Takeshi Kuroda

New antiinflammatory agents 4-hydroxy-2(1H)-oxo-1-phenyl-1,8-naphthyridine-3- carboxamides 7 were designed and synthesized via a valuable intermediate, 1-phenyl-2H-pyrido[2,3-d][1,3]oxazine-2,4(1H)-dione (9). The nature of substituents on the amide nitrogen had a pronounced effect on antiinflamatory activity. Studies of structure-activity relationships led to compounds 33 and 34 bearing a pyridine ring on the amide nitrogen. Compounds 33 and 34 were active against carrageenin-, zymosan-, and ara

Abstract Gravity wave (GW) activity in the lower and middle atmosphere of Mars during the global dust storm of 2018 has been studied for the first time using a high‐resolution (GW‐resolving) general circulation model. Dust storm simulations were compared with those utilizing the climatological distribution of dust in the absence of storms. Both scenarios are based on observations of the dust optical depth by the Mars Climate Sounder instrument on board the Mars Reconnaissance Orbiter. The modeli

Seasonal changes in baroclinic wave activity during northern autumns ( L s = 195–225°) and winters ( L s = 280–300°) are studied with a Martian general circulation model. For the weak dust load, the simulated s = 2 harmonic with 3.1 sols period dominates near the surface, while s = 1 (5.5 sols period) is more prominent at higher altitudes during autumns. In winters, the s = 1 wave has stronger amplitudes and a deep (up to 0.1 mb) vertical structure. These simulations are consistent with observat

The formation of CO 2 ice clouds in the northern winter polar atmosphere of Mars and their relation to baroclinic planetary waves, which dominate local dynamics, are studied using a general circulation model. The simulation shows that clouds are formed at altitudes of up to ∼ 40 km, and their occurrence correlates to a large degree with the cold phases of transient planetary waves. Ice particles formed up to ∼ 20 km can reach the surface in the form of snowfall in certain longitude regions, whil

Abstract Global characteristics of the small‐scale gravity wave (GW) field in the Martian atmosphere obtained from a high‐resolution general circulation model (GCM) are presented for the first time. The simulated GW‐induced temperature variances are in a good agreement with available radio occultation data in the lower atmosphere between 10 and 30 km. The model reveals a latitudinal asymmetry with stronger wave generation in the winter hemisphere and two distinctive sources of GWs: mountainous r

The spin-relaxation process of A-band exciton in GaN is observed by spin-dependent pump and probe reflectance measurement with subpicosecond time resolution. The spin-relaxation times at 150−225K are 0.47−0.25ps. These are at least one order of magnitude shorter than those of the other III-V compound semiconductors. The spin-relaxation time τs is found to be proportional to T−1.4, where T is the temperature.

We report on the first detection of the semiannual oscillation (SAO) in the Martian atmosphere. The semiannual periodicity is found in the difference between day‐ and night‐time atmospheric temperatures, a good proxy for solar tides, measured from Mars Global Surveyor. Simulations with a general circulation model proved that this modulation of tidal amplitudes is a manifestation of the SAO of zonal winds in Martian tropics. Our numerical experiments revealed significant differences in driving me

Abstract The paper presents results of simulations with a high‐resolution (equivalent to ∼67‐km grid size) Martian general circulation model (MGCM) from the surface up to the mesosphere for a full Martian year. The obtained climatology of the small‐scale disturbances can serve as a proxy for gravity waves (GWs) that are largely not resolved by MGCMs with conventional grid resolution and thus have to be parameterized. GW activity varies greatly with season and geographical location, which contrad

Abstract Results of simulations with a new high-resolution Martian general circulation model (MGCM) (T106 spectral resolution, or ~67-km horizontal grid size) have been analyzed to reveal global distributions of gravity waves (GWs) during the solstice and equinox periods. They show that shorter-scale harmonics progressively dominate with height, and the body force per unit mass (drag) they impose on the larger-scale flow increases. Mean magnitudes of the drag in the middle atmosphere are tens of