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Results for “Convergence”

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At least 37 records · Page 2Linked to original sources
PubMed1999

Prospective comparison of convergence insufficiency and normal binocular children on CIRS symptom surveys. Convergence Insufficiency and Reading Study (CIRS) group.

PURPOSE: To test the validity-related evidence of a child and a parent symptom survey developed by the Convergence Insufficiency and Reading Study (CIRS) group. METHODS: A case comparison method was used to measure differences in symptoms between 14 school-aged children (ages 8 to 13 years) with Convergence Insufficiency (CI) and 14 children with normal binocular vision (NBV). RESULTS: A pooled t-test indicated that CI children and their parents scored higher than the NBV children and their parents on the child's survey (p<0.001) and parent's survey (p<0.001), respectively. CI children also scored significantly higher (p<0.03) on the Conners' Rating Scale for Parents. CONCLUSIONS: The results suggest that the CIRS symptom survey is a valid instrument for differentiating CI children from those with normal binocular vision. Additionally, children in this age group were able to respond to a broad range of symptom questions associated with CI.

Adolescent↗
PubMed2002

The moderating influence of job performance dimensions on convergence of supervisory and peer ratings of job performance: unconfounding construct-level convergence and rating difficulty.

Meta-analysis was used to cumulate the correlations between supervisor and peer ratings for different dimensions of job performance. The general pattern in the data suggested that raters from the same organizational level disagree as much as raters from different levels. Methods were used to separate the effects of rating difficulty and lack of construct-level convergence on the correlation between supervisor and peer ratings. The authors found complete construct-level convergence for ratings of overall job performance, productivity, effort, job knowledge, quality, and leadership but not for ratings of administrative competence, interpersonal competence, and compliance or acceptance of authority. Higher rating difficulty was more strongly associated with lower mean observed peer-supervisor correlations than were construct-level disagreements between peers and supervisors. Implications for research and practice are discussed.

Adult↗
PubMed2000

Direct computation of multiple 3D flow convergence isovelocity surfaces from digital 3D reconstruction of colour Doppler data of the flow convergence region: an in vitro study with differently shaped orifices.

AIMS: Evaluation of the accuracy of direct computation of multiple three-dimensional (3D) flow convergence (FC) isovelocities by using digital reconstruction of colour Doppler data of the flow convergence region. METHODS AND RESULTS: We used a conventional ultrasound system (ATL HDI 3000) connected to a computer workstation via Ethernet link. The digital 3D datasets were directly transferred to a Silicon Graphic Imaging Octane workstation for later measurement. We generated nine pulsatile flows (20-60 ml/beat), with peak flow rates (67-180 ml/s), through three orifices (circular, rectangular and triangular, S=0.24 cm(2)). The 3D reconstructions of FC surface areas from multi-threshold velocities, including aliasing velocities were analysed to quantify the peak flow rate. For all orifices, linear regression demonstrated excellent correlation between the 3D calculated and electromagnetic flow meter recorded data. While there was a high correlation for 3D computation of flow rate from the single best Nyquist of 24 cm/s (r=0.97-0.98, SEE=7 .75-12.58 ml/s), the ability to average three threshold velocities (15, 18 and 24 cm/s) yielded an improved correlation (r=0.98-0.99, SEE=5.70-7.73 ml/s). CONCLUSIONS: Direct computation of multiple 3D FC isovelocities from digital reconstruction of colour Doppler data of the FC region provides the potential to accurately quantify the complex asymmetric spatial flow events at any selected velocity.

Blood Flow Velocity↗
PubMed2005

High-precision quantum thermochemistry on nonquasiharmonic potentials: converged path-integral free energies and a systematically convergent family of generalized Pitzer-Gwinn approximations.

Accurate quantum mechanical (QM) vibrational-rotational partition functions for HOOD, D(2)O(2), H(18)OOH, H(2)(18)O(2), D(18)OOH, and H(18)OOD are determined using a realistic potential energy surface for temperatures ranging from 300 to 2400 K by using the TT-FPI-ESPE path-integral Monte Carlo method. These data, together with our prior results for H(2)O(2), provide benchmarks for testing approximate methods of estimating isotope effects for systems with torsional motions. Harmonic approximations yield poor accuracy for these systems, and although the well-known Pitzer-Gwinn (PG) approximation provides better results for absolute partition functions, it yields the same results as the harmonic approximation for isotope effects because these are intrinsically quantal phenomena. We present QM generalizations of the PG approximation that can provide high accuracy for both isotope effects and absolute partition functions. These approximations can be systematically improved until they approach the accurate result and converge rapidly. These methods can also be used to obtain affordable estimates of zero-point energies from accurate partition functions-even those at relatively high temperatures.

Journal Article↗
PubMed2005

Developmental plasticity in Macrophiothrix brittlestars: are morphologically convergent larvae also convergently plastic?

The pluteus larval forms of sea urchins (echinoids) and brittlestars (ophiuroids) use an internal skeleton to project arms that bear a long ciliated band used in swimming and feeding. The length of this ciliated band influences rates of maximum food clearance for larvae of both echinoderm classes and affects rates of growth and development in the plankton. Phylogenetic and morphological evidence, however, tend to support the view that the pluteus morphologies of the two classes are independently derived. Studies with echinoplutei have shown that investment in skeletal growth and ciliated band length changes in response to food conditions, with poorly fed larvae investing more in growth of the larval skeleton and arms either absolutely or in relation to other larval or developing postlarval structures. We present evidence for similar plasticity of skeletal growth in ophioplutei. We examined four species in the brittlestar genus Macrophiothrix that spanned a 3.8-fold range in egg size. Sibling larvae in 14 male-female crosses were reared with high (H) or low (L) food rations, and measurements were recorded for five skeletal arm rods and three non-arm body dimensions. The expression of adaptive plasticity (significantly longer arms in L versus H cultures on a given day) was apparent for most crosses in M. koehleri, the species with the smallest egg size. In the single cross for M. longipeda, larvae from L cultures had longer arms for their body length or stomach width than did larvae from H cultures. In these cases, plasticity was similar in timing, persistence, and magnitude to previously published results from echinoplutei. If internal skeletons are independently derived in the two classes, then plasticity in the expression of this homoplastic trait may itself be homoplastic.

Age Factors↗