7 research outputs found
Medical Robotics
No full textThe evolution of robotics in surgery is a new and exciting development. Surgical robotics brings together many disparate areas of research such as: design, development and modeling of robotic systems, nonlinear control, safety in medical robotics, ergonomics in minimally invasive procedures, and last but not the least, surgery. Over the past decade there have been significant advances in basic research and technology that have made it possible for the development of robots for surgery. One of the main advantages of robots is the increased precision and repeatability in carrying out surgical procedures, which were not possible in the past by a human surgeon. Robots and computers in conjunction can perform complex computations at much higher speeds compared to humans. On the other hand, humans are more adept in integrating diverse sources of information and making decisions based on their past experience of working in that field. They are also dexterous on the “human’ ’ scale, have very strong hand-eye coordination and an excellent sense of touch. Robots on the other hand have very good accuracy in carrying out pre-specified tasks, are not prone to fatigue or boredom, can carry out fast computations for surgical planning based on 3-D imaging data and other sensory feedback, and can also be designed for a wide range of operating conditions and scales. There are however severe limitations of robots and humans. One of the main disadvantages of robots is that they have poor judgment capability, limited dexterity and poor hand-eye coordination. Humans on the other hand cannot operate beyond their physical capability (their natural scale of operation) and are prone to tremor and fatigue [Taylor96]. Robots are thus seen more as augmenting human capabilities rather than replacing surgeons. The strengths and weaknesses of humans and robots are summarized in Table 1. Several robotic systems have been developed for surgical procedures. Some of the key areas where robotics has made a significant impact are orthopaedics, neurosurgery, laparoscopic procedures, opthalmic surgery, and cardiac surgery
Authorship and authority in the sanskrit literary tradition of the swaminarayana movement: Śikṣāpatrī and Satsaṅgijīvanam
Get PDFThis paper presents what the Satsaṅgijīvanam, a text by Śatānanda-Muni about the life and teachings of Sahajānanda, the founder of the Swaminarayana Movement, in two different passages reports about the authorship of the Śikṣāpatrī. It would appear that Swaminarayana (the name by which the founder came to be known) wrote the Śikṣāpatrī well before Śatānanda produced the version included in the Satsaṅgijīvanam. What the Satsaṅgijīvanam tells us about the authorship and the process of transmission of the Satsaṅgijīvanam itself complicates the evaluation of the Satsaṅgijīvanam as a historical document. Yet, the fact that the text shows that Swaminarayana may not be the author of the currently known Śikṣāpatrī invites reflection about the function of texts in the traditional selfperception and in the history of the Swaminarayana Movement
Authorship and Authority in the Sanskrit Literary Tradition of the Swaminarayana Movement: Śikṣāpatrī and Satsaṅgijīvanam
Get PDFThis paper presents what the Satsaṅgijīvanam, a text by Śatānanda-Muni about the life and teachings of Sahajānanda, the founder of the Swaminarayana Movement, in two different passages reports about the authorship of the Śikṣāpatrī. It would appear that Swaminarayana (the name by which the founder came to be known) wrote the Śikṣāpatrī well before Śatānanda produced the version included in the Satsaṅgijīvanam. What the Satsaṅgijīvanam tells us about the authorship and the process of transmission of the Satsaṅgijīvanam itself complicates the evaluation of the Satsaṅgijīvanam as a historical document. Yet, the fact that the text shows that Swaminarayana may not be the author of the currently known Śikṣāpatrī invites reflection about the function of texts in the traditional self-perception and in the history of the Swaminarayana Movement
Optical properties of InAsBi and optimal designs of lattice-matched and strain-balanced III-V semiconductor superlattices
Get PDFabstract: The optical properties of bulk InAs[subscript 0.936]Bi[subscript 0.064] grown by molecular beam epitaxy on a (100)-oriented GaSb substrate are measured using spectroscopic ellipsometry. The index of refraction and absorption coefficient are measured over photon energies ranging from 44 meV to 4.4 eV and are used to identify the room temperature bandgap energy of bulk InAs[subscript 0.936]Bi[subscript 0.064] as 60.6 meV. The bandgap of InAsBi is expressed as a function of Bi mole fraction using the band anticrossing model and a characteristic coupling strength of 1.529 eV between the Bi impurity state and the InAs valence band. These results are programmed into a software tool that calculates the miniband structure of semiconductor superlattices and identifies optimal designs in terms of maximizing the electron-hole wavefunction overlap as a function of transition energy. These functionalities are demonstrated by mapping the design spaces of lattice-matched GaSb/InAs[subscript 0.911]Sb[subscript 0.089] and GaSb/InAs[subscript 0.932]Bi[subscript 0.068] and strain-balanced InAs/InAsSb, InAs/GaInSb, and InAs/InAsBi superlattices on GaSb. The absorption properties of each of these material systems are directly compared by relating the wavefunction overlap square to the absorption coefficient of each optimized design. Optimal design criteria are provided for key detector wavelengths for each superlattice system. The optimal design mid-wave infrared InAs/InAsSb superlattice is grown using molecular beam epitaxy, and its optical properties are evaluated using spectroscopic ellipsometry and photoluminescence spectroscopy.This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Journal of Applied Physics and may be found at http://aip.scitation.org/doi/10.1063/1.4953027
Structural and Optical Properties of Molecular Beam Epitaxy Grown InAsBi Bulk Layers and Quantum Wells
Get PDFabstract: InAsBi is a narrow direct gap III-V semiconductor that has recently attracted considerable attention because its bandgap is tunable over a wide range of mid- and long-wave infrared wavelengths for optoelectronic applications. Furthermore, InAsBi can be integrated with other III-V materials and is potentially an alternative to commercial II-VI photodetector materials such as HgCdTe.
Several 1 μm thick, nearly lattice-matched InAsBi layers grown on GaSb are examined using Rutherford backscattering spectrometry and X-ray diffraction. Random Rutherford backscattering measurements indicate that the average Bi mole fraction ranges from 0.0503 to 0.0645 for the sample set, and ion channeling measurements indicate that the Bi atoms are substitutional. The X-ray diffraction measurements show a diffraction sideband near the main (004) diffraction peak, indicating that the Bi mole fraction is not laterally uniform in the layer. The average out of plane tetragonal distortion is determined by modeling the main and sideband diffraction peaks, from which the average unstrained lattice constant of each sample is determined. By comparing the Bi mole fraction measured by random Rutherford backscattering with the InAsBi lattice constant for the sample set, the lattice constant of zinc blende InBi is determined to be 6.6107 Å.
Several InAsBi quantum wells tensilely strained to the GaSb lattice constant with dilute quantities of Bi are characterized using photoluminescence spectroscopy. Investigation of the integrated intensity as a function of carrier excitation density spanning 5×1025 to 5×1026 cm-3 s-1 indicates radiative dominated recombination and high quantum efficiency over the 12 to 250 K temperature range. The bandgap of InAsBi is ascertained from the photoluminescence spectra and parameterized as a function of temperature using the Einstein single oscillator model. The dilute Bi mole fraction of the InAsBi quantum wells is determined by comparing the measured bandgap energy to that predicted by the valence band anticrossing model. The Bi mole fraction determined by photoluminescence agrees reasonably well with that estimated using secondary ion mass spectrometry.Dissertation/ThesisMasters Thesis Materials Science and Engineering 201
ASSESMENT OF CRITICAL SUCCESS FACTORS FOR SMART CITIES USING SIGNIFICANCE INDEX METHOD
Get PDFABSTRACT Smart development emphasis on a holistic development with combination of all key dimensions of urbanizatio
Characterizing the subharmonic response of four new microbubble formulations compared with three commercially-available ultrasound contrast agents
No full textSubharmonic imaging (i.e., receiving signal at half the transmitting frequency) is a promising technique to detect ultrasound contrast agents in the circulation. The aim of this study was to characterize the subharmonic enhancement of four new microbubble formulations (MBF-1 to 4), compared with three commercially-available contrast agents (Definity, Sonazoid and SonoVue), and to compare this subharmonic enhancement with the fundamental response. The new microbubble formulations consisted of either C3F8 or 2% C3F8 and 98% N-2 as the inner gas, and had different shell configurations containing polyethylene glycol 4000. Equal concentrations of each reconstituted contrast agent were investigated in vitro using a flow phantom. Radiofrequency data were acquired at four transmitting frequencies (2.5, 3.0, 3.5 and 4.0 MHz), four pulse-inversion configurations (1-4 cycles/pulse) and four scanner acoustic output levels (25, 52, 77 and 100%). Enhancement was derived as the relative increase in signal amplitude after contrast was added. Subharmonic enhancement of the new microbubble formulations were generally less affected by transmitting frequency, pulse length and acoustic output level than the commercially-available contrast agents (p < 0 : 0 5 was considered statistically significant for main and interaction effects). Mean subharmonic enhancement over all transmitting conditions for the new microbubble formulations (MBF-1 8 : 4 +/- 4 : 0; MBF-2 8 : 5 +/- 3 : 8; MBF-3 6 : 5 +/- 3 : 1; MBF-4 7 : 5 +/- 3 : 2 dB) were within the range exhibited by the commercially-available contrast agents (Definity 6 : 1 +/- 3 : 4; Sonazoid 7 : 0 +/- 3 : 4; SonoVue 1 0 : 7 +/- 3 : 2 dB). The subharmonic enhancement was similar to or higher than the fundamental response across all contrast agents investigated. Subharmonic imaging may be applied to detect the new microbubble formulations in future work.CPCI-S(ISTP)[email protected]
