663 research outputs found

    Possibility of an ultra-precise optical clock using the 61S063P0o6 ^1S_0 \to 6 ^3P^o_0 transition in 171,173^{171, 173}Yb atoms held in an optical lattice

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    We report calculations designed to assess the ultimate precision of an atomic clock based on the 578 nm 61S0>63P0o6 ^1S_0 --> 6 ^3P^o_0 transition in Yb atoms confined in an optical lattice trap. We find that this transition has a natural linewidth less than 10 mHz in the odd Yb isotopes, caused by hyperfine coupling. The shift in this transition due to the trapping light acting through the lowest order AC polarizability is found to become zero at the magic trap wavelength of about 752 nm. The effects of Rayleigh scattering, higher-order polarizabilities, vector polarizability, and hyperfine induced electronic magnetic moments can all be held below a mHz (about a part in 10^{18}), except in the case of the hyperpolarizability larger shifts due to nearly resonant terms cannot be ruled out without an accurate measurement of the magic wavelength.Comment: 4 pages, 1 figur

    Development of wirelessly-powered, extracranial brain activator (ECBA) in a large animal model for the future non-invasive human neuromodulation

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    As transcranial electrical stimulation (tES) is an emerging and promising technique for neuromodulation, we developed a novel device; wirelessly-powered, extracranial brain activator (ECBA), which is mounted subcutaneously, and its neuromodulation effect was investigated. The oscillatory changes in electrocorticography (EcoG) were analyzed from two types of stimulation. Two weeks prior to the recording experiment, we underwent surgery for implantation of subdural strips and ECBA module over centroparietal regions of anesthetized beagles. Low-frequency stimulation (LFS) and subsequent high-frequency stimulation (HFS) protocols (600 pulses respectively) were applied. Then, the power changes before and after each stimulation in five different bands were compared. A significantly larger voltage difference with subcutaneous than transcutaneous stimulation measured at EcoG channels indicated a substantial current attenuation between the skin and skull. Compared with the baseline, all subjects showed consistently decreased delta power and increased gamma power after HFS. LFS also induced a similar, but opposite, pattern of power change in four beagles. The results from this study indicate that LFS and HFS with our novel ECBA can consistently and effectively modulate neural activity of the cortex, inducing neural inhibition and facilitation functions, respectively. Future studies are necessary to further ensuring a consistent efficacy and long-term safety.11Ysciescopu

    Patient characteristics and health system factors associated with adjuvant radiation therapy receipt in older women with early-stage endometrial cancer

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    Introduction: Among women with early-stage endometrial cancer (EC), age, stage, grade, and histology are used to determine fitness for adjuvant radiation therapy (RT) administration. We examined non-cancer factors associated with adjuvant RT receipt in older women with early-stage EC. Materials & methods: Using data from the Surveillance Epidemiology and End Results cancer registry program linked with Medicare claims, we identified 25,654 women (aged ≥66 years) diagnosed with first primary stage I-II EC during 2004–2017 who underwent a hysterectomy. Diagnosis and procedure codes were used to identify adjuvant RT claims filed for the seven-month period post-hysterectomy. Multivariable log-binomial regression was used to estimate adjuvant RT prevalence associated with patient characteristics and health system factors after adjustment for age, frailty, and endometrial factors. Results: Adjuvant RT was less commonly administered to Asian American and Pacific Islander patients than non-Hispanic White patients (Prevalence ratio [PR], 0.84; 95% confidence interval [CI], 0.73 to 0.97). Compared to women treated in the Northeast region, women treated other regions of the US were less likely to undergo adjuvant RT (PR, 0.75; 95% CI, 0.71 to 0.79). Residing in rural or high neighborhood-poverty counties was associated with lower adjuvant RT administration. Higher comorbidity score was not associated with reduced prevalence of adjuvant RT receipt; however, women with high probability of predicted probability of frailty were less likely to undergo adjuvant RT (PR, 0.67; 95% CI, 0.55 to 0.81) compared to women with low probability of frailty. Women who received lymph node assessment were more likely to undergo adjuvant RT compared to women who did not (PR, 1.43; 95% CI, 1.34 to 1.51). Women treated by a gynecologic oncologist were more likely to undergo adjuvant RT compared to women treated by a non-gynecologic oncologist (PR 1.09; 95% CI, 1.04 to 1.14). Adjuvant RT was more commonly administered to women treated in larger academic hospitals. Discussion: Findings suggest that various non-cancer factors affect the delivery of adjuvant RT to older women with early-stage EC in real-world oncology practice. Advancing our understanding of factors associated with adjuvant RT administration may help expand equitable access to RT

    Adjuvant radiation therapy and health-related quality of life among older women with early-stage endometrial cancer: an analysis using the SEER-MHOS linkage

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    Purpose: Radiation therapy (RT) has been associated with decreased health-related quality of life (HRQOL) in clinical trials of early-stage endometrial cancer (EC), but few studies have examined the association in real-world settings. We assessed HRQOL associated with adjuvant RT for older women with early-stage EC within a large U.S. population-based registry resource. Methods: The Surveillance Epidemiology and End Results and the Medicare Health Outcomes Survey linkage (1998–2017) was used to identify women with early-stage EC aged ≥ 65 years at survey who received surgery and were diagnosed ≥ 1-year prior (n = 1,140). HRQOL was evaluated with the 36-item Short-Form Health Survey (SF-36) until 2006 and the Veterans RAND 12-Item Health Survey (VR-12) post 2006. Ordinary least squares regression was used to estimate mean difference (MD) in T scores and 95% confidence intervals (CIs) comparing treatment groups (surgery alone, adjuvant external beam radiation therapy [EBRT], or adjuvant vaginal brachytherapy [VBT]) after accounting for confounders using propensity score weighting. Results: Overall, RT was not associated with physical health (MD = 0.97; 95% CI = − 1.13, 3.07) or mental health (MD = − 0.78; 95% CI = − 2.60, 1.05) relative to surgery alone. In analyses by RT type, adjuvant VBT was associated with better general health on the SF-36/VR-12 subscale (MD = 3.59; 95% CI = 0.56, 6.62) relative to surgery alone. No statistically significant associations were observed for adjuvant VBT and physical or mental health, or for adjuvant EBRT and any HRQOL domain. Conclusion: Older women with early-stage EC treated with adjuvant RT did not report worse physical and mental HRQOL scores compared to those treated with surgery alone, though relevant symptoms should be evaluated further to fully understand the disease and treatment specific aspects of the HRQOL

    Adverse Urinary System Diagnoses among Older Women with Endometrial Cancer

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    Background: Endometrial cancer and its treatment may impact urinary system function, but few large-scale studies have examined urinary diagnoses among endometrial cancer survivors. We investigated the risk of several urinary outcomes among older women with endometrial cancer compared with similar women without a cancer history. Methods: Women aged 66þ years with an endometrial cancer diagnosis during 2004–2017 (N ¼ 44,386) and women without a cancer history (N ¼ 221,219) matched 1:5 on exact age, race/ ethnicity, and state were identified in the Surveillance, Epidemiology, and End Results-Medicare linked data. ICD-9 and -10 diagnosis codes were used to define urinary outcomes in the Medicare claims. HRs for urinary outcomes were estimated using multivariable Cox proportional hazards regression models. Results: Relative to women without cancer, endometrial cancer survivors were at an increased risk of several urinary system diagnoses, including lower urinary tract infection [HR, 2.36; 95% confidence interval (CI), 2.32–2.40], urinary calculus (HR, 2.22; 95% CI, 2.13–2.31), renal failure (HR, 2.28; 95% CI, 2.23–2.33), and chronic kidney disease (HR, 1.85; 95% CI, 1.81–1.90). Similar associations were observed in sensitivity analyses limited to 1þ and 5þ years after endometrial cancer diagnosis. Black race, higher comorbidity index, higher stage or grade cancer, non-endometrioid histology, and treatment with chemotherapy and/or radiation were often significant predictors of urinary outcomes among endometrial cancer survivors. Conclusions: Our results suggest that, among older women, the risk of urinary outcomes is elevated after endometrial cancer. Impact: Monitoring for urinary diseases may be a critical part of long-term survivorship care for older women with an endometrial cancer history

    Light-cone QCD Sum Rules for the Λ\Lambda Baryon Electromagnetic Form Factors and its magnetic moment

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    We present the light-cone QCD sum rules up to twist 6 for the electromagnetic form factors of the Λ\Lambda baryon. To estimate the magnetic moment of the baryon, the magnetic form factor is fitted by the dipole formula. The numerical value of our estimation is μΛ=(0.64±0.04)μN\mu_\Lambda=-(0.64\pm0.04)\mu_N, which is in accordance with the experimental data and the existing theoretical results. We find that it is twist 4 but not the leading twist distribution amplitudes that dominate the results.Comment: 13 page, 7 figures, accepted for publication in Euro. Phys. J.

    Nucleon Polarizabilities from Deuteron Compton Scattering within a Green's-Function Hybrid Approach

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    We examine elastic Compton scattering from the deuteron for photon energies ranging from zero to 100 MeV, using state-of-the-art deuteron wave functions and NN-potentials. Nucleon-nucleon rescattering between emission and absorption of the two photons is treated by Green's functions in order to ensure gauge invariance and the correct Thomson limit. With this Green's-function hybrid approach, we fulfill the low-energy theorem of deuteron Compton scattering and there is no significant dependence on the deuteron wave function used. Concerning the nucleon structure, we use Chiral Effective Field Theory with explicit \Delta(1232) degrees of freedom within the Small Scale Expansion up to leading-one-loop order. Agreement with available data is good at all energies. Our 2-parameter fit to all elastic γd\gamma d data leads to values for the static isoscalar dipole polarizabilities which are in excellent agreement with the isoscalar Baldin sum rule. Taking this value as additional input, we find \alpha_E^s= (11.3+-0.7(stat)+-0.6(Baldin)) x 10^{-4} fm^3 and \beta_M^s = (3.2-+0.7(stat)+-0.6(Baldin)) x 10^{-4} fm^3 and conclude by comparison to the proton numbers that neutron and proton polarizabilities are essentially the same.Comment: 47 pages LaTeX2e with 20 figures in 59 .eps files, using graphicx. Minor modifications; extended discussion of theoretical uncertainties of polarisabilities extraction. Version accepted for publication in EPJ

    Backward pion-nucleon scattering

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    A global analysis of the world data on differential cross sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3 GeV is performed in a Regge model. Including the NαN_\alpha, NγN_\gamma, Δδ\Delta_\delta and Δβ\Delta_\beta trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable uu, in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3 GeV. Our analysis suggests a G39G_{39} resonance with a mass of 2.83 GeV as member of the Δβ\Delta_{\beta} trajectory from the corresponding Chew-Frautschi plot.Comment: 12 pages, 16 figure

    Reaction Front in an A+B -> C Reaction-Subdiffusion Process

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    We study the reaction front for the process A+B -> C in which the reagents move subdiffusively. Our theoretical description is based on a fractional reaction-subdiffusion equation in which both the motion and the reaction terms are affected by the subdiffusive character of the process. We design numerical simulations to check our theoretical results, describing the simulations in some detail because the rules necessarily differ in important respects from those used in diffusive processes. Comparisons between theory and simulations are on the whole favorable, with the most difficult quantities to capture being those that involve very small numbers of particles. In particular, we analyze the total number of product particles, the width of the depletion zone, the production profile of product and its width, as well as the reactant concentrations at the center of the reaction zone, all as a function of time. We also analyze the shape of the product profile as a function of time, in particular its unusual behavior at the center of the reaction zone
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