80 research outputs found

    Tunneling Lifetime of the ttc/VIp Conformer of Glycine in Low-Temperature Matrices

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    Conformer ttc/VIp of glycine and glycine-N,N,O-d(3) has been prepared in low-temperature Ar, Kr, Xe, and N-2 matrices by near-infrared (NIR) laser irradiation of the first OH stretching overtone of conformer ttt/Ip. Glycine (and glycine-N,N,O-d(3)) ttc/VIp was found to convert back to ttt/Ip in the dark by hydrogen-atom tunneling. The observed half-lives of ttc/VIp in Ar, Kr, and Xe matrices at 12 K were 4.4 +/- 1 s (50.0 +/- 1 h), 4.0 +/- 1 s (48.0 +/- 1 h), and 2.8 +/- 1 s (99.3 +/- 2 h), respectively. In correspondence with the observation for the cis-to-trans conversion of formic and acetic acid, the tunneling half-life of glycine ttc/VIp in a N-2 matrix is more than 3 orders of magnitude longer (6.69 X 10(3) and 1.33 X 10(4) s for two different sites) than in noble gas matrices due to complex formation with the host molecules. The present results are important to understand the lack of experimental observation of some computationally predicted conformers of glycine and other amino acids

    Stability and secondary resonances in the spatial restricted three-body problem for small mass ratios

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    This paper is devoted to the study of secondary resonances and the stability of the Lagrangian point L-4 in the spatial restricted three-body problem for moderate mass ratios mu, meaning that mu <= 0.0045. However, we concentrated our investigations on small mass ratios mu <= 0.001, which represent the mass ratios for stable configurations of tadpole orbits in the Solar system. The stability is investigated by numerical methods, computing stability maps in different parameter planes. We started investigating the mass of the secondary: from Earth-mass bodies up to Jupiter-mass bodies. In addition, we changed the orbital elements (eccentricity and inclination) of the secondary and Trojan body. For this parameter space, we found high-order secondary resonances, which are present for various inclinations. To determine secondary resonances we used Rabe's equation and the frequency analysis. In addition, we investigated the stability in and around these secondary resonances

    Development and validation of a composite disease activity score for juvenile idiopathic arthritis

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    Objective. To develop and validate a composite disease activity score for juvenile idiopathic arthritis (JIA), the Juvenile Arthritis Disease Activity Score (JADAS). Methods. The JADAS includes 4 measures: physician global assessment of disease activity, parent/patient global assessment of well-being, active joint count, and erythrocyte sedimentation rate. These variables are part of the American College of Rheumatology (ACR) Pediatric 30 (Pedi 30), Pedi 50, and Pedi 70 criteria for improvement. Validation analyses were conducted on &gt;4,500 patients and included assessment of construct validity, discriminant validity, and responsiveness to change. Three versions of the JADAS were tested based on 71-joint (range 0 \u2013101), 27-joint (range 0 \u201357), or 10-joint (range 0 \u2013 40) counts. Statistical performances of the JADAS were compared with those of 2 rheumatoid arthritis composite scores, the Disease Activity Score in 28 joints (DAS28) and the Clinical Disease Activity Index (CDAI). Results. The JADAS demonstrated good construct validity, yielding strong correlations with JIA activity measures not included in the score and moderate correlations with the Childhood Health Assessment Questionnaire. Correlations obtained for the 3 JADAS versions were comparable, but superior to those yielded by the DAS28 and CDAI. The area under the curve of the JADAS predicted long-term disease outcome, measured as radiographic progression over 3 years. In 2 clinical trials, the JADAS discriminated well between ACR Pedi 30, Pedi 50, and Pedi 70 response and revealed strong responsiveness to clinical change. Conclusion. The JADAS was found to be a valid instrument for assessment of disease activity in JIA and is potentially applicable in standard clinical care, observational studies, and clinical trials

    Validity of a three-variable juvenile arthritis disease activity score in children with new-onset juvenile idiopathic arthritis

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    &lt;p&gt;Objectives To investigate the validity and feasibility of the Juvenile Arthritis Disease Activity Score (JADAS) in the routine clinical setting for all juvenile idiopathic arthritis (JIA) disease categories and explore whether exclusion of the erythrocyte sedimentation rate (ESR) from JADAS (the ‘JADAS3’) influences correlation with single markers of disease activity.&lt;/p&gt; &lt;p&gt;Methods JADAS-71, JADAS-27 and JADAS-10 were determined at baseline for an inception cohort of children with JIA in the Childhood Arthritis Prospective Study. JADAS3-71, JADAS3-27 and JADAS3-10 were determined using an identical formula but with exclusion of ESR. Correlation of JADAS with JADAS3 and single measures of disease activity/severity were determined by category.&lt;/p&gt; &lt;p&gt;Results Of 956 eligible children, sufficient data were available to calculate JADAS-71, JADAS-27 and JADAS-10 at baseline in 352 (37%) and JADAS3 in 551 (58%). The median (IQR) JADAS-71, JADAS-27 and JADAS-10 for all 352 children was 11 (5.9–18), 10.4 (5.7–17) and 11 (5.9–17.3), respectively. Median JADAS and JADAS3 varied significantly with the category (Kruskal–Wallis p=0.0001), with the highest values in children with polyarticular disease patterns. Correlation of JADAS and JADAS3 across all categories was excellent. Correlation of JADAS71 with single markers of disease activity/severity was good to moderate, with some variation across the categories. With the exception of ESR, correlation of JADAS3-71 was similar to correlation of JADAS-71 with the same indices.&lt;/p&gt; &lt;p&gt;Conclusions This study is the first to apply JADAS to all categories of JIA in a routine clinical setting in the UK, adding further information about the feasibility and construct validity of JADAS. For the majority of categories, clinical applicability would be improved by exclusion of the ESR.&lt;/p&gt
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