Wavelet analysis of the magnetic field fluctuations in the Martian foreshock is performed. Dynamical features of wave spectra are compared with plasma measurements of backstreaming ions and ...simulation results for all available data from the Phobos-2 spacecraft. A detailed analysis reveals the complex, fine structure of the ULF waves. It is shown that enhancement of this electromagnetic activity (mostly, at frequencies higher than the proton gyrofrequency) coincides with entry of the spacecraft into a bunch of exospheric protons reflected from the bow shock. Emissions near cyclotron frequencies of H+, He+, O+ are also recorded. These waves indicate pickup processes in the upstream region of Mars.
Mode conversion at the Jovian plasma sheet boundary Perraut, Sylvaine; Roux, Alain; Louarn, Philippe ...
Journal of Geophysical Research: Space Physics,
1 July 1998, Volume:
103, Issue:
A7
Journal Article
Peer reviewed
Open access
The plasma wave data obtained by Galileo in Jupiter's magnetosphere often exhibit three distinct frequency bands in the frequency range between a few hertz and a few kilohertz. It is shown that these ...emissions are generally electromagnetic. They are identified by relating their characteristic frequencies to the solutions of the cold plasma dispersion relation. Four modes are possible: X, Z, O, and whistler. Knowing the electron gyrofrequency ƒce measured by the fluxgate magnetometer, we have considered two different hypotheses for the observed lower‐frequency cutoff of the intermediate frequency emissions which occur below ƒce. Under these assumptions, characteristic frequencies have been computed from the cold plasma theory and compared with the set of cutoff frequencies derived from the observations. Consistency checks lead to the identification of the intermediate frequency band as being on O mode with a low‐frequency cutoff at the electron plasma frequency ƒp. Below the O mode, Galileo detects whistler mode emissions (below ƒp). Above ƒce the observed emission is consistent with being X mode. An attempt is made to identify the source of the O mode radiation. Quasi‐electrostatic waves are sometimes identified below the upper hybrid frequency when the plasma sheet boundary is crossed. We suggest that these electrostatic waves, which are presumably generated by field‐aligned electron beams flowing along plasma sheet boundary, are successively mode converted into Z and later O mode. Thus the O mode observed mostly outside the plasma sheet is generated by mode conversion of primary electrostatic waves.
The plasma wave data obtained by Galileo in Jupiter's magnetosphere often exhibit three distinct frequency bands in the frequency range between a few hertz and a few kilohertz. It is shown that these ...emissions are generally EM. They are identified by relating their characteristic frequencies to the solutions of the cold plasma dispersion relation. Four modes are possible: X, Z, O, and whistler. Knowing the electron gyrofrequency f(ce) measured by the fluxgate magnetometer, we have considered two different hypotheses for the observed lower-frequency cutoff of the intermediate frequency emissions that occur below f(ce). Under these assumptions, characteristic frequencies are computed from the cold plasma theory and compared with the set of cutoff frequencies derived from the observations. Consistency checks led to the identification of the intermediate frequency band as being on O mode with an LF cutoff at the electron plasma frequency f(p). Below the O mode, Galileo detects whistler mode emissions (below f(p)). Above f(ce) the observed emission is consistent with being X mode. The O mode observed mostly outside the plasma sheet is generated by mode conversion of primary electrostatic waves. (Author)
To evaluate outcome at 5 1/2 years after randomization in eyes that underwent cryotherapy and in control eyes of patients in the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity.
...During infancy, patients with bilateral threshold retinopathy of prematurity (ROP) were assigned to receive cryotherapy for one eye and no cryotherapy for the other eye. Those with threshold ROP in only one eye (asymmetric) were randomly assigned to cryotherapy or no cryotherapy for that eye. Then, 5 1/2 years later, testers who were masked to the treatment status of each eye measured the patients' monocular visual acuity by using the log of the minimum angle of resolution visual acuity chart that was used in the Early Treatment of Diabetic Retinopathy Study. This was the most refined visual acuity testing yet performed on this cohort. Structural outcome was evaluated by participating ophthalmologists' assessment of ROP residua in the posterior pole of the fundus.
Patients were 291 children who had been preterm infants with birth weights of less than 1251 g in whom threshold ROP had developed. Two hundred forty patients had bilateral threshold ROP, and 51 had threshold ROP in only one eye.
For the 234 children examined, both visual acuity and fundus structure showed a reduction in unfavorable outcomes in treated vs control eyes: 47.1% vs 61.7%, respectively (P<.005), for visual acuity and 26.9% vs 45.4%, respectively (P<.001), for fundus status. Detailed analysis of visual acuity outcomes for all eyes revealed that while fewer treated eyes (31.5%) than control eyes (48%) were blind (P<.001), there was a slight trend toward fewer eyes with a visual acuity of 20/40 or better in the treated (13%) vs control (17%) groups (P=.19).
The results support the long-term efficacy and safety of cryotherapy in the treatment of severe ROP. However, the data show preliminary evidence of a possible adverse effect of this treatment on visual acuity.
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