Search

This photo essay focuses on the landscapes of the Sonoran Desert—and the imperialist project of a border wall between the U.S. and Mexico—as a way of investigating the manner in which something as generic as a wall takes on particular and discrete politico‐affective forms. This short provocation explores the ways that violent and distasteful objects create, and subsequently come to characterize grotesque spectacles. [ABSTRACT FROM AUTHOR]

Animal-borne video cameras equipped with depth and temperature sensors were deployed on 16 reef manta rays (Mobula alfredi) in Raa Atoll, Maldives and 12 oceanic manta rays (Mobula birostris) in the Revillagigedo Archipelago, Mexico. These deployments provided descriptive behavioural data that give vital context to existing biotelemetry data and enabled a comparison of the social dynamics between the two manta ray species. Overall, cruising was the most dominant daytime behaviour recorded for both species. For M. alfredi , cleaning was the second most common behaviour, followed by courtship and feeding. No courtship behaviour was recorded for M. birostris. Across M. alfredi and M. birostris deployments, individuals spent an average of 43 and 8% of recorded time interacting with conspecifics, respectively. Sociability was higher in M. alfredi than M. birostris , however the findings should be interpreted with caution beyond the two deployment populations and times. Crittercams captured multiple courtship events of M. alfredi at depths greater than recreational scuba diving limits and captured previously undocumented interspecific interactions with M. mobular. Crittercam deployments also recorded M. alfredi travelling in groups and hugging the contours of the ocean floor, possibly as a tactic to reduce predation risk and/or improve swimming efficiency, enforcing the importance of this novel technology as a valuable tool to gain new insight into the ecological drivers of habitat use by these species. Lastly, these quantitative and descriptive results provide context for future hypothesis-driven research questions using animal-borne video cameras for mobulid rays. [ABSTRACT FROM AUTHOR]

The influence of thunderstorms' atmospheric electric fields (AEF) on secondary cosmic rays (CR) detected at high altitude was studied. Using data obtained during the period October 2019 to March 2020 by the Solar Neutron Telescope (SNT) and a Boltek EFM-100 AEF monitor installed in the Sierra Negra Cosmic Ray Observatory (SN-CRO) located at 4580 m a.s.l. in Mexico. With measurements from the EFM-100, 15 thunderstorms were identified during the established period. Based on the general theory of AEF effects on CR, due to acceleration and deceleration of secondary charged CR particles by AEF, proposed by Dorman (2004), we calculated, as a first approximation, the effect on the total charged component (1.15%–3.47%) at the observation level of the SN-CRO. Simulations of air showers in the presence of a simplified electric field were performed with the CORSIKA code and EXPACS software to complement the calculations. When thunderstorms occurred above SN-CRO, significant fluctuations in the average counting rate of three SNT channels were observed and were consistent with the calculated intensity variations. [ABSTRACT FROM AUTHOR]

• Solar neutron flux. • Simulations. • Olar neutron telescope. We performed simulations of the solar neutron (n s) flux in the Earth's atmosphere associated with three significant flares (X17 of September 07, 2005, X1.3 of September 07, 2017 and M2.9 of September 08, 2017). The input of the simulations was calculated on the basis of n s signals detected at ground level by the Solar Neutron Telescope of Sierra Negra (SNT-SN), in Mexico, and by the FIB scintillator of the Space Environment Data Acquisition-Attached Payload on board of the International Space Station. Since n s can produce Extensive Air Showers (EAS) in the Earth's atmosphere, we used the CORSIKA code and FLUKA subroutines to simulate the particle fluxes associated with the X17, X1.3 and M2.9 flares. We studied the average longitudinal variations of particle flux and energy loss through the atmosphere to estimate the n s flux impinging on the SNT-SN. The results of the simulated interactions and multiplicities of the particles, as a function of their energy, showed that 11–13% of the n s , released by the X17 flare, could overcome the atmospheric attenuation and propagate from the top of the atmosphere to the SNT-SN (4580 m a.s.l.) without producing EAS. On the other hand, n s associated with the X1.3 and M2.9 flares were lost due to atmospheric attenuation and the production of new particles; therefore, they were not detected at ground level by the SNT- SN. The characterization of these events allowed to develop an automatic tool for the analysis of n s emissions associated with solar flares. [ABSTRACT FROM AUTHOR]

This paper presents a simulation/experimental technique used in the design of optimum performance read-out electronics for a new cosmic ray telescope composed of scintillator bars. This new detector, called SciBar Cosmic Ray Telescope (SciCRT), is installed on top of Sierra Negra volcano in Mexico, operating at an atmospheric depth of 575 g cm−2. The severe atmospheric conditions and high background rate of the place currently limit the performance of the detector, therefore the requirements of our design are low power consumption and high throughput rate. The simulation developed considers the interaction of high energy cosmic ray muons with the scintillator bar, generation and propagation of photons inside a wavelength shifting fiber (WLS) fiber and the detection by a multi-anode photomultiplier (MAPMT). To produce realistic signals coming from the interaction of particles, our method relies on the extraction of different parameters throughout experiment to include them in the simulation. In addition, the paper presents a muon cosmic ray experiment designed to validate the results of the simulation and test the performance of the new electronics. [ABSTRACT FROM AUTHOR]