We describe four-dimensional Lorentzian algebraic Ricci solitons. In sharp contrast with the Riemannian situation, any four-dimensional Lie group admits a left-invariant Lorentz metric which is a Ricci soliton.

This article focuses on the placement of ruins in the Mixtec landscape and in painted screen-fold manuscripts or codices during the Late Postclassic period, with an eye toward shedding light on broader Mesoamerican dynamics. I argue that while ruins of previous ages constituted meaningful links to the past in and of themselves, much of their significance, or even “vibrancy,” in the Postclassic inhered from the processes of persons journeying to and from them across the landscape. In the highly mountainous terrain of the Mixtec highlands, this movement frequently involved dramatic vertical ascents and descents, a phenomenon accentuated in the surviving codices from the region. Drawing from archaeological, textual, and iconographic evidence, I argue that this vertical movement to and from ruins of the past was closely intertwined with Mesoamerican understandings of temporality, and that traversing up and down the landscape could effectively constitute a kind of movement through time. Consistent with our grasp of Mesoamerican temporalities more generally, these spatiotemporal movements should not be seen as linear or teleological but instead as largely cyclical and bound up with concerns surrounding cosmic renewal.

Tail biting in growing pigs is both a sign and cause of impaired welfare. On one-day visits to ten Finnish farms, we assessed weaned pigs between approximately 4 to 10 weeks of age. On each farm, tail health was assessed at the pen level in 2–15 rooms (n = 81) selected randomly within age strata (n = 3), and on individual level in one high-prevalence pen per age category (n = 37 pens). Risk factors for tail biting were assessed in 2–3 age-representative rooms per farm according to 57 resource- and animal-based questions on environment, hygiene, health, feeding and enrichment. Tail health data were reduced into three pen- and three individual-level principal components. Component scores were used as outcome variables when establishing effects of risk factors on tail health using regression tree analysis and mixed modelling. Tail health deteriorated over the weaner period, especially from the first to the second third. Besides age, risk factors for impaired tail health consisted predominantly of shortcomings related to basic needs, such as adequate resting areas and enrichment. In the individual-level data, different risk factors could be associated with different types of tail lesions in problem pens, suggesting distinct aetiologies. In conclusion, improvements to the early environment in the farms studied here may have a significant positive impact on the well-being of pigs, not only post-weaning, but potentially permanently if experiencing less tail biting in early life leads to prevention later.

Este trabajo tiene un doble objetivo, por un lado, profundizar el estudio de las prácticas alimentarias y la dieta de las poblaciones que habitaron la costa sur de la Laguna Mar Chiquita, mediante el análisis de microrrestos vegetales en contenedores cerámicos y, por otro, conocer las modalidades de producción de dichos objetos, en vínculo con estas prácticas culinarias, desde una perspectiva tecnológica. Para ello, se analizaron 34 fragmentos, procedentes de los sitios El Diquecito e Isla Orihuela Playa Sudeste, correspondientes al Holoceno tardío. Entre los artefactos identificados se encuentran vasijas simples y compuestas, abiertas y cerradas. Los análisis permitieron identificar tanto especies vegetales silvestres (algarrobo, chañar y Arecaceae) como cultivadas (maíz, zapallo o calabaza, porotos, papa y mandioca), evidenciando una notable diversidad en las plantas seleccionadas y el uso de recipientes específicos según las preparaciones. Este abordaje multidisciplinar integra información arqueobotánica y tecnológica sobre los recipientes cerámicos, sus formas, usos y funciones, contribuyendo a comprender los modos de vida y prácticas cotidianas de estas poblaciones cazadoras-recolectoras-horticultoras, destacando su interacción con las plantas en las llanuras cordobesas.