Foreigners vs. Migrants

In recent years, Colombia, has witnessed a transformation in terms of human mobility. In a contradictory scenario where economic wealth, growth and opulence overlap with hunger, unemployment, conflict and poverty, Colombia experienced two main forms of human mobilization: internal displacement from rural areas to cities as a result of the armed conflict, and emigration looking for new opportunities abroad. However, recently Colombia has become a key point for human mobility—due primarily to the international human mobility from Venezuela. As a result, it is today an immigration, emigration and transit hot spot. The Covid-19 pandemic and an increase of human mobility in Colombia have emphasized the contrast between two groups: those who arrive by foot and those who can afford aerial transport. We will argue that during the Covid-19 pandemic, national authorities in the main cities have adopted differing treatments towards low- income migrants, as opposed to foreign tourists/investors. To do this, we will focus our analysis on the restrictions imposed to enter the country, as a policy has been structured to exclude migrants crossing by foot trying to reach a main city, while appealing to foreign tourists/investors. This paper aims to show how the authorities’ narratives separate the terms “migrants” and “foreigners” as starkly different, giving them a distinctive treatment when entering the country. “Migration” usually refers to the poorer individuals from Latin America (predominantly Venezuelan), while the concept of “foreigner” typically refers to the wealthy people from the global north. In this sense, the way in which a person enters the country determines how they will be treated by authorities and communities. This is a consequence of a normalized aporophobia, as Cortina defined, that undervalues migrants and favors foreigners.

Urban Air Mobility—A 6G Use Case?

The increasing popularity of Unmanned Aerial Vehicles (UAV) has resulted in exponential growth of the market owing to numerous applications that have been facilitated by advances in battery technology and wireless communications. Given the successes of UAVs thus far, researchers are already gearing towards aerial transport systems that consist of dense deployment of both UAVs and Personal Aerial Vehicles (PAVs) with human passengers. Although the fifth-generation mobile network (5G) key performance indicators have been optimised to support drone use cases for both high data rates and low latency applications, future aerial transport systems will require stricter network key performance indicators to support the expected massive deployment of aerial vehicles taking into account network capacity and distance between the base station and the aerial vehicles, among others. In this article, we present our perspective, vision, architecture, requirements and key performance indicators for future aerial wireless networks supported by 6G for Urban Air Mobility (UAM). Furthermore, we review key enabling technologies and discuss future challenges for incorporating aerial wireless networks in 6G.

The oldest record of window fly supports a Gondwanan origin of the family (Diptera: Scenopinidae)

Palaeobiogeographic hypotheses need to be based on accurate palaeomaps and phylogenies of the concerned clades with a fossil record as complete as possible. Here we re-analyse the palaeobiogeography of the small fly family Scenopinidae, based on its first record in the mid-Cretaceous Burmese amber that we describe herein as Burmaprorates alagracilis gen. et sp. nov. and we assign to the subfamily Proratinae. At that time, the corresponding palaeobiota was an isolated island in the Southern part of the Tethys Ocean far away from the Laurasian plate and with general wind circulation unfavorable for aerial transport from Laurasia to the “Burmese Terrane”. Our results challenge and question the hypothesis of a North-Central American origin for the Scenopinidae at the beginning of the Cretaceous, and support a new hypothesis of a South Gondwanan origin.

Air Pollution of Nature Reserves near Cities in Russia

Today, protected natural areas cover about 15% of the Earth’s land. These areas by definition are supposed to be free of pollution; they nevertheless suffer from the effects of aerial transport of anthropogenic polluting substances. In this study, we evaluated the impact of settlements on protected natural areas to determine the optimal distance beyond which the anthropogenic influence would be minimal. For this purpose, we analyzed the particle size distribution and the content of metals in fresh snow samples collected in the Bastak Nature Reserve and the neighboring Birobidzhan city (Russian Federation). Both sites contained comparable proportions of PM10 and contents of heavy metals, which points to the transportation of air pollutants from the city to the reserve. The results of the analysis were summarized and compared with the available data on other nature reserves and nearby populated localities. Based on the research data, pollutant emissions should be decreased for cities that are closer than 50 km to nature reserves. Moreover, authorities should take into consideration atmospheric factors and distance to the nearest settlement when establishing new protected natural areas.

Energy distribution in Dual-UAV collaborative transportation through load sharing

In this paper, a novel dual-UAV collaborative aerial transport strategy based on energy distribution and load sharing is proposed. This paper presents the first experimental demonstration of dual-UAV collaborative aerial transport while distributing power consumption. The demonstration is performed while distributing the power consumption between two drones sharing a load based on their battery state of charge. A numerical model of the dual-hex-rotor-payload is used to validate the proposed strategy. Numerical and hardware tests were conducted to demonstrate the load distribution using multiple UAV with certain spatial configurations. Finally, collaborative aerial transport test scenarios are performed numerically and experimentally. The simulation and experimental results show the effectiveness and applicability of the proposed strategy.

Superb autorotator: rapid decelerations in impulsively launched samaras

Autorotation of botanical samaras, with a consequent reduction in their rate of descent, increases dispersal range in the presence of horizontal winds. Samaras in initial free fall from rest pass through a brief transitional phase prior to reaching their minimum rate of descent and stable autorotation. By contrast, intense wind gusts and elastic recoil of tree branches can produce impulsive samara detachment and accelerate them rapidly through the air. Here, we investigate the autorotation of maple samaras when launched with a high initial impulse. Norway maple seeds catapulted either vertically or horizontally at approximately 9 m s −1 exhibited remarkably high and rapid decelerations (10–15 g ) and reached a near-zero translational speed in less than 150 ms. The initial rotational frequency of catapulted seeds was up to four times greater than that ultimately reached during steady-state autorotation. These helicopter seeds thus transiently produce very high lift forces (at Reynolds numbers near approximately 10 4 ) that act to enhance aerial transport. These findings are relevant to the modelling of long-distance seed dispersal in unsteady flows, as well as to the design of deceleration mechanisms based on lift generation, rather than drag-based devices such as parachutes.