Developmental Changes of Prefrontal Activation in Humans: A Near-Infrared Spectroscopy Study of Preschool Children and Adults

Previous morphological studies indicated that development of the human prefrontal cortex (PFC) appears to continue into late adolescence. Although functional brain imaging studies have sought to determine the time course of functional development of the PFC, it is unclear whether the developmental change occurs after adolescence to adulthood and when it achieves a peak because of the narrow or discontinuous range in the participant's age. Moreover, previous functional studies have not focused on the anterior frontal region, that is, the frontopolar regions (BA9/10). Thus, the present study investigated the developmental change in frontopolar PFC activation associated with letter fluency task by using near-infrared spectroscopy (NIRS), in subjects from preschool children to adults. We analyzed the relative concentration of hemoglobin (ΔHb) in the prefrontal cortex measured during the activation task in 48 typically-developing children and adolescents and 22 healthy adults. Consistent with prior morphological studies, we found developmental change with age in the children/adolescents. Moreover, the average Δoxy-Hb in adult males was significantly larger than that in child/adolescent males, but was not true for females. These data suggested that functional development of the PFC continues into late adolescence. Although the developmental change of the frontopolar PFC was independent of gender from childhood to adolescence, in adulthood a gender difference was shown

Effects of Unilateral Compound-Eye Removal on the Photoperiodic Responses of Nymphal Development in the Cricket Modicogryllus siamensis

The cricket, Modicogryllus siamensis, shows clear photoperiodic responses at 25 degrees C in nymphal development. Under long-day conditions (LD16:8), nymphs became adults about 50 days after hatching, while under short-day conditions (LD8:16) the duration of nymphal stage extended to more than 130 days. Under constant dark conditions, two developmental patterns were observed: about 60% of crickets became adults slightly slower than under the long-day conditions, and the rest at later than 100 days after hatching, like those under the short-day conditions. When the compound eye was unilaterally removed on the 2nd day of hatching, an increase of molting and an extension of the nymphal period were observed under the long-day conditions, while under the short-day conditions, some crickets developed faster and others slower than intact crickets. These results suggest that this cricket receives photoperiodic information through the compound eye, that a pair of the compound eyes is required for a complete photoperiodic response, and that interaction between bilateral circadian clocks may be also involved in the response

Perfect Intrinsic Squeezing at the Superradiant Phase Transition Critical Point

Some of the most exotic properties of the quantum vacuum are predicted in ultrastrongly coupled photon–atom systems; one such property is quantum squeezing leading to suppressed quantum fluctuations of photons and atoms. This squeezing is unique because (1) it is realized in the ground state of the system and does not require external driving, and (2) the squeezing can be perfect in the sense that quantum fluctuations of certain observables are completely suppressed. Specifically, we investigate the ground state of the Dicke model, which describes atoms collectively coupled to a single photonic mode, and we found that the photon–atom fluctuation vanishes at the onset of the superradiant phase transition in the thermodynamic limit of an infinite number of atoms. Moreover, when a finite number of atoms is considered, the variance of the fluctuation around the critical point asymptotically converges to zero, as the number of atoms is increased. In contrast to the squeezed states of flying photons obtained using standard generation protocols with external driving, the squeezing obtained in the ground state of the ultrastrongly coupled photon–atom systems is resilient against unpredictable noise

The effects of hazard risk information on locations of firms by industry in tsunami-prone coastal areas

The construction of seawalls changes the risk of tsunami inundation and the locations of firms behind the seawalls. In order to estimate the benefits of seawalls and to design land use planning behind seawalls, it is necessary to know the impact of risk reduction on the location of firms. To capture such impacts, we estimate the effects of changes in tsunami inundation risk information on the number of firms behind the seawalls. The data is from Japanese areas with a high possibility of a tsunami. There are regional fixed effects by industry and spatial heterogeneities in risks due to the topographic conditions. We first rigorously derive a fixed-effects model in uncertain situations with expected profits of firms, and theoretically find that, unlike in situations of certainty, we should factor in the interaction between regional fixed effects and the change in risks besides the usual regional fixed effects. Our empirical estimation finds that awareness of a high inundation risk has a negative impact on industries with demand in a wide range of areas, such as manufacturing and wholesale, but no impact on industries with localized demand, such as education and clinics