Topside Measurements at Jicamarca During the 2019-2020 Deep Solar Minimum.

We present measurements of the equatorial topside ionosphere above Jicamarca made during extremely low solar flux conditions during the deep solar minimum of 2019-2020. Measurements were made in October, 2019, February, 2020, and September, 2020. The main features observed are a large and extended decrease in noontime temperatures unlike that seen in studies at moderate solar flux levels, predawn ionospheric heating as early as 0300 LT, large day-to-day variability in the O+/H+ transition height, and negligible helium ion concentration at all altitudes. Data from the Ion Velocity Meter (IVM) instrument onboard the Ionospheric Connection Explorer (ICON) and the Topside Ionospheric Plasma Monitor (SSIES) onboard the Defense Meteorological Satellite Program (DMSP) satellites are used to assess agreement with ISR data and assist with the analysis of the predawn heating phenomena. We also analyze the data in light of the SAMI2-PE model which shows less agreement with the data than at higher solar flux. The main areas of discrepancy with the data are outlined, such as the absence of significant predawn heating, less pronounced decreases in noontime temperatures, and much higher O+ fractions at high altitudes, particularly in September. Finally, a sensitivity analysis of the model to various forcing agents such as neutral winds, plasma drifts, solar flux, and heat flow is performed. A discussion is presented on bridging the discrepancies in future model runs. Novel techniques of clutter removal and noise power bias correction are introduced and described in the appendices.

The Ionospheric Connection Explorer Mission: Mission Goals and Design.

The Ionospheric Connection Explorer, or ICON, is a new NASA Explorer mission that will explore the boundary between Earth and space to understand the physical connection between our world and our space environment. This connection is made in the ionosphere, which has long been known to exhibit variability associated with the sun and solar wind. However, it has been recognized in the 21st century that equally significant changes in ionospheric conditions are apparently associated with energy and momentum propagating upward from our own atmosphere. ICON's goal is to weigh the competing impacts of these two drivers as they influence our space environment. Here we describe the specific science objectives that address this goal, as well as the means by which they will be achieved. The instruments selected, the overall performance requirements of the science payload and the operational requirements are also described. ICON's development began in 2013 and the mission is on track for launch in 2017. ICON is developed and managed by the Space Sciences Laboratory at the University of California, Berkeley, with key contributions from several partner institutions.

Assessment of the subchronic oral toxicity of d-limonene in dogs.

Several hydrocarbons, including d-limonene, have been shown to produce a male-rat-specific nephrotoxicity that is manifested acutely as exacerbation of hyaline droplet formation. In a study to assess the presence or absence of this response in a non-rodent species, the dog was selected as a relevant model because of an earlier report suggesting that d-limonene may be nephrotoxic in this species. Five male and five female adult beagle dogs per treatment group were gavaged twice daily over a 6-month period with tap-water (control) or d-limonene at 0.12 or 1.2 ml/kg body weight/day (100 or 1000 mg/kg body weight/day). The highest daily dose was determined in a pilot study to be close to the maximum tolerated dose for emesis (ED50 1.6 ml/kg body weight). The test compound was administered in divided doses to minimize the incidence of emesis. Feed consumption and body weight were unaffected by treatment. Linear regression analyses indicated a positive dose-related trend for absolute and relative female kidney weight and relative male kidney weight. There were no histopathological changes in the kidneys, evaluated by both haematoxylin and eosin and Mallory-Heidenhain staining, that could be associated with the organ-weight changes. Furthermore, there was no evidence of hyaline droplet accumulation nor of any other sign of hydrocarbon-induced nephropathy typical of those seen in male rats treated with d-limonene. Thus, dogs are refractory to the hyaline droplet nephropathy observed in male rats, thereby providing additional evidence that the male rat kidney is uniquely sensitive to hydrocarbons like d-limonene, and that this specific male rat nephropathic response may be inappropriate for interspecies extrapolation and human risk assessment.

Discrepant changes in plasminogen by two different assays in patients receiving streptokinase.

The fluorogenic synthetic substrate and radial immunodiffusion assays of plasma plasminogen were compared before and after administration of intravenous streptokinase in differing doses to 57 patients being treated for acute myocardial infarction. There was a moderate correlation (r = 0.73, slope = 0.221, intercept = 1.005, n = 57 pairs) in the two assays of plasma plasminogen before the administration of streptokinase. After streptokinase, however, the correlation of the two assays was poor (r = 0.28, slope = 0.03, y-intercept = 0.003, n = 57 pairs). The decrease in plasma plasminogen by the fluorogenic synthetic substrate assay after streptokinase averaged 95 +/- 5%, with little variation between doses. In contrast, the percentage decrease in plasma plasminogen after streptokinase by the radial immunodiffusion assay averaged only 30 +/- 11%. The percentage change in plasma plasminogen by the two assays is significantly different (P = 0.001). The discrepancy in the percentage change in plasma plasminogen after streptokinase as measured by the fluorogenic synthetic substrate assay and the radial immunodiffusion assay can be explained by a lack of specificity for the antibody to plasminogen in the radial immunodiffusion kit. Antigen-antibody precipitin rings were observed after incubation of antibody with a mixture presumed to contain plasmin, plasmin-alpha 2 antiplasmin complexes, and plasmin-fibrin/fibrinogen degradation products. Based on these data, the fluorogenic synthetic substrate assay for plasma plasminogen is a superior means of following plasminogen depletion in response to thrombolytic therapy after streptokinase treatment for acute myocardial infarction.

Whole body retention in rats of different 191Pt compounds following inhalation exposure.

The whole body retention, excretion, lung clearance, distribution, and concentration of 191Pt in other tissues was determined in rats following a single inhalation exposure to different chemical forms of 191Pt. The chemical forms of 191Pt used in study were 191PtCl4, 191Pt(SO4)2, 191PtO, and 191Pt metal. Immediately after exposure most of the 191Pt was found in the gastrointestinal and respiratory tract. Movement of the 191Pt through the gastrointestinal tract was rapid, most of the 191Pt being eliminated within 24 hr after exposure. Lung clearance was much slower, with a clearance half-time of about 8 days. In addition to the lungs, kidney and bone contained the highest concentrations of 191Pt.

Inhalation toxicology of automotive emissions as affected by an oxidation exhaust catalyst.

Preliminary data are given on the acute inhalation toxicology of automotive emissions as affected by an oxidation exhaust catalyst. The catalyst effectively reduced CO and HC in the exhause which apparently had an effect (at least in a closed exposure system) on oxidant and NO2 levels by altering the HC/NOx ratio. There was a resultant reduction in biological effects due to the exposure. The catalyst altered the type of particulate to one which probably contained sulfuric acid as a major component. No evidence was present in these acute exposures to suggest a toxic response due to the higher sulfate emissions or possible catalyst attrition products. The effects of long-term exposure have not yet been investigated.

Preliminary studies on the toxicity and metabolism of palladium and platinum.

Preliminary data are given on the LD50 of PdCl2 following different routes of exposure and on the LD50 of PtCl4 following intravenous exposure. The retention, tissue distribution, and excretion of 103Pd and 191Pt in rats was determined following oral, intravenous, intratracheal, and inhalation exposure. The highest retention for both 103Pd and 191Pt was obtained following intravenous dosing, and the lowest retention occurred after oral dosing. Following a single oral dose, almost all of the 103Pd and 191Pt was excreted in the feces due to nonabsorption, whereas after intravenous dosing, similar quantities were excreted in both the urine and feces. Tissues containing the highest concentrations of these metals were the kidney, spleen and liver. Following intravenous dosing of pregnant rats, a small amount of 103Pd and 191Pt was found in the fetuses.