Transition between toroidic orders in dielectric metasurfaces by polarization of the incident wave

We propose a design and perform a theoretical and experimental study of optical properties of a metasurface composed of hexagonal oligomers of dielectric particles that somewhat resemble characteristics of multiferroics. It can maintain both toroidic and antitoroidic orders in the dynamical response on irradiation by a linearly polarized plane wave. These orders originate from the dark states of toroidal dipole moments. Due to the consciously chosen perturbation in the oligomers, the orders are excited at the same frequency by the wave with orthogonal polarization. The excitation of these orders results in different characteristics of the electric near-field localization. This has significant potential for several applications, which are thoroughly discussed.

Use of mammals in a semi-arid region of Brazil: an approach to the use value and data analysis for conservation

BACKGROUND

This study aimed to survey the knowledge and use of mammals by the residents of the rural community of Capivara in the municipality of Solânea (Paraíba State, Northeast Brazil) and to propose a new method of using the use value as a tool for data analysis in ethnozoological surveys.

METHODS

The uses attributed to mammals were recorded through semi-structured interviews conducted with the breadwinners (men and women) living in the community. The species were identified through guided tours, by descriptions made by the interviewees, and using specimens donated by them, as well as by comparison with the pertinent scientific literature (morphological and ecological). Through the use value differentiated analysis, it was possible to distinguish the current use value of the species (effective use) from their potential use value (knowledge, but no effective use) to determine their real importance related to the uses cited by the studied group.

RESULTS

Nineteen species were cited; however, only 17 of them were identified and then distributed in 13 families. The other species were identified at the genus level Leopardus sp. and order Rodentia. The species were classified into 6 categories of use: food, captive breeding, zootherapeutic, artisanal, magic/religious, and veterinary purposes.

CONCLUSIONS

This article discusses possible conservation solutions, given the irregular exploitation of some species, warning about the biodiversity, and traditional knowledge conservation.

Local knowledge, use, and conservation of wild birds in the semi-arid region of Paraíba state, northeastern Brazil

BACKGROUND

The use of wild birds, for several purposes, is directly associated with cultural, ecological, and conservation issues. This study aimed to inventory the wild birds known and used in three communities in Paraíba state, northeast Brazil, and to investigate the sociocultural context in which these activities occur.

METHODS

A total of 179 people (98 women and 81 men) were interviewed. Data were collected through free interviews, using semi-structured forms, and posing questions about the use of local wild birds. The species were identified by direct observation of the birds, analysis of photographic records, and the use of a scientific guide.

RESULTS

Each species' use value (UV) was calculated in three different ways: UV_general, UV_current, and UV_potential. These UVs ranged from 0.01 to 1.15 for UV_g, 0 to 0.21 for UV_c, and 0.01 to 1.02 for UV_p. A total of 99 species, 81 genera, and 40 families were recorded and classified into the use categories of food, breeding, and medicinal. Thraupidae (12 species), Columbidae, Accipitridae, and Icteridae (8 species each) were the most diverse families.

CONCLUSIONS

The use of wild birds is a widespread activity in the studied areas, where many species are used. This demonstrates the need to conduct studies to assess the pressure suffered by these bird species, as well as the need to create public policies that intervene in the use and conservation of wild birds.