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1.
J Chem Phys ; 138(1): 014309, 2013 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-23298043

RESUMEN

The potential energy function of the ground X (3)Σ(g)(-) electronic state of (16)O(2) has been obtained in analytical form by employing a fully quantum-mechanical direct potential fitting method. Term values generated from highly precise Dunham coefficients were employed in the direct fit, yielding a potential energy function that is accurate up to υ = 31, or up to an energy that is 90% of the dissociation limit. The term values are represented with a standard deviation of 0.0031 cm(-1) by the quantum-mechanical eigenvalues of the derived potential energy function. There is considerable evidence for N-dependent nonadiabatic coupling between the ground X (3)Σ(g)(-) electronic state and the b (1)Σ(g)(+) excited electronic state.

2.
J Chem Phys ; 132(9): 094105, 2010 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-20210387

RESUMEN

A collection of 16,544 fluorescence series spectroscopic line positions involving the A (1)Sigma(u)(+)-->X (1)Sigma(g)(+) transition in Cs(2) has been analyzed by a modern direct potential fitting procedure to generate the first fully analytical potential energy function for the ground electronic state, and precise energy term values for the excited A (1)Sigma(u)(+) state. The potential function yields an accurate representation of spectroscopic data that span 99.24% of the well depth and the number of fitted parameters is significantly less than half the number of parameters determined in conventional Dunham analyses. A novel variant of the Morse/long-range potential model has been employed in the representation of the ground state potential, and a critical comparison has been made with an extended modified Lennard-Jones potential model. Proper account has been taken of the known long-range van der Waals form of the potential, and our final potential function is determined with constrained literature values of the C(8) and C(10) dispersion energy coefficients, along with a fitted value of C(6)=3.31(5) x 10(7) cm(-1) A(6)=6870(100) a.u. The fitted dissociation energy (D(e)) is compared with the precisely known value based on the recent analysis of data from a two-photon transfer process (STIRAP) in ultracold Cs atoms. It is concluded that hyperfine effects in the X (1)Sigma(g)(+) state are not negligible, and that the estimate of D(e)=3649.84(7) cm(-1) obtained in this work represents an effective dissociation limit lying between the two lowest hyperfine limits. Precise rotational and centrifugal distortion constants for the ground electronic state have also been calculated through conventional perturbation theory. These estimates are fully consistent with the derived potential function and the experimental spectroscopic information.


Asunto(s)
Algoritmos , Cesio/química , Espectrometría de Masas/métodos , Modelos Químicos , Simulación por Computador , Dimerización
3.
Prim Care Diabetes ; 11(2): 112-118, 2017 04.
Artículo en Inglés | MEDLINE | ID: mdl-28131651

RESUMEN

Obesity rates in Cyprus are very high and epidemiological information on type 2 diabetes mellitus is limited. The correlates of type 2 diabetes among adults remain unknown in the Cypriot population. Thus, the purpose of this study is to provide the first national estimate of the prevalence of type 2 diabetes and investigate its correlates. A randomly stratified nationally sample of 1001 adults aged 18-80 participated in the study. Only 950 subjects completed the study. All subjects were free of any diseases (known diabetes, kidney, liver), medication and supplementation. The overall prevalence of diabetes and pre-diabetes based on WHO criteria was 9.2% and 16.3%, respectively. After adjusting for age, energy intake, smoking and physical activity participants with obesity (BMI) (OR=2.00, P<0.001), waist circumference (WC) (OR=2.08, P<0.001), hypertension (HT) (OR=1.99, P<0.001) and hypercholesterolemia (HC) (OR=2.07, P<0.007) were most likely to develop T2DM compared with the normal ones. The odds of having diabetes were also found significant between subjects with high levels of triglycerides (TG) (OR=1.49, P<0.007), compared with the normal ones and between subjects with low levels of HDL (OR=1.44, P<0.008) compared with the ones with high levels of HDL. The prevalence of type 2 diabetes in Cyprus is relatively medium-high. However, the pre-diabetes rates are very high showing a promising increase toward total rates of type 2 diabetes. Obesity, HT, WC, TG, HC and low HDL are all strong correlates of type 2 diabetes. Healthy education programs should be initiated for young and older-aged people and those with described abnormal risk factors.


Asunto(s)
Diabetes Mellitus Tipo 2/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Presión Sanguínea , Índice de Masa Corporal , Comorbilidad , Chipre/epidemiología , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/diagnóstico , Femenino , Humanos , Hipercolesterolemia/sangre , Hipercolesterolemia/diagnóstico , Hipercolesterolemia/epidemiología , Hipertensión/diagnóstico , Hipertensión/epidemiología , Hipertensión/fisiopatología , Estilo de Vida , Lípidos/sangre , Modelos Logísticos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Obesidad/diagnóstico , Obesidad/epidemiología , Oportunidad Relativa , Estado Prediabético/sangre , Estado Prediabético/diagnóstico , Estado Prediabético/epidemiología , Prevalencia , Factores de Riesgo , Circunferencia de la Cintura , Adulto Joven
4.
J Phys Chem A ; 110(19): 6261-70, 2006 May 18.
Artículo en Inglés | MEDLINE | ID: mdl-16686460

RESUMEN

All literature pure rotational and vibration-rotational spectroscopic data on the ground X (1)Sigma(+) electronic state of HF and DF, together with the entire set of spectroscopic line positions from analyses of the B (1)Sigma(+) --> X (1)Sigma(+) emission band systems of HF and DF, have been used in a global least-squares fit to the radial Hamiltonian operators, in compact analytic form, for both electronic states. With a data set consisting of 6157 spectroscopic line positions, the reduced standard deviation of the fit was sigma = 1.028. Sets of quantum mechanically significant rotational and centrifugal distortion constants were calculated for both electronic states using Rayleigh-Schrödinger perturbation theory.


Asunto(s)
Algoritmos , Electrones , Ácido Fluorhídrico/química , Análisis de los Mínimos Cuadrados , Análisis Espectral , Teoría Cuántica
5.
J Chem Phys ; 121(7): 2992-3008, 2004 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-15291609

RESUMEN

A collection of 21,559 highly precise spectroscopic line positions from pure rotational and vibration-rotational spectra for seven isotopomers of carbon monoxide in the X1sigma+ ground electronic state has been employed in direct least-squares fits of the rovibrational Hamiltonian operator obtained from Watson's work [J. Mol. Spectrosc. 80, 411 (1980)] and that obtained by Herman and Ogilvie [Adv. Chem. Phys 103, 187 (1998)]. Fully analytical models are used for the various functions, including the Born-Oppenheimer internuclear potential function, and an account is taken of breakdown of the Born-Oppenheimer approximation. The resulting representations are more compact than currently available traditional Ukl/deltakl extended Dunham descriptions, and they generate quantum-mechanical eigenvalues that reproduce reliably the spectroscopic line positions to within the associated measurement uncertainties. Rayleigh-Schrodinger perturbation theory has been used to calculate highly accurate rotational and centrifugal distortion constants Bupsilon-Oupsilon for nine isotopomers of carbon monoxide. These constants are just as successful at reconstructing the observed spectroscopic information as the quantum-mechanical eigenvalues of the fitted Hamiltonian operators.

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