Acute haemolysis in childhood falciparum malaria

Acute haemolysis associated with clinical episodes of high-level Plasmodium falciparum parasitaemia was studied in 20 children from an holoendemic area (coastal Tanzania). The change in blood haemoglobin (Hb) concentration ranged from -46 to +5 g/L during the 72-h observation period and was linearly related to maximum parasitaemia. Balance studies between loss of blood Hb, increase in plasma Hb and appearance of Hb in the urine indicated that extravascular clearance of red cells was the predominant mode of erythrocyte clearance. Most subjects, however, showed minor signs of intravascular haemolysis. The plasma Hb was ≪1% of blood Hb and haemoglobinuria was detected in 14/20 children but the excretion of Hb in urine was \u3c0.5% of total Hb loss. Haemoglobinuria was, however, a marker of severe haemolysis, since the maximum blood Hb loss in children without haemoglobinuria was 10 g/L. Erythrocyte-bound opsonins known to induce erythrophagocytosis, i.e., complement C3c fragments and autologous IgG, were increased in all patients. In the patients with major haemolysis, the changes correlated to the haemolysis over time. Hence, a similar mechanism for predominantly extravascular erythrocyte clearance may be operative in acute malarial anaemia, normal erythrocyte senescence and other forms of acute haemolysis

A new perspective on the irregular satellites of Saturn - I Dynamical and collisional history

The dynamical features of the irregular satellites of the giant planets argue against an in-situ formation and are strongly suggestive of a capture origin. Since the last detailed investigations of their dynamics, the total number of satellites have doubled, increasing from 50 to 109, and almost tripled in the case of Saturn system. We have performed a new dynamical exploration of Saturn system to test whether the larger sample of bodies could improve our understanding of which dynamical features are primordial and which are the outcome of the secular evolution of the system. We have performed detailed N--Body simulations using the best orbital data available and analysed the frequencies of motion to search for resonances and other possible perturbing effects. We took advantage of the Hierarchical Jacobian Symplectic algorithm to include in the dynamical model of the system also the gravitational effects of the two outermost massive satellites, Titan and Iapetus. Our results suggest that Saturn's irregular satellites have been significantly altered and shaped by the gravitational perturbations of Jupiter, Titan, Iapetus and the Sun and by the collisional sweeping effect of Phoebe. In particular, the effects on the dynamical evolution of the system of the two massive satellites appear to be non-negligible. Jupiter perturbs the satellites through its direct gravitational pull and, indirectly, via the effects of the Great Inequality, i.e. its almost resonance with Saturn. Finally, by using the Hierarchical Clustering Method we found hints to the existence of collisional families and compared them with the available observational data.Comment: 26 Pages, 27 Figures, 4 Table

Spectrophotometric investigation of Phobos with the Rosetta OSIRIS-NAC camera and implications for its collisional capture

TheMartian satellite Phobos has been observed on 2007 February 24 and 25, during the pre- and post-Mars closest approach (CA) of the ESA Rosetta spacecraftMars swing-by. The goal of the observations was the determination of the surface composition of different areas of Phobos, in order to obtain new clues regarding its nature and origin. Near-ultraviolet, visible and near-infrared (263.5-992.0 nm) images of Phobos's surface were acquired using the Narrow Angle Camera of the OSIRIS instrument onboard Rosetta. The six multi-wavelength sets of observations allowed a spectrophotometric characterization of different areas of the satellite, belonging respectively to the leading and trailing hemisphere of the anti-Mars hemisphere, and also of a section of its sub-Mars hemisphere. The pre-CA spectrophotometric data obtained with a phase angle of 19° have a spectral trend consistent within the error bars with those of unresolved/disc-integrated measurements present in the literature. In addition, we detect an absorption band centred at 950 nm, which is consistent with the presence of pyroxene. The post-CA observations cover from NUV to NIR a portion of the surface (0° to 43°E of longitude) never studied before. The reflectance measured on our data does not fit with the previous spectrophotometry above 650 nm. This difference can be due to two reasons. First, the OSIRIS observed area in this observation phase is completely different with respect to the other local specific spectra and hence the spectrum may be different. Secondly, due to the totally different observation geometry (the phase angle ranges from 137° to 140°), the differences of spectral slope can be due to phase reddening. The comparison of our reflectance spectra, both pre-and post-CA, with those of D-type asteroids shows that the spectra of Phobos are all redder than the mean D-type spectrum, but within the spectral dispersion of other D-types. To complement this result, we performed an investigation of the conditions needed to collisionally capture Phobos in a way similar to that proposed for the irregular satellites of the giant planets. Once put in the context of the current understanding of the evolution of the early Solar system, the coupled observational and dynamical results we obtained strongly argue for an early capture of Phobos, likely immediately after the formation of Mars. © 2012 The Authors

Mapping Vesta: First Results from Dawn’s Survey Orbit

The geologic objectives of the Dawn Mission [1] are to derive Vesta’s shape, map the surface geology, understand the geological context and contribute to the determination of the asteroids’ origin and evolution.Geomorphology and distribution of surface features will provide evidence for impact cratering, tectonic activity, volcanism, and regolith processes. Spectral measurements of the surface will provide evidence of the compositional characteristics of geological units. Age information, as derived from crater sizefrequency distributions, provides the stratigraphic context for the structural and compositional mapping results, thus revealing the geologic history of Vesta. We present here the first results of the Dawn mission from data collected during the approach to Vesta, and its first discrete orbit phase – the Survey Orbit, which lasts 21 days after the spacecraft had established a circular polar orbit at a radius of ~3000 km with a beta angle of 10°-15°

Geoscientific mapping of Vesta by the Dawn mission

The geologic objectives of the Dawn Mission [1] are to derive Vesta’s shape, map the surface geology, understand the geological context and contribute to the determination of the asteroids’ origin and evolution. Geomorphology and distribution of surface features will provide evidence for impact cratering, tectonic activity, volcanism, and regolith processes. Spectral measurements of the surface will provide evidence of the compositional characteristics of geological units. Age information, as derived from crater size-frequency distributions, provides the stratigraphic context for the structural and compositional mapping results into the stratigraphic context and thus revealing the geologic history of Vesta

Morphology of the Auroral Tail of Io, Europa, and Ganymede From JIRAM L-Band Imager

Jupiter hosts intense auroral activity associated with charged particles precipitating into the planet's atmosphere. The Galilean moons orbiting within the magnetosphere are swept by the magnetic field: the resulting perturbation travels along field lines as Alfven waves, which are able to accelerate electrons toward the planet, producing satellite-induced auroral emissions. These emissions due to the moons, known as footprints, can be detected in various wavelengths (UV, visible, IR) outside the main auroral emission as multiple bright spots followed by footprint tails. Since 2016 the Juno spacecraft orbiting Jupiter has surveyed the polar regions more than 30 times at close distances. Onboard the spacecraft, the Jovian InfraRed Auroral Mapper (JIRAM) is an imager and spectrometer with an L-band imaging filter suited to observe auroral features at unprecedented spatial resolution. JIRAM revealed a rich substructure in the footprint tails of Io, Europa, and Ganymede, which appear as a trail of quasi-regularly spaced bright sub-dots whose intensity fades away along the emission trail as the spatial separation from the footprint increases. The fine structure of the Europa and Ganymede footprint tails is reported in this work for the first time. We will also show that the typical distance between subsequent sub-dots is the same for all three moons at JIRAM resolution in both hemispheres. In addition, the sub-dots observed by JIRAM are static in a frame corotating with Jupiter. A feedback mechanism between the ionosphere and the magnetosphere is suggested as a potential candidate to explain the morphology of the footprint tails

Spectroscopic Characterization of Mineralogy Across Vesta: Evidence of Different Lithologies

The average spectrum of Vesta, obtained by VIR in the range 0.25-5.1 microns, shows clear evidence of absorption bands due to pyroxenes and thermal emissions beyond 3.5 11m. Vesta shows considerable variability across its surface in terms of spectral reflectance and emission, band depths, bands widths and bands centers, reflecting a complex geological history. Vesta's average spectrum and inferred mineralogy resemble those of howardite meteorites. On a regional scale, significant deviations are seen: the south polar 500km Rheasilvia impact crater has a higher diogenitic component, and equatorial regions show a higher eucritic component. This lithologic distribution, with a concentration of Mg-pyroxenes in the Rheasilvia area, reinforces the hypothesis of a deeper diogenitic crust excavated by the impact that formed the Rheasilvia crater, and an upper eucritic crust, whose remnants are seen in the equatorial region. This scenario has implications for Vesta differentiation, consistent with magma ocean models. However, serial magmatism models could also have concentrated pyroxene cumulates in plutons emplaced within the lower crust