96 research outputs found
High resolution spectroscopic analysis of seven giants in the bulge globular cluster NGC 6723
Globular clusters associated with the Galactic bulge are important tracers of
stellar populations in the inner Galaxy. High resolution analysis of stars in
these clusters allows us to characterize them in terms of kinematics,
metallicity, and individual abundances, and to compare these fingerprints with
those characterizing field populations. We present iron and element ratios for
seven red giant stars in the globular cluster NGC~6723, based on high
resolution spectroscopy. High resolution spectra () of seven K
giants belonging to NGC 6723 were obtained with the FEROS spectrograph at the
MPG/ESO 2.2m telescope. Photospheric parameters were derived from FeI
and FeII transitions. Abundance ratios were obtained from line-to-line spectrum
synthesis calculations on clean selected features. An intermediate metallicity
of [Fe/H] dex and a heliocentric radial velocity of
were found for NGC 6723. Alpha-element
abundances present enhancements of dex,
dex, dex, and
dex. Similar overabundance is found for the iron-peak Ti with
dex. Odd-Z elements Na and Al present abundances of
dex and dex, respectively. Finally,
the s-element Ba is also enhanced by dex. The enhancement
levels of NGC 6723 are comparable to those of other metal-intermediate bulge
globular clusters. In turn, these enhancement levels are compatible with the
abundance profiles displayed by bulge field stars at that metallicity. This
hints at a possible similar chemical evolution with globular clusters and the
metal-poor of the bulge going through an early prompt chemical enrichment
Early warning system based on data mining to identify crime patterns
The analysis of criminal information is critical for the purpose of
preventing the occurrence of offenses, so the crime records committed in the
past are analyzed including perpetrators. The main objective was to identify
crime patterns in the city of Bogota, Colombia, supported using Early Warning
System based on data mining (CRISP-DM method). The research results show
the identification of 12 different criminal profiles demonstrating that the Early
Warning System is applicable since it managed to significantly reduce the time
devoted to the processes of registering complaints and searching for criminal
profiles.Universidad Peruana de Ciencias Aplicadas, Universidad de la Costa, Corporación Universitaria Latinoamericana
The Milky Way Bulge: Observed properties and a comparison to external galaxies
The Milky Way bulge offers a unique opportunity to investigate in detail the
role that different processes such as dynamical instabilities, hierarchical
merging, and dissipational collapse may have played in the history of the
Galaxy formation and evolution based on its resolved stellar population
properties. Large observation programmes and surveys of the bulge are providing
for the first time a look into the global view of the Milky Way bulge that can
be compared with the bulges of other galaxies, and be used as a template for
detailed comparison with models. The Milky Way has been shown to have a
box/peanut (B/P) bulge and recent evidence seems to suggest the presence of an
additional spheroidal component. In this review we summarise the global
chemical abundances, kinematics and structural properties that allow us to
disentangle these multiple components and provide constraints to understand
their origin. The investigation of both detailed and global properties of the
bulge now provide us with the opportunity to characterise the bulge as observed
in models, and to place the mixed component bulge scenario in the general
context of external galaxies. When writing this review, we considered the
perspectives of researchers working with the Milky Way and researchers working
with external galaxies. It is an attempt to approach both communities for a
fruitful exchange of ideas.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen
E., Peletier R., Gadotti D., Springer Publishing. 36 pages, 10 figure
Bacterial Toxicity of Potassium Tellurite: Unveiling an Ancient Enigma
Biochemical, genetic, enzymatic and molecular approaches were used to demonstrate, for the first time, that tellurite (TeO(3) (2−)) toxicity in E. coli involves superoxide formation. This radical is derived, at least in part, from enzymatic TeO(3) (2−) reduction. This conclusion is supported by the following observations made in K(2)TeO(3)-treated E. coli BW25113: i) induction of the ibpA gene encoding for the small heat shock protein IbpA, which has been associated with resistance to superoxide, ii) increase of cytoplasmic reactive oxygen species (ROS) as determined with ROS-specific probe 2′7′-dichlorodihydrofluorescein diacetate (H(2)DCFDA), iii) increase of carbonyl content in cellular proteins, iv) increase in the generation of thiobarbituric acid-reactive substances (TBARs), v) inactivation of oxidative stress-sensitive [Fe-S] enzymes such as aconitase, vi) increase of superoxide dismutase (SOD) activity, vii) increase of sodA, sodB and soxS mRNA transcription, and viii) generation of superoxide radical during in vitro enzymatic reduction of potassium tellurite
Screening for antimicrobial activity of ten medicinal plants used in Colombian folkloric medicine: A possible alternative in the treatment of non-nosocomial infections
BACKGROUND: The antimicrobial activity and Minimal Inhibitory Concentration (MIC) of the extracts of Bidens pilosa L., Bixa orellana L., Cecropia peltata L., Cinchona officinalis L., Gliricidia sepium H.B. & K, Jacaranda mimosifolia D.Don, Justicia secunda Vahl., Piper pulchrum C.DC, P. paniculata L. and Spilanthes americana Hieron were evaluated against five bacteria (Staphylococcus aureus, Streptococcus β hemolític, Bacillus cereus, Pseudomonas aeruginosa, and Escherichia coli), and one yeast (Candida albicans). These plants are used in Colombian folk medicine to treat infections of microbial origin. METHODS: Plants were collected by farmers and traditional healers. The ethanol, hexane and water extracts were obtained by standard methods. The antimicrobial activity was found by using a modified agar well diffusion method. All microorganisms were obtained from the American Type Culture Collection (ATCC). MIC was determined in the plant extracts that showed some efficacy against the tested microorganisms. Gentamycin sulfate (1.0 μg/ml), clindamycin (0.3 μg/ml) and nystatin (1.0 μg/ml) were used as positive controls. RESULTS: The water extracts of Bidens pilosa L., Jacaranda mimosifolia D.Don, and Piper pulchrum C.DC showed a higher activity against Bacillus cereus and Escherichia coli than gentamycin sulfate. Similarly, the ethanol extracts of all species were active against Staphylococcus aureus except for Justicia secunda. Furthermore, Bixa orellana L, Justicia secunda Vahl. and Piper pulchrum C.DC presented the lowest MICs against Escherichia coli (0.8, 0.6 and 0.6 μg/ml, respectively) compared to gentamycin sulfate (0.9 8g/ml). Likewise, Justicia secunda and Piper pulchrum C.DC showed an analogous MIC against Candida albicans (0.5 and 0.6 μg/ml, respectively) compared to nystatin (0.6 μg/ml). Bixa orellana L, exhibited a better MIC against Bacillus cereus (0.2 μg/ml) than gentamycin sulfate (0.5 μg/ml). CONCLUSION: This in vitro study corroborated the antimicrobial activity of the selected plants used in folkloric medicine. All these plants were effective against three or more of the pathogenic microorganisms. However, they were ineffective against Streptococcus β hemolytic and Pseudomonas aeruginosa. Their medicinal use in infections associated with these two species is not recommended. This study also showed that Bixa orellana L, Justicia secunda Vahl. and Piper pulchrum C.DC could be potential sources of new antimicrobial agents
Latin American consumption of major food groups: Results from the ELANS study
Background
The Latin American (LA) region is still facing an ongoing epidemiological transition and shows a complex public health scenario regarding non-communicable diseases (NCDs). A healthy diet and consumption of specific food groups may decrease the risk of NCDs, however there is a lack of dietary intake data in LA countries.
Objective
Provide updated data on the dietary intake of key science-based selected food groups related to NCDs risk in LA countries.
Design
ELANS (Latin American Study of Nutrition and Health) is a multicenter cross-sectional study assessing food consumption from an urban sample between15 to 65 years old from 8 LA countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Peru, and Venezuela). Two 24-HR were obtained from 9, 218 individuals. The daily intake of 10 food groups related to NCDs risk (fruits; vegetables; legumes/beans; nuts and seeds; whole grains products; fish and seafood; yogurt; red meat; processed meats; sugar-sweetened beverages (ready-to-drink and homemade)) were assessed and compared to global recommendations. Results Only 7.2% of the overall sample reached WHO's recommendation for fruits and vegetables consumption (400 grams per day). Regarding the dietary patterns related to a reduced risk of NCDs, among the overall sample legumes and fruits were the food groups with closer intake to the recommendation, although much lower than expected (13.1% and 11.5%, respectively). Less than 3.5% of the sample met the optimal consumption level of vegetables, nuts, whole grains, fish and yogurt. Largest country-dependent differences in average daily consumption were found for legumes, nuts, fish, and yogurt. Mean consumption of SSB showed large differences between countries.
Conclusion
Diet intake quality is deficient for nutrient-dense food groups, suggesting a higher risk for NCDs in the urban LA region in upcoming decades. These data provide relevant and up-to-date information to take urgent public health actions to improve consumption of critically foods in order to prevent NCDs. Copyright
The Gaia-ESO Survey::Exploring the complex nature and origins of the Galactic bulge populations
Context. As observational evidence steadily accumulates, the nature of the Galactic bulge has proven to be rather complex: the structural, kinematic, and chemical analyses often lead to contradictory conclusions. The nature of the metal-rich bulge - and especially of the metal-poor bulge - and their relation with other Galactic components, still need to be firmly defined on the basis of statistically significant high-quality data samples. Aims. We used the fourth internal data release of the Gaia-ESO survey to characterize the bulge metallicity distribution function (MDF), magnesium abundance, spatial distribution, and correlation of these properties with kinematics. Moreover, the homogeneous sampling of the different Galactic populations provided by the Gaia-ESO survey allowed us to perform a comparison between the bulge, thin disk, and thick disk sequences in the [Mg/Fe] vs. [Fe/H] plane in order to constrain the extent of their eventual chemical similarities. Methods. We obtained spectroscopic data for ∼2500 red clump stars in 11 bulge fields, sampling the area -10° ≥ l ≥ +8° and -10° ≥ b ≥ -4° from the fourth internal data release of the Gaia-ESO survey. A sample of ∼6300 disk stars was also selected for comparison. Spectrophotometric distances computed via isochrone fitting allowed us to define a sample of stars likely located in the bulge region. Results. From a Gaussian mixture models (GMM) analysis, the bulge MDF is confirmed to be bimodal across the whole sampled area. The relative ratio between the two modes of the MDF changes as a function of b, with metal-poor stars dominating at high latitudes. The metal-rich stars exhibit bar-like kinematics and display a bimodality in their magnitude distribution, a feature which is tightly associated with the X-shape bulge. They overlap with the metal-rich end of the thin disk sequence in the [Mg/Fe] vs. [Fe/H] plane. On the other hand, metal-poor bulge stars have a more isotropic hot kinematics and do not participate in the X-shape bulge. Their Mg enhancement level and general shape in the [Mg/Fe] vs. [Fe/H] plane is comparable to that of the thick disk sequence. The position at which [Mg/Fe] starts to decrease with [Fe/H], called the "knee", is observed in the metal-poor bulge at [Fe/H]knee = -0:37 ± 0:09, being 0.06 dex higher than that of the thick disk. Although this difference is inside the error bars, it suggest a higher star formation rate (SFR) for the bulge than for the thick disk. We estimate an upper limit for this difference of Δ[Fe/H]knee = 0:24 dex. Finally, we present a chemical evolution model that suitably fits the whole bulge sequence by assuming a fast (<1 Gyr) intense burst of stellar formation that takes place at early epochs. Conclusions.We associate metal-rich stars with the bar boxy/peanut bulge formed as the product of secular evolution of the early thin disk. On the other hand, the metal-poor subpopulation might be the product of an early prompt dissipative collapse dominated by massive stars. Nevertheless, our results do not allow us to firmly rule out the possibility that these stars come from the secular evolution of the early thick disk. This is the first time that an analysis of the bulge MDF and α-abundances has been performed in a large area on the basis of a homogeneous, fully spectroscopic analysis of high-resolution, high S/N data
Árboles del Santuario Histórico de Machu Picchu: Monitoreo de diversidad y carbono a largo plazo
Understanding how the richness, diversity, and carbon monitoring vary and are distributed through altitudinal gradients in Andean montane forests is essential to understand how these forests are adapting to global warming effects. Botanical explorations and general collections were carried out within the limits of the Historic Sanctuary of Machu Picchu in an altitude gradient of 1600 to 4200 m.a.s.l. Two permanent plots of 1.0 ha were established in the sectors of Intipunku (SHM – 01) at an altitude of 2,653 m.a.s.l and Kantupata (SHM-02) at an altitude of 3,200 m.a.s.l., with the standardized methodology of RAINFOR in 2013 and remedied in 2016. We updated the number of tree species for the Historic Sanctuary of Machu Picchu, 364 species are reported so far, this catalog includes all wild and cultivated species but also tree ferns and palm trees. In recent years, four new tree species have been described whose TYPE collections come from SHM forests: Ocotea alveatavan der Werff, Ocotea mollivillosavan der Werff (Lauraceae), Bunchosia cuscanaW.R. Anderson (Malpighiaceae), Ficus machupicchuensisC.C. Berg (Moraceae). In the two permanent plots, a total of 69 species were recorded in 1286 individuals. Individually in the SHM – 01 plot, 26 families, 36 genera and 45 species were recorded in 682 individuals; and in the SHM – 02 plot: 22 families, 28 genera and 31 species in 604 individuals. Stored aerial biomass was higher in the Intipunku sector (146 Mg ha-1) compared to Kantupata sector (101 Mg ha-1). Our research shows that the Andean forests of Machu Picchu provide important ecosystem services, and there is still much to do in terms of scientic research. The continued discovery of new tree species in the locality demonstrates the need for conservation to protect forests that support some of the highest levels of endemism in the world
Panning for gold, but finding helium: discovery of the ultra-stripped supernova SN2019wxt from gravitational-wave follow-up observations
We present the results from multi-wavelength observations of a transient
discovered during the follow-up of S191213g, a gravitational wave (GW) event
reported by the LIGO-Virgo Collaboration as a possible binary neutron star
merger in a low latency search. This search yielded SN2019wxt, a young
transient in a galaxy whose sky position (in the 80\% GW contour) and distance
(150\,Mpc) were plausibly compatible with the localisation uncertainty of
the GW event. Initially, the transient's tightly constrained age, its
relatively faint peak magnitude (\,mag) and the band
decline rate of \,mag per 5\,days appeared suggestive of a compact
binary merger. However, SN2019wxt spectroscopically resembled a type Ib
supernova, and analysis of the optical-near-infrared evolution rapidly led to
the conclusion that while it could not be associated with S191213g, it
nevertheless represented an extreme outcome of stellar evolution. By modelling
the light curve, we estimated an ejecta mass of , with
Ni comprising of this. We were broadly able to reproduce its
spectral evolution with a composition dominated by helium and oxygen, with
trace amounts of calcium. We considered various progenitors that could give
rise to the observed properties of SN2019wxt, and concluded that an
ultra-stripped origin in a binary system is the most likely explanation.
Disentangling electromagnetic counterparts to GW events from transients such as
SN2019wxt is challenging: in a bid to characterise the level of contamination,
we estimated the rate of events with properties comparable to those of
SN2019wxt and found that such event per week can occur within the
typical GW localisation area of O4 alerts out to a luminosity distance of
500\,Mpc, beyond which it would become fainter than the typical depth of
current electromagnetic follow-up campaigns.Comment: By the ENGRAVE collaboration (engrave-eso.org). 35 pages, 20 figures,
final version accepted by A&
Lenguaje probabilístico: un camino para el desarrollo de la alfabetización probabilística. Un estudio de caso en el aula de Educación Primaria
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