Case Report  [PDF]
Ranjit Kr. Baruah
Open Journal of Orthopedics (OJO) , 2014, DOI: 10.4236/ojo.2014.47030
Abstract: Quiescent Type of H. Rosen & Stage 2 of C.L. Romano et al. for Infected Non Union of Femur after K-nailing (Küntscher nailing) require no debridement & removal of nail and therefore can be treated by a single stage procedure. There are a few reports of treating aseptic non-union of femur by compression alone or compression distraction over nail by Ilizarov Technique. However, no case of Infected Non-Union femur being treated by Accordion Manoeuvre with Ilizarov over nail in situ (i.e. without exchange nailing) has been reported so far. Here, we are reporting a case of Infected Non-Union following K-nailing for a fracture shaft of femur in a 15-year-old female, who was treated by this technique as a single stage procedure. An Ilizarov frame was mounted on the femur with nail in situ followed by Accordion Manoeuvre. The fracture was healed in 5.6 months with two cycles of Accordion Manoeuvre followed by rhythmic compression. There was no recurrence of infection.
A Rare Case of Anterior Sacral Meningocele (ASM) in a Young Patient  [PDF]
Shanu Gambhir, Mark Winder, Gareth Owen
Open Journal of Modern Neurosurgery (OJMN) , 2016, DOI: 10.4236/ojmn.2016.61003
Abstract: We report a 24-year-old male who presented with abdominal distension, constipation and left sided groin pain. CT and MRI of the abdomen/spine were performed which showed a large anterior sacral meningocele occupying most of the pelvic and abdominal cavity and displacement of their respective contents. Initially a posterior approach with lumbosacral laminectomy (L5 - S4) was performed. The ostium of the meningocele was identified with several nerve roots identified passing through, adjacent and into the defect. As nerve roots traversed the ostium, watertight closure was not feasible without sacrificing nerve roots. Subsequent MRI demonstrated recurrence of approximately 60% of the anterior sacral meningocele. We therefore opted to approach the ASM anteriorly via an anterior approach with the help of colorectal surgical colleague. The ASM was completely embedded within the sigmoid and upper to mid rectal mesentry, with its own vascular supply to the thick walled capsule. This case highlights the need for a combined approach due to the incorporation of the pseudomeningocele into the omentum with the development of its own blood supply.
Genetic Algorithm for the Design of Optimal IIR Digital Filters  [PDF]
Ranjit Singh, Sandeep K. Arya
Journal of Signal and Information Processing (JSIP) , 2012, DOI: 10.4236/jsip.2012.33038
Abstract: This paper presents the design of Optimal Infinite-Impulse Response (IIR) digital filters using Genetic Algorithm (GA). IIR filter is essentially a digital filter with Recursive responses. Since the error surface of digital IIR filters is generally nonlinear and multimodal, global optimization techniques are required in order to avoid local minima. This paper presents heuristic way for the designing IIR filters. GA is a powerful global optimization algorithm introduced in combinatorial optimization problems. The paper finds the optimum Coefficients of IIR digital filter through GA. Design of Lowpass and High pass IIR digital filter is proposed to provide estimate of transition band. It is found that the calculated values are more optimal than fda tool available for the design of filter in MATLAB. The simulation result of the employed examples shows an improvement on transition band and mean-square-error (MSE). The position of pole-zero is also presented to describe stability and results are compared with Simulated Annealing (SA) method.
Experimental and Parameterization Method for Evaluation of Dry Deposition of S Compounds to Natural Surfaces  [PDF]
Ranjit Kumar, K. Maharaj Kumari
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.24043
Abstract: This paper deals with parameterization method based on meteorological parameters for calculation of dry deposition of S compounds on natural surface (leaf of Cassia siamea) and direct measurement method. A scheme based on meteorological parameters has been evolved to calculate the dry deposition theoretically and a computer program has been developed. Experimentally dry deposition flux of S on leaf of Cassia siamea was measured by exposing the leaf surfaces on non-dewy, non-foggy and non rainy days and washing the leaf surfaces with deionised water and samples were analyzed by Dionex Dx-500 Ion Chromatograph. Atmospheric concentration of SO2 was 3.54±1.41 μg m-3 and particulate SO42- was 2.72±1.15 μg m-3. Theoretically obtained dry deposition velocity of SO2 and SO42- are 0.32 cm s-1 and 0.75cm s-1, respectively. The calculated deposition of S as total sulphate (gaseous SO2 and particulate SO42-) to Cassia leaf was 2.05±0.78mg m-2 d-1 and experimentally obtained dry deposition of S as sulphate was 1.07±1.35 mg m-2 d-1. The experimentally and theoretically obtained mean values for S as SO42- are comparable.
Osteoclastoma of Proximal Ulna―Atypical Location in a 13-Year-Old Child  [PDF]
Siddaram Patil, Ranjit Kumar Yalamanchili
Open Journal of Orthopedics (OJO) , 2014, DOI: 10.4236/ojo.2014.43009
Abstract: Giant cell tumour (GCT) or osteoclastoma is a very rare locally invasive bone tumour that occurs close to the joint. The ulnar metaphysis is an unusual site for an Osteoclastoma with occurrence rate of 0.45% to 3.2% as reported in literature [1]. Most of the patients seek traditional methods of treatment before orthopaedic consultation and present lately with extensive involvement of the tumour into soft tissues and articular surface, making the joint preservation difficult or impossible. For reconstruction, several options have been described, which include fibular autografts, allografts and cement augmentation. Inherent to all these procedures is the risk of delayed union of the graft and preserving functional mobility of the joint. We report a rare case of a proximal ulna GCT diagnosed in a 13-year-old girl. It was treated with intralesional curettage, and autologous maternal iliac crest bone grafting augmented with bone cement reconstruction.
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