Noncredible Effort during Pediatric Neuropsychological Exam: A Case Series and Literature Review

Neuropsychological test interpretation rests upon the assumption that the examinee has exerted full effort. If an individual provides inadequate effort during exam, the resulting data will be invalid and represent an underestimate of the person's true abilities. Although youth have been assumed historically to be less capable of deception than adults, acts of deception in childhood are not uncommon, even in normative populations. Yet, very few cases of children who have provided suboptimal effort during neuropsychological exam have appeared in the scientific literature. We present six clinical cases illustrating that children down to at least age 8 years can present with noncredible performance. The cases include those in which clear external incentives could be identified to those in which intrinsic or psychological factors were presumed to predominate. The fairly diverse nature of the presented cases, along with other recent work, suggests that suboptimal effort in children is apt to occur more frequently than previously recognized, even if it might occur less often than in comparable adult samples. In most of the presented cases, noncredible performance would not have been detected definitively by clinical judgment alone, reinforcing the value of routinely incorporating symptom validity tests into the neuropsychological assessment of school-aged children. The number of effort tests that have demonstrated utility in children pales in comparison to those available to the adult practitioner, although recent research now supports the use of several standalone measures with pediatric patients.     

Vortex dynamics in La1.86Sr0. 14CuO4 studied by magnetoresistivity

Abstract

Vortex dynamics in La_1.86Sr_0.14CuO₄ have been studied by the measurement of ρ_c ^//i (T, H), where ρ_c ^//i is the c-axis resistivity for H//i (i = c or a-b). We argue that, at temperatures higher than the irreversibility temperature T _irr, the usual vortex picture breaks down owing to the thermal motion of vortices, resulting in a T- and T _in-dependent anisotropic parameter γ. After taking into account the dependence of γ on T and T _irr, we show that at each given temperature we can rescale the ρ_c ^//a-b (T, H) data onto the corresponding ρ_c ^//c (T, H) curves. This scaling property clearly indicates that the Lorentz-force-free mechanism is responsible for ρ_c ^//a-b (T, H). Furthermore, we also show that the measured ρ_c ^//a-b (T, H) data can be explained in terms of the recently developed extended Josephson coupling model which is verified by rescaling ρ_c ^//a-b (T) data for various fields onto a single curve.     

Nature of shear flow lines in equal-channel angular-pressed metals and alloys

The nature of shear flow lines in equal-channel angular-pressed (ECAPed) metals has been investigated experimentally and theoretically. Experimental results indicate that, for metals pressed in a right-angle die, the shear flow lines often have an angle of ～27° with respect to the extrusion direction. It is suggested that the shear flow lines are composed of a group of elongated grains with an elongation direction that deviates slightly from that of the shear flow lines.     

Scanning electron microscopy-electron channelling contrast investigation of recrystallization during cyclic deformation of ultrafine grained copper processed by equal channel angular pressing

Cyclic deformation has been performed at ambient temperature on ultrafine-grained copper processed by equal channel angular pressing. Observations by electron channelling contrast in a scanning electron microscope revealed that pronounced recrystallization occurred and several distinct dislocation configurations such as dislocation walls and labyrinth structures were found within the recrystallized regions. A model is proposed to account for the evolution of recrystallization, emphasizing that its development results from an interaction between the cyclic deformation and the growth of recrystallized regions. The formation of recrystallized regions of different sizes is discussed.     

Amorphization of TiNi induced by high-pressure torsion

Using high-resolution electron microscopy, we investigated the initial stages of high-pressure-torsion-induced crystalline-to-amorphous transformation of TiNi. It is found that the deformation-induced amorphization initiated from dislocation core regions in the interior of grains and from grain boundaries. It is believed that both the energy stored in the dislocations and the energy stored in the grain boundaries contribute significantly to driving the crystalline-to-amorphous transformation.     

Semiquantitative analysis of surface relief due to martensite formation in Fe-Mn-Si-based shape memory alloys by atomic force microscopy

Semiquantitative analysis of the surface relief caused by martensite formation in Fe-Mn-Si-based shape memory alloys has been performed by atomic force microscopy. It is found, for the thermally induced martensite transformation, that all three possible variants of martensite with the same {111} habit plane appear while, for the stress-induced martensite transformation, only one martensite variant is likely to form. For the former case, martensite plates with various variants are formed on the same habit plane in such a way that the shape strains of those plates are self-accommodated macroscopically, but each martensite plate itself is a single variant and not a multivariant plate as has been reported in the literature. For the latter case, it is especially emphasized that all the martensite plates formed in the well 'trained' sample have the same variant, which is one of the most important conditions for exhibiting a good shape memory effect.     

Elastic modelling of periodic composites with particle interactions

The mechanical properties of periodic composites containing identical spherical particles are investigated using the principles of micromechanics and homogenization procedures. The averaged strain and stress fields are derived in terms of an eight-particle interaction. The effective elasticity with the cubic symmetry tensor is explicitly obtained. If the interaction term is dropped, then one recovers the conventional Mori–Tanaka model. With further approximations, the dilute model and the self-consistent model can also be obtained within the proposed framework. It is observed that the particle interactions make no contribution to the effective bulk modulus, a result that is consistent with other models and experiments for composites with cubic lattices.     

PbO compensation in the growth of PbWO4: Y3+ crystals

The light yield of Y³⁺-doped PbWO₄ crystals increases after low-dose-rate irradiation with?γ?rays, and the radiation hardness is sensitive to annealing temperature. In the PWO growth procedure, an excess of PbO in the starting materials is a convenient method of compensating for PbO volatility. The relationship between the excess of PbO and the abnormal radiation behaviour has been investigated. The mechanism of the normal excess of PbO in the growth of PWO: Y³⁺ is discussed.     

Valence band structure of the NiAl–Mo alloy from the photoelectron spectrum

The valence band structures of the NiAl–Mo alloy was investigated by photoelectron spectroscopy. The valence band spectra of the NiAl–Mo alloy was shifted away from the Fermi level so that the Ni-d-band centroid moved to a higher energy by 0.22 eV as Mo was added. A possible explanation lied in the overlap of Ni-d bands in the energy with Mo-d and Al-p bands. The participation of Mo-d bands was correlated with the site preference of Mo in NiAl alloys.     

Synthesis and evolution of crystalline garnet phases in Y3Sc5– x Ga x O12

Mixed-metal oxides with the composition Y₃Sc _x Ga_{5? x} O₁₂ (x?=?2.0, 2.1, 2.2, 2.25, 2.3, 2.4, 2.5, and 3.0) have been prepared by an aqueous sol–gel method. The effects of scandium substitution on the garnet phase formation were studied by IR spectroscopy and X-ray powder diffraction (XRD). The XRD data indicate that single-phase Y₃Sc _x Ga_{5? x} O₁₂ ceramic samples were obtained for x?=?2.0, 2.1, 2.2, 2.25, 2.3, and 2.4. The results also show that the formation of Y₃Sc _x Ga_{5? x} O₁₂ garnets depends on the molar ratio of scandium and gallium in the investigated composition, and consequently on the mean cationic radius at the Al³⁺ sites. The variation of lattice parameters for the Y₃Sc _x Ga_{5? x} O₁₂ phases with different x is reported.