693 research outputs found

    The Measurement of Strength in Children: Is the Peak Value Truly Maximal?

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    It is unclear whether the measurement of maximum muscle strength in younger children can be performed accurately due to factors such as motivation and maturity (i.e., the ability to receive instruction). If there is a large change in a ratio between muscular strength and size from the youngest to the oldest, then this might provide some indication that the youngest may not have been able to voluntarily activate their muscles for reasons mentioned previously. The purpose of this study was to observe the ratio between handgrip strength (HGS) and forearm muscle thickness (MT) across differing ages in younger children. A total of 1133 preschool children (559 boys and 574 girls) between the ages of 4.5 and 6.5 years had MT and HGS measurements and calculated the ratio of HGS/MT (kg/cm). Linear regression was used to assess the impact of age and sex on the dependent variables of MT, HGS, and the HGS/MT ratio. The HGS/MT ratio increases moderately from age 4.5 to 6.5 in both boys and girls. However, the difference in this ratio was small between the age ranges in this sample. Our results indicate children as young as 4.5 may be accurately measured with the handgrip strength test

    Direct perturbation theory on the shift of Electron Spin Resonance

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    We formulate a direct and systematic perturbation theory on the shift of the main paramagnetic peak in Electron Spin Resonance, and derive a general expression up to second order. It is applied to one-dimensional XXZ and transverse Ising models in the high field limit, to obtain explicit results including the polarization dependence for arbitrary temperature.Comment: 5 pages (no figures) in REVTE

    Frustrated quantum-spin system on a triangle coupled with ege_g lattice vibrations - Correspondence to Longuet-Higgins et al.'s Jahn-Teller model -

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    We investigate the quantum three spin model (S1,S2,S3)({\bf S_1},{\bf S_2},{\bf S_3}) of spin=1/2=1/2 on a triangle, in which spins are coupled with lattice-vibrational modes through the exchange interaction depending on distances between spin sites. The present model corresponds to the dynamic Jahn-Teller system EgegE_g\otimes e_g proposed by Longuet-Higgins {\it et al.}, Proc.R.Soc.A.{\bf 244},1(1958). This correspondence is revealed by using the transformation to Nakamura-Bishop's bases proposed in Phys.Rev.Lett.{\bf 54},861(1985). Furthermore, we elucidate the relationship between the behavior of a chiral order parameter χ^=S1(S2×S3){\hat \chi}={\bf S_1\cdot(S_2\times S_3)} and that of the electronic orbital angular momentum ^z{\hat \ell_z} in EgegE_g\otimes e_g vibronic model: The regular oscillatory behavior of the expectation value forvibronicstructureswithincreasingenergycanalsobefoundinthatof for vibronic structures with increasing energy can also be found in that of . The increase of the additional anharmonicity(chaoticity) is found to yield a rapidly decaying irregular oscillation of

    Findings of N-Isopropyl-p-(^<123>I)-Iodoamphetamine SPECT in Mitochondrial encephalomyopathy with lactic acidosis and strokelike episodes (MELAS) : Case report and review of literature

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    This study investigated the recollections of child survivors of the 2004 Asian tsunami in terms of their vantage point and posttraumatic stress disorder (PTSD) responses. Five years after the tsunami, 110 children (aged 7-13 years) living in Aceh, Indonesia were assessed for source of memories of the tsunami (personal memory or second-hand source), vantage point of the memory, and were administered the Children's Revised Impact of Event Scale-13. Fifty-three children (48%) met criteria for PTSD. Two-thirds of children reported direct memories of the tsunami and one-third reported having memories based on reports from other people. More children (97%) who reported an indirect memory of the tsunami recalled the event from an onlooker's perspective to some extent than those who recalled the event directly (63%). Boys were more likely to rely on stories from others to reconstruct their memory of the tsunami, and to adopt an observer perspective. Boys who adopted an observer's perspective had less severe PTSD than those who adopted a field perspective. These findings suggest that, at least in the case of boys, an observer perspectives of trauma can be associated with levels of PTSD

    Two-magnon Raman scattering in spin-ladder geometries and the ratio of rung and leg exchange constants

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    We discuss ways in which the ratio of exchange constants along the rungs and legs of a spin-ladder material influences the two-magnon Raman scattering spectra and hence can be determined from it. We show that within the Fleury-Loudon-Elliott approach, the Raman line-shape does not change with polarization geometries. This lineshape is well known to be difficult to calculate accurately from theory. However, the Raman scattering intensities do vary with polarization geometries, which are easy to calculate. With some assumptions about the Raman scattering Hamiltonian, the latter can be used to estimate the ratio of exchange constants. We apply these results to Sugai's recent measurements of Raman scattering from spin-ladder materials such as La6_6Ca8_8Cu24_{24}O41_{41} and Sr14_{14}Cu24_{24}O41_{41}.Comment: 5 pages, revtex. Latest version focuses on ladder materials, with a detailed examination of the role of Heisenberg-like coupling constants which appear in the Fleury-Loudon-Elliott scattering operator but are rarely discussed in the literatur

    High-performance pipeline for MutMap and QTL-seq

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    [Summary] Bulked segregant analysis implemented in MutMap and QTL-seq is a powerful and efficient method to identify loci contributing to important phenotypic traits. However, the previous pipelines were not user-friendly to install and run. Here, we describe new pipelines for MutMap and QTL-seq. These updated pipelines are approximately 5–8 times faster than the previous pipeline, are easier for novice users to use, and can be easily installed through bioconda with all dependencies. [Availability] The new pipelines of MutMap and QTL-seq are written in Python and can be installed via bioconda. The source code and manuals are available online (MutMap: https://github.com/YuSugihara/MutMap, QTL-seq: https://github.com/YuSugihara/QTL-seq)

    Electron Spin Resonance in S=1/2 antiferromagnetic chains

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    A systematic field-theory approach to Electron Spin Resonance (ESR) in the S=1/2S=1/2 quantum antiferromagnetic chain at low temperature TT (compared to the exchange coupling JJ) is developed. In particular, effects of a transverse staggered field hh and an exchange anisotropy (including a dipolar interaction) δ\delta on the ESR lineshape are discussed. In the lowest order of perturbation theory, the linewidth is given as Jh2/T2\propto Jh^2/T^2 and (δ/J)2T\propto (\delta/J)^2 T, respectively. In the case of a transverse staggered field, the perturbative expansion diverges at lower temperature; non-perturbative effects at very low temperature are discussed using exact results on the sine-Gordon field theory. We also compare our field-theory results with the predictions of Kubo-Tomita theory for the high-temperature regime, and discuss the crossover between the two regimes. It is argued that a naive application of the standard Kubo-Tomita theory to the Dzyaloshinskii-Moriya interaction gives an incorrect result. A rigorous and exact identity on the polarization dependence is derived for certain class of anisotropy, and compared with the field-theory results.Comment: 53 pages in REVTEX, 7 figures in EPS included; revised version with missing references and correction
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