University of Florence

About: University of Florence is a education organization based out in Florence, Toscana, Italy. It is known for research contribution in the topics: Population & Carbonic anhydrase. The organization has 27292 authors who have published 79599 publications receiving 2341684 citations. The organization is also known as: Università degli studi di Firenze & Universita degli studi di Firenze.

Asynchronous carbon sink saturation in African and Amazonian tropical forests

Abstract: Structurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions. Climate-driven vegetation models typically predict that this tropical forest ‘carbon sink’ will continue for decades. Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53–0.79), in contrast to the long-term decline in Amazonian forests. Therefore the carbon sink responses of Earth’s two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature. Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth’s intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth’s climate.

Biology of human TH1 and TH2 cells.

Abstract: Evidence is accumulating to suggest the existence of polarized human T-cell responses, reminiscent of TH1 and TH2 subsets described for mouse T cells. Human TH1 cells preferentially develop during infections by intracellular bacteria and trigger phagocyte-mediated host defense, whereas TH2 cells, which predominate during helminthic infestations and in response to common environmental allergens, are responsible for phagocyte-independent host response. Human TH1 and TH2 cells exhibit not only different functional properties but probably also distinct surface markers; TH2, but not TH1, clones express membrane CD30 and release the soluble form of CD30, a member of the TNF receptor superfamily. The cytokine profile of "natural immunity" evoked by different offending agents in the context of different host genetic backgrounds appears to be the most critical factor in determining the phenotype of the subsequent specific response. IL-12 and IFN-alpha and gamma produced by macrophages and NK cells favor the development of TH1 cells, whereas the early production of IL-4 by a still-unidentified cell type favors the development of TH2 cells. Clearly, polarized human TH1 and TH2 responses not only play different roles in protection, they can also promote different immunopathological reactions. Strong and persistent TH1 responses seen to be involved in organ-specific autoimmunity, contact dermatitis, and some chronic inflammatory disorders of unknown etiology. In contrast, polarized TH2 responses favor a reduced protection against the majority of infectious agents (including HIV) and, in genetically predisposed hosts, are responsible for triggering of allergic atopic disorders.

A controlled study of associated dental anomalies

Abstract: The purpose of this study was to reveal patterns of association among seven types of dental anomalies (aplasia of second premolars, small size of maxillary lateral incisors, infraocclusion of primary molars, enamel hypoplasia, ectopic eruption of first molars, supernumerary teeth, and palatal displacement of maxillary canines) in an untreated orthodontic population, ages 7 to 14. The prevalence of associated tooth anomalies in seven groups of 100 subjects selected according to one primarily diagnosed dental anomaly was compared with the prevalence of the examined dental anomalies in a control group of 1,000 subjects. Significant reciprocal associations (p < 0.005) were found among five of the anomalies (aplasia of second premolars, small size of maxillary lateral incisors, infraocclusion of primary molars, enamel hypoplasia, and palatal displacement of maxillary canines), suggesting a common genetic origin for these conditions. Supernumerary teeth appeared to be a separate etiological entity with respect to all other examined tooth anomalies. The existence of associations between different tooth anomalies is clinically relevant, as the early diagnosis of one anomaly may indicate an increased risk for others.