Search results for " maximum"
showing 10 items of 303 documents
Caribbean hydroclimate and vegetation history across the last glacial period
2019
Abstract We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Multiple proxies were used to reconstruct Caribbean hydroclimate and vegetation variability on orbital to millennial timescales. In particular, our proxies indicate a shift to more abundant C4 (compared to C3) vegetation and/or reduced soil activity during the Last Glacial Maximum. Our results confirm the close link of Caribbean precipitation to North Atlantic climate variability, insolation and the strength of the AMOC. The associated variations in Caribbean SSTs and the shift of the ITCZ led to substantial changes of the hydro…
Time of emergence of Mediterranean summer maximum temperature.
2016
The time at which the signalof climate change emerges from the noise of natural climate variability is called “time of emergence”. This timeis analyzed here based on summertime mean maximum temperature in the Mediterranean basin for RCP8.5 andRCP4.5 scenarios. This time would be around 2040-50 (2060-70) in the eastern (western) basin. Differencesbetween the optimistic and pessimistic scenarios give a mean shift of around 15 years with the time ofemergence occurring earlier for RCP8.5 scenario.
STOCHASTIC DYNAMICS OF TWO PICOPHYTOPLANKTON POPULATIONS IN A REAL MARINE ECOSYSTEM
2013
A stochastic reaction-diffusion-taxis model is analyzed to get the stationary distribution along water column of two species of picophytoplankton, that is picoeukaryotes and Prochlorococcus. The model is valid for weakly mixed waters, typical of the Mediterranean Sea. External random fluctuations are considered by adding a multiplicative Gaussian noise to the dynamical equation of the nutrient concentration. The statistical tests show that shape and magnitude of the theoretical concentration profile exhibit a good agreement with the experimental findings. Finally, we study the effects of seasonal variations on picophytoplankton groups, including an oscillating term in the auxiliary equation…
Late Upper Palaeolithic hunter-gatherers in the Central Mediterranean: New archaeological and genetic data from the Late Epigravettian burial Oriente…
2019
AbstractGrotta d’Oriente, a small coastal cave located on the island of Favignana (Sicily, Italy) is a key site for the study of the early human colonization of Sicily. The individual known as Oriente C was found in the lower portion of an anthropogenic deposit containing typical local Late Upper Palaeolithic (Late Epigravettian) stone assemblages. Two radiocarbon dates on charcoal from the deposit containing the burial are consistent with the archaeological context and refer Oriente C to a period spanning about 14,200-13,800 cal. BP. Anatomical features are close to those of Late Upper Palaeolithic populations of the Mediterranean and show strong affinity with Palaeolithic individuals of S…
Data Mining Technique (Maximum Entropy Model) for Mapping Gully Erosion Susceptibility in the Gorganrood Watershed, Iran
2019
Soil erosion is a serious problem affecting most of the countries. This study was carried out in Gorganrood Watershed (Iran), which extends for 10,197 km2 and is severely affected by gully erosion. A gully headcut inven- tory map consisting of 307 gully headcut points was provided by Google Earth images, field surveys, and national reports. Gully conditioning factors including sig- nificant geo-environmental and morphometric variables were selected as predictors. Maximum entropy (ME) model was exploited to model gully susceptibility, whereas the area under the ROC curve (AUC) and draw- ing receiver operating characteristic (ROC) curves were employed to evaluate the performance of the model.…
What is the origin of the Scottish populations of the European endemic Cherleria sedoides (Caryophyllaceae)?
2015
Cherleria sedoides L. (Minuartia sedoides (L.) Hiern) is a montane perennial which, with some species in Minuartia sect. Spectabiles, is more closely related to Scleranthus than to other Minuartia species and is therefore best restored to the reinstated and redefined genus Cherleria. Reconstruction of the ancestral area of the clade containing C. sedoides suggests that it evolved in the Alps or the Balkan peninsula. The species now has an unusual distribution, being present in the mountains of southern Europe and Scotland but absent from the Arctic. Three historical scenarios that might have led to the presence of the species in Scotland are outlined and tested by a molecular analysis compa…
Demogenomic modeling of the timing and the processes of early European farmers differentiation
2020
AbstractThe precise genetic origins of the first Neolithic farming populations, as well as the processes and the timing of their differentiation, remain largely unknown. Based on demogenomic modeling of high-quality ancient genomes, we show that the early farmers of Anatolia and Europe emerged from a multiphase mixing of a Near Eastern population with a strongly bottlenecked Western hunter-gatherer population after the Last Glacial Maximum. Moreover, the population branch leading to the first farmers of Europe and Anatolia is characterized by a 2,500-year period of extreme genetic drift during its westward range expansion. Based on these findings, we derive a spatially explicit model of the…
A critical assessment of methods for the determination of the shear stress amplitude in multiaxial fatigue criteria belonging to critical plane class
2015
Abstract Multiaxial high cycle fatigue criteria based on the critical plane approach necessitate unambiguous definitions of the amplitude and mean value of the shear stress (τa and τm) acting on the material planes. Four of the existing definitions relate the values of τa and τm to a geometrical element of the curve described by the tip of the shear stress vector (curve Ψ), respectively, the radius of the Minimum Circumscribed Circle, the Longest Chord, the Longest Projection, the diagonal of the Maximum Rectangular Hull (MRH). In this paper a critical assessment of the above definitions is proposed, focusing on that based on the concept of MRH, which is the most recently developed. The mai…
A multi-site study to classify semi-natural grassland types
2009
International audience; Calibration and validation of simulation models describing herbage growth or feed quality of seminatural grasslands is a complex task for agronomists without investing effort into botanical surveys. To facilitate such modelling efforts, a limited number of grassland types were identified using a functional classification of species. These grassland types were characterized by three descriptors required to model herbage growth or feed quality: the abundance-weighted mean leaf dry matter content across grass species, the relative abundance of grasses, and an estimate of species richness. We conducted a multi-site analysis over 749 grasslands from eight temperate region…
Vecchi e nuovi problemi in tema di intervento dei creditori nell’esecuzione (note a margine di Cass. S.U. n. 61 del 7 gennaio 2014)
2015
Nel contributo in oggetto l'autore, muovendo dalla decisione delle Sezioni Unite della Cassazione n. 61 del 7 gennaio 2014, coglie l'occasione per riesaminare le vecchie e nuove problematiche sottese all’intervento dei creditori nel processo esecutivo. Il primo tema affrontato è quello della par condicio creditorum, che viene esaminata nella sua storia evolutiva dal Code Napoleon, al suo periodo di massima estensione, dato dal codice del 1940, fino al suo ridimensionamento a seguito delle riforme del 2005. Esamina quindi la possibilità del possibile superamento quoad effectum della distinzione tra intervento di creditori con titolo e senza titolo, alla luce delle evoluzioni della giurisprud…