公教育の経済価値に関する実証研究：日本の不動産市場を用いた分析

Tohoku University若林緑課

What do high-achieving graduates bring to nonacademic track high schools?

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Does Spontaneous Symmetry Breaking Occur in Periodically Driven Low-Dimensional Non-Equilibrium Classical Systems?

Equilibrium systems do not show spontaneous continuous symmetry breaking in one and two dimensions, as the thermal fluctuation washes away the long-range orders. A trivial way to suppress fluctuations and realize the long-range orders in low-dimensional systems is just to consider the ground state at zero temperature. A less trivial example would be an out-of-equilibrium system driven by periodic driving forces instead of thermal agitation. If the amplitude of the driving force is sufficiently small, the periodic force of frequency $\omega_0$ only excites the eigenmode of the eigenfrequency $\omega_0$. Therefore, the fluctuations are largely suppressed even near the critical point, if it exists. Does this mechanism allow spontaneous symmetry breaking in low dimensions? We here address this question by using the mean-spherical model driven by spatially uncorrelated but temporally periodic driving forces. We show that the model undergoes the ferromagnetic phase transition for any $d>0$. Furthermore, the model for the conserved order parameter (model B) exhibits hyperuniformity, which has been previously reported for chiral active matter.Comment: 6 pages, 4 figure

Association between perceived exertion and executive functions with serve accuracy among male university tennis players: A pilot study

Serve in tennis is a very important strokes and is positively correlated with the rankings of the Association of Tennis Professionals ranking. This study investigated the associations between time-course changes in the ratings for perceived exertion, executive function, and second serve accuracy during 30-min tennis exercise sessions. Eleven Japanese male tennis players participated in the study, and their executive function and second serve performance were evaluated using the paper version of the Stroop Color and Word Test, followed by a serve performance test. The participants took part in a 30-min tennis exercise program and performed the Stroop Color and Word Test, heart rate (HR) check, and second serve accuracy test before and after the tennis exercise. Pearson correlation was used to determine the relationships between the ratings for perceived exertion, interference scores on Stroop Color and Word Test performance, and second serve performance. Post exercise, the rating of perceived exertion tended to correlate with serve accuracy (r = −0.57, p = 0.07) and interference score (r = 0.65, p = 0.03). The pre-to-post changes in second serve accuracy were negatively associated with the changes in interference score (r = −0.54, p = 0.08) and interference score in the posttest (r = −0.73, p = 0.01). The results suggest that time-course changes in executive function when playing tennis are positively associated with the accuracy of the second serve. These findings expand the previous knowledge regarding the positive association between time-course changes in executive functions and percentage of points won when playing tennis by including more specific skills (i.e., second serve accuracy)

Adsorption enhancement of nitrogen gas by atomically heterogeneous nanospace of boron nitride

In this study, porous boron nitride (p-BN) with hexagonal phase boron nitride (h-BN) pore walls was synthesized using high-temperature calcination. Negligible variation in pore-wall structure can be observed in powder X-ray diffraction (XRD) profiles and infrared (IR) spectra. However, a highly stable p-BN with a stable pore structure even at 973 K under the oxidative conditions is obtained when synthesized at higher than 1573 K under nitrogen gas flow. For p-BN, this stability is obtained by generating h-BN microcrystals. Nitrogen adsorption–desorption isotherms at 77 K provide type-IV features and typical adsorption–desorption hysteresis, which suggests micropore and mesopore formation. Moreover, adsorption–desorption isotherms of Ar at 87 K are measured and compared with those of nitrogen. The relative adsorbed amount of nitrogen (i.e., the amount of nitrogen normalized by that of Ar at each relative pressure or adsorption potential value) on p-BN is considerably larger than that on microporous carbon at low-pressure regions, which suggests the existence of strong adsorption sites on the p-BN surface. In fact, the relative number of adsorbed nitrogen molecules to that of Ar on p-BN is, at most, 150%–200% larger than that on microporous carbon for the same adsorption potential state. Furthermore, additional adsorption enhancement to nitrogen between P/P0 = 10−5 and 10−3 can be observed for p-BN treated at 1673 K, which suggests the uniformly adsorbed layer formation of nitrogen molecules in the vicinity of a basal planar surface. Thus, unlike typical nanoporous sp2 carbons, p-BN materials have the potential to enhance adsorption for certain gas species because of their unique surface state