Nightside condensation of iron in an ultrahot giant exoplanet.

Ultrahot giant exoplanets receive thousands of times Earth's insolation1,2. Their high-temperature atmospheres (greater than 2,000 kelvin) are ideal laboratories for studying extreme planetary climates and chemistry3-5. Daysides are predicted to be cloud-free, dominated by atomic species6 and much hotter than nightsides5,7,8. Atoms are expected to recombine into molecules over the nightside9, resulting in different day and night chemistries. Although metallic elements and a large temperature contrast have been observed10-14, no chemical gradient has been measured across the surface of such an exoplanet. Different atmospheric chemistry between the day-to-night ('evening') and night-to-day ('morning') terminators could, however, be revealed as an asymmetric absorption signature during transit4,7,15. Here we report the detection of an asymmetric atmospheric signature in the ultrahot exoplanet WASP-76b. We spectrally and temporally resolve this signature using a combination of high-dispersion spectroscopy with a large photon-collecting area. The absorption signal, attributed to neutral iron, is blueshifted by -11 ± 0.7 kilometres per second on the trailing limb, which can be explained by a combination of planetary rotation and wind blowing from the hot dayside16. In contrast, no signal arises from the nightside close to the morning terminator, showing that atomic iron is not absorbing starlight there. We conclude that iron must therefore condense during its journey across the nightside.

Closing Connectivity Gap: An Overview of Mobile Coverage Solutions for Not-Spots in Rural Zones.

Access to broadband communications in different parts of the world has become a priority for some governments and regulatory authorities around the world in recent years. Building new digital roads and pursuing a connected society includes looking for easier access to the internet. In general, not all areas where people congregate are fully covered, especially in rural zones, thus restricting access to data communications and inducing inequality. In the present review article, we have comprehensively surveyed the use of three platforms to deliver broadband services to such remote and low-income areas, and they are proposed as follows: unmanned aerial vehicles (UAV), altitude platforms (AP), and low-Earth orbit (LEO) satellites. These novel strategies support the connected and accessible world hypothesis. Hence, UAVs are considered a noteworthy solution since their efficient maneuverability can solve rural coverage issues or not-spots.

Bone marrow mononuclear cells stimulate angiogenesis when transplanted into surgically induced fibrocollagenous tunnels: results from a canine ischemic hindlimb model.

Progenitor cell transplantation has been considered as a potential angiogenesis therapy for the ischemic hindlimb. In this work we performed an ischemic hindlimb model in dogs. We ligated the middle sacra and the external right iliac arteries. After 7 days, the femoral artery was ligated and removed, and three Silastic tubes were inserted into the gracilis muscle to create fibrocollagenous tunnels. After Silastic implantation, we administered saline or granulocyte colony stimulating factor (G-CSF) subcutaneously daily during 5 days. Fourteen days after device positioning we transplanted bone marrow mononuclear cells (BMMC) into the tunnels previously formed by Silastic tube reaction. Twenty-eight days later, contrasted angiographies were performed and angiographic scores were calculated. Also, vessels and endothelial cells and proliferating cells were identified by immunochemistry of muscle sections. Results demonstrated that BMMC transplantation enriched by G-CSF administration significantly stimulates angiogenesis in the ischemic hindlimb, and more than BMMC transplantation alone. Transplantation of progenitor cells in an appropriate extracellular matrix is a potential therapy for hindlimb ischemia.