Equivalent Phase Shift Research Articles

Electrically and magnetically tunable microwave device using (Ba, Sr) TiO3/Y3Fe5O12 multilayer

Ferroelectric (Ba0.6Sr0.4)TiO3 (BST) thin films have been deposited by pulsed laser deposition onto single-crystal Y3Fe5O12 (YIG) substrates with/without a MgO buffer layer. The structure and microwave properties of the BST films have been investigated as a function of substrate orientation and O2 deposition pressures (50–800 mTorr). The crystallographic orientation of BST film varies with the deposition conditions. The dielectric properties of the ferroelectric were measured using interdigitated capacitors deposited on top of the BST film. BST films exhibit high tunability (20–40%) and high dielectric Q=1/cosδ (30–50) with a dc bias field of 67 kV/cm at 10 GHz. A coplanar waveguide transmission line was fabricated from a (001)-oriented BST film on (111)YIG which exhibited a 17° differential phase shift with an applied dc bias field of 21 kV/cm (10 GHz). An equivalent differential phase shift was achieved with a magnetic field of 160 Gauss.

Frequency Agile Microwave Applications Using (Ba,Sr)TiO3/Y3Fe5O12 Multilayer Grown by Pulsed Laser Deposition

Abstract(Ba,Sr)TiO3 (BST) thin films have been deposited by pulsed laser deposition (PLD) onto single crystal Y3Fe5O12 (YIG) substrates with/without an MgO buffer layer. The structure and microwave properties of BST films have been investigated as function of substrate orientation and O2 deposition pressures (5-800m Torr). The orientation of BST film is varies with the deposition conditions. The dielectric constant, loss tangent, and change in dielectric constant with an applied electric field have been measured at room temperature using interdigitated capacitors at 0.1 – 20 GHz. Polycrystalline BST films have a high tunability (∼40%) with a dc bias field of 67kV/cm and a dielectric Q (=l/tanδ) between 30 and 40, while (001) oriented BST films have a lower tunability (∼20%) but higher dielectric Q (∼50). A coplanar waveguide transmission line was fabricated from a (001) oriented BST film on (111)YIG which exhibited a 17° differential phase shift with an applied dc bias of 21 kV/cm. An equivalent differential phase shift was achieved with a magnetic field of 160Guass.

Respiration response curve analysis of heart rate variability.

A noninvasive study was conducted on intact awake humans to characterize the dynamic response of the heart to the vagus during slow-, comfortable-, and fast-paced respiration (8, 12, and 18 breaths/min), under both sitting and standing conditions. The respiration response curve (RRC) of respiration-associated vagal effects on the heart was estimated, and characteristics of entrainment and frequency dependence on respiration were demonstrated. It was shown that the degree of entrainment and magnitude of phase resetting decrease with increase of pacing rate from 8 to 18 breaths/min. Further, the RRC was examined by overlapping equivalent phase shifts in different respiration cycles. This examination of the RRC can help us not only to find the common pattern underlying the RRC during different respiration cycles but also to perceive its variation related to degree of entrainment.

Effect of laser phase noise in Sagnac interferometers

A theoretical analysis of the responsivity and the noise caused by backscattering in a Sagnac interferometer used as a sensor for reciprocal measurands, such as acoustic waves, is presented. Both Rayleigh backscattering and reflections from splices are taken into account. The noise power is found to increase proportionally to the source coherence time, and a noise equivalent phase shift in the range of 0.1*10/sup -6/ rad r.m.s./Hz/sup 1/2/ is predicted for typical fibers and diode lasers. Experimentally, a noise equivalent phase shift of 2.5*10/sup -7/ rad r.m.s./Hz/sup 1/2/ at 10 kHz was observed, with a detector current of 3 mu A. >

Light Exposure Induces Equivalent Phase Shifts of the Endogenous Circadian Rhythms of Circulating Plasma Melatonin and Core Body Temperature in Men*

Release of melatonin into the circulation by the pineal occurs almost exclusively during the nighttime hours. It has been proposed that this daily rhythm, like that of body temperature, reflects the output of a central circadian pacemaker in humans. In order to investigate the relationship of the circadian rhythms of body temperature and melatonin in humans and compare their resetting responses to light, we characterized the endogenous 24-h profiles of these rhythms in eight young male adults during constant routines before and after exposure to a stimulus consisting of bright light, room light, and darkness/sleep. We found that the time of the fitted maximum of the endogenous melatonin rhythm consistently preceded the fitted temperature minimum by a mean +/- SE of 1.8 +/- 0.2 h. Bright-light exposure induced substantial and equivalent phase shifts of the melatonin and temperature rhythms (mean +/- SE difference in the phase-shifting response, 0.03 +/- 0.32 h), and the body temperature and melatonin rhythms thus maintained their usual phase relationship even after light-induced circadian phase inversion. These results are consistent with the hypothesis that the endogenous circadian components of both the plasma melatonin and body temperature rhythms are generated by a single central circadian pacemaker in humans. Furthermore, using the time of the fitted temperature minimum as a reference standard, we found that the fitted maximum of the endogenous 24-h melatonin profile was a more reliable phase marker than the onset of the nocturnal rise of melatonin (F = 4.48; P less than 0.01).

Real-time, vibration-compensated CO2 interferometer operation on the DIII-D tokamak

A multichannel, two-color, quadrature heterodyne interferometer is used to measure the line density in the DIII-D tokamak. The unique feature of this real-time vibration-compensated interferometer is the combination of high speed (1 MHz), high resolution (2π/256), and wide range (±8193 fringes). Quadrature phase information from a CO2 laser (10.6 μm) and a He–Ne laser (0.63 μm) are digitized with high-speed (6 MHz) flash digitizers. Zero crossings of the signals are counted with digital circuitry yielding quarter fringe resolution with a 4-MHz bandwidth. Further fringe resolution of 1/256 is provided at 350 kHz by a PROM which uses the digital signals as input to a look-up table. Analog line density is presently available at 80 kHz with a system noise equivalent phase shift of ±2/256. Error monitoring is provided for low signal amplitude and exceeding the maximum fringe rate. In addition, a method to prevent coating of in-vessel mirrors due to plasma and vessel wall cleaning discharges has been developed.

Nuclear Matter Properties for Nonstatic One-Boson-Exchange Potential with Retardation

Nuclear matter properties are evaluated using our nonstatic OBEP. The binding energy of nuclear matter is calculated to the first-order reaction ~atrix G. As the nucleon-nucleon interaction, four kinds. of potentials are considered that reprodu~e approximately equivalent phase shift, but differ from each other in the core potential (static Gaussian or velocity' dependent) and in the retarded effect (included or not). Our OBEP including retardation gives -12 MeV in binding energy at a saturation density kF=l.5 fm- 1 • The retarded effect of the OBEP is appreciable on the off-energy-shell G-matrices, and decreases simultaneously 2.0~2.5 MeV in the binding energy and ~0.05 fm- 1 (in Fermi momentum) in the density. The relativistic correction to the Bethe-Goldstone equation tends to increase the binding and the density. The defect wave function and wound integral for each potential case are examined· in detail.

Nuclear saturation and the smoothness of nucleon-nucleon potentials

Abstract The two-nucleon and nuclear matter problems are solved by matrix inversion in momentum space. Direct matrix inversion of the Lippman-Schwinger and Brueckner equations is shown to be useful for general nuclear potentials including ones that are local, nonlocal, weak, strong, central, or noncentral. This flexibility is employed to study the relationship between nuclear saturation and the smoothness of the two-nucleon interaction. Five potentials are considered that give approximately equivalent phase shifts but differ in their smoothness. Two examples of smooth potentials with very weak nonlocal tensor terms are given. The potentials are classified according to their smoothness by calculating the wave function defect and the wound integral for each case. The binding energy of nuclear matter is calculated for each potential using the effective mass and angle-averaged Pauli operator approximations. A self-consistent hole spectrum and a free particle spectrum are used. A systematic dependence of saturation on the smoothness of the two-nucleon interaction is found. Only strong potentials with strong tensor terms yield correct saturation, whereas very smooth potentials produce overbinding and large equilibrium densities.