Dust grains fall from Saturn's D-ring into its equatorial upper atmosphere.

The sizes of Saturn's ring particles range from meters (boulders) to nanometers (dust). Determination of the rings' ages depends on loss processes, including the transport of dust into Saturn's atmosphere. During the Grand Finale orbits of the Cassini spacecraft, its instruments measured tiny dust grains that compose the innermost D-ring of Saturn. The nanometer-sized dust experiences collisions with exospheric (upper atmosphere) hydrogen and molecular hydrogen, which forces it to fall from the ring into the ionosphere and lower atmosphere. We used the Magnetospheric Imaging Instrument to detect and characterize this dust transport and also found that diffusion dominates above and near the altitude of peak ionospheric density. This mechanism results in a mass deposition into the equatorial atmosphere of ~5 kilograms per second, constraining the age of the D-ring.

Case series of recurrent inguinal hernia after primary TREPP repair: re-TREPP seems feasible and safe.

INTRODUCTION: The Trans REctussheath PrePeritoneal (TREPP) mesh repair was introduced in 2006 to decrease the risk of postoperative inguinal pain in hernia surgery. For the repair of a recurrent inguinal hernia after a primary TREPP an alternative open anterior route (Lichtenstein) may seem the most logical option, but coincides with an increased risk of chronic postoperative inguinal pain. Therefore, this study aimed to evaluate the feasibility of a second TREPP procedure to repair a recurrent inguinal hernia after an initial TREPP repair. METHODS: Consecutive patients with a recurrent inguinal hernia after a primary TREPP, repaired by a re-TREPP were retrospectively included in the study. Data, retrieved from the electronic patient files, were combined with the clinical findings at the outpatient department where the patients were physically investigated according to a priorly written and registered protocol. RESULTS: Overall about 1800 TREPPs were performed between 2006 and 2013. Since the introduction of TREPP in 2006, 40 patients presented with a recurrence in our center. From this group 19 patients were re-operated with the TREPP technique. No intraoperative complications occurred. There was one conversion from re-TREPP to Lichtenstein and no re-recurrences occurred to date. Ten out of 19 patients could be clinically evaluated with a mean follow-up period of 37 months (range 11-95). None of these patients (n=10) complained of chronic postoperative inguinal pain. Two patients reported discomfort. One patient died non procedure related, three weeks after re-TREPP of sudden cardiac death. CONCLUSION: These first experiences with re-TREPP for secondary inguinal hernia repair are encouraging for the aspects of feasibility and safety, particularly in experienced surgical hands.

In situ measurements of Saturn's ionosphere show that it is dynamic and interacts with the rings.

The ionized upper layer of Saturn's atmosphere, its ionosphere, provides a closure of currents mediated by the magnetic field to other electrically charged regions (for example, rings) and hosts ion-molecule chemistry. In 2017, the Cassini spacecraft passed inside the planet's rings, allowing in situ measurements of the ionosphere. The Radio and Plasma Wave Science instrument detected a cold, dense, and dynamic ionosphere at Saturn that interacts with the rings. Plasma densities reached up to 1000 cubic centimeters, and electron temperatures were below 1160 kelvin near closest approach. The density varied between orbits by up to two orders of magnitude. Saturn's A- and B-rings cast a shadow on the planet that reduced ionization in the upper atmosphere, causing a north-south asymmetry.

The TREPP as alternative technique for recurrent inguinal hernia after Lichtenstein's repair: A consecutive case series.

BACKGROUND: Recurrent inguinal hernias after initial repair with mesh are preferably treated via an alternative route (e.g. posterior after anterior). For recurrent inguinal hernias after an anterior repair such as Lichtenstein's, an endoscopic approach such as the total extraperitoneal or transabdominal preperitoneal technique (TEP or TAPP) is recommended if expertise is present. The TransREctus sheath PrePeritoneal (TREPP) technique is a promising open posterior technique and could be an alternative to endoscopic methods. This study aims to evaluate the results of the TREPP technique for recurrent inguinal hernia. MATERIALS AND METHODS: Consecutive patients who underwent a TREPP repair for recurrent hernia after initial operation according to Lichtenstein were included in a retrospective manner. A minimum of one year follow-up after the TREPP repair was maintained. Data retrieved from the patient files were combined with the findings at an outpatient department visit. RESULTS: Between January 2006 and December 2013 fifty-two patients were eligible for inclusion of which 38 patients were clinically evaluated. The mean follow-up of these thirty-eight patients was 65 months (range 17-108 months) in which 2 patients had developed a re-recurrence. One patient reported chronic postoperative inguinal pain (CPIP) since the TREPP and four patients experienced CPIP since the primary inguinal hernia repair. Peri-operative and <30 day complications were rare and no severe adverse events occurred. CONCLUSION: TREPP seems to be a feasible alternative for recurrent inguinal hernia repair after an initial operation according to Lichtenstein. It may yield extra advantages compared to endoscopic repairs, such as a short learning curve, spinal anesthesia and lower costs.

The variable rotation period of the inner region of Saturn's plasma disk.

We show that the plasma and magnetic fields in the inner region of Saturn's plasma disk rotate in synchronism with the time-variable modulation period of Saturn's kilometric radio emission. This relation suggests that the radio modulation has its origins in the inner region of the plasma disk, most likely from a centrifugally driven convective instability and an associated plasma outflow that slowly slips in phase relative to Saturn's internal rotation. The slippage rate is determined by the electrodynamic coupling of the plasma disk to Saturn and by the drag force exerted by its interaction with the Enceladus neutral gas torus.

Radar soundings of the ionosphere of Mars.

We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types of ionospheric echoes are observed, ranging from vertical echoes caused by specular reflection from the horizontally stratified ionosphere to a wide variety of oblique and diffuse echoes. The oblique echoes are believed to arise mainly from ionospheric structures associated with the complex crustal magnetic fields of Mars. Echoes at the electron plasma frequency and the cyclotron period also provide measurements of the local electron density and magnetic field strength.

Cassini measurements of cold plasma in the ionosphere of Titan.

The Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe (LP) sensor observed the cold plasma environment around Titan during the first two flybys. The data show that conditions in Saturn's magnetosphere affect the structure and dynamics deep in the ionosphere of Titan. The maximum measured ionospheric electron number density reached 3800 per cubic centimeter near closest approach, and a complex chemistry was indicated. The electron temperature profiles are consistent with electron heat conduction from the hotter Titan wake. The ionospheric escape flux was estimated to be 10(25) ions per second.

Radio and plasma wave observations at Saturn from Cassini's approach and first orbit.

We report data from the Cassini radio and plasma wave instrument during the approach and first orbit at Saturn. During the approach, radio emissions from Saturn showed that the radio rotation period is now 10 hours 45 minutes 45 +/- 36 seconds, about 6 minutes longer than measured by Voyager in 1980 to 1981. In addition, many intense impulsive radio signals were detected from Saturn lightning during the approach and first orbit. Some of these have been linked to storm systems observed by the Cassini imaging instrument. Within the magnetosphere, whistler-mode auroral hiss emissions were observed near the rings, suggesting that a strong electrodynamic interaction is occurring in or near the rings.

Control of Jupiter's radio emission and aurorae by the solar wind.

Radio emissions from Jupiter provided the first evidence that this giant planet has a strong magnetic field and a large magnetosphere. Jupiter also has polar aurorae, which are similar in many respects to Earth's aurorae. The radio emissions are believed to be generated along the high-latitude magnetic field lines by the same electrons that produce the aurorae, and both the radio emission in the hectometric frequency range and the aurorae vary considerably. The origin of the variability, however, has been poorly understood. Here we report simultaneous observations using the Cassini and Galileo spacecraft of hectometric radio emissions and extreme ultraviolet auroral emissions from Jupiter. Our results show that both of these emissions are triggered by interplanetary shocks propagating outward from the Sun. When such a shock arrives at Jupiter, it seems to cause a major compression and reconfiguration of the magnetosphere, which produces strong electric fields and therefore electron acceleration along the auroral field lines, similar to the processes that occur during geomagnetic storms at the Earth.