Inner southern magnetosphere observation of Mercury via SERENA ion sensors in BepiColombo mission

Mercury's southern inner magnetosphere is an unexplored region as it was not observed by earlier space missions. In October 2021, BepiColombo mission has passed through this region during its first Mercury flyby. Here, we describe the observations of SERENA ion sensors nearby and inside Mercury's magnetosphere. An intermittent high-energy signal, possibly due to an interplanetary magnetic flux rope, has been observed downstream Mercury, together with low energy solar wind. Low energy ions, possibly due to satellite outgassing, were detected outside the magnetosphere. The dayside magnetopause and bow-shock crossing were much closer to the planet than expected, signature of a highly eroded magnetosphere. Different ion populations have been observed inside the magnetosphere, like low latitude boundary layer at magnetopause inbound and partial ring current at dawn close to the planet. These observations are important for understanding the weak magnetosphere behavior so close to the Sun, revealing details never reached before.

Jupiter's X-Ray and UV Dark Polar Region

We present 14 simultaneous Chandra X-ray Observatory (CXO)-Hubble Space Telescope (HST) observations of Jupiter's Northern X-ray and ultraviolet (UV) aurorae from 2016 to 2019. Despite the variety of dynamic UV and X-ray auroral structures, one region is conspicuous by its persistent absence of emission: the dark polar region (DPR). Previous HST observations have shown that very little UV emission is produced by the DPR. We find that the DPR also produces very few X-ray photons. For all 14 observations, the low level of X-ray emission from the DPR is consistent (within 2-standard deviations) with scattered solar emission and/or photons spread by Chandra's Point Spread Function from known X-ray-bright regions. We therefore conclude that for these 14 observations the DPR produced no statistically significant detectable X-ray signature.

SERENA: Particle Instrument Suite for Determining the Sun-Mercury Interaction from BepiColombo

The ESA-JAXA BepiColombo mission to Mercury will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric particle dynamics at Mercury as well as their interactions with solar wind, solar radiation, and interplanetary dust. The particle instrument suite SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) is flying in space on-board the BepiColombo Mercury Planetary Orbiter (MPO) and is the only instrument for ion and neutral particle detection aboard the MPO. It comprises four independent sensors: ELENA for neutral particle flow detection, Strofio for neutral gas detection, PICAM for planetary ions observations, and MIPA, mostly for solar wind ion measurements. SERENA is managed by a System Control Unit located inside the ELENA box. In the present paper the scientific goals of this suite are described, and then the four units are detailed, as well as their major features and calibration results. Finally, the SERENA operational activities are shown during the orbital path around Mercury, with also some reference to the activities planned during the long cruise phase.

ANAEROBIC GLYCOGENOLYSIS IN THE MUSCLES OF RANA PIPIENS LIVING AT LOW TEMPERATURES

1. A considerable proportion of R. pipiens caught in the spring and stored without food for several weeks at about 4 degrees C. had gastrocnemii that did not break down glycogen when they contracted anaerobically to complete exhaustion. A smaller number of the same muscles did not produce lactate. 2. There was no evident relation between failure to break down glycogen and the glycogen content of such muscles, some of which had more than 500 mg. of glycogen per 100 gm. of tissue. 3. The hypothesis of Meyerhof and his followers that aerobic contraction of frog muscles may at times take place with sources of energy other than carbohydrate is therefore extended to include anaerobic contraction.

Correlations of maternal buprenorphine dose, buprenorphine, and metabolite concentrations in meconium with neonatal outcomes

For the first time, relationships among maternal buprenorphine dose, meconium buprenorphine and metabolite concentrations, and neonatal outcomes are reported. Free and total buprenorphine and norbuprenorphine, nicotine, opiates, cocaine, benzodiazepines, and metabolites were quantified in meconium from 10 infants born to women who had received buprenorphine during pregnancy. Neither cumulative nor total third-trimester maternal buprenorphine dose predicted meconium concentrations or neonatal outcomes. Total buprenorphine meconium concentrations and buprenorphine/norbuprenorphine ratios were significantly related to neonatal abstinence syndrome (NAS) scores >4. As free buprenorphine concentration and percentage free buprenorphine increased, head circumference decreased. Thrice-weekly urine tests for opiates, cocaine, and benzodiazepines and self-reported smoking data from the mother were compared with data from analysis of the meconium to estimate in utero exposure. Time of last drug use and frequency of use during the third trimester were important factors associated with drug-positive meconium specimens. The results suggest that buprenorphine and metabolite concentrations in the meconium may predict the onset and frequency of NAS.

Generalized approach to Ewald sums

We derive Ewald sum formulas for potential energy and force for a system of point charges interacting with an arbitrary, long-range central potential. The system is made neutral by a uniform background of opposite charge interacting with the same potential. These formulas can be readily used in computer numerical simulations of model physical systems. In particular, expressions for the potential energy and the force have been obtained in both two and three dimensions for Coulomb and other power-law potentials, Yukawa systems, and for an electronic bilayer. We discuss numerical results and their accuracy for various systems and, based on our analysis, suggest values to be used for the parameters that appear in the Ewald sums.

The Interaction of the Atmosphere of Enceladus with Saturn's Plasma

During the 14 July 2005 encounter of Cassini with Enceladus, the Cassini Plasma Spectrometer measured strong deflections in the corotating ion flow, commencing at least 27 Enceladus radii (27 x 252.1 kilometers) from Enceladus. The Cassini Radio and Plasma Wave Science instrument inferred little plasma density increase near Enceladus. These data are consistent with ion formation via charge exchange and pickup by Saturn's magnetic field. The charge exchange occurs between neutrals in the Enceladus atmosphere and corotating ions in Saturn's inner magnetosphere. Pickup ions are observed near Enceladus, and a total mass loading rate of about 100 kilograms per second (3 x 10(27) H(2)O molecules per second) is inferred.

Production of oxygen by electronically induced dissociations in ice

A solid-state chemical model is given for the production of O2 by electronic excitation of ice, a process that occurs on icy bodies in the outer solar system. Based on a review of the relevant available laboratory data, we propose that a trapped oxygen atom-water complex is the principal precursor for the formation of molecular oxygen in low-temperature ice at low fluences. Oxygen formation then occurs through direct excitation of this complex or by its reaction with a freshly produced, nonthermal O from an another excitation event. We describe a model for the latter process that includes competition with precursor destruction and the effect of sample structure. This allows us to put the ultraviolet photon, low-energy electron, and fast-ion experiments on a common footing for the first time. The formation of the trapped oxygen atom precursor is favored by the preferential loss of molecular hydrogen and is quenched by reactions with mobile H. The presence of impurity scavengers can limit the trapping of O, leading to the formation of oxygen-rich molecules in ice. Rate equations that include these reactions are given and integrated to obtain an analytic approximation for describing the experimental results on the production and loss of molecular oxygen from ice samples. In the proposed model, the loss rate varies, roughly, inversely with solid-state defect density at low temperatures, leading to a yield that increases with increasing temperature as observed. Cross sections obtained from fits of the model to laboratory data are evaluated in light of the proposed solid-state chemistry.

Composition and Dynamics of Plasma in Saturn's Magnetosphere

During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 RS (where RS is the radial distance from the center of Saturn), whereas inside, the plasma consists primarily of a corotating comet-like mix of water-derived ions with approximately 3% N+. Over the A and B rings, we found an ionosphere in which O2+ and O+ are dominant, which suggests the possible existence of a layer of O2 gas similar to the atmospheres of Europa and Ganymede.

Energy loss by keV ions in silicon

Using silicon photodiodes with an ultrathin passivation layer, the average total energy lost to silicon target electrons (electronic stopping) by incident low energy ions and the recoil target atoms they generate is directly measured. We find that the total electronic energy deposition and the ratio of the total nuclear to electronic stopping powers for the incident ions and their recoils each follow a simple, universal representation, thus enabling systematic prediction of ion-induced effects in silicon. We also observe a velocity threshold at 0.05 a.u. for the onset of electronic stopping.

Comparing the use of short-acting and long-acting calcium channel blockers in an HMO

One of the questions surrounding the controversy over the risks of MI among hypertensives taking calcium channel blockers (CCBs) is the dosage form, and whether the short-acting form may be more likely than the long-acting to increase the risk of MI. This preliminary study compared HMO members receiving the two dosage forms by sociodemographic and clinical characteristics, and by utilization (hospital, office visits, emergency room, outside of HMO services) prior to and during CCB use. The sampling frame was members with one or more dispensings for a CCB 1990 through 1994. Incident users were those who received one or more CCB dispensings and no cardiovascular disease-related drugs the year prior to their first dispensing of a CCB. CCB users were those who had at least 90 days of continuous CCB use. Short-acting outnumbered long-acting users by eight to one. Few incident users of long-acting CCBs were found. Among incident users, diagnoses and comorbidities were similar. In general, short-acting users appeared to have less risk of exposure to heart-related medications, but similar risks of exposure to non-heart-related drugs and to utilization of the various services during the year prior to first use. The odds of being exposed to heart-related medications and non-heart related medications and use of services during periods of use of CCBs were similar in general, but where differences were observed, the odds of being exposed were less among short-acting users. Users of the two dosage forms in this setting prior to reports questioning the safety of short-acting CCBs were different quantitatively and qualitatively making a retrospective comparative study difficult, perhaps not possible, due to substantial selection bias among users. Further patient selection bias has also undoubtedly occurred subsequent to the reports. The final answer to the relative safety and effectiveness of the different dosage forms of calcium channel blockers is likely to have come from randomized clinical trials.

Molecular dynamics study of a bilayer electron gas: single particle properties

The single-particle dynamical properties of a strongly coupled, classical, symmetric electronic bilayer system have been investigated by molecular dynamics simulation. Results for the velocity correlation function, the single-particle scattering function, and their respective Fourier transforms have been calculated, and their behavior, as a function of the interlayer separation d, has been analyzed. The single-particle scattering function in particular, shows dramatic effects when the bilayer attains a staggered square lattice structure. This occurs when the interlayer separation is around 0.8a (a is the Wigner-Seitz radius), where our previous study showed a marked decrease in the diffusion coefficient.

The production of oxidants in Europa's surface

The oxidants produced by radiolysis and photolysis in the icy surface of Europa may be necessary to sustain carbon-based biochemistry in Europa's putative subsurface ocean. Because the subduction of oxidants to the ocean presents considerable thermodynamic challenges, we examine the formation of oxygen and related species in Europa's surface ice with the goal of characterizing the chemical state of the irradiated material. Relevant spectral observations of Europa and the laboratory data on the production of oxygen and related species are first summarized. Since the laboratory data are incomplete, we examine the rate equations for formation of oxygen and its chemical precursors by radiolysis and photolysis. Measurements and simple rate equations are suggested that can be used to characterize the production of oxidants in Europa's surface material and the chemical environment produced by radiolysis. Possible precursor molecules and the role of radical trapping are examined. The possibility of oxygen reactions on grain surfaces in Europa's regolith is discussed, and the earlier estimates of the supply of O(2) to the atmosphere are increased.