5,381 research outputs found

    Ultracold atoms at unitarity within quantum Monte Carlo

    Full text link
    Variational and diffusion quantum Monte Carlo (VMC and DMC) calculations of the properties of the zero-temperature fermionic gas at unitarity are reported. The ratio of the energy of the interacting to the non-interacting gas for a system of 128 particles is calculated to be 0.4517(3) in VMC and 0.4339(1) in the more accurate DMC method. The spherically-averaged pair-correlation functions, momentum densities, and one-body density matrices are very similar in VMC and DMC, but the two-body density matrices and condensate fractions show some differences. Our best estimate of the condensate fraction of 0.51 is a little smaller than values from other quantum Monte Carlo calculations

    Quantum Monte Carlo study of the Ne atom and the Ne+ ion

    Full text link
    We report all-electron and pseudopotential calculations of the ground-stateenergies of the neutral Ne atom and the Ne+ ion using the variational and diffusion quantum Monte Carlo (DMC) methods. We investigate different levels of Slater-Jastrow trial wave function: (i) using Hartree-Fock orbitals, (ii) using orbitals optimized within a Monte Carlo procedure in the presence of a Jastrow factor, and (iii) including backflow correlations in the wave function. Small reductions in the total energy are obtained by optimizing the orbitals, while more significant reductions are obtained by incorporating backflow correlations. We study the finite-time-step and fixed-node biases in the DMC energy and show that there is a strong tendency for these errors to cancel when the first ionization potential (IP) is calculated. DMC gives highly accurate values for the IP of Ne at all the levels of trial wave function that we have considered

    Blood lead levels in pregnant women of high and low socioeconomic status in Mexico City.

    Get PDF
    This study examined the determinants of blood lead (BPb) in 513 pregnant women in Mexico City: 311 from public hospital prenatal clinics, representing primarily women of low socioeconomic status (SES), and 202 from private hospitals, primarily women of high SES. Overall, BPb levels ranged from 1.38 to 29 micrograms/dl, with geometric means of 6.7 and 11.12 micrograms/dl for women from private and public hospitals, respectively. The crude geometric means difference obtained by t-test was 4.42 (p < 0.001). BPb was measured from January 1994 to August 1995 and showed higher levels during fall and winter and lower levels during spring and summer. The main BPb determinants were the use of lead-glazed ceramics in women from public hospitals and season of the year in women from private hospitals. Consumption of tortillas (corn bread rich in calcium) decreased BPb levels in the lower SES group, but the relationship was not statistically significant (p > 0.05). Consumption of milk products significantly (p < 0.05) reduced BPb levels in the higher SES group. In 112 women whose diets were deficient in calcium, taking calcium supplements lowered their blood lead levels about 7 micrograms/dl. A predictive model fitted to these data, using the strongest predictors plus gestational age, showed a difference of 14 micrograms/dl between the best and worst scenarios in women from public hospitals. Avoiding use of lead-glazed ceramics, consuming diets rich in calcium, and, if needed, taking calcium supplements, would be expected to result in substantial lowering of BPb, especially in pregnant women of low socioeconomic status

    Strong Discontinuities in the Complex Photonic Band Structure of Transmission Metallic Gratings

    Get PDF
    Complex photonic band structures (CPBS) of transmission metallic gratings with rectangular slits are shown to exhibit strong discontinuities that are not evidenced in the usual energetic band structures. These discontinuities are located on Wood's anomalies and reveal unambiguously two different types of resonances, which are identified as horizontal and vertical surface-plasmon resonances. Spectral position and width of peaks in the transmission spectrum can be directly extracted from CPBS for both kinds of resonances.Comment: 4 pages, 4 figures, REVTeX version

    A Novel Clinical and Stress Cardiac Magnetic Resonance (C-CMR-10) Score to Predict Long-Term All-Cause Mortality in Patients with Known or Suspected Chronic Coronary Syndrome

    Full text link
    [EN] Vasodilator stress cardiac magnetic resonance (stressCMR) has shown robust diagnostic and prognostic value in patients with known or suspected chronic coronary syndrome (CCS). However, it is unknown whether integration of stressCMR with clinical variables in a simple clinical-imaging score can straightforwardly predict all-cause mortality in this population. We included 6187 patients in a large registry that underwent stressCMR for known or suspected CCS. Several clinical and stressCMR variables were collected, such as left ventricular ejection fraction (LVEF) and ischemic burden (number of segments with stress-induced perfusion defects (PD)). During a median follow-up of 5.56 years, we registered 682 (11%) all-cause deaths. The only independent predictors of all-cause mortality in multivariable analysis were age, male sex, diabetes mellitus (DM), LVEF and ischemic burden. Based on the weight of the chi-square increase at each step of the multivariable analysis, we created a simple clinical-stressCMR (C-CMR-10) score that included these variables (age >= 65 years = 3 points, LVEF 5 segments = 1 point). This 0 to 10 points C-CMR-10 score showed good performance to predict all-cause annualized mortality rate ranging from 0.29%/year (score = 0) to >4.6%/year (score >= 7). The goodness of the model and of the C-CMR-10 score was separately confirmed in 2 internal cohorts (n> 3000 each). We conclude that a novel and simple clinical-stressCMR score, which includes clinical and stressCMR variables, can provide robust prediction of the risk of long-term all-cause mortality in a population of patients with known or suspected CCS.This work was supported by the Instituto de Salud Carlos III and co-funded by Fondo Europeo de Desarrollo Regional (FEDER) (grant numbers PI17/01836 and CIBERCV16/11/00486).Marcos-Garces, V.; Gavara-Doñate, J.; Monmeneu-Menadas, JV.; Lopez-Lereu, MP.; Pérez, N.; Rios-Navarro, C.; De Dios, E.... (2020). A Novel Clinical and Stress Cardiac Magnetic Resonance (C-CMR-10) Score to Predict Long-Term All-Cause Mortality in Patients with Known or Suspected Chronic Coronary Syndrome. Journal of Clinical Medicine. 9(6):1-13. https://doi.org/10.3390/jcm9061957S11396Hendel, R. C., Friedrich, M. G., Schulz-Menger, J., Zemmrich, C., Bengel, F., Berman, D. S., … Nagel, E. (2016). CMR First-Pass Perfusion for Suspected Inducible Myocardial Ischemia. JACC: Cardiovascular Imaging, 9(11), 1338-1348. doi:10.1016/j.jcmg.2016.09.010Chang, S.-A., & Kim, R. J. (2016). The Use of Cardiac Magnetic Resonance in Patients with Suspected Coronary Artery Disease: A Clinical Practice Perspective. Journal of Cardiovascular Ultrasound, 24(2), 96. doi:10.4250/jcu.2016.24.2.96Kiaos, A., Tziatzios, I., Hadjimiltiades, S., Karvounis, C., & Karamitsos, T. D. (2018). Diagnostic performance of stress perfusion cardiac magnetic resonance for the detection of coronary artery disease. International Journal of Cardiology, 252, 229-233. doi:10.1016/j.ijcard.2017.11.066Li, M., Zhou, T., Yang, L., Peng, Z., Ding, J., & Sun, G. (2014). Diagnostic Accuracy of Myocardial Magnetic Resonance Perfusion to Diagnose Ischemic Stenosis With Fractional Flow Reserve as Reference. JACC: Cardiovascular Imaging, 7(11), 1098-1105. doi:10.1016/j.jcmg.2014.07.011Siontis, G. C., Mavridis, D., Greenwood, J. P., Coles, B., Nikolakopoulou, A., Jüni, P., … Windecker, S. (2018). Outcomes of non-invasive diagnostic modalities for the detection of coronary artery disease: network meta-analysis of diagnostic randomised controlled trials. BMJ, k504. doi:10.1136/bmj.k504Nagel, E., Greenwood, J. P., McCann, G. P., Bettencourt, N., Shah, A. M., Hussain, S. T., … Berry, C. (2019). Magnetic Resonance Perfusion or Fractional Flow Reserve in Coronary Disease. New England Journal of Medicine, 380(25), 2418-2428. doi:10.1056/nejmoa1716734Siontis, G. C., Branca, M., Serruys, P., Silber, S., Räber, L., Pilgrim, T., … Hunziker, L. (2019). Impact of left ventricular function on clinical outcomes among patients with coronary artery disease. European Journal of Preventive Cardiology, 26(12), 1273-1284. doi:10.1177/2047487319841939Buckert, D., Kelle, S., Buss, S., Korosoglou, G., Gebker, R., Birkemeyer, R., … Bernhardt, P. (2016). Left ventricular ejection fraction and presence of myocardial necrosis assessed by cardiac magnetic resonance imaging correctly risk stratify patients with stable coronary artery disease: a multi-center all-comers trial. Clinical Research in Cardiology, 106(3), 219-229. doi:10.1007/s00392-016-1042-5Catalano, O., Moro, G., Perotti, M., Frascaroli, M., Ceresa, M., Antonaci, S., … Priori, S. G. (2012). Late gadolinium enhancement by cardiovascular magnetic resonance is complementary to left ventricle ejection fraction in predicting prognosis of patients with stable coronary artery disease. Journal of Cardiovascular Magnetic Resonance, 14(1). doi:10.1186/1532-429x-14-29Lipinski, M. J., McVey, C. M., Berger, J. S., Kramer, C. M., & Salerno, M. (2013). Prognostic Value of Stress Cardiac Magnetic Resonance Imaging in Patients With Known or Suspected Coronary Artery Disease. Journal of the American College of Cardiology, 62(9), 826-838. doi:10.1016/j.jacc.2013.03.080Gargiulo, P., Dellegrottaglie, S., Bruzzese, D., Savarese, G., Scala, O., Ruggiero, D., … Filardi, P. P. (2013). The Prognostic Value of Normal Stress Cardiac Magnetic Resonance in Patients With Known or Suspected Coronary Artery Disease. Circulation: Cardiovascular Imaging, 6(4), 574-582. doi:10.1161/circimaging.113.000035Kwong, R. Y., Ge, Y., Steel, K., Bingham, S., Abdullah, S., Fujikura, K., … Simonetti, O. P. (2019). Cardiac Magnetic Resonance Stress Perfusion Imaging for Evaluation of Patients With Chest Pain. Journal of the American College of Cardiology, 74(14), 1741-1755. doi:10.1016/j.jacc.2019.07.074Marcos-Garces, V., Gavara, J., Monmeneu, J. V., Lopez-Lereu, M. P., Bosch, M. J., Merlos, P., … Bodi, V. (2020). Vasodilator Stress CMR and All-Cause Mortality in Stable Ischemic Heart Disease. JACC: Cardiovascular Imaging, 13(8), 1674-1686. doi:10.1016/j.jcmg.2020.02.027Heitner, J. F., Kim, R. J., Kim, H. W., Klem, I., Shah, D. J., Debs, D., … Judd, R. M. (2019). Prognostic Value of Vasodilator Stress Cardiac Magnetic Resonance Imaging. JAMA Cardiology, 4(3), 256. doi:10.1001/jamacardio.2019.0035Bodi, V., Sanchis, J., Lopez-Lereu, M. P., Nunez, J., Mainar, L., Monmeneu, J. V., … Llacer, A. (2007). Prognostic Value of Dipyridamole Stress Cardiovascular Magnetic Resonance Imaging in Patients With Known or Suspected Coronary Artery Disease. Journal of the American College of Cardiology, 50(12), 1174-1179. doi:10.1016/j.jacc.2007.06.016Bodi, V., Husser, O., Sanchis, J., Núñez, J., Monmeneu, J. V., López-Lereu, M. P., … Llacer, Á. (2012). Prognostic Implications of Dipyridamole Cardiac MR Imaging: A Prospective Multicenter Registry. Radiology, 262(1), 91-100. doi:10.1148/radiol.11110134Ponikowski, P., Voors, A. A., Anker, S. D., Bueno, H., Cleland, J. G. F., Coats, A. J. S., … van der Meer, P. (2016). 2016 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. European Heart Journal, 37(27), 2129-2200. doi:10.1093/eurheartj/ehw128Marschner, I. C., Colquhoun, D., Simes, R. J., Glasziou, P., Harris, P., Singh, B. B., … Tonkin, A. (2001). Long-term risk stratification for survivors of acute coronary syndromes. Journal of the American College of Cardiology, 38(1), 56-63. doi:10.1016/s0735-1097(01)01360-2Knuuti, J., Wijns, W., Saraste, A., Capodanno, D., Barbato, E., Funck-Brentano, C., … Cuisset, T. (2019). 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. European Heart Journal, 41(3), 407-477. doi:10.1093/eurheartj/ehz425Klem, I., Shah, D. J., White, R. D., Pennell, D. J., van Rossum, A. C., Regenfus, M., … Kim, R. J. (2011). Prognostic Value of Routine Cardiac Magnetic Resonance Assessment of Left Ventricular Ejection Fraction and Myocardial Damage. Circulation: Cardiovascular Imaging, 4(6), 610-619. doi:10.1161/circimaging.111.964965Grothues, F., Smith, G. C., Moon, J. C. ., Bellenger, N. G., Collins, P., Klein, H. U., & Pennell, D. J. (2002). Comparison of interstudy reproducibility of cardiovascular magnetic resonance with two-dimensional echocardiography in normal subjects and in patients with heart failure or left ventricular hypertrophy. The American Journal of Cardiology, 90(1), 29-34. doi:10.1016/s0002-9149(02)02381-0Timmis, A., Raharja, A., Archbold, R. A., & Mathur, A. (2018). Validity of inducible ischaemia as a surrogate for adverse outcomes in stable coronary artery disease. Heart, 104(21), 1733-1738. doi:10.1136/heartjnl-2018-313230Pontone, G., Andreini, D., Bertella, E., Loguercio, M., Guglielmo, M., Baggiano, A., … Masci, P. G. (2015). Prognostic value of dipyridamole stress cardiac magnetic resonance in patients with known or suspected coronary artery disease: a mid-term follow-up study. European Radiology, 26(7), 2155-2165. doi:10.1007/s00330-015-4064-xHeydari, B., Juan, Y.-H., Liu, H., Abbasi, S., Shah, R., Blankstein, R., … Kwong, R. Y. (2016). Stress Perfusion Cardiac Magnetic Resonance Imaging Effectively Risk Stratifies Diabetic Patients With Suspected Myocardial Ischemia. Circulation: Cardiovascular Imaging, 9(4). doi:10.1161/circimaging.115.004136Vincenti, G., Masci, P. G., Monney, P., Rutz, T., Hugelshofer, S., Gaxherri, M., … Schwitter, J. (2017). Stress Perfusion CMR in Patients With Known and Suspected CAD. JACC: Cardiovascular Imaging, 10(5), 526-537. doi:10.1016/j.jcmg.2017.02.006Buckert, D., Cieslik, M., Tibi, R., Radermacher, M., Rottbauer, W., & Bernhardt, P. (2017). Cardiac magnetic resonance imaging derived quantification of myocardial ischemia and scar improves risk stratification and patient management in stable coronary artery disease. Cardiology Journal, 24(3), 293-304. doi:10.5603/cj.a2017.0036Zemrak, F., & Petersen, S. E. (2011). Late Gadolinium Enhancement CMR Predicts Adverse Cardiovascular Outcomes and Mortality in Patients With Coronary Artery Disease: Systematic Review and Meta-Analysis. Progress in Cardiovascular Diseases, 54(3), 215-229. doi:10.1016/j.pcad.2011.07.003El Aidi, H., Adams, A., Moons, K. G. M., Den Ruijter, H. M., Mali, W. P. T. M., Doevendans, P. A., … Leiner, T. (2014). Cardiac Magnetic Resonance Imaging Findings and the Risk of Cardiovascular Events in Patients With Recent Myocardial Infarction or Suspected or Known Coronary Artery Disease. Journal of the American College of Cardiology, 63(11), 1031-1045. doi:10.1016/j.jacc.2013.11.048Fox, K. A. A., Metra, M., Morais, J., & Atar, D. (2019). The myth of ‘stable’ coronary artery disease. Nature Reviews Cardiology, 17(1), 9-21. doi:10.1038/s41569-019-0233-ySchiele, F., Ecarnot, F., & Chopard, R. (2017). Coronary artery disease: Risk stratification and patient selection for more aggressive secondary prevention. European Journal of Preventive Cardiology, 24(3_suppl), 88-100. doi:10.1177/2047487317706586Fordyce, C. B., Douglas, P. S., Roberts, R. S., Hoffmann, U., Al-Khalidi, H. R., … Patel, M. R. (2017). Identification of Patients With Stable Chest Pain Deriving Minimal Value From Noninvasive Testing. JAMA Cardiology, 2(4), 400. doi:10.1001/jamacardio.2016.5501Papireddy, M. R., Lavie, C. J., Deoker, A., Mamudu, H., & Paul, T. K. (2018). New Algorithm for the Prediction of Cardiovascular Risk in Symptomatic Adults with Stable Chest Pain. Current Cardiology Reports, 20(5). doi:10.1007/s11886-018-0973-
    corecore