A low-energy effective Yang-Mills theory for quark and gluon confinement

We derive a gauge-invariant low-energy effective model of the Yang-Mills theory. We find that the effective gluon propagator belongs to the Gribov-Stingl type and agrees with it when a mass term which breaks nilpotency of the BRST symmetry is included. We show that the effective model with gluon propagator of the Gribov-Stingl type exhibits both quark and gluon confinement: the Wilson loop average has the area law and the Schwinger function violates reflection positivity. However, we argue that both quark and gluon confinement can be obtained even in the absence of such a mass term.Comment: 5 pages, no figures; accepted for publication in Physical Review D (Rapid Communication

The economic and environmental benefits of adopting natural gas in isolated systems of Amazonas state, Brazil

The Amazonas state in Brazil faces unique challenges regarding energy planning for its 95 isolated systems, which are remote areas not connected to the national power grid and primarily rely on diesel to generate electricity. These challenges include dense forests, low population density, low overall energy demands, and restrictions on transporting oil derivatives via waterways. However, the discovery of onshore reserves of natural gas in the state and investments in infrastructure, such as the construction of gas pipelines, have provided an opportunity to replace diesel with this cleaner and more cost-effective energy source. This study aims to assess the feasibility of completely replacing diesel-powered generators with natural gas in 14 isolated systems located near the Urucu-Manaus gas pipeline, as well as the Azulão and Japiim production fields. The methodology employed in this study aims to provide a comprehensive assessment of the economic and environmental impact of transitioning from diesel to natural gas in isolated systems. This assessment focuses on two key topics: fuel costs and CO2 emissions resulting from electricity generation. The analysis results indicate that transitioning from diesel to natural gas can bring significant economic and environmental benefits. The switch to natural gas would reduce fuel costs by more than 40% and decrease CO2 emissions from combustion (in one case, 39.6% and in other cities, between 16.75% and 27.10%), promoting savings for additional investments in efficiency and sustainability. Implementing these changes makes it possible to achieve a better quality of life for citizens in isolated communities by providing access to a more reliable and sustainable energy source.</p

NGC 2782: a merger remnant with young stars in its gaseous tidal tail

We have searched for young star-forming regions around the merger remnant NGC 2782. By using GALEX FUV and NUV imaging and HI data we found seven UV sources, located at distances greater than 26 kpc from the center of NGC 2782, and coinciding with its western HI tidal tail. These regions were resolved in several smaller systems when Gemini/GMOS r-band images were used. We compared the observed colors to stellar population synthesis models and we found that these objects have ages of ~1 to 11 Myr and masses ranging from 10^3.9 to 10^4.6 Msun. By using Gemini/GMOS spectroscopic data we confirm memberships and derive high metallicities for three of the young regions in the tail (12+log(O/H)=8.74\pm0.20, 8.81\pm0.20 and 8.78\pm0.20). These metallicities are similar to the value presented by the nuclear region of NGC 2782 and also similar to the value presented for an object located close to the main body of NGC 2782. The high metallicities measured for the star-forming regions in the gaseous tidal tail of NGC 2782 could be explained if they were formed out of highly enriched gas which was once expelled from the center of the merging galaxies when the system collided. An additional possibility is that the tail has been a nursery of a few generations of young stellar systems which ultimately polluted this medium with metals, further enriching the already pre-enriched gas ejected to the tail when the galaxies collided.Comment: 11 pages, 5 figures. Accepted for publication in MNRA

Star formation in low density HI gas around the Elliptical Galaxy NGC2865

Interacting galaxies surrounded by HI tidal debris are ideal sites for the study of young clusters and tidal galaxy formation. The process that triggers star formation in the low-density environments outside galaxies is still an open question. New clusters and galaxies of tidal origin are expected to have high metallicities for their luminosities. Spectroscopy of such objects is, however, at the limit of what can be done with existing 8-10m class telescopes, which has prevented statistical studies of these objects. NGC2865 is an UV-bright merging elliptical galaxy with shells and extended HI tails. The regions observed in this work were previously detected using multi-slit imaging spectroscopy. We obtain new multislit spectroscopy of six young star-forming regions around NGC2865, to determine their redshifts and metallicities. The six emission-line regions are located 16-40 kpc from NGC2865 and they have similar redshifts. They have ages of ~10Myears and an average metallicity of 12+log(O/H) ~ 8.6, suggesting a tidal origin for the regions. It is noted that they coincide with an extended HI tail, which has projected density of N$_{HI}$ < 10$^{19}$ cm$^{-2}$, and displays a low surface brightness counterpart. These regions may represent the youngest of the three populations of star clusters already identified in NGC2865. The high, nearly-solar, oxygen abundances found for the six regions in the vicinity of NGC2865 suggest that they were formed by pre-enriched material from the parent galaxy, from gas removed during the last major merger. Given the mass and the location of the HII regions, we can speculate that these young star-forming regions are potential precursors of globular clusters that will be part of the halo of NGC2865 in the future. Our result supports the use of the multi-slit imaging spectroscopy as a useful tool for finding nearly-formed stellar systems around galaxies.Comment: 7 pages, 2 figures accepted in A&

Nitric oxide genotoxicity protection by Ginkgo biloba extract

Over the last years, the Ginkgo biloba plant has grown a considerably good reputation within the scientific community and today its potential in terms of beneficial effects is well sustained in the literature [1]. Most of the studies involving the use of plant material, however, only face their antioxidant properties and just a little was explored relatively to their antigenotoxic activity. The excessive production of oxidative species, being reactive oxygen species (ROS) or reactive nitrogen species (RNS), can be stressful to the cell to a point where they compromise survival. In between their molecular targets, ROS can affect DNA, possibly causing the loss of its stability and integrity, imposing a very dangerous threat. NO is recognized for its biological roles in the regulation of vasodilation, and nervous system and immune system signaling as well as for its potentially adverse effects [2]. Depending on the molecules NO encounters inside the cell, it may oxidize into peroxynitrite or dinitrogen trioxide (among many others), both molecules being able to interact with and modify DNA [3]. The chemical analysis of the ethanolic Ginkgo biloba extract (GBE), revealed the presence of some characteristic compounds.. Also, a protective effect against SNP was observed in viability assays, in which fission yeast Schizosaccharomyces pombe wild type strains and DNA repair-affected mutants were used. Cell cycle analysis revealed that incubation with GBE alone causes a quicker advance in cell cycle progression and that treatment with GBE slightly reduces the delay caused by SNP. Finally, experiments involving the oxidative stress response protein Pap1 fused with GFP pointed to a possible protection mechanism, where cell interaction with the extract may be functioning as a mild stress elicitor, preparing cells for the stress induced by NO. Putting all the evidence together, GBE protects cells from the effect of SNP through a DNA-repair independent mechanism, which may involve the scavenging of NO and subsequent decrease in DNA modifications, and/or the signalling of oxidative stress-response proteins preventing the excessive accumulation of oxidant molecules.This work is supported by: European Investment Funds by FEDER/COMPETE/POCI– Operacional Competitiveness and Internacionalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.info:eu-repo/semantics/publishedVersio

Supersymmetrization of the Radiation Damping

We construct a supersymmetrized version of the model to the radiation damping \cite{03} introduced by the present authors \cite{ACWF}. We dicuss its symmetries and the corresponding conserved Noether charges. It is shown this supersymmetric version provides a supersymmetric generalization of the Galilei algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action can be splited into dynamically independent external and internal sectors.Comment: 9 page