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Mood disorders (e.g. depression, apathy, and anxiety) are often observed in stroke patients, exhibiting a negative impact on functional recovery associated with various physical disorders and cognitive dysfunction. Consequently, post-stroke symptoms are complex and difficult to understand. In this study, we aimed to clarify the cross-sectional relationship between mood disorders and motor/cognitive functions in stroke patients. An artificial neural network architecture was devised to predict three types of mood disorders from 36 evaluation indices obtained from functional, physical, and cognitive tests on 274 patients. The relationship between mood disorders and motor/cognitive functions were comprehensively analysed by performing input dimensionality reduction for the neural network. The receiver operating characteristic curve from the prediction exhibited a moderate to high area under the curve above 0.85. Moreover, the input dimensionality reduction retrieved the evaluation indices that are more strongly related to mood disorders. The analysis results suggest a stress threshold hypothesis, in which stroke-induced lesions promote stress vulnerability and may trigger mood disorders.

Aim The prediction of functional outcome is essential in the management of acute ischemic stroke patients. We aimed to explore the various prognostic factors with multivariate linear discriminant analysis or neural network analysis and evaluate the associations between candidate factors, baseline characteristics, and outcome. Methods Acute ischemic stroke patients (n=1,916) with premorbid modified Rankin Scale (mRS) scores of 0-2 were analyzed. The prediction models with multivariate linear discriminant analysis (quantification theory type II) and neural network analysis (log-linearized Gaussian mixture network) were used to predict poor functional outcome (mRS 3-6 at 3 months) with various prognostic factors added to age, sex, and initial neurological severity at admission. Results Both models revealed that several nutritional statuses and serum alkaline phosphatase (ALP) levels at admission improved the predictive ability. Of the 1,484 patients without missing data, 560 patients (37.7%) had poor outcomes. The patients with poor outcomes had higher ALP levels than those without (294.3±259.5 vs. 246.3±92.5 U/l, P＜0.001). Multivariable logistic analyses revealed that higher ALP levels (1-SD increase) were independently associated with poor stroke outcomes after adjusting for several confounding factors, including the neurological severity, malnutrition status, and inflammation (odds ratio 1.21, 95% confidence interval 1.02- 1.49). Several nutritional indicators extracted from prediction models were also associated with poor outcome. Conclusion Both the multivariate linear discriminant and neural network analyses identified the same indicators, such as nutritional status and serum ALP levels. These indicators were independently associated with functional stroke outcome.

Mg x Zn 1-x S mixed-alloy films have been grown on (100)-oriented GaAs substrates by low-pressure metalorganic chemical vapor deposition. Optical and structural properties of the films have been investigated by means of time-integrated and time-resolved photoluminescence (PL) spectroscopy. Up to about x Mg = 0.5, Mg x Zn 1-x S films were crystallized in zincblende phase. With increasing Mg composition ratio above x Mg = 0.5, both zincblende and wurtzite structures coexisted. It was found from time-resolved PL measurement that the main emission was due to the recombination of localized excitons, which was caused by alloy fluctuation. It was also found that the degree of localization increased with the Mg composition ratio.

Mg x Zn 1-x S mixed films have been grown on (100)-oriented GaAs substrates by low-pressure metalorganic chemical vapor deposition. In the range of Mg composition (x) up to about 0.4, the mixed crystals were grown only in the zincblende phase. The 4.2K photoluminescence spectrum in the crystal with x Mg = 0.39 was dominated by the strong ultraviolet emission around 300 nm. The growth of Cd y Zn 1-y S/ZnS/Mg x Zn 1-x S separate confinement heterostructures (SCHs) was performed and ultraviolet emission at about 340 nm from a Cd 0.23 Zn 0.77 S well layer in SCH was observed at RT for the first time.

Two-photon absorption processes of biexcitons in ZnS-based quantum-well structures have been studied by means of photoluminescence excitation spectroscopy. The peak position of two-photon absorption of biexcitons was dependent on the detected energy position in the photoluminescence excitation measurement. The energy difference between the one-photon exciton resonance and the two-photon biexciton resonance increased as the detected energy position was moved towards the lower-energy side of the biexciton luminescence. This result indicated the biexciton localization and the resultant increase in the biexciton binding energy.

Recombination dynamics of dense excitonic systems in CdxZn1−xS–ZnS quantum-well structures has been studied by means of time-resolved luminescence spectroscopy. Experimental evidence for biexciton formation was obtained. Furthermore, ultraviolet stimulated emission was observed just at the energy position of the biexciton luminescence. It was proposed that the stimulated emission was due to the biexciton decay process.

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High-quality ZnS epitaxial layers were grown by low-pressure metalorganic chemical vapor deposition using all gaseous sources. The photoluminescence spectrum of high-quality ZnS epitaxial layers at 4.2 K was dominated by the radiative recombination of free excitons. The free-exciton luminescence was observed even at room temperature (300 K). The linewidth broadening of the free-exciton luminescence with increase in temperature was analyzed in terms of exciton–LO-phonon and exciton–acoustic-phonon scattering processes.