The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Christopher P. Search - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity limits of coupled resonator optical waveguide (Crow) gyroscopes when subject to material losses
Gyroscopy and Navigation, 2015Co-Authors: Dmitriy Kalantarov, Christopher P. SearchAbstract:In recent years there has been a growing interest in optical microresonators as viable low cost on chip micro-optical gyroscopes with navigation grade sensitivities. Here, we analyze and compare the rotational sensitivity of coupled resonator optical waveguide (Crow) gyroscopes to equivalent single resonator gyroscopes under various geometric constraints and device parameters. We show that the Crow gyros offer a sensitivity enhancement over conventional single resonator gyros at low propagation losses. However, the single ring resonator gyro is found to be more stable over a wider range of propagation losses as well as boasting greater sensitivities for larger propagation losses compared to a Crow of the same size. Furthermore, an analysis of the maximum achievable sensitivity for different material technologies (Hydex, silicon oxynitride, and SOI) is conducted. While all materials achieved tactical grade sensitivities, Hydex shows the greatest potential for Crow gyros because of the stability of its sensitivity over a wide range of device parameters.
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Effect of resonator losses on the sensitivity of coupled resonator optical waveguide gyroscopes
Optics Letters, 2014Co-Authors: Dmitriy Kalantarov, Christopher P. SearchAbstract:Recently there has been a growing interest in microphotonic integrated optical gyroscopes. Here, we analyze the effect of resonator losses on the rotational sensitivity of a coupled resonator optical waveguide (Crow) gyroscope in comparison to a single passive resonator gyroscope of the same size. We show that the Crow gyro offers a superior sensitivity only for very low propagation losses. Moreover, the single ring resonator gyro is found to have a sensitivity that is stable over wide range of resonator losses as well as boasting greater sensitivities than the Crow gyro for propagation losses in the resonators exceeding 10−1 dB/cm.
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Ultra-sensitive chip scale Sagnac gyroscope based on periodically modulated coupling of a coupled resonator optical waveguide
Optics Express, 2012Co-Authors: Christopher Sorrentino, John R. E. Toland, Christopher P. SearchAbstract:We analyze the sensitivity to inertial rotations Ω of a micron scale integrated gyroscope consisting of a coupled resonator optical waveguide (Crow). We show here that by periodic modulation of the evanescent coupling between resonators, the sensitivity to rotations can be enhanced by a factor up to 109 in comparison to a conventional Crow with uniform coupling between resonators. Moreover, the overall shape of the transmission through this Crow superlattice is qualitatively changed resulting in a single sharp transmission resonance located at Ω = 0s−1 instead of a broad transmission band. The modulated coupling therefore allows the Crow gyroscope to operate without phase biasing and with sensitivities suitable for inertial navigation even with the inclusion of resonator losses.
Pamela D. Waterman - One of the best experts on this subject based on the ideXlab platform.
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Jim Crow and estrogen-receptor-negative breast cancer: US-born black and white non-Hispanic women, 1992–2012
Cancer Causes & Control, 2017Co-Authors: Nancy Krieger, Jaquelyn L. Jahn, Pamela D. WatermanAbstract:Purpose It is unknown whether Jim Crow—i.e., legal racial discrimination practiced by 21 US states and the District of Columbia and outlawed by the US Civil Rights Act in 1964—affects US cancer outcomes. We hypothesized that Jim Crow birthplace would be associated with higher risk of estrogen-receptor-negative (ER−) breast tumors among US black, but not white, women and also a higher black versus white risk for ER− tumors. Methods We analyzed data from the SEER 13 registry group (excluding Alaska) for 47,157 US-born black non-Hispanic and 348,514 US-born white non-Hispanic women, aged 25–84 inclusive, diagnosed with primary invasive breast cancer between 1 January 1992 and 31 December 2012. Results Jim Crow birthplace was associated with increased odds of ER− breast cancer only among the black, not white women, with the effect strongest for women born before 1965. Among black women, the odds ratio (OR) for an ER− tumor, comparing women born in a Jim Crow versus not Jim Crow state, equaled 1.09 (95% confidence interval [CI] 1.06, 1.13), on par with the OR comparing women in the worst versus best census tract socioeconomic quintiles (1.15; 95% CI 1.07, 1.23). The black versus white OR for ER− was higher among women born in Jim Crow versus non-Jim Crow states (1.41 [95% CI 1.13, 1.46] vs. 1.27 [95% CI 1.24, 1.31]). Conclusions The unique Jim Crow effect for US black women for breast cancer ER status underscores why analysis of racial/ethnic inequities must be historically contextualized.
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jim Crow and estrogen receptor negative breast cancer us born black and white non hispanic women 1992 2012
Cancer Causes & Control, 2017Co-Authors: Nancy Krieger, Jaquelyn L. Jahn, Pamela D. WatermanAbstract:It is unknown whether Jim Crow—i.e., legal racial discrimination practiced by 21 US states and the District of Columbia and outlawed by the US Civil Rights Act in 1964—affects US cancer outcomes. We hypothesized that Jim Crow birthplace would be associated with higher risk of estrogen-receptor-negative (ER−) breast tumors among US black, but not white, women and also a higher black versus white risk for ER− tumors. We analyzed data from the SEER 13 registry group (excluding Alaska) for 47,157 US-born black non-Hispanic and 348,514 US-born white non-Hispanic women, aged 25–84 inclusive, diagnosed with primary invasive breast cancer between 1 January 1992 and 31 December 2012. Jim Crow birthplace was associated with increased odds of ER− breast cancer only among the black, not white women, with the effect strongest for women born before 1965. Among black women, the odds ratio (OR) for an ER− tumor, comparing women born in a Jim Crow versus not Jim Crow state, equaled 1.09 (95% confidence interval [CI] 1.06, 1.13), on par with the OR comparing women in the worst versus best census tract socioeconomic quintiles (1.15; 95% CI 1.07, 1.23). The black versus white OR for ER− was higher among women born in Jim Crow versus non-Jim Crow states (1.41 [95% CI 1.13, 1.46] vs. 1.27 [95% CI 1.24, 1.31]). The unique Jim Crow effect for US black women for breast cancer ER status underscores why analysis of racial/ethnic inequities must be historically contextualized.
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the unique impact of abolition of jim Crow laws on reducing inequities in infant death rates and implications for choice of comparison groups in analyzing societal determinants of health
American Journal of Public Health, 2013Co-Authors: Nancy Krieger, Pamela D. Waterman, Jarvis T Chen, Brent A Coull, Jason BeckfieldAbstract:Objectives. We explored associations between the abolition of Jim Crow laws (i.e., state laws legalizing racial discrimination overturned by the 1964 US Civil Rights Act) and birth cohort trends in infant death rates.Methods. We analyzed 1959 to 2006 US Black and White infant death rates within and across sets of states (polities) with and without Jim Crow laws.Results. Between 1965 and 1969, a unique convergence of Black infant death rates occurred across polities; in 1960 to 1964, the Black infant death rate was 1.19 times higher (95% confidence interval [CI] = 1.18, 1.20) in the Jim Crow polity than in the non–Jim Crow polity, whereas in 1970 to 1974 the rate ratio shrank to and remained at approximately 1 (with the 95% CI including 1) until 2000, when it rose to 1.10 (95% CI = 1.08, 1.12). No such convergence occurred for Black–White differences in infant death rates or for White infants.Conclusions. Our results suggest that abolition of Jim Crow laws affected US Black infant death rates and that vali...
Amnon Yariv - One of the best experts on this subject based on the ideXlab platform.
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Coupled resonator optical waveguides (Crow)
Advanced Optical and Quantum Memories and Computing II, 2005Co-Authors: Jacob Scheuer, Joyce K. S. Poon, George T. Paloczi, Amnon YarivAbstract:We investigate theoretically and experimentally the characteristics, performance and possible applications of coupled resonator optical waveguides (Crows). The ability to engineer the dispersion properties of a Crow and especially the ability to realize ultra-slow group velocities paves the way for various applications such as delay lines, optical memories and all-optical switching. Simple analytic expressions for the time delay, usable bandwidth and overall losses in Crow delay lines are derived and compared to exact numerical simulation. Good quantitative agreement is found between the theoretical transmission function obtained by transfer matrix formalism and the measurement of a Crow interferometer realized in polymer material.
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propagation and second harmonic generation of electromagnetic waves in a coupled resonator optical waveguide
Journal of The Optical Society of America B-optical Physics, 2000Co-Authors: Reginald K Lee, Amnon YarivAbstract:Using both the tight-binding approximation and the finite-difference time domain method, we analyze two types of coupled-resonator optical waveguide (Crow), a coupled-microdisks waveguide and a waveguide composed of coupled defect cavities in a two-dimensional photonic crystal. We find that the dispersion relation of the Crow band can be simply described by a small coupling parameter , and the spatial characteristics of the Crow modes remain the same as those of the single-resonator high Q modes. As applications of these unique properties, we demonstrate that Crows can be utilized in constructing waveguides without cross talk and enhance the efficiency of second-harmonic generation.
Nancy Krieger - One of the best experts on this subject based on the ideXlab platform.
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Jim Crow and estrogen-receptor-negative breast cancer: US-born black and white non-Hispanic women, 1992–2012
Cancer Causes & Control, 2017Co-Authors: Nancy Krieger, Jaquelyn L. Jahn, Pamela D. WatermanAbstract:Purpose It is unknown whether Jim Crow—i.e., legal racial discrimination practiced by 21 US states and the District of Columbia and outlawed by the US Civil Rights Act in 1964—affects US cancer outcomes. We hypothesized that Jim Crow birthplace would be associated with higher risk of estrogen-receptor-negative (ER−) breast tumors among US black, but not white, women and also a higher black versus white risk for ER− tumors. Methods We analyzed data from the SEER 13 registry group (excluding Alaska) for 47,157 US-born black non-Hispanic and 348,514 US-born white non-Hispanic women, aged 25–84 inclusive, diagnosed with primary invasive breast cancer between 1 January 1992 and 31 December 2012. Results Jim Crow birthplace was associated with increased odds of ER− breast cancer only among the black, not white women, with the effect strongest for women born before 1965. Among black women, the odds ratio (OR) for an ER− tumor, comparing women born in a Jim Crow versus not Jim Crow state, equaled 1.09 (95% confidence interval [CI] 1.06, 1.13), on par with the OR comparing women in the worst versus best census tract socioeconomic quintiles (1.15; 95% CI 1.07, 1.23). The black versus white OR for ER− was higher among women born in Jim Crow versus non-Jim Crow states (1.41 [95% CI 1.13, 1.46] vs. 1.27 [95% CI 1.24, 1.31]). Conclusions The unique Jim Crow effect for US black women for breast cancer ER status underscores why analysis of racial/ethnic inequities must be historically contextualized.
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jim Crow and estrogen receptor negative breast cancer us born black and white non hispanic women 1992 2012
Cancer Causes & Control, 2017Co-Authors: Nancy Krieger, Jaquelyn L. Jahn, Pamela D. WatermanAbstract:It is unknown whether Jim Crow—i.e., legal racial discrimination practiced by 21 US states and the District of Columbia and outlawed by the US Civil Rights Act in 1964—affects US cancer outcomes. We hypothesized that Jim Crow birthplace would be associated with higher risk of estrogen-receptor-negative (ER−) breast tumors among US black, but not white, women and also a higher black versus white risk for ER− tumors. We analyzed data from the SEER 13 registry group (excluding Alaska) for 47,157 US-born black non-Hispanic and 348,514 US-born white non-Hispanic women, aged 25–84 inclusive, diagnosed with primary invasive breast cancer between 1 January 1992 and 31 December 2012. Jim Crow birthplace was associated with increased odds of ER− breast cancer only among the black, not white women, with the effect strongest for women born before 1965. Among black women, the odds ratio (OR) for an ER− tumor, comparing women born in a Jim Crow versus not Jim Crow state, equaled 1.09 (95% confidence interval [CI] 1.06, 1.13), on par with the OR comparing women in the worst versus best census tract socioeconomic quintiles (1.15; 95% CI 1.07, 1.23). The black versus white OR for ER− was higher among women born in Jim Crow versus non-Jim Crow states (1.41 [95% CI 1.13, 1.46] vs. 1.27 [95% CI 1.24, 1.31]). The unique Jim Crow effect for US black women for breast cancer ER status underscores why analysis of racial/ethnic inequities must be historically contextualized.
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the unique impact of abolition of jim Crow laws on reducing inequities in infant death rates and implications for choice of comparison groups in analyzing societal determinants of health
American Journal of Public Health, 2013Co-Authors: Nancy Krieger, Pamela D. Waterman, Jarvis T Chen, Brent A Coull, Jason BeckfieldAbstract:Objectives. We explored associations between the abolition of Jim Crow laws (i.e., state laws legalizing racial discrimination overturned by the 1964 US Civil Rights Act) and birth cohort trends in infant death rates.Methods. We analyzed 1959 to 2006 US Black and White infant death rates within and across sets of states (polities) with and without Jim Crow laws.Results. Between 1965 and 1969, a unique convergence of Black infant death rates occurred across polities; in 1960 to 1964, the Black infant death rate was 1.19 times higher (95% confidence interval [CI] = 1.18, 1.20) in the Jim Crow polity than in the non–Jim Crow polity, whereas in 1970 to 1974 the rate ratio shrank to and remained at approximately 1 (with the 95% CI including 1) until 2000, when it rose to 1.10 (95% CI = 1.08, 1.12). No such convergence occurred for Black–White differences in infant death rates or for White infants.Conclusions. Our results suggest that abolition of Jim Crow laws affected US Black infant death rates and that vali...
Jacob Scheuer - One of the best experts on this subject based on the ideXlab platform.
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side coupled adjacent resonators Crow formation of mid band zero group velocity
Optics Express, 2009Co-Authors: Ori Weiss, Jacob ScheuerAbstract:A side coupled adjacent resonators Crow (SC-Crow) structure is presented. The dispersion relation, group velocity and GVD are found numerically and analytically using a transfer matrix method. The structure shows fast and slow transmission of light. Zero group velocity is present at the ends of the Brillouin zone, but also in other parts of it. Infinite and finite SC-Crow structures show band gaps created by Bragg and ring resonances. Pulse propagation at slow group velocities is highly dispersive, but easier to manage at higher group velocities. The differences between SC-Crow, SCISSOR and Crow waveguides are studied in detail.
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Coupled resonator optical waveguides (Crow)
Advanced Optical and Quantum Memories and Computing II, 2005Co-Authors: Jacob Scheuer, Joyce K. S. Poon, George T. Paloczi, Amnon YarivAbstract:We investigate theoretically and experimentally the characteristics, performance and possible applications of coupled resonator optical waveguides (Crows). The ability to engineer the dispersion properties of a Crow and especially the ability to realize ultra-slow group velocities paves the way for various applications such as delay lines, optical memories and all-optical switching. Simple analytic expressions for the time delay, usable bandwidth and overall losses in Crow delay lines are derived and compared to exact numerical simulation. Good quantitative agreement is found between the theoretical transmission function obtained by transfer matrix formalism and the measurement of a Crow interferometer realized in polymer material.