688 research outputs found
The creative element in secondary school children’s writing
In Part One, the nature and development of the type of expressive English writing found in many junior and some secondary schools, frequently called 'creative writing', is examined. Views and definitions of creative writing, the psychological foundations behind child-centred school activities, and ways of helping the development of creative writing, are discussed within the context of personal growth rather than mere development of a skill. Current psychological opinion and experiment on the nature of creative behaviour in relation to general intellectual ability is considered, and there are reviews of anecdotal as well as more scientific approaches to problems of developing and marking English writing. Two investigations are reported in Part Two. The first is into the development of creative writing ability. Writing was sampled from the 1965 intake of five secondary schools at the beginning, middle and end of the children's first two years. The work of random samples of 10 children from each school was assessed by a team of five judges to form a multiple impression mark for each of the 50 children. A statistically significant improvement over the first-two individual years, and a highly significant improvement over the first two years was found. However, differences in the quality of writing between 4 of the 5 school samples were found to be statistically insignificant after analyses of co-variance over any of the three periods. The girls' grammar sample had a significant superiority in a first year and the two-year period analyses over both the other grammar samples and the two secondary modern samples. Quantitative developments are also investigated. The second investigation examines the effect of varied and strong sensory stimulation, and the absence of it, on the writing of three groups, each consisting of 24 11+ secondary modern boys who were taught in. different ways, samples of writing being drawn at the beginning and end of a 12-week period. A statistically significant difference was found between Groups III and II: the experimental Group III achieving the best results, and the sensorily ‘deprived' but more intelligent Group I doing better than the third Group II, which had been less adequately stimulated than Group III, Recommendations for further research are made
^25Mg NMR study of the MgB_2 superconductor
^25Mg NMR spectra and nuclear spin-lattice relaxation time, T_1, have been
measured in polycrystalline ^25MgB_2 with a superconducting transition
temperature T_c = 39.0 K in zero magnetic field. From the first order and
second order quadrupole perturbed NMR spectrum a quadrupole coupling frequency
nu_Q = 222(1.5) kHz is obtained. T_1T = 1090(50) sK and Knight shift K_c =
242(4) ppm are temperature independent in the normal conducting phase. The
^25Mg Korringa ratio equals to 0.95 which is very close to the ideal value of
unity for s-electrons. The comparison of the experimental nu_Q, T_1T, and K_c
with the corresponding values obtained by LDA calculations shows an excellent
agreement for all three quantities.Comment: 4 pages including 4 eps-figures, revtex
Discrete two-generator subgroups of over non-archimedean local fields
Let be a non-archimedean local field with residue field of characteristic
. We give necessary and sufficient conditions for a two-generator subgroup
of to be discrete, where either or
contains no elements of order . We give a practical algorithm to decide
whether such a subgroup is discrete. We also give practical algorithms to
decide whether a two-generator subgroup of either or
(where is a finite extension of ) is dense. A
crucial ingredient for this work is a structure theorem for two-generator
groups acting by isometries on a -tree.Comment: 19 pages, 5 figures, 1 table. Version 2 has some minor update
Correlation between oxygen isotope effects on the transition temperature and the magnetic penetration depth in high-temperature superconductors close to optimal doping
The oxygen-isotope (^{16}O/^{18}O) effect (OIE) on the in-plane magnetic
penetration depth \lambda_{ab}(0) in optimally-doped YBa_2Cu_3O_{7-\delta} and
La_{1.85}Sr_{0.15}CuO_4, and in slightly underdoped YBa_2Cu_4O_8 and
Y_{0.8}Pr_{0.2}Ba_2Cu_3O_{7-\delta} was studied by means of muon-spin rotation.
A substantial OIE on \lambda_{ab}(0) with an OIE exponent
\beta_O=-d\ln\lambda_{ab}(0)/d\ln M_O\approx - 0.2 (M_O is the mass of the
oxygen isotope), and a small OIE on the transition temperature T_c with an OIE
exponent \alpha_O=-d\ln T_{c}/d \ln M_O\simeq0.02 to 0.1 were observed. The
observation of a substantial isotope effect on \lambda_{ab}(0), even in
cuprates where the OIE on T_c is small, indicates that lattice effects play an
important role in cuprate HTS.Comment: 6 pages, 4 figure
The dimpling in the CuO_2 planes of YBa_2Cu_3O_x (x=6.806-6.984, T=20-300 K) measured by yttrium EXAFS
The dimpling of the CuO_2 planes (spacing between the O2,3 and Cu2 layers) in
YBa_2Cu_3O_x has been measured as a function of oxygen concentration and
temperature by yttrium x-ray extended-fine-structure spectroscopy (EXAFS). The
relative variations of the dimpling with doping (x=6.806-6.984) and temperature
(20-300 K) are weak (within 0.05 AA), and arise mainly from displacements of
the Cu2 atoms off the O2,3 plane towards Ba. The dimpling appears to be
connected with the transition from the underdoped to the overdoped regimes at
x=6.95, and with a characteristic temperature in the normal state, T*=150 K.Comment: 6 pages, 2 ps figs, LaTEX, Elsevier Elsart styl
Magnetic excitations in the spin-trimer compounds Ca3Cu3-xNix(PO4)4 (x=0,1,2)
Inelastic neutron scattering experiments were performed for the spin-trimer
compounds Ca3Cu3-xNix(PO4)4 (x=0,1,2) in order to study the dynamic magnetic
properties. The observed excitations can be associated with transitions between
the low-lying electronic states of linear Cu-Cu-Cu, Cu-Cu-Ni, and Ni-Cu-Ni
trimers which are the basic constituents of the title compounds. The exchange
interactions within the trimers are well described by the Heisenberg model with
dominant antiferromagnetic nearest-neighbor interactions J. For x=0 we find
JCu-Cu=-4.74(2) meV which is enhanced for x=1 to JCu-Cu=-4.92(6) meV. For x=1
and x=2 we find JCu-Ni=-0.85(10) meV and an axial single-ion anisotropy
parameter DNi=-0.7(1) meV. While the x=0 and x=1 compounds do not exhibit
long-range magnetic ordering down to 1 K, the x=2 compound shows
antiferromagnetic ordering below TN=20 K, which is compatible with the
molecular-field parameter 0.63(12) meV derived by neutron spectroscopy.Comment: 22 pages (double spacing), 1 table, 9 figures, Submitted to Phys.
Rev. B (2007
Direct observation of impurity-induced magnetism in an S = 1/2 antiferromagnetic Heisenberg 2-leg spin ladder
Nuclear magnetic resonance and magnetization measurements were used to probe
the magnetic features of single-crystalline Bi(Cu(1-x)Znx)2PO6 with 0<x<0.05 at
temperatures between 2.6 K and 300 K. The simple lineshape of the 31P NMR
signals of the pristine compound changes considerably for x>0 and we present
clear evidence for a temperature dependent variation of the local magnetization
close to the Zn sites. The generic nature of this observation is indicated by
results of model calculations on appropriate spin systems of limited size
employing QMC methods.Comment: 4 pages, 4 figure
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