Coherent structures in the near field of a free jet have been studied. Experiments are carried out for the free jets issuing from round and square nozzles using a water channel. Instantaneous velocity profiles are obtained in the radial direction by using an ultrasonic velocity profile (UVP) monitor. Coherent structures in the radial direction are investigated in terms of the proper orthogonal decomposition (POD). In the distributions of eigenfunction at each POD mode and energy contribution from each POD mode, there is no remarkable difference between round and square jets. In the power spectra of the random coefficient at the first POD mode, however, there is a broad peak in the case of round jet.
In a cavity quantum electrodynamics (QED) system, where atoms coherently interact with photons in a cavity, the eigenstates of the system are the superposition states of atoms and cavity photons, the so-called dressed states of atoms. When two cavities are connected by an optical fiber with negligible loss, the coherent coupling between the cavities gives rise to photonic normal modes. One of these normal modes is the fiber-dark mode, in which photons are delocalized in the two distant cavities. Here we demonstrate the setting of coupled-cavities QED, where two nanofiber cavity-QED systems are coherently connected by a meter-long low-loss channel in an all-fiber fashion. Specifically, we observe dressed states of distant atoms with delocalized photons of the fiber-dark normal mode. Our system will provide a platform for the study of delocalized atomic and photonic states, photonic many-body physics, and distributed quantum computation.
Abstract A system of ultracold atoms in an optical lattice has been regarded as an ideal quantum simulator for a Hubbard model with extremely high controllability of the system parameters. While making use of the controllability, a comprehensive measurement across the weakly to strongly interacting regimes in the Hubbard model to discuss the quantum many-body state is still limited. Here we observe a great change in the excitation energy spectra across the two regimes in an atomic Bose–Hubbard system by using a spectroscopic technique, which can resolve the site occupancy in the lattice. By quantitatively comparing the observed spectra and numerical simulations based on sum rule relations and a binary fluid treatment under a finite temperature Gutzwiller approximation, we show that the spectra reflect the coexistence of a delocalized superfluid state and a localized insulating state across the two regimes.
Cardiac arrhythmia and bradycardia occasionally occur from the effect of inhaled anesthetic agent and opioid on cardiac conduction. We experienced a case of intermittent bradycardia-dependent bundle branch block (IBDBBB) during sevoflurane and remifentanil anesthesia. A 17-year-old woman suffering from recurrent left ottitis media was scheduled for tympanoplasty under general anesthesia. Her preoperative electrocardiogram (ECG) revealed normal sinus rhythm at heart rate (HR) of 48 beats x min(-1). Her tracheal was intubated following anesthesia induction with propofol and vecuronium, and anesthesia was maintained using inhalation of 40% oxygen with air and 1.5-2.0% sevoflurane, and continuous venous infusion of remifentanil at a rate of 0.15 microg x kg(-1) min(-1). Two hours 20 minutes after starting operation, the P-P interval was constant but the waveforms of low and broad QRS complexes appeared intermittently on the ECG monitor. The blood pressure remained stable at 95/55 mmHg and the HR decreased to 46 beats x min(-1). The waveform of pulse oxymetric oxygen saturation (Spo2) did not change. We diagnosed the ECG pattern as IBDBBB. After intravenous injection of atropine 0.5 mg, the waveforms of QRS complexes recovered to normal sinus rhythm at HR 90 beats x min(-1). Sevoflurane and remifentanil in adolescence could induce ventricular conduction disturbance and result in IBDBBB. Atropine could be effective for IBDBBB induced by sevoflurane and remifentanil.
We present in this paper a study of the azimuthal anisotropy of the motion field observed during a six-day campaign in March 1986 using the MU radar in Shigaraki, Japan. The radial wind velocity was observed at 20° zenith angle, at every 30° of azimuth during four days, and at every 45° during two days. A jet stream was present during the entire six days. The average radial velocity variance from 10.4 to 19.2 km was calculated every four minutes and then averaged over 20 minutes or one hour. The average variance was found to be a strong function of both azimuth and time. The azimuthal variations were analyzed in terms of the mean and the first and second harmonics. The mean is proportional to the kinetic energy per unit mass of the radial wind fluctuations, and the first harmonic is proportional to the vertical flux of horizontal momentum per unit mass. The strong azimuthal variation was usually dominated by the second harmonic; i.e., with two peaks, but was occasionally dominated by the first harmonic, with one peak. The phase of the first harmonic was usually westward, but the phase of the second harmonic was quite variable. It was shown by a development of gravity wave theory that all of the observed azimuthal variations could probably be caused by a gravity wave field whose parameters vary with time.
Abstract Seismic exploration was conducted along a profile running through the Aira caldera located in southern Kyushu, Japan. The caldera was formed by an ignimbrite eruption approximately 30 ka BP, namely, the “AT eruption,” which produced the Ito ignimbrite and widespread Aira-Tanzawa ash. This analysis aimed to clarify the detailed P -wave velocity structure beneath the caldera. Accordingly, 829 inland seismic stations and 42 ocean bottom seismographs were deployed along the 195 km-long seismic profile to record seismic waves generated by numerous controlled seismic sources. A detailed velocity structure of the active Aira caldera was successfully obtained to depths of 20 km through travel-time tomography. A substantial structural difference was observed in the thicknesses of the low-velocity zones between the eastern and western sides in the shallowest region of the Aira caldera, suggesting that the Aira caldera is composed of at least two calderas: the AT caldera associated with the AT eruption, and the Wakamiko caldera associated with the post-AT eruption. Perhaps the most interesting feature of the caldera structure is the existence of a substantially high-velocity zone at depths of 6–11 km beneath the center area of the AT caldera, which can be interpreted as the cooled and solidified magma reservoir formed during or after the AT eruption. In addition, a low-velocity region with approximately 15 km depths indicated a deep magma reservoir. Based on these novel and past research results, a new magma supply model in the Aira caldera was proposed. Further, the spatial distribution of the magma reservoir associated with the AT eruption 30 ka BP was estimated, while the future possibility of larger eruptions in this caldera was discussed.
We describe in this paper preliminary results on the characteristics of the wind velocity and temperature profiles obtained through rocketsonde measurements during the DYANA campaign. The wind velocity profiles in the height region of 20-90km, obtained with the rocketsondes, were compared with the results simultaneously observed with the MU (middle and upper atmosphere) radar at 60-100km. The profiles were consistent with each other up to 80km, when they were smoothed out for a height range of 8km. While for wind velocity fluctuations with vertical scales of a few km, the rocketsonde results showed significantly larger amplitudes than those obtained with the MU radar above 60km. Consideration of the vertical wavenumber spectra of the wind velocity fluctuations suggested that the maximum height range of the rocketsonde profile, by which the gravity wave characteristics can be delineated, seemed to be limited only up to about 60km. The background zonal winds were westward in the stratosphere, but they exhibited large time variations, coinciding with a minor stratospheric sudden warming. The temperature profiles also indicated great variability near the stratopause and in the mesosphere, probably due to the effect of the enhanced activity of planetary waves.
