The disappearance of many North American megafauna at the end of the Pleistocene is a contentious topic. While the proposed causes for megafaunal extinction are varied, most researchers fall into ...three broad camps emphasizing human overhunting, climate change, or some combination of the two. Understanding the cause of megafaunal extinctions requires the analysis of through-time relationships between climate change and megafauna and human population dynamics. To do so, many researchers have used summed probability density functions (SPDFs) as a proxy for through-time fluctuations in human and megafauna population sizes. SPDFs, however, conflate process variation with the chronological uncertainty inherent in radiocarbon dates. Recently, a new Bayesian regression technique was developed that overcomes this problem-Radiocarbon-dated Event-Count (REC) Modelling. Here we employ REC models to test whether declines in North American megafauna species could be best explained by climate changes, increases in human population densities, or both, using the largest available database of megafauna and human radiocarbon dates. Our results suggest that there is currently no evidence for a persistent through-time relationship between human and megafauna population levels in North America. There is, however, evidence that decreases in global temperature correlated with megafauna population declines.
Colorectal basidiobolomycosis in a dog Marclay, Margaux; Langohr, Ingeborg M.; Gaschen, Frederic P. ...
Journal of veterinary internal medicine,
September 2020, Letnik:
34, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A 7‐year‐old castrated male French Bulldog was examined for chronic large intestinal enteropathy. A colonic mass and thickened rectal mucosa were identified, and histopathologic examination of ...endoscopic biopsy specimens disclosed eosinophilic proctitis with large (5‐20 μm), irregularly shaped, pauciseptate hyphae that were Gomori methenamine silver and periodic acid‐Schiff positive. Amplification and sequencing of ribosomal DNA extracted from paraffin‐embedded tissues yielded a sequence with 97% identity to GenBank sequences for Basidiobolus ranarum. After itraconazole, terbinafine, and prednisone administration, clinical signs resolved rapidly, and sonographic lesions were largely absent after 6 weeks. Treatment was discontinued by the owner 15 weeks after diagnosis. Three weeks later, the dog collapsed acutely and was euthanized. Necropsy identified metastatic islet cell carcinoma and grossly unremarkable colorectal tissues. However, histopathology of the rectum disclosed multifocal submucosal granulomas with intralesional hyphae morphologically similar to those previously observed. This report is the first to describe medical treatment of gastrointestinal basidiobolomycosis in a dog.
The term “extreme event” is commonly used to describe high-impact, unanticipated natural events, like floods, tsunamis, earthquakes, and volcanic eruptions. It first appeared in the scientific ...literature in the 1950s and has since spread to disciplines as diverse as economics, psychology, medicine, and engineering. The term is increasingly being applied to the study of historical, prehistorical, and deep-time events across a broad range of scales, and it is widely acknowledged that such events have had profound impacts on the Earth’s biodiversity and cultures. Understandably, then, how people think about, define, and study extreme events varies considerably. With extreme events expected to become more frequent, longer lasting, and more intense in the coming decades as a result of global warming, the differing extreme event definitions—both across and within disciplines—is likely to lead to confusion among researchers and pose significant challenges for predicting and preparing for extreme events and their impacts on natural and social systems. With this in mind, we conducted a systematic quantitative review of 200 randomly selected, peer-reviewed “extreme event” research papers (sourced from Web of Science, accessed January 2020) from the biological, societal, and earth sciences literature with the aim of quantifying several pertinent features of the research sample. On the one hand, our analysis found a great deal of variability among extreme event papers with respect to research interests, themes, concepts, and definitions. On the other hand, we found a number of key similarities in how researchers think about and study extreme events. One similarity we encountered was that researchers tend to view extreme events within a particular temporal context and quite often in terms of rates of change. Another similarity we encountered was that researchers often think of and study extreme events in terms of risks, vulnerabilities, and impacts. The similarities identified here may be useful in developing a common and comprehensive definition of what constitutes an extreme event, and should allow for more comparative research into extreme events at all spatio-temporal scales which, we predict, will provide important new insights into the nature of extreme events.
The second millennium CE in Europe is known for both climatic extremes and bloody conflict. Europeans experienced the Medieval Warm Period and the Little Ice Age, and they suffered history-defining ...violence like the Wars of the Roses, Hundred Years War, and both World Wars. In this paper, we describe a quantitative study in which we sought to determine whether the climatic extremes affected conflict levels in Europe between 1,005 and 1980 CE. The study involved comparing a well-known annual historical conflict record to four published temperature reconstructions for Central and Western Europe. We developed a Bayesian regression model that allows for potential threshold effects in the climate–conflict relationship and then tested it with simulated data to confirm its efficacy. Next, we ran four analyses, each one involving the historical conflict record as the dependent variable and one of the four temperature reconstructions as the sole covariate. Our results indicated that none of the temperature reconstructions could be used to explain variation in conflict levels. It seems that shifts to extreme climate conditions may have been largely irrelevant to the conflict generating process in Europe during the second millennium CE.
Ngalau Gupin is a broad karstic cave system in the Padang Highlands of western Sumatra, Indonesia. Abundant fossils, consisting of mostly isolated teeth from small-to large-sized animals, were ...recovered from breccias cemented on the cave walls and unconsolidated sediments on the cave floor. Two loci on the walls and floors of Ngalau Gupin, named NG-A and NG-B respectively, are studied. We determine that NG-B most likely formed as a result of the erosion and redeposition of material from NG-A. The collection reveals a rich, diverse Pleistocene faunal assemblage (Proboscidea, Primates, Rodentia, Artiodactyla, Perissodactyla, Carnivora) largely analogous to extant fauna in the modern rainforests of Sumatra. The hippopotamid Hexaprotodon represents the only globally extinct taxon in deposits from Sumatra and the first record of this animal from the island. This fossil assemblage is dated using combined U-series/ESR dating analyses of several teeth that yield a finite age of between ~160 and ~115 ka, depending on the modalities of the dose rate evaluation. Moreover, a direct U-series age estimate of ~70 ka is obtained on the Hexaprotodon specimen, providing a minimum age constraint for the fossil that is compatible with the combined U-series/ESR results. These results suggest that the faunal assemblage at Ngalau Gupin correlates with late MIS 6 or early MIS 5. Ngalau Gupin likely reflects the formation of a fossil assemblage with two primary taphonomic pathways: a prime-aged dominated macrofauna component initially produced by carnivores but subsequently accumulated by porcupines and transported to the cave, and a microfauna component likely accumulated by small carnivores. Decalcification of the cemented deposit has further resulted in loss of fossil and other sedimentary material. This site adds important new chronologically constrained fossil mammal data for the Pleistocene record of Sumatra, an island relatively poorly investigated for Southeast Asia.
Recent advances in interdisciplinary archaeological research in Arabia have focused on the evolution and historical development of regional human populations as well as the diverse patterns of ...cultural change, migration, and adaptations to environmental fluctuations. Obtaining a comprehensive understanding of cultural developments such as the emergence and lifeways of Neolithic groups has been hindered by the limited preservation of stratified archaeological assemblages and organic remains, a common challenge in arid environments. Underground settings like caves and lava tubes, which are prevalent in Arabia but which have seen limited scientific exploration, offer promising opportunities for addressing these issues. Here, we report on an archaeological excavation and a related survey at and around Umm Jirsan lava tube in the Harrat Khaybar, north-western Saudi Arabia. Our results reveal repeated phases of human occupation of the site ranging from at least the Neolithic through to the Chalcolithic/Bronze Age. Pastoralist use of the lava tube and surrounding landscape is attested in rock art and faunal records, suggesting that Umm Jirsan was situated along a pastoral route linking key oases. Isotopic data indicates that herbivores primarily grazed on wild grasses and shrubs rather than being provided with fodder, while humans had a diet consistently high in protein but with increasing consumption of C3 plants through-time, perhaps related to the emergence of oasis agriculture. While underground and naturally sheltered localities are globally prominent in archaeology and Quaternary science, our work represents the first such combined records for Saudi Arabia and highlight the potential for interdisciplinary studies in caves and lava tubes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
8.
Pathology in Practice Vargo, Cheryl L; Strzok, Emily C; Howerth, Elizabeth W ...
Journal of the American Veterinary Medical Association,
03/2022, Letnik:
259, Številka:
S2
Journal Article
Recenzirano
Odprti dostop
In collaboration with the American College of Veterinary Pathologists.
What is the most humane way to kill amphibians and small reptiles that are used in research? Historically, such animals were often killed by cooling followed by freezing, but this method was outlawed ...by ethics committees because of concerns that ice-crystals may form in peripheral tissues while the animal is still conscious, putatively causing intense pain. This argument relies on assumptions about the capacity of such animals to feel pain, the thermal thresholds for tissue freezing, the temperature-dependence of nerve-impulse transmission and brain activity, and the magnitude of thermal differentials within the bodies of rapidly-cooling animals. A review of published studies casts doubt on those assumptions, and our laboratory experiments on cane toads (Rhinella marina) show that brain activity declines smoothly during freezing, with no indication of pain perception. Thus, cooling followed by freezing can offer a humane method of killing cane toads, and may be widely applicable to other ectotherms (especially, small species that are rarely active at low body temperatures). More generally, many animal-ethics regulations have little empirical basis, and research on this topic is urgently required in order to reduce animal suffering.
The small size and relatively challenging environmental conditions of the semi-isolated Maltese archipelago mean that the area offers an important case study of societal change and human-environment ...interactions. Following an initial phase of Neolithic settlement, the “Temple Period” in Malta began ∼5.8 thousand years ago (ka), and came to a seemingly abrupt end ∼4.3 ka, and was followed by Bronze Age societies with radically different material culture. Various ideas concerning the reasons for the end of the Temple Period have been expressed. These range from climate change, to invasion, to social conflict resulting from the development of a powerful “priesthood.” Here, we explore the idea that the end of the Temple Period relates to the 4.2 ka event. The 4.2 ka event has been linked with several examples of significant societal change around the Mediterranean, such as the end of the Old Kingdom in Egypt, yet its character and relevance have been debated. The Maltese example offers a fascinating case study for understanding issues such as chronological uncertainty, disentangling cause and effect when several different processes are involved, and the role of abrupt environmental change in impacting human societies. Ultimately, it is suggested that the 4.2 ka event may have played a role in the end of the Temple Period, but that other factors seemingly played a large, and possibly predominant, role. As well as our chronological modelling indicating the decline of Temple Period society in the centuries before the 4.2 ka event, we highlight the possible significance of other factors such as a plague epidemic.
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