716 research outputs found
Ischemic Heart Disease Geography of the United States: Models of Environmental Influence With a Focus on the Eastern Highlands
Author Institution: Social Science Division, Shawnee State UniversityRegional differences exist in ischemic heart disease (IHD) mortality rates in the United States. These variations may in part be related to environmental factors. An examination was conducted in the U.S. on a sample of 101 county age-adjusted ischemic heart disease death rates and several possible environmental factors. A multiple regression model suggests that a combination of altitude, snowfall frequency, median family income, air pollution, and location in the Eastern Highlands may explain about 46% of the variance in ischemic heart disease mortality rates. Some facet of the environment in the Eastern Highlands may contribute to the higher rates found in that region. Coal worker's pneumoconiosis was suspected and tested with no concrete conclusion. The results suggest the importance of environment in the suspected multifactorial etiology of ischemic heart disease, but replication and further research is required
Kangerlussuaq: evolution and maturation of a cultural landscape in Greenland
The cultural landscape reflects the composite influences of the regional physical, cultural, and technological environments. It is a dynamic entity which evolves over time and the perceptions of its human inhabitants is influential in the process. This paper is a descriptive analysis of Kangerlussuaq, a young but maturing settlement located in west Greenland near the inland ice. The site's natural resource base did not attract permanent settlement by the Inuit or Scandinavian colonists, but in the early days of the World War II, the American military took advantage of the exceptional flying conditions here and established an air base. In time, civilian functions developed as Kangerlussuaq became the hub for air travel in Greenland. A transitory utilitarian settlement was eventually transformed into a more permanent settlement. In recent years there seems to be a growing sense of community and place attachment as the cultural landscape begins to exhibit more of the components of a real 'town'
I look at you to learn: Effects of the owner's sex on social learning in domestic dogs
Dogs have been shown to be able to learn from a human demonstrator. However, to date, there have been no studies investigating the effect of the demonstrator?s sex on such learning. The aim of our study was to evaluate this effect by comparing an experimental condition in which dogs received a demonstration from their owner on how to manipulate one of two possible containers to obtain food and a control condition without any human demonstration. Each of these conditions was divided into two groups: male-owned and female-owned dogs.Overall, the dogs performed better in the experimental condition compared to the control condition. This was evidentbased ona higher frequency of correct choices and opening the correct container, as well as a higher frequency of contact and gaze towards the demonstration. The female-owned group benefited from the demonstration by choosing the correct container more frequentlyin the experimental condition compared to the control. Conversely, male-owned dogs chose the correct container more often and looked more frequently at the demonstration than female-owned dogs, without differences between conditions. This could indicate a higher capacity for problem-solvingin this group of dogs beyond the human demonstration, and therefore would not reflect a modulatory effect of the owner?s sex over social learning in particular. In conclusion, the sex of the demonstrator seems to have an effect on social learning in dogs when the demonstrator is a female owner. This might have an impact on several applied settings as well as sampling criteria in canine social cognition research.Fil: Dzik, Marina Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; ArgentinaFil: Gutierrez Torres, J. S.. Universidad Central; ColombiaFil: Berdugo Lattke, M. L.. Universidad Central; ColombiaFil: Bentosela, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; Argentin
Flavonoids, bioactive components of propolis, exhibit cytotoxic activity and induce cell cycle arrest and apoptosis in human breast cancer cells MDA-MB-231 and MCF-7 : A comparative study
Breast cancer is one of the most common causes of mortality in women. Flavonoids, among other compounds, are bioactive constituents of propolis. In this comparative study, we investigated the effects of flavonoids apigenin (API), genistein (GEN), hesperidin (HES), naringin (NAR) and quercetin (QUE) on the proliferation, apoptosis, and cell cycle of two different human cancer cells - MDA-MB-231, estrogen-negative, and MCF-7, estrogen-positive receptor breast carcinoma cells. Many cytotoxic reports of flavonoids were performed by MTT assay. However, it's reported that MTT is reduced in metabolically active cells and yields an insoluble purple formazan, which indicates that obtained cytotoxic results of flavonoids could be inconsistent. Cell viability was measured by NR, neutral red assay, while the percentage of apoptotic cells and cell cycle arrest were determined by flow cytometry and Muse cell cycle assay, respectively. The results showed a high dose-dependent effect in cell viability tests. IC50 values were as follows (MCF-7/MDA-MB-231, for 48 h, in \u3bcM): 9.39/50.83 for HES, 25.19/88.17 for API, 40.26/333.51 for NAR, 49.49/47.50 for GEN and 95.12/130.10 for QUE. Flavonoid-induced apoptosis was dose- and time-dependent, for both cancer cell lines, though flavonoids were more active on MCF-7 cells. The flavonoids also induced cell cycle arrest in cancer cells
In Vitro
The aim of the presented study was to examine the antimicrobial activity of ethanol extract of Polish propolis (EEPP) against biofilm-forming CoNS strains in vitro. Our results revealed that EEPP displayed varying degrees of activity against CoNS with MIC values ranging from 1.56 to 0.78 mg/mL. The average MIC was 1.13 ± 0.39 mg/mL while calculated MIC50 and MIC90 values were 0.78 mg/mL and 1.56 mg/mL, respectively. The biofilm formation ability by all tested S. epidermidis strains was inhibited at EEPP concentrations ranging from 0.39 to 1.56 mg/mL. The degree of reduction of AlamarBlue was directly associated with the proliferation of S. epidermidis strains. The increased proliferation of S. epidermidis strains was observed after 12 and 24 hours of incubation in the presence of EEPP concentrations ranging from 0.025 to 0.39 mg/mL. These results suggest that antimicrobial activities of EEPP against S. epidermidis expressed as the reduction of bacterial growth, reduction of biofilm formation ability, and the intensity of proliferation were significantly affected by incubation time and EEPP concentration used as well as the interactions between these factors
The taxonomy and anatomy of rauisuchian archosaurs from the Late Triassic of Germany and Poland
The German Late Triassic archosaur Teratosaurus suevicus is a historically important taxon, being the first described rauisuchian. Unfortunately the holotype is a single element, a maxilla, which is poorly preserved and incomplete. We redescribe this maxilla and identify a single potential autapomorphy. The fragmentary type specimen complicates attempts to refer additional material to this taxon, and other unassociated archosaur and rauisuchian specimens from the Mittlerer Stubensandstein of Germany cannot be referred to T. suevicus with any degree of confidence. The stratigraphically older T. silesiacus, from the upper Carnian of Poland, is represented by a much more complete and better preserved specimen. Comparison of the maxillae of T. suevicus and T. silesiacus reveals that the two are distinct taxa, contra recent suggestions, but also that they do not share any synapomorphies or a unique combination of characters relative to Postosuchus kirkpatricki and other rauisuchians. Thus, the Polish material must be transferred to a new genus, Polonosuchus gen. nov. Both Polonosuchus and Teratosaurus are very similar to Postosuchus kirkpatricki, and the three taxa are likely closely related
Increases in sampling support the southern Gondwanan hypothesis for the origin of dinosaurs
Dinosaurs were ubiquitous in terrestrial ecosystems through most of the Mesozoic and are still diversely represented in the modern fauna in the form of birds. Recent efforts to better understand the origins of the group have resulted in the discovery of many new species of early dinosaurs and their closest relatives (dinosauromorphs). In addition, recent re-examinations of early dinosaur phylogeny have highlighted uncertainties regarding the interrelationships of the main dinosaur lineages (Sauropodomorpha, Theropoda and Ornithischia), and questioned the traditional hypothesis that the group originated in South Gondwana and gradually dispersed over Pangaea. Here, we use a historical approach to examine the impact of new fossil discoveries and changing phylogenetic hypotheses on biogeographic scenarios for dinosaur origins over 20 years of research time, and analyse the results in the light of different fossil record sampling regimes. Our results consistently optimize South Gondwana as the ancestral area for Dinosauria, as well as for more inclusive clades including Dinosauromorpha, and show that this hypothesis is robust to increased taxonomic and geographic sampling and divergent phylogenetic results. Our results do not find any support for the recently proposed Laurasian origin of dinosaurs and suggest that a southern Gondwanan origin is by far the most plausible given our current knowledge of the diversity of early dinosaurs and non-dinosaurian dinosauromorphs
The apparatus composition and architecture of Erismodus quadridactylus and the implications for element homology in prioniodinin conodonts
The apparatus composition and architecture of prioniodinin conodonts is poorly understood, largely because few prioniodinin taxa are represented by articulated oral feeding apparatuses (natural assemblages) in the fossil record, but also due to the highly variable gradational morphology of their constituent elements that makes apparatus reconstruction problematic. We describe here a natural assemblage of Erismodus quadridactylus (Stauffer), a prioniodinin, from the Sandbian (Late Ordovician) of North Dakota, USA. The assemblage demonstrates that the apparatus architecture of Erismodus is similar to those of late Palaeozoic prioniodinins namely, Kladognathus Rexroad and Hibbardella Bassler, but also has similarities with ozarkodinin apparatuses. In addition, there is evidence to suggest that E. quadridactylus shares topological similarities to balognathid architecture, with respect to the position of its inferred P elements. The apparatus composition and architecture presented here indicate that, at least with respect to the M–S array, an ‘ozarkodinin‐type’ bauplan is probably more widely representative across prioniodontids. The assemblage demonstrates that element morphotypes traditionally considered to lie within the S array are M elements, whereas others traditionally interpreted as P elements are found in the S array. These observations are used as a basis for refining concepts of element homology among prioniodinin conodonts and their closest relatives
The fate of the homoctenids (Tentaculitoidea) during the Frasnian-Famennian mass extinction (Late Devonian)
The homoctenids (Tentaculitoidea) are small, conical-shelled marine animals which are amongst the most abundant and widespread of all Late Devonian fossils. They were a principal casualty of the Frasnian-Famennian (F-F, Late Devonian) mass extinction, and thus provide an insight into the extinction dynamics. Despite their abundance during the Late Devonian, they have been largely neglected by extinction studies. A number of Frasnian-Famennian boundary sections have been studied, in Poland, Germany, France, and the United States. These sections have yielded homoctenids, which allow precise recognition of the timing of the mass extinction. It is clear that the homoctenids almost disappear from the fossil record during the latest Frasnian “Upper Kellwasser Event”. The coincident extinction of this pelagic group, and the widespread development of intense marine anoxia within the water column, provides a causal link between anoxia and the F-F extinction. Most notable is the sudden demise of a group, which had been present in rock-forming densities, during this anoxic event. One new species, belonging to Homoctenus is described, but is not formally named here
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