National University of La Plata

About: National University of La Plata is a education organization based out in La Plata, Argentina. It is known for research contribution in the topics: Population & Stars. The organization has 12993 authors who have published 30013 publications receiving 495118 citations. The organization is also known as: UNLP & Universidad Nacional de La Plata.

Effect of short-term ozone treatments on tomato (Solanum lycopersicum L.) fruit quality and cell wall degradation.

Abstract: We evaluated the effect of short-term gaseous ozone treatment (10 μL/L; 10 min) on tomato fruit quality and cell wall degradation. The treatments did not modify fruit color, sugar content, acidity, or antioxidant capacity but reduced fruit damage and weight loss and induced the accumulation of phenolic compounds. In addition, softening was delayed in ozone-treated fruit. Cell wall analysis showed that exposure to ozone decreased pectin but not hemicellulose solubilization. Polyuronide depolymerization was also reduced in ozone-treated fruit. While the treatments did not alter the activity of the pectin-degrading enzymes polygalacturonase (PG) and β-Galactosidase (β-Gal), a clear decrease in pectin methyl esterase (PME) was found. Results show that short-term ozone treatments might be useful to reduce fruit damage and excessive softening, two of the main factors limiting tomato postharvest life, without negatively affecting other quality attributes. The impact of the treatments on fruit softening might be ...

The EXOSAT data on GX 339-4: further evidence for an "intermediate" state

Abstract: We have studied the fast timing and spectral behavior of the black hole candidate (BHC) GX 339-4 using all 1-20 keV EXOSAT ME data: the 1983 July, 1984 March, 1984 May, and 1985 April observations. In 1985 April, GX 339-4 was in a weak low state (0.03 × 10-9 ergs cm-2 s-1, 2-10 keV). The X-ray spectrum was a hard power law with a photon index α of 1.82, and the power spectrum, though ill-constrained by the data, was consistent with a typical BHC low-state spectrum. During the other three pointings the system was brighter (1.5 × 10-9 ergs cm-2 s-1, 2-10 keV), an ultrasoft component was present in the spectrum, and the power law was steeper (α ~ 3.5 in 1984; in 1983 it was not well measured); the power spectrum showed a flat-topped band-limited noise component with a break frequency of ~4.5 Hz and a fractional rms amplitude of ~7%. Comparing flux levels, X-ray spectra, and power spectra, we conclude that in these observations GX 339-4 was in a state intermediate between the usual BHC low and high states. The system was ~4 times brighter than in its usual low state, 4 times fainter than in its usual high state, and an order of magnitude fainter than in its very high state. We compare these results to those recently obtained on other BHCs, and conclude that this "intermediate-state" behavior is a common characteristic of BHCs, which occurs at levels intermediate between the high and the low state. We argue that this result can be used to resolve the long-standing issue of the dependence of the power spectral break frequency in the low state on mass accretion rate, and strengthens the idea that low-state noise and very high state noise may have a common origin. We briefly discuss a possible interpretation for the changes in break frequency in the low state and between low state and intermediate state.

Double degenerate mergers as progenitors of high-field magnetic white dwarfs

Abstract: High-field magnetic white dwarfs have been long suspected to be the result of stellar mergers. However, the nature of the coalescing stars and the precise mechanism that produces the magnetic field are still unknown. Here, we show that the hot, convective, differentially rotating corona present in the outer layers of the remnant of the merger of two degenerate cores can produce magnetic fields of the required strength that do not decay for long timescales. Using a state-of-the-art Monte Carlo simulator, we also show that the expected number of high-field magnetic white dwarfs produced in this way is consistent with that found in the solar neighborhood.

Challenges and opportunities with drug repurposing: finding strategies to find alternative uses of therapeutics

Abstract: Drug repurposing (also known as drug repositioning, drug reprofiling, indication expansion or indication shift) involves establishing new medical uses for already known drugs, including approved, d...