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The study of small rodents is challenging because of the difficulty of observing and sampling them in the wild. Although noninvasive approaches have proven effective for large mammals, such an approach has rarely been applied to rodents. Here, we describe a novel noninvasive approach for sampling rodent hairs in tropical forest and caves in Gabon, and present cytochrome b sequence data from hair samples obtained using this technique. Twenty-six unknown rodent hair samples were randomly selected for this study from a larger set of samples collected from 2 sites in Gabon (Lastoursville and Franceville). These samples were captured using 3 types of hair traps made from 20 cm long cylindrical tubes of plastic sheathing composed of either: (i) 50-mm diameter red electric cable; (ii) gray polyvinyl chloride (PVC) pipes; or (iii) a larger PVC pipe of 100-mm diameter. Traps were placed along ~200 m long transects laid either on the forest floor, on tree trunks, or within caves and baited with a tethered palm nut. From this sample subset, we were able to obtain a 429-bp fragment of the mitochondrial cytochrome b gene from 17 samples. Nearly all samples could be identified to the species level using a neighbor-joining tree analysis based on published sequences. Five murid rodents were identified (Praomys petteri, P. missonei, Lophuromys spp., Malacomys longipes, and Grammomys spp.) and 1 Red-legged Sun Squirrel (Heliosciurus rufobrachium). This study shows that it is possible to amplify and sequence hair samples collected noninvasively from small forest rodents in the tropics and that such an approach could provide important genetic data on species that would otherwise be difficult to study. 

High-energy cosmic rays that hit the Earth can be used to study large-scale atmospheric perturbations. After a first interaction in the upper parts of the atmosphere, cosmic rays produce a shower of particles that sample it down to the detector level. The HAWC (High-Altitude Water Cherenkov) gamma-ray observatory in Central Mexico at 4,100 m elevation detects air shower particles continuously with 300 water Cherenkov detectors with an active area of 12,500 m2. On January 15th, 2022, HAWC detected the passage of the pressure wave created by the explosion of the Hunga volcano in the Tonga islands, 9,000 km away, as an anomaly in the measured rate of shower particles. The HAWC measurements are used to determine the propagation speed of four pressure wave passages, and correlate the variations of the shower particle rates with the barometric pressure changes. The profile of the shower particle rate and atmospheric pressure variations for the first transit of the pressure wave at HAWC is compared to the pressure measurements at the Tonga island, near the volcanic explosion. By using the cosmic-ray propagation in the atmosphere as a probe for the pressure, it is possible to achieve very high time-resolution measurements. Moreover, the high-altitude data from HAWC allows to observe the shape of the pressure anomaly with less perturbations compared to sea level detectors. Given the particular location and the detection method of HAWC, our high-altitude data provides valuable information that contributes to fully characterize this once-in-a-century phenomenon.