Radar evidence of subglacial liquid water on Mars Orosei, R; Lauro, S E; Pettinelli, E ...
Science (American Association for the Advancement of Science),
08/2018, Letnik:
361, Številka:
6401
Journal Article
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The presence of liquid water at the base of the martian polar caps has long been suspected but not observed. We surveyed the Planum Australe region using the MARSIS (Mars Advanced Radar for ...Subsurface and Ionosphere Sounding) instrument, a low-frequency radar on the Mars Express spacecraft. Radar profiles collected between May 2012 and December 2015 contain evidence of liquid water trapped below the ice of the South Polar Layered Deposits. Anomalously bright subsurface reflections are evident within a well-defined, 20-kilometer-wide zone centered at 193°E, 81°S, which is surrounded by much less reflective areas. Quantitative analysis of the radar signals shows that this bright feature has high relative dielectric permittivity (>15), matching that of water-bearing materials. We interpret this feature as a stable body of liquid water on Mars.
Context. The orbit of Phobos is currently known with a 1 σ precision of 300 m, mostly directed along its track. Most previous determinations were made with the help of the Super-Resolution Channel ...(SRC) channel of the HRSC camera on board Mars Express (MEX). The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board MEX crosses the orbit of Phobos every 7 months on average and can be used to measure the distance between MEX and Phobos at the time of approach. Aims. We compared data from the MARSIS radar on board MEX to simulations using different shape models in order to provide measurements of the position of Phobos that can be used as control points for the determination of its orbit. Methods. We measured the range offset between SAR syntheses of MARSIS datasets and SAR syntheses of coherent simulations taken as a reference, and link this to the offset of Phobos along its trajectory. Results. We provide a set of measurements of range offsets made with MARSIS alongside the corresponding Phobos along-track offsets that would produce those discrepancies. We also provide measurements of the distance between Phobos and MARSIS. We performed those measurements for two different Phobos shape models and two different Phobos ephemerides, discussing the potential source of error in the range measurements. An estimation of the MARSIS instrumental delay for band III is derived from this work.
Jupiter's aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet's magnetic field lines. A northern and a southern main auroral oval are ...visible, surrounded by small emission features associated with the Galilean moons. We present infrared observations, obtained with the Juno spacecraft, showing that in the case of Io, this emission exhibits a swirling pattern that is similar in appearance to a von Kármán vortex street. Well downstream of the main auroral spots the extended tail is split in two. Both of Ganymede's footprints also appear as a pair of emission features, which may provide a remote measure of Ganymede's magnetosphere. These features suggest that magnetohydrodynamic interaction between Jupiter and its moon is more complex than previously anticipated.
In this work, we present the most updated catalog of Io hot spots based on Juno/JIRAM data. We find 242 hot spots, including 23 previously undetected. Over the half of the new hot spots identified, ...are located at high northern and southern latitudes (>70°). We observe a latitudinal variability and a larger concentration of hot spots in the polar regions, in particular in the North. The comparison between JIRAM and the most recent Io hot spot catalogs listing power output (Veeder et al., 2015, https://doi.org/10.1016/j.icarus.2014.07.028; de Kleer, de Pater, et al., 2019, https://doi.org/10.3847/1538-3881/ab2380), shows JIRAM detected 63% and 88% of the total number of hot spots, respectively. Furthermore, JIRAM observed 16 of the 34 faint hot spots previously identified. JIRAM data revealed thermal emission from 5 dark pateræ inferred to be active from color ratio images, thus confirming that these are hot spots.
Plain Language Summary
We mapped the hot spot distribution on Io's surface by analyzing the images acquired by the JIRAM instrument onboard the Juno spacecraft. We identified 242 hot spots, including 23 not present in other catalogs. A large number of the new hot spots identified are in the polar regions, specifically in the northern hemisphere. The comparison between our work and the most recent and updated catalog reveals that JIRAM detected 82% of the most powerful hot spots previously identified and half of the intermediate‐power hot spots, thus showing that these are still active. JIRAM detected 16 out of the 34 faint hot spots previously reported. The resolution of JIRAM may not have been sufficient to detect these faint hot spots, or activity might have faded or stopped.
Key Points
We produced a new Io hot spot map based on Juno/JIRAM data
We identified 242 hot spots, including 23 previously undetected
The latitudinal hot spot distribution is uneven with a larger concentration at the poles
The Italian health system is highly decentralized, with most administrative and organizational powers governed by Regions and rather limited powers at national level. The state has full control over ...the definition of the core benefit package (LEA) but there is evidence that the actual provision of these services varies greatly across Regions.
The familiar axisymmetric zones and belts that characterize Jupiter's weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes. Two-dimensional turbulence in ...combination with the Coriolis β-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows. The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur. Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles. Jovian polar regions are not visible from Earth owing to Jupiter's low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter's equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis β-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn's polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.
•AUC of dose–response models is sensitive to the observational dose-range of the fitted data•AUC value of NTCP models is driven by intrinsic characteristics of the model and by the clinical setting ...of the data used to develop them.•AUC is problematic when used to compare the discriminative performance of NTCP models.
Normal tissue complication probability (NTCP) models are probabilistic models that describe the risk of radio-induced toxicity in tissues or organs. In the field of radiotherapy, the area under the ROC curve (AUC) is widely used to estimate the performance in risk prediction of NTCP models.
In this work, we derived an analytical expression of the AUC for the logistic NTCP model in the case of both symmetrical and asymmetrical dose (to the normal tissue) windows around D50. Using numerical simulations, we studied the behavior of the AUC in general clinical settings, enforcing non-logistic NTCP models (Lyman-Kutcher-Burman and LogEUD) and including risk factors beyond the dose. We validated our findings using real-world radiotherapy data sets of prostate cancer patients.
Our analytical expression of the AUC made explicit the dependence on both the steepness of the logistic curve (β) and the dose window width (w), showing that an increase of w pushes AUC towards higher values. Increasing values of the AUC with increasing values of w were consistently observed across simulated data sets with diverse clinical settings from published studies and real clinical data sets.
Our results reveal that the AUC of NTCP models inherits intrinsic characteristics from the clinical setting of the data set on which the models are developed, and warn against the use of the AUC to compare the performance of models constructed upon data from trials in which substantially different dose ranges were administered or accounting for different risk factors beyond the dose.
This paper is a phenomenological description of the ionospheric plasma and induced magnetospheric boundary (IMB) response to two different types of upstream solar wind events impacting Mars in March ...2008, at the solar minimum. A total of 16 Mars Express orbits corresponding to five consecutive days is evaluated. Solar TErrestrial RElations Observatory‐B (STEREO‐B) at 1 AU and Mars Express and Mars Odyssey at 1.644 AU detected the arrival of a small transient interplanetary coronal mass ejection (ICME‐like) on the 6 and 7 of March, respectively. This is the first time that this kind of small solar structure is reported at Mars's distance. In both cases, it was followed by a large increase in solar wind velocity that lasted for ~10 days. This scenario is simulated with the Wang‐Sheeley‐Arge (WSA) ‐ ENLIL + Cone solar solar wind model. At Mars, the ICME‐like event caused a strong compression of the magnetosheath and ionosphere, and the recovery lasted for ~3 orbits (~20 h). After that, the fast stream affected the upper ionosphere and the IMB, which radial and tangential motions in regions close to the subsolar point are analyzed. Moreover, a compression in the Martian plasma system is also observed, although weaker than after the ICME‐like impact, and several magnetosheath plasma blobs in the upper ionosphere are detected by Mars Express. We conclude that, during solar minimum and at aphelion, small solar wind structures can create larger perturbations than previously expected in the Martian system.
Key Points
Martian plasma system response to space weather disturbances during low solar activity
Propagation of an ICME‐like transient and a fast solar wind stream from STEREO‐B to Mars
Longitudinal and radial inner boundary movements at Mars
The Jovian Infrared Auroral Mapper (JIRAM) is an imager/spectrometer on board NASA/Juno mission for the study of the Jovian aurorae. The first results of JIRAM's imager channel observations of the ...H3+ infrared emission, collected around the first Juno perijove, provide excellent spatial and temporal distribution of the Jovian aurorae, and show the morphology of the main ovals, the polar regions, and the footprints of Io, Europa and Ganymede. The extended Io “tail” persists for ~3 h after the passage of the satellite flux tube. Multi‐arc structures of varied spatial extent appear in both main auroral ovals. Inside the main ovals, intense, localized emissions are observed. In the southern aurora, an evident circular region of strong depletion of H3+ emissions is partially surrounded by an intense emission arc. The southern aurora is brighter than the north one in these observations. Similar, probably conjugate emission patterns are distinguishable in both polar regions.
Key Points
Detailed observation of a very long tail of the Io magnetic footprint
Identification of thin multiple arc structures in the northern and southern ovals, and of bright spots and depletion in the south pole
Filamentation of alternatively upward and downward current in the 0°–90° SIII sector in the north
Background
Until very recently the only therapeutic alternative for the management of patients affected by gout/hyperuricemia that did not respond to a first-line treatment based on allopurinol alone ...or who cannot tolerate allopurinol was febuxostat, a xanthine oxidase non-purine-selective inhibitor. Lately, however, a new therapeutic alternative has become available for the management of this pathology: lesinurad, a urate transporter inhibitor.
Objective
To objective of this study was to evaluate the cost effectiveness of lesinurad/allopurinol in comparison with febuxostat as a second-line therapeutic strategy for the management of patients affected by gout and hyperuricemia that did not respond to a first-line therapy based on allopurinol alone.
Methods
A Markov model was built based on the natural history of the pathology; patients entered the model according to their level of serum uric acid concentration and flowed across it according to their response to the therapy. The analysis was carried out considering the perspective of the Italian National Health Service on a lifetime horizon and 6-month cycles. Costs and quality-adjusted life-years (QALYs) were discounted at a 3.5% yearly rate. The results of the model were expressed in terms of incremental cost-effectiveness ratio (ICER). Both a one-way and a multi-way Monte–Carlo analysis were carried out in order to check the robustness of the results achieved.
Results
The ICER derived from the comparison was equal to €77.53/QALY on the lifetime horizon, as there was a higher level of costs associated with the combination as compared with febuxostat (€10,658.27 vs. €10,645.87, for a differential of €12.40) and a higher level of QALYs achieved (7.77 vs. 7.61, for a differential of 0.16).
Conclusions
The lesinurad/allopurinol combination is recommended for the treatment of patients affected by gout/hyperuricemia in the Italian Health System as it appears to be cost effective and thus sustainable for the Italian healthcare sector.
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