The evolution of mechanisms involved in vertebrate endothermy

Endothermy, i.e. the endogenous production of metabolic heat, has evolved multiple times among vertebrates, and several strategies of heat production have been studied extensively by physiologists over the course of the twentieth century. The independent acquisition of endothermy by mammals and birds has been the subject of many hypotheses regarding their origin and associated evolutionary constraints. Many groups of vertebrates, however, are thought to possess other mechanisms of heat production, and alternative ways to regulate thermogenesis that are not always considered in the palaeontological literature. Here, we perform a review of the mechanisms involved in heat production, with a focus on cellular and molecular mechanisms, in a phylogenetic context encompassing the entire vertebrate diversity. We show that endothermy in mammals and birds is not as well defined as commonly assumed by evolutionary biologists and consists of a vast array of physiological strategies, many of which are currently unknown. We also describe strategies found in other vertebrates, which may not always be considered endothermy, but nonetheless correspond to a process of active thermogenesis. We conclude that endothermy is a highly plastic character in vertebrates and provides a guideline on terminology and occurrences of the different types of heat production in vertebrate evolution. This article is part of the theme issue ‘Vertebrate palaeophysiology’.

Archeology of tattoos and other brands in the contemporary body: the mystical stigma to body art

This study aims to characterize the phenomena of tattoos, piercings and other brands and signals produced along the body length, so expressive among teenagers and young contemporaries, to then relate them to other cultural events involving the body, located in the religious field and the other in the aesthetic: the mystical stigmata and body art, respectively. The three events (tattoos and piercings, body art and mystical stigmata), although in its own way and according to the temporal and ideological circumstances that have defined, show the plastic character of the meat, as a guarantee for the subject of virtual triumph over natural.

The evolution of avian wing shape and previously unrecognized trends in covert feathering

Avian wing shape has been related to flight performance, migration, foraging behaviour and display. Historically, linear measurements of the feathered aerofoil and skeletal proportions have been used to describe this shape. While the distribution of covert feathers, layered over the anterior wing, has long been assumed to contribute to aerofoil properties, to our knowledge no previous studies of trends in avian wing shape assessed their variation. Here, these trends are explored using a geometric–morphometric approach with landmarks describing the wing outline as well as the extent of dorsal and ventral covert feathers for 105 avian species. We find that most of the observed variation is explained by phylogeny and ecology but shows only a weak relationship with previously described flight style categories, wing loading and an investigated set of aerodynamic variables. Most of the recovered variation is in greater primary covert feather extent, followed by secondary feather length and the shape of the wing tip. Although often considered a plastic character strongly linked to flight style, the estimated ancestral wing morphology is found to be generally conservative among basal parts of most major avian lineages. The radiation of birds is characterized by successive diversification into largely distinct areas of morphospace. However, aquatic taxa show convergence in feathering despite differences in flight style, and songbirds move into a region of morphospace also occupied by basal taxa but at markedly different body sizes. These results have implications for the proposed inference of flight style in extinct taxa.

High Pressure Nano-Destruction of a Brittle Polymeric Materials Surface

The regularity of the erosion wear of a surface of a brittle polymeric material under the conditions of high-pressure (high-velocity) water-jet impact was examined using the atomic-force microscope. Investigations results proved that the elementary mechanism of erosive failure of brittle polymers in response to pressure and cyclic loads at micro and nanolevel may have brittle character, as well as elastoplastic and plastic character under severer regimes. The process of hardening of the fine (nanolevel) superficial layers of PMMA material has been determined in conditions of high-velocity water-drop loading.

The effect of changing plant density on floral initiation and development of barley (cv. Sultan)

SummaryBarley plants were grown at low, high, increasing and decreasing densities in an attempt to manipulate the environment. The effects on tiller production and development were measured.Increasing density with time had less effect than decreasing it. Tiller number was the most plastic character, tiller production being earlier in those plants which emerged into low density, being delayed or inhibited in other treatments. The number of spikelets/ear and the length of the inflorescence were found to be less stable characters than the stage of ear development. Percentage spikelet survival showed a downward trend, with increasing density stress.

Review Lecture: The float glass process

My subject is the float process for making flat glass. I would like, first of all, to put the float process into perspective by describing briefly, and in simple terms, the methods used for making flat glass before and at the time of the invention of the float process and then to describe the development of the process itself and the position it occupies in the flat glass industry today. Finally, I would like to describe in as much depth as time allows, three of the main problems which had to be tackled in developing this process. The Egyptians seem to have been the first people to realize what could be done with glass when it is hot and plastic, and they made vessels for cosmetics and perfumes by, it is assumed, trailing molten glass around a shaped core. By Roman times glass was being blown and moulded, cut and engraved, painted and gilded, and the Romans had mastered the plastic character of heat softened glass so fundamental to today’s processes.