The following classes of categories are shown to be weakly Mal’tsev in the sense of the author: (i) a suitable class of algebras with cancellation; (ii) the dual of any quasi-adhesive category; (iii) the dual of any extensive category with pullback-stable epimorphisms; (iv) the dual of any solid quasi-topos. The examples in (i) include all the Mal’tsev varieties of algebras such as groups, rings, Lie algebras, etc., but also distributive lattices and commutative monoids with cancellation. The examples in (ii)-(iv) capture many of the familiar aspects of topological spaces. © 2014, Springer Science+Business Media Dordrecht.

Over the last decade, impelled by the huge open source software community support, the low cost Arduino platform presents itself as an alternative for digital sound processing. Although Arduino is generally used for small applications for the artistic and maker community, its built-in Analog to digital converter can be used for sound capturing, processing and reproduction. Equipped with a powerful AVR 8 bit RISC microcontroller, the Arduino, can achieve up to 200kHz with a 10 bit resolution according to the Atmel ATmega328P datasheet that is the AVR core that we are going to focus on this article. Realizing the hardware potential, software suppliers like Matworks or National instruments, have included the Arduino packages on the software accessories of MATLAB and LABView. This work presents some of the sound capabilities and specific limitations of the Arduino platform, enfacing its connection and installation with MATLAB software. A series of examples of the Arduino interface with MATLAB are detail and shown in order to facilitate users initiation of MATLAB and Arduino Digital Sound Processing enhancing education fostering.

During the summer season, ozone concentrations regularly exceed the legislation limits in the North of Portugal, namely at Douro Norte monitoring station. The origin of such ozone episodes has been widely reported in several studies although uncertainties regarding its origin still remain. This work intends to investigate how the ozone concentrations measured at the Douro Norte nearest stations, located at west and east directions, are related to those measured at Douro Norte by means of coherence and phase transformations methods. The episodes were selected according to the magnitude of the hourly ozone peaks and the occurrence of exceedances of the threshold value at least in two sites. The results point out that 60 % of the selected episodes highlight significant dependence between Douro Norte station and the other two monitoring sites, with different phase signal and a delay range from 2 to 4 h.