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41.
Background
Several studies have shown that Stroop interference is stronger in children than in adults. However, in a standard Stroop paradigm, stimulus interference and response interference are confounded. The purpose of the present study was to determine whether interference at the stimulus level and the response level are subject to distinct maturational patterns across childhood. Three groups of children (6–7 year-olds, 8–9 year-olds, and 10–12 year-olds) and a group of adults performed a manual Color-Object Stroop designed to disentangle stimulus interference and response interference. This was accomplished by comparing three trial types. In congruent (C) trials there was no interference. In stimulus incongruent (SI) trials there was only stimulus interference. In response incongruent (RI) trials there was stimulus interference and response interference. Stimulus interference and response interference were measured by a comparison of SI with C, and RI with SI trials, respectively. Event-related potentials (ERPs) were measured to study the temporal dynamics of these processes of interference.Results
There was no behavioral evidence for stimulus interference in any of the groups, but in 6–7 year-old children ERPs in the SI condition in comparison with the C condition showed an occipital P1-reduction (80–140 ms) and a widely distributed amplitude enhancement of a negative component followed by an amplitude reduction of a positive component (400–560 ms). For response interference, all groups showed a comparable reaction time (RT) delay, but children made more errors than adults. ERPs in the RI condition in comparison with the SI condition showed an amplitude reduction of a positive component over lateral parietal (-occipital) sites in 10–12 year-olds and adults (300–540 ms), and a widely distributed amplitude enhancement of a positive component in all age groups (680–960 ms). The size of the enhancement correlated positively with the RT response interference effect.Conclusion
Although processes of stimulus interference control as measured with the color-object Stroop task seem to reach mature levels relatively early in childhood (6–7 years), development of response interference control appears to continue into late adolescence as 10–12 year-olds were still more susceptible to errors of response interference than adults. 相似文献42.
I. S. Nizamov R. Z. Salikhov I. D. Nizamov V. Yu. Yakimov G. G. Sergeenko E. S. Batyeva R. A. Cherkasov 《Russian Journal of General Chemistry》2018,88(11):2307-2313
Reactions of quinine with dithioacids based on (1R)-endo-(+)-fenchol, (1S)-endo-(–)-borneol, and (S)-(–)-menthol have afforded optically active quinine salts. Chiral diquinine salts have been obtained in the reactions of quinine with bisthiophosphonic acids based on triethylene glycol and resorcinol. 相似文献
43.
The photoconductive gain, hole photocurrent spectra in the mid-infrared range, and band-to-band photoluminescence spectra in arrays of Ge/Si quantum dots with different elemental compositions of the heterointerface are measured. The diffusive mixing of the materials of the matrix and the dots is controlled by varying the temperature at which the Ge layers are overgrown with Si. It is found that the formation of abrupt heterointerfaces leads to the enhancement of the hole photocurrent and quenching of photoluminescence. The results are explained by an increase in the lifetime of nonequilibrium holes owing to the suppression of their capture into the bound states of quantum dots. 相似文献
44.
A. V. Yakimov 《Radiophysics and Quantum Electronics》1999,42(6):521-524
We discuss two alternative approaches relating the occurrence of 1/f noise in semiconductors with fluctuations in the mobility
of current carriers. In the first approach, 1/f noise is associated with fluctuations in scattering of the carriers by the
acoustic phonons of the lattice. According to the second approach, the source of 1/f noise is fluctuations in the scattering
cross section of mobile defects. Experimental data in favor of the first approach are analyzed. It is shown that, to explain
the data in terms of the model of fluctuations in the scattering cross section of mobile defects, a new effect must exist.
Namely, manufacturing a semiconductor with an increased degree of doping must result in a proportional decrease in the density
of mobile defects that are responsible for the generation of 1/f noise.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 6, pp. 590–594, June 1999. 相似文献
45.
The plane problem of the plate planing at a constant velocity on the surface of a heavy, ideal, incompressible, finite-depth fluid is considered. The approximate, depth-independent expression for the force acting on the plate is derived from the linear distribution of the fluid velocity along the plate and the height of the flow stagnation point, without regard for jet formation near the leading edge. In this approximate formulation the plate drag depends on its velocity and the trailing edge immersion and does not depend on the planing angle. Experiments and numerical calculations in the exact formulation are performed in the near-critical flow regimes. It is shown that the wave patterns in the experiments and numerical calculations coincide, the formula for the drag being in agreement with the numerical experiments. An approximate criterion of the formation of waves going away from the plate in the forward direction is proposed. 相似文献
46.
T. N. Fursova V. V. Kedrov O. G. Rybchenko S. Z. Shmurak E. B. Yakimov A. A. Mazilkin 《Physics of the Solid State》2017,59(12):2423-2429
Europium alumoborate EuAl3(BO3)4 microcrystals have been synthesized by the flux method at a temperature of 1050°C. The obtained crystals have different morphologies: both plane-faced and skeletal microcrystals have been observed. Infrared spectroscopy, cathodeluminescence, and transmission electron microscopy investigations of individual microcrystals showed that the spectral and structural characteristics of these morphological forms coincide. The obtained crystals are characterized by the rhombohedral symmetry (sp. gr. R32) with the inclusions of C2/c monoclinic phase domains. 相似文献
47.
E.B. Yakimov P.S. Vergeles A.V. Govorkov A.Y. Polyakov N.B. Smirnov In-Hwan Lee Cheul Ro Lee S.J. Pearton 《Superlattices and Microstructures》2009,45(4-5):308-313
Results demonstrating the ability of EBIC and CL methods for ELOG GaN films characterization are presented. It is shown that EBIC measurements allow us to estimate not only the lateral distribution of diffusion length but also the donor distribution in such films. Donor concentration is found to be different in slit and wing regions. A difference in CL and EBIC images is revealed, which is explained by band bending near the boundaries where two overgrowing fronts meet. 相似文献
48.
Ya. L. Shabel’nikova E. B. Yakimov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(6):894-896
The X-ray-beam-induced current (XBIC) method is used to calculate the contrasts of dislocations and grain boundaries perpendicular to a surface as a function of the diffusion length of minority charge carriers and the X-ray probe width. The results are compared with the contrasts of the same defects determined via the electron-beam-induced current (EBIC) techniques. It is demonstrated that the XBIC contrasts of grain boundaries and dislocations can be several times greater than those obtained in the EBIC mode in the case of a rather narrow X-ray beam. The XBIC contrast always exceeds that of EBIC in semiconductors with a large diffusion length even if the X-ray beam is rather wide. 相似文献
49.
It is shown experimentally that the excitation of interband optical transitions in arrays of Ge/n-Si(001) quantum dots leads to a decrease in the concentration of electrons in the conduction band. The phenomenon observed is due to the formation of negatively charged exciton complexes in Ge islands and represents the first experimental confirmation of the spatial separation of electrons in the silicon matrix surrounding the islands. 相似文献
50.
Spectra of the photocurrent of holes in δ-doped Si layers with Ge quantum dots in weak external electric fields have been studied. It has been established that the photocurrent of the holes in the photovoltaic mode changes its sign with the increase in the impurity concentration in the δ layers. It has been found that there is a voltage range in the vicinity of the zero bias in which the direction of the photocurrent is determined by the wavelength of the exciting radiation. 相似文献