27 research outputs found
BioloĆĄko suzbijanje maslinine muhe Bactrocera oleae (Rossi) (Diptera: Tephritidae) u sustavu integrirane zaĆĄtite: kratak pregled
State-of-the-art and research prospectings in biological and integrated control of the olive fly B.oleae were briefly discussed.U radu su, na osnovi literaturnih podataka, prikazana aktualna znanja o maslinovoj muhi i moguÄe mjere suzbijanja u sustavu integrirane proizvodnje masline
Progetto SUREVEG «Strip-cropping and recycling of waste for biodiverse and resoURce-Efficient intensive VEGetable production"
The poster presents the objectives of the SUREVEG project, with the aim to discuss with the farmers who participated to the Open Day of July, 5th 2018 organized by the CREA on the limits and potential development of the strip-cropping application in organic vegetable cropping systems in Central Italy
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The Complex Behaviour of s-Process Element Abundances at Young Ages
Open clusters appear as simple objects in many respects, with a high degree of homogeneity in their (initial) chemical composition, and the typical solar-scaled abundance pattern that they exhibit for the majority of the chemical species. The striking singularity is represented by heavy elements produced from the slow process of the neutron-capture reactions. In particular, young open clusters (ages less than a few hundred Myr) give rise to the so-called barium puzzle: that is an extreme enhancement in their [Be/Fe] ratios, up to a factor of four of the solar value, which is not followed by other nearby s-process elements (e.g., lanthanum and cerium). The definite explanation for such a peculiar trend is still wanting, as many different solutions have been envisaged. We review the status of this field and present our new results on young open clusters and the pre-main sequence star RZ Piscium
The Complex Behaviour of s-Process Element Abundances at Young Ages
Open clusters appear as simple objects in many respects, with a high degree of homogeneity in their (initial) chemical composition, and the typical solar-scaled abundance pattern that they exhibit for the majority of the chemical species. The striking singularity is represented by heavy elements produced from the slow process of the neutron-capture reactions. In particular, young open clusters (ages less than a few hundred Myr) give rise to the so-called barium puzzle: that is an extreme enhancement in their [Be/Fe] ratios, up to a factor of four of the solar value, which is not followed by other nearby s-process elements (e.g., lanthanum and cerium). The definite explanation for such a peculiar trend is still wanting, as many different solutions have been envisaged. We review the status of this field and present our new results on young open clusters and the pre-main sequence star RZ Piscium
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The Abundance of S-Process Elements: Temporal and Spatial Trends from Open Cluster Observations
Spectroscopic observations of stars belonging to open clusters, with well-determined ages and distances, are a unique tool for constraining stellar evolution, nucleosynthesis, mixing processes, and, ultimately, Galactic chemical evolution. Abundances of slow (s) process neutron capture elements in stars that retain their initial surface composition open a window into the processes that generated them. In particular, they give us information on their main site of production, i.e., the low-and intermediate-mass Asymptotic Giant Branch (AGB) stars. In the present work, we review some observational results obtained during the last decade that contributed to a better understanding of the AGB phase: the growth of s-process abundances at recent epochs, i.e., in the youngest stellar populations; the different relations between age and [s/Fe] in distinct regions of the disc; and finally the use of s-process abundances combined with those of α elements, [s/α], to estimate stellar ages. We revise some implications that these observations had both on stellar and Galactic evolution, and on our ability to infer stellar ages
Assessing the Origin of Phosphonic Acid Residues in Organic Vegetable and Fruit Crops: The Biofosf Project Multi-Actor Approach
Recently, on the EU market, phosphonic acid residues were detected in many organic goods, although fosetyl-derivates and phosphite salts are not allowed by Reg. EC n. 889/2009. The BIOFOSF project "Solving phosphite issue in organic fruit and horticultural crops" aimed at verifying whether the phosphonic acid contamination could be due to unproper use of fertilizers/plant protection products by organic farmers, or to the plant's ability to self-produce it spontaneously. Applying a participative approach, field case-studies on potato, rocket lettuce, and pears were carried out (organic vs. integrated systems). The ethyl-phosphonic acid and phosphonic acid were determined in soil, tubers, leaves, fruits, tree woody organs, used fertilizers, and plant protection products to correlate them to the applied farming management. Tested crops were not able to self-synthetize phosphonic acid, being its detection due to: (i) external inputs not allowed in organic farming; (ii) fertilizers/plant protection products allowed in organic farming, contaminated by fosetyl or phosphite. In addition, it was found that tree crops can stock the phosphite in their woody organs, then translocate it from branches to leaves and fruits over time. Regression models applied to field data showed that fruit trees decontamination could take more than 5 years, depending on the starting value of phosphonic acid contamination, useful to define the phosphite maximum residue limit in organic fruit crops
How Magnetic Activity Alters What We Learn from Stellar Spectra
Magnetic fields and stellar spots can alter the equivalent widths of absorption lines in stellar spectra, varying during the activity cycle. This also influences the information that we derive through spectroscopic analysis. In this study, we analyze high-resolution spectra of 211 sunlike stars observed at different phases of their activity cycles, in order to investigate how stellar activity affects the spectroscopic determination of stellar parameters and chemical abundances. We observe that the equivalent widths of lines can increase as a function of the activity index log R'HK
during the stellar cycle, which also produces an artificial growth of the stellar microturbulence and a decrease in effective temperature and metallicity. This effect is visible for stars with activity indexes log RHK -5.0 (i.e., younger than 4-5 Gyr), and it is more significant at higher activity levels. These results have fundamental implications on several topics in astrophysics that are discussed in the paper, including stellar nucleosynthesis,
chemical tagging, the study of Galactic chemical evolution, chemically anomalous stars, the structure of the Milky
Way disk, stellar formation rates, photoevaporation of circumstellar disks, and planet hunting.L.S. and A.I.K. acknowledge financial support from the
Australian Research Council (Discovery Project 170100521).
A.R.C. acknowledges the support from the Australian Research
Council (DECRA 190100656). J.M. thanks support by
FAPESP (2018/04055-8) and CNPq (Bolsa de Produtividade).
J.Y.G. acknowledges the support from CNPq. This research
was supported by the Australian Research Council Centre of
Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO
3D), through project number CE17010001
The GALAH survey: tracing the Galactic disk with Open Clusters
Open clusters are unique tracers of the history of our own Galaxy's disk.
According to our membership analysis based on \textit{Gaia} astrometry, out of
the 226 potential clusters falling in the footprint of GALAH or APOGEE, we find
that 205 have secure members that were observed by at least one of the survey.
Furthermore, members of 134 clusters have high-quality spectroscopic data that
we use to determine their chemical composition. We leverage this information to
study the chemical distribution throughout the Galactic disk of 21 elements,
from C to Eu. The radial metallicity gradient obtained from our analysis is
0.0760.009 dex kpc, which is in agreement with previous works
based on smaller samples. Furthermore, the gradient in the [Fe/H] - guiding
radius (r) plane is 0.0730.008 dex kpc. We show
consistently that open clusters trace the distribution of chemical elements
throughout the Galactic disk differently than field stars. In particular, at
given radius, open clusters show an age-metallicity relation that has less
scatter than field stars. As such scatter is often interpreted as an effect of
radial migration, we suggest that these differences are due to the physical
selection effect imposed by our Galaxy: clusters that would have migrated
significantly also had higher chances to get destroyed. Finally, our results
reveal trends in the [X/Fe]rage space, which are important
to understand production rates of different elements as a function of space and
time.Comment: 18 pages, 10 figures, accepted for publication MNRA
VizieR Online Data Catalog: Complete line list and solar values (Baratella+, 2020)
Line list used in this study (table2.dat), complete of the atomic data, references of the log(gf) values adopted and with equivalent width and abundances measured in the Sun. (1 data file)