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Spatial distribution of alien trees was studied on Pre-Delta National Park (PNPD-Entre Ríos, Argentina), by distance sampling techniques. Potential distribution was modelled by Kriging interpolation technique. Generated maps were overlapped with PNPD zonification map and environmental units map. We recorded forest structural data, tree phenology and tree control management actions, in order to characterize the processes of invasion. We obtained maps of potential distribution of Melia azedrach, Broussonetia papyrifera, Ligustrum lucidum, Brachychiton populneus, Fraxinus sp. and Morus alba L. The latter was the dominant species in all studied sectors (cliffs, islands and highlands). As for the management actions carried out with trees of the PNPD, about 50% of the specimens of M. alba subjected to mechanical control (banding technique) showed regrowth, indicating its high survival capacity. [ABSTRACT FROM AUTHOR]

A substitution naturally determines a directed graph with an ordering of the edges incident at each vertex. We describe a simple method by which any primitive substitution can be modified (without materially changing the bi-infinite fixed points of the substitution) so that points in the substitution minimal shift are in bijective correspondence with one-sided infinite paths on its associated directed graph. Using this correspondence, we show that primitive substitutive sequences in the substitution minimal shift are precisely those sequences represented by eventually periodic paths. We use directed graphs to show that all measures of cylinders in a substitution minimal shift lie in a finite union of geometric sequences, confirming a conjecture of Boshernitzan. Our methods also yield sufficient conditions for a geometric realization of a primitive substitution to be "almost injective. [ABSTRACT FROM AUTHOR]

Investigates the descendants of primitive substitutions designated s. Evidence that the set of all descendants of s is finite for each primitive substitution; Proof contradicting previous studies which state than an interval exchange transformation defined over a quadratic field has only finitely many descendants; Nonperiodic sequence fixed by s.

Abstract: The Pampa Norte region is a great plain characterized by low slopes and accumulation of hundreds of meters of thick loose sediments. A high morphostructure denominated San Guillermo block stands out in the central plain, the Tostado–Selva scarp forming its western boundary. It is located in an intraplate setting characterized by low tectonic activity. However recent uplift can be inferred by means of terrain analysis and the sedimentology of the Palo Negro Fm. Pond deposits (Palo Negro Fm.) observed in the scarp suggest topographic inversion during the Late Quaternary in the Palo Negro area. The morphology indicates that the deformation was widely distributed, forming a gentle (ca. 5 m amplitude and 13 km wavelength) asymmetric fold. Low sinuosity lineaments located in the base of the scarp, coincident with knick points in the topographic profile, can be interpreted as the projection of tip-lines by high-angle fault-propagation. This geometry is compatible with reverse kinematics on blind faults. A deformation style with reactivation of pre-existing faults is consistent with structural observations. Seismic reflectors suggest the presence of Cretaceous high-angle normal faults, and the orientation of lineaments is similar to the orientation of the graben systems and transverse accommodation zones originated during the opening of the South Atlantic Ocean. One OSL dating of 67.4±5.1 kyr B.P (from Palo Negro Fm. supposed as deposited on a flat plain floor) and a height difference of 9.5 m measured in the Tostado–Selva scarp account for an averaged uplift rate of 0.14 mm/year. [Copyright &y& Elsevier]

Summary Monthly and daily precipitation extremes over La Plata Basin (LPB) are analyzed in the framework of the CLARIS-LPB Project. A review of the studies developed during the project and results of additional research are presented and discussed. Specific aspects of analysis are focused on large-scale versus local processes impacts on the intensity and frequency of precipitation extremes over LPB, and on the assessment of specific wet and dry spell indices and their changed characteristics in future climate scenarios. The analysis is shown for both available observations of precipitation in the region and ad-hoc global and regional models experiments. The Pacific, Indian and Atlantic Oceans can all impact precipitation intensity and frequency over LPB. In particular, considering the Pacific sector, different types of ENSO events (i.e. canonical vs Modoki or East vs Central) have different influences. Moreover, model projections indicate an increase in the frequency of precipitation extremes over LPB during El Niño and La Ninã events in future climate. Local forcings can also be important for precipitation extremes. Here, the feedbacks between soil moisture and extreme precipitation in LPB are discussed based on hydric conditions in the region and model sensitivity experiments. Concerning droughts, it was found that they were more frequent in the western than in the eastern sector of LPB during the period of 1962–2008. On the other hand, observations and model experiments agree in that the monthly wet extremes were more frequent than the dry extremes in the northern and southern LPB sectors during the period 1979–2001, with higher frequency in the south. [ABSTRACT FROM AUTHOR]

Objective: A high plasma cholesterol level is a major predisposing factor for coronary artery disease, and new treatments are currently under consideration. Supported by the close relationship between cholesterol and bile acid metabolism, recent studies have reported a hypocholesterolaemic effect of the bile acid ursodeoxycholic acid (UDCA) in patients with primary biliary cirrhosis but, unfortunately, no data are available in primary hypercholesterolaemia. We performed this study to evaluate the effects of oral administration of UDCA on serum lipoprotein patterns in patients with primary hypercholesterolaemia. Design and Setting: A double-blind, placebo-controlled, crossover study with a 4-week washout period carried out at an outpatient clinic at a university hospital. Study Participants: Twelve individuals with a total serum cholesterol level >5.17 mmol/L. Intervention: Patients were assigned to receive UDCA (8 to 10 mg/kg/day) or placebo for 28 days. They then crossed over to receive the other treatment after a 4-week washout period. Main Outcome Measures and Results: Serum total, low density lipoprotein (LDL), high density lipoprotein (HDL), very low density lipoprotein (VLDL) cholesterol and apoprotein A and B were determined before and after 28-day UDCA and placebo administration. After UDCA administration, the mean (±SD) total serum cholesterol level decreased significantly from 6.37 ± 1.01 mmol/L to 6.06 ± 0.97 mmmol/L (F = 5.7, p = 0.041); no significant differences from baseline were observed in LDL, HDL, VLDL cholesterol, apoprotein A and B. No significant changes in serum lipid parameters occurred after the placebo period. When compared with placebo, the UDCA-induced decrease in total serum cholesterol levels was statistically significant (F = 5.5, p = 0.043). Conclusion: This study shows that UDCA reduces total serum cholesterol levels in patients with mild to moderate hypercholesterolaemia. This effect suggests that the administration of UDCA may improve cholesterol metabolism in these individuals. [ABSTRACT FROM AUTHOR]