Sud-Est des États-Unis

vignette|Les États en rouge foncé sont habituellement inclus dans les définitions du Sud-Est des États-Unis. Les États en rouge clair sont moins souvent considérés comme en faisant partie. Le Sud-Est des États-Unis (voir aussi Sud des États-Unis) est une région géographique regroupant les États du sud, de l'océan Atlantique (Floride) au Texas (exclu). Il se caractérise par une ouverture sur le golfe du Mexique, un climat tropical (sud de la Floride) et surtout subtropical, marqué par la chaleur et le passage des cyclones en été. La population possède des origines très diverses : les Afro-Américains sont relativement nombreux dans les anciens États esclavagistes, les Hispaniques sont particulièrement présents en Floride. Histoire Époque précolombienne thumb|Francois Bernard, Village Choctaw, . Le Sud-Est des États-Unis fut d'abord peuplé par des groupes paléoindiens nomades qui se sont sédentarisés après la dernière glaciation. La région fut influencée par la civ

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ENV-220: Fundamentals in ecology

The students will learn the fundamentals in ecology with the goal to perceive the environment beyond its physical and chemical characteristics. Starting from basic concepts, they will acquire mechanistic understanding of biodiversity, ecosystem functioning and global change.

CS-401: Applied data analysis

This course teaches the basic techniques, methodologies, and practical skills required to draw meaningful insights from a variety of data, with the help of the most acclaimed software tools in the data science world (pandas, scikit-learn, Spark, etc.)

Zoonotic Leprosy in the Southeastern United States

Stewart Cole, Rahul Sharma, Pushpendra Singh

Nine-banded armadillos (Dasypus novemcinctus) are naturally infected with Mycobacterium leprae and have been implicated in zoonotic transmission of leprosy. Early studies found this disease mainly in Texas and Louisiana, but armadillos in the southeastern United States appeared to be free of infection. We screened 645 armadillos from 8 locations in the southeastern United States not known to harbor enzootic leprosy for M. leprae DNA and antibodies. We found M. leprae infected armadillos at each location, and 106 (16.4%) animals had serologic/PCR evidence of infection. Using single-nucleotide polymorphism variable number tandem repeat genotyping/genome sequencing, we detected M. leprae genotype 31-2-v1 among 35 armadillos. Seven armadillos harbored a newly identified genotype (31-2-v15). In comparison, 52 human patients from the same region were infected with 31 M. leprae types. However, 42.3% (22/52) of patients were infected with 1 of the 2 M. leprae genotype strains associated with armadillos. The geographic range and complexity of zoonotic leprosy is expanding.

Centers Disease Control2015

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High aerosol acidity despite declining atmospheric sulfate concentrations over the past 15 years

Hairun Guo, Athanasios Nenes

Particle acidity affects aerosol concentrations, chemical composition and toxicity. Sulfate is often the main acid component of aerosols, and largely determines the acidity of fine particles under 2.5 μm in diameter, PM2.5. Over the past 15 years, atmospheric sulfate concentrations in the southeastern United States have decreased by 70%, whereas ammonia concentrations have been steady. Similar trends are occurring in many regions globally. Aerosol ammonium nitrate concentrations were assumed to increase to compensate for decreasing sulfate, which would result from increasing neutrality. Here we use observed gas and aerosol composition, humidity, and temperature data collected at a rural southeastern US site in June and July 2013 (ref.), and a thermodynamic model that predicts pH and the gas-particle equilibrium concentrations of inorganic species from the observations to show that PM2.5 at the site is acidic. pH buffering by partitioning of ammonia between the gas and particle phases produced a relatively constant particle pH of 0-2 throughout the 15 years of decreasing atmospheric sulfate concentrations, and little change in particle ammonium nitrate concentrations. We conclude that the reductions in aerosol acidity widely anticipated from sulfur reductions, and expected acidity-related health and climate benefits, are unlikely to occur until atmospheric sulfate concentrations reach near pre-anthropogenic levels. © 2016 Macmillan Publishers Limited. All rights reserved.

Nature Publishing Group2016

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Enhanced formation of isoprene-derived organic aerosol in sulfur-rich power plant plumes during Southeast Nexus

Hairun Guo, Athanasios Nenes

We investigate the effects of anthropogenic sulfate on secondary organic aerosol (SOA) formation from biogenic isoprene through airborne measurements in the southeastern United States as part of the Southeast Nexus (SENEX) field campaign. In a flight over Georgia, organic aerosol (OA) is enhanced downwind of the Harllee Branch power plant but not the Scherer power plant. We find that the OA enhancement is likely caused by the rapid reactive uptake of isoprene epoxydiols (IEPOX) in the sulfate-rich plume of Harllee Branch, which was emitting at least 3 times more sulfur dioxide (SO2) than Scherer, and more aerosol sulfate was produced downwind. The contrast in the evolution of isoprene-derived OA concentration between two power plants with different SO2 emissions provides an opportunity to investigate the magnitude and mechanisms of particle sulfate on isoprene-derived OA formation. We estimate that 1 μgsm-3 reduction of sulfate would decrease the isoprene-derived OA by 0.23 ± 0.08 μgsm-3. Based on a parameterization of the IEPOX heterogeneous reactions, we find that the effects of sulfate on isoprene-derived OA formation in the power plant plume arises from enhanced particle surface area and particle acidity, which increases both IEPOX uptake to particles and subsequent aqueous-phase reactions, respectively. The observed relationships between isoprene-OA, sulfate, particle pH, and particle water in previous field studies are explained using these findings. © 2016. American Geophysical Union. All Rights Reserved.

Wiley-Blackwell2016

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Sud des États-Unis

Le Sud des États-Unis, souvent appelé le Sud américain (anglais : American South) et surnommé , constitue une grande région appartenant au Sud-Est et au Sud-Centre des États-Unis. Le Sud a un héri

Caroline du Nord

La Caroline du Nord (North Carolina) est un État du Sud des États-Unis. Sa capitale est Raleigh, et sa plus grande ville est Charlotte et son agglomération (Metrolina). Avec en 2010, estimée à en 2

Atlanta

Atlanta ( ; en anglais : ) est la capitale et la ville la plus peuplée de l'État de Géorgie, aux États-Unis. Selon les dernières estimations du Bureau du recensement des États-Unis (2019), la municipa