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.

Relations between timing features and colors in the x-ray binary 4u 0614+09

Abstract: We study the correlations between timing and X-ray spectral properties in the low-mass X-ray binary 4U 0614+09 using a large (265 ks) data set obtained with the Rossi X-Ray Timing Explorer. We find strong quasi-periodic oscillations (QPOs) of the X-ray flux, like the kilohertz QPOs in many other X-ray binaries with accreting neutron stars, with frequencies ranging from 1329 Hz down to 418 Hz and perhaps as low as 153 Hz. We report the highest frequency QPO yet from any low-mass X-ray binary at 1329 ? 4 Hz, which has implications for neutron star structure. This QPO has a 3.5 ? single-trial significance; for an estimated 40 trials the significance is 2.4 ?. Besides the kilohertz QPOs, the Fourier power spectra show four additional components: high-frequency noise (HFN), described by a broken power law with a break frequency between 0.7 and 45 Hz, very low frequency noise (VLFN), which is fitted as a power law below 1 Hz, and two broad Lorentzians with centroid frequencies varying from 6 to 38 Hz and from 97 to 158 Hz, respectively. We find strong correlations between the frequencies of the kilohertz QPOs, the frequency of the 6-38 Hz broad Lorentzian, the break frequency of the HFN, the strength of both the HFN and the VLFN, and the position of the source in the hard X-ray color versus intensity diagram. The frequency of the 97-158 Hz Lorentzian does not correlate with these parameters. We also find that the relation between power density and break frequency of the HFN is similar to that established for black hole candidates in the low state. We suggest that the changing mass accretion rate is responsible for the correlated changes in all these parameters.

Heat treatments delay ripening and postharvest decay of strawberry fruit

Abstract: Fully red strawberries (Fragaria × ananassa Duch. cv. Selva) were treated for 1−5 h at temperatures ranging from 39 to 50 °C. After treatments, fruits were placed at 0 °C overnight and then held at 20 °C for 3 days. Most of the heat treatments improved strawberry shelf life, with best results obtained for fruit heated at 42 °C and 48 °C for 3 h. Heat treatments prevented fungal development and decreased the number of damaged fruits. These treatments were then used to treat strawberries at 50−75% red to analyze effects on firmness, surface color, anthocyanin content, PAL activity, polypeptide composition, and protein synthesis. Softening rate and external color development was less in fruit heated at 48 °C compared to the control, while treatment at 42 °C did not significantly affect these parameters. However, both treatments reduced anthocyanin accumulation and PAL activity relative to the controls. In addition, treatment at 48 °C for 3 h reduced protein synthesis, but this effect was partially reversed a...

Oxidative desaturation of α-linolenic, linoleic, and stearic acids by human liver microsomes

Abstract: The desaturation of stearic, linoleic, and α-linolenic acids by human liver microsomes were studied. The microsomes were isolated from liver biopsies obtained during operations. It was shown that human liver microsomes are able to desaturate 1-14C-α-linolenic acid to octadeca-6,9,12,15-tetraenoic acid; 1-14C-linoleic acid to γ-linolenic acid; and 1-14C-stearic acid to oleic acid in the same system described in the rat. However, the desaturation activity obtained was low compared to other mammals. This effect was attributed to fasting, premedication, or the anaesthesia.

Search for invisible decays of a Higgs boson using vector-boson fusion in pp collisions at √s=8 TeV with the ATLAS detector

Abstract: A search for a Higgs boson produced via vector-boson fusion and decaying into invisible particles is presented, using 20.3 fb−1 of proton-proton collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC. For a Higgs boson with a mass of 125 GeV, assuming the Standard Model production cross section, an upper bound of 0.28 is set on the branching fraction of H → invisible at 95% confidence level, where the expected upper limit is 0.31. The results are interpreted in models of Higgs-portal dark matter where the branching fraction limit is converted into upper bounds on the dark-matter-nucleon scattering cross section as a function of the dark-matter particle mass, and compared to results from the direct dark-matter detection experiments.