Quantum Mechanics of Guiding Center Motion in Strong Magnetic Field (Coherent State Path Integral Approach)

A new approach is proposed for the quantum mechanics of guiding center motion in strong magnetic field. This is achieved by use of the coherent state path integral for the coupled systems of the cyclotron and the guiding center motion. We are specifically concerned with the effective action for the guiding center degree, which can be used to get the Bohr- Sommerfeld quantization scheme. The quantization rule is similar to the one for the vortex motion as a dynamics of point particles

Weyl Starobinsky inflation

In Starobinsky inflation with a Weyl squared Lagrangian $-\alpha C^2$, where $\alpha$ is a coupling constant, we study the linear stability of cosmological perturbations on a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker background. In this theory, there are two dynamical vector modes propagating as ghosts for $\alpha>0$, whose condition is required to avoid tachyonic instabilities of vector perturbations during inflation. The tensor sector has four propagating degrees of freedom, among which two of them correspond to ghost modes. However, tensor perturbations approach constants after the Hubble radius crossing during inflation, and hence the classical instabilities are absent. In the scalar sector, the Weyl curvature gives rise to a ghost mode coupled to the scalaron arising from the squared Ricci scalar. We show that two gauge-invariant gravitational potentials, which are both dynamical in our theory, are subject to exponential growth after the Hubble radius crossing. There are particular gauge-invariant combinations like the curvature perturbations whose growth is suppressed, but it is not possible to remove the instability of other propagating degrees of freedom present in the perturbed metric. This violent and purely classical instability present in the scalar sector makes the background unviable. Furthermore, the presence of such classical instability makes the quantization of the modes irrelevant, and the homogeneous inflationary background is spoiled by the Weyl curvature term.Comment: 24 pages, 3 figure

Wirelessly Powered Sensing Fertilizer for Precision and Sustainable Agriculture

Sensor networks comprising small wireless sensor devices facilitate the collection of environmental information and increase the efficiency of outdoor practices, including agriculture. However, the sensor-device installation density of a network is limited because conventional sensor devices must be removed after use. In this study, a sustainable dense sensing system that combines simplified degradable sensor devices, wireless power supply, and thermal-camera image-based information recognition is proposed. The proposed wireless-power-driven sensor device comprises a biodegradable nanopaper substrate, natural wax, and an eco-friendly tin conductive line. The sensor device emits a thermal signal based on the soil moisture content. The thermal camera simultaneously acquires the soil moisture-content data and sensor-device location. The majority of the sensor-device components are biodegradable, and the residual components have a minimal adverse impact on the environment. Additionally, the fertilizer component in the substrate promotes plant growth. The proposed sensing concept introduces a novel direction for realizing hyperdense sensor networks and contributes to the development of social systems that combine sustainability with meticulous environmental management.Kasuga T., Mizui A., Koga H., et al. Wirelessly Powered Sensing Fertilizer for Precision and Sustainable Agriculture. Advanced Sustainable Systems , (2023); https://doi.org/10.1002/adsu.202300314

Reduction in BDNF from inefficient precursor conversion influences nest building and promotes depressive-like behavior in mice

Kojima, M.; Otabi, H.; Kumanogoh, H.; Toyoda, A.; Ikawa, M.; Okabe, M.; Mizui, T. Reduction in BDNF from Inefficient Precursor Conversion Influences Nest Building and Promotes Depressive-Like Behavior in Mice. Int. J. Mol. Sci. 2020, 21, 3984. https://doi.org/10.3390/ijms2111398

Electrodeposition of cellulose nanofibers as an efficient dehydration method

Kasuga T., Li C., Mizui A., et al. Electrodeposition of cellulose nanofibers as an efficient dehydration method. Carbohydrate Polymers 340, 122310 (2024); https://doi.org/10.1016/j.carbpol.2024.122310.Dehydration of a cellulose nanofiber (CNF)/water dispersion requires large amounts of energy and time due to the high hydrophilicities and high specific surface areas of the CNFs. Various dehydration methods have been proposed for CNF/water dispersions; however, an efficient dehydration method for individually dispersed CNFs is needed. Here, electrodeposition of CNFs was evaluated as a dehydration method. Electrodeposition at a DC voltage of 10 V on a 0.2 wt% CNF/water dispersion resulted in a concentration of ∼1.58 wt% in 1 h. The dehydration energy efficiency was ∼300 times greater than that of dehydration by evaporation. The concentrated CNF hydrogels recovered after electrodeposition were redispersed with a simple neutralization process, and clear transparent films were obtained by drying after redispersion. This work provides a new method for dehydration and reuse of individually dispersed CNF/water dispersions and provides new insights into control of the hierarchical structures of CNFs by electrodeposition

Trace of the Median Tectonic Line in Mima area, eastern Shikoku

Tracing outcrops of shear zone were used to describe the geometry and structure of the Median Tectonic Line in Mima area, eastrn Shikoku. A distinct new fault outcrop was discovered between the Mino and Ikuchi Faults at the northern slope of the Mt. Boso. These two faults are regarded as a single continuous fault. The analysis of surface fabrics of quartz in fault in fault gauge has been carried out to determine relative fault activity events