Water ice and organics on the surface of the asteroid 24 Themis.

It has been suggested that Earth's current supply of water was delivered by asteroids, some time after the collision that produced the Moon (which would have vaporized any of the pre-existing water). So far, no measurements of water ice on asteroids have been made, but its presence has been inferred from the comet-like activity of several small asteroids, including two members of the Themis dynamical family. Here we report infrared spectra of the asteroid 24 Themis which show that ice and organic compounds are not only present on its surface but also prevalent. Infrared spectral differences between it and other asteroids make 24 Themis unique so far, and our identification of ice and organics agrees with independent results that rule out other compounds as possible sources of the observed spectral structure. The widespread presence of surface ice on 24 Themis is somewhat unexpected because of the relatively short lifetime of exposed ice at this distance ( approximately 3.2 au) from the Sun. Nevertheless, there are several plausible sources, such as a subsurface reservoir that brings water to the surface through 'impact gardening' and/or sublimation.

Spectrally blue hydrated parent body of asteroid (162173) Ryugu.

Ryugu is a carbonaceous rubble-pile asteroid visited by the Hayabusa2 spacecraft. Small rubble pile asteroids record the thermal evolution of their much larger parent bodies. However, recent space weathering and/or solar heating create ambiguities between the uppermost layer observable by remote-sensing and the pristine material from the parent body. Hayabusa2 remote-sensing observations find that on the asteroid (162173) Ryugu both north and south pole regions preserve the material least processed by space weathering, which is spectrally blue carbonaceous chondritic material with a 0-3% deep 0.7-µm band absorption, indicative of Fe-bearing phyllosilicates. Here we report that spectrally blue Ryugu's parent body experienced intensive aqueous alteration and subsequent thermal metamorphism at 570-670 K (300-400 °C), suggesting that Ryugu's parent body was heated by radioactive decay of short-lived radionuclides possibly because of its early formation 2-2.5 Ma. The samples being brought to Earth by Hayabusa2 will give us our first insights into this epoch in solar system history.

Widespread carbon-bearing materials on near-Earth asteroid (101955) Bennu.

Asteroid (101955) Bennu is a dark asteroid on an Earth-crossing orbit that is thought to have assembled from the fragments of an ancient collision. We use spatially resolved visible and near-infrared spectra of Bennu to investigate its surface properties and composition. In addition to a hydrated phyllosilicate band, we detect a ubiquitous 3.4-micrometer absorption feature, which we attribute to a mix of organic and carbonate materials. The shape and depth of this absorption feature vary across Bennu's surface, spanning the range seen among similar main-belt asteroids. The distribution of the absorption feature does not correlate with temperature, reflectance, spectral slope, or hydrated minerals, although some of those characteristics correlate with each other. The deepest 3.4-micrometer absorptions occur on individual boulders. The variations may be due to differences in abundance, recent exposure, or space weathering.

Demonstration and quatification of IgE antibodies against Paracoccidioides brasiliensis in Paracoccidioidomycosis

Using a radiommunossay technique, we have determined the total IgE concentration ans specific IgE antibody level against Paracoccidioides brasiliensis in the sera of patients with mycologically confirmed active paracoccidioimomycosis. Patients with aspergilloma, or individuals from the endemic area were also examined. The levelof total IgE was siginificantly elevated in 9 out of 10 cases of paracoccidioidomycosis. The mean level of specific IgE against P. brasiliensis was significantly higher in the serum of the patients in comparison with control individuals. The percentage of specific IgE levels in paracoccidioidomycosis sera and in the other mycoses were statistically significant. Or results suggest a possible involvement of specific IgE antibodies agaisnt P. brasileiensis in the immune response of patients with paracoccidioidomycosis. The hypermmunoglobulinemia E may be related to the T-cell defect that characterizes the severe forms of the disease

Las micosis único problema de salud pública / Mycosis as a single public health problem

Se plantea el problema de las micosis profundas y un campo de acción de la salud pública en Venezuela, su clasificación, estado actual, y se hace un estudio de dicho problema en algunas regiones del país