411 research outputs found
z~2: An Epoch of Disk Assembly
We explore the evolution of the internal gas kinematics of star-forming
galaxies from the peak of cosmic star-formation at to today.
Measurements of galaxy rotation velocity , which quantify ordered
motions, and gas velocity dispersion , which quantify disordered
motions, are adopted from the DEEP2 and SIGMA surveys. This sample covers a
continuous baseline in redshift from to , spanning 10 Gyrs. At
low redshift, nearly all sufficiently massive star-forming galaxies are
rotationally supported (). By , the percentage of
galaxies with rotational support has declined to 50 at low stellar mass
() and 70 at high stellar mass
(). For , the percentage
drops below 35 for all masses. From to now, galaxies exhibit
remarkably smooth kinematic evolution on average. All galaxies tend towards
rotational support with time, and it is reached earlier in higher mass systems.
This is mostly due to an average decline in by a factor of 3 since a
redshift of 2, which is independent of mass. Over the same time period,
increases by a factor of 1.5 for low mass systems, but does not
evolve for high mass systems. These trends in and with
time are at a fixed stellar mass and should not be interpreted as evolutionary
tracks for galaxy populations. When galaxy populations are linked in time with
abundance matching, not only does decline with time as before, but
strongly increases with time for all galaxy masses. This enhances the
evolution in . These results indicate that is a
period of disk assembly, during which the strong rotational support present in
today's massive disk galaxies is only just beginning to emerge.Comment: 12 pages, 8 figures, submitted to Ap
Producción agroecológica de frutas y hortalizas en el primer cordón del Conurbano Bonaerense
Desde el año 2011 funciona en el partido de Morón, provincia de Buenos Aires el Espacio de Agroecología Urbana. Que a través de un proyecto de “Agroecología Urbana y Educación para la Soberanía Alimentaria”; en el marco del Plan de Desarrollo Estratégico del Municipio de Morón junto a la Asociación Civil CEHLAC, el Programa Nacional ProHuerta y con el apoyo del Ministerio de Desarrollo Social propone un espacio demostrativo, educativo y productivo. La dimensión productiva del Proyecto es llevada a cabo por el emprendimiento Morón Surco. La producción se realiza a través de técnicas agroecológicas y se comercializa a través de redes de economía social y solidaria, generando puestos de trabajo autogestivo en un ambiente saludable y respetuoso. En los últimos años a partir del desarrollo productivo y comunitario, junto al incremento en la demanda local de alimentos saludables, el Emprendimiento logró un aumento significativo en el número de familias abastecidas. A nivel local, Morón Surco es pionero en el desarrollo sustentable de alimentos agroecológicos en zona urbana. Los logros alcanzados en su breve historia es una evidencia del potencial de su contribución a la Soberanía Alimentaria.Eje B2 Paisajes, Territorios y Agroecología (Relatos de experiencias)Facultad de Ciencias Agrarias y Forestale
Interactions between environmental contaminants and gastrointestinal parasites: novel insights from an integrative approach in a marine predator
Environmental contaminants and parasites are ubiquitous stressors that can affect animal physiology and derive from similar dietary sources (co-exposure). To unravel their interactions in wildlife, it is thus essential to quantify their concurring drivers. Here, the relationship between blood contaminant residues (11 trace elements and 17 perfluoroalkyl substances) and nonlethally quantified gastrointestinal parasite loads was tested while accounting for intrinsic (sex, age, and mass) and extrinsic factors (trophic ecology inferred from stable isotope analyses and biologging) in European shags Phalacrocorax aristotelis. Shags had high mercury (range 0.65–3.21 μg g–1 wet weight, ww) and extremely high perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) residues (3.46–53 and 4.48–44 ng g–1 ww, respectively). Males had higher concentrations of arsenic, mercury, PFOA, and PFNA than females, while the opposite was true for selenium, perfluorododecanoic acid (PFDoA), and perfluooctane sulfonic acid (PFOS). Individual parasite loads (Contracaecum rudolphii) were higher in males than in females. Females targeted pelagic-feeding prey, while males relied on both pelagic- and benthic-feeding organisms. Parasite loads were not related to trophic ecology in either sex, suggesting no substantial dietary co-exposure with contaminants. In females, parasite loads increased strongly with decreasing selenium:mercury molar ratios. Females may be more susceptible to the interactive effects of contaminants and parasites on physiology, with potential fitness consequences
Ebola viral load at diagnosis associates with patient outcome and outbreak evolution
BACKGROUND. Ebola virus (EBOV) causes periodic outbreaks of life-threatening EBOV disease in Africa. Historically, these outbreaks have been relatively small and geographically contained; however, the magnitude of the EBOV outbreak that began in 2014 in West Africa has been unprecedented. The aim of this study was to describe the viral kinetics of EBOV during this outbreak and identify factors that contribute to outbreak progression.
METHODS. From July to December 2014, one laboratory in Sierra Leone processed over 2,700 patient samples for EBOV detection by quantitative PCR (qPCR). Viremia was measured following patient admission. Age, sex, and approximate time of symptom onset were also recorded for each patient. The data was analyzed using various mathematical models to find trends of potential interest.
RESULTS. The analysis revealed a significant difference (P = 2.7 × 10–77) between the initial viremia of survivors (4.02 log10 genome equivalents [GEQ]/ml) and nonsurvivors (6.18 log10 GEQ/ml). At the population level, patient viral loads were higher on average in July than in November, even when accounting for outcome and time since onset of symptoms. This decrease in viral loads temporally correlated with an increase in circulating EBOV-specific IgG antibodies among individuals who were suspected of being infected but shown to be negative for the virus by PCR.
CONCLUSIONS. Our results indicate that initial viremia is associated with outcome of the individual and outbreak duration; therefore, care must be taken in planning clinical trials and interventions. Additional research in virus adaptation and the impacts of host factors on EBOV transmission and pathogenesis is needed
Impact of adherence to individual quality-of-care indicators on the prognosis of bloodstream infection due to Staphylococcus aureus: a prospective observational multicentre cohort
Objectives: To analyse the adherence and impact of quality-of-care indicators (QCIs) in the management of Staphylococcus aureus bloodstream infection in a prospective and multicentre cohort. Methods: Analysis of the prospective, multicentre international S. Aureus Collaboration cohort of S. Aureus bloodstream infection cases observed between January 2013 and April 2015. Multivariable analysis was performed to evaluate the impact of adherence to QCIs on 90-day mortality. Results: A total of 1784 cases were included. Overall, 90-day mortality was 29.9% and mean follow-up period was 118 days. Adherence was 67% (n = 1180/1762) for follow-up blood cultures, 31% (n = 416/ 1342) for early focus control, 77.6% (n = 546/704) for performance of echocardiography, 75.5% (n = 1348/ 1784) for adequacy of targeted antimicrobial therapy, 88.6% (n = 851/960) for adequacy of treatment duration in non-complicated bloodstream infections and 61.2% (n = 366/598) in complicated blood-stream infections. Full bundle adherence was 18.4% (n = 328/1784). After controlling for immortal time bias and potential confounders, focus control (adjusted hazard ratio = 0.76; 95% CI, 0.59-0.99; p 0.038) and adequate targeted antimicrobial therapy (adjusted hazard ratio = 0.75; 95% CI, 0.61-0.91; p 0.004) were associated with low 90-day mortality. Discussion: Adherence to QCIs in S. Aureus bloodstream infection did not reach expected rates. Apart from the benefits of application as a bundle, focus control and adequate targeted therapy were inde-pendently associated with low mortality. Francesc Escrihuela-Vidal, Clin Microbiol Infect 2023;29:498 (c) 2022 The Authors. Published by Elsevier Ltd on behalf of European Society of Clinical Microbiology and Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/)
CEERS: Diversity of Lyman-Alpha Emitters during the Epoch of Reionization
We analyze rest-frame ultraviolet to optical spectra of three -
galaxies whose Ly-emission lines were previously detected with
Keck/MOSFIRE observations, using the JWST/NIRSpec observations from the Cosmic
Evolution Early Release Science (CEERS) survey. From NIRSpec data, we confirm
the systemic redshifts of these Ly emitters, and emission-line ratio
diagnostics indicate these galaxies were highly ionized and metal poor. We
investigate Ly line properties, including the line flux, velocity
offset, and spatial extension. For the one galaxy where we have both NIRSpec
and MOSFIRE measurements, we find a significant offset in their flux
measurements ( greater in MOSFIRE) and a marginal difference in
the velocity shifts. The simplest interpretation is that the Ly
emission is extended and not entirely encompassed by the NIRSpec slit. The
cross-dispersion profiles in NIRSpec reveal that Ly in one galaxy is
significantly more extended than the non-resonant emission lines. We also
compute the expected sizes of ionized bubbles that can be generated by the
Ly sources, discussing viable scenarios for the creation of sizable
ionized bubbles (1 physical Mpc). The source with the highest-ionization
condition is possibly capable of ionizing its own bubble, while the other two
do not appear to be capable of ionizing such a large region, requiring
additional sources of ionizing photons. Therefore, the fact that we detect
Ly from these galaxies suggests diverse scenarios on escape of
Ly during the epoch of reionization. High spectral resolution spectra
with JWST/NIRSpec will be extremely useful for constraining the physics of
patchy reionization.Comment: Submitted to ApJ (18 pages, 7 figures, 2 tables
First Look at z > 1 Bars in the Rest-Frame Near-Infrared with JWST Early CEERS Imaging
Stellar bars are key drivers of secular evolution in galaxies and can be
effectively studied using rest-frame near-infrared (NIR) images, which trace
the underlying stellar mass and are less impacted by dust and star formation
than rest-frame UV or optical images. We leverage the power of {\it{JWST}}
CEERS NIRCam images to present the first quantitative identification and
characterization of stellar bars at based on rest-frame NIR F444W images
of high resolution (~1.3 kpc at z ~ 1-3). We identify stellar bars in these
images using quantitative criteria based on ellipse fits. For this pilot study,
we present six examples of robustly identified bars at with spectroscopic
redshifts, including the two highest redshift bars at ~2.136 and 2.312
quantitatively identified and characterized to date. The stellar bars at ~
1.1-2.3 presented in our study have projected semi-major axes of ~2.9-4.3 kpc
and projected ellipticities of ~0.41-0.53 in the rest-frame NIR. The barred
host galaxies have stellar masses ~ to
, star formation rates of ~ 21-295 yr, and
several have potential nearby companions. Our finding of bars at ~1.1-2.3
demonstrates the early onset of such instabilities and supports simulations
where bars form early in massive dynamically cold disks. It also suggests that
if these bars at lookback times of 8-10 Gyr survive out to present epochs,
bar-driven secular processes may operate over a long time and have a
significant impact on some galaxies by z ~ 0.Comment: 16 pages, 5 figures. Accepted for Publication in Astrophysical
Journal Letter
Near-infrared emission line diagnostics for AGN from the local Universe to redshift 3
Optical rest-frame spectroscopic diagnostics are usually employed to
distinguish between star formation and AGN-powered emission. However, this
method is biased against dusty sources, hampering a complete census of the AGN
population across cosmic epochs. To mitigate this effect, it is crucial to
observe at longer wavelengths in the rest-frame near-infrared (near-IR), which
is less affected by dust attenuation and can thus provide a better description
of the intrinsic properties of galaxies. AGN diagnostics in this regime have
not been fully exploited so far, due to the scarcity of near-IR observations of
both AGNs and star-forming galaxies, especially at redshifts higher than 0.5.
Using Cloudy photoionization models, we identify new AGN - star formation
diagnostics based on the ratio of bright near-infrared emission lines, namely
[SIII] 9530 Angstrom, [CI] 9850 Angstrom, [PII] 1.188 , [FeII] , and [FeII] to Paschen lines (either Pa or
Pa), providing simple, analytical classification criteria. We apply
these diagnostics to a sample of 64 star-forming galaxies and AGNs at 0 < z <
1, and 65 sources at 1 < z < 3 recently observed with JWST-NIRSpec in CEERS. We
find that the classification inferred from the near-infrared is broadly
consistent with the optical one based on the BPT and the [SII]/H ratio.
However, in the near-infrared, we find more AGNs than in the
optical (13 instead of 8), with 5 sources classified as 'hidden' AGNs, showing
a larger AGN contribution at longer wavelengths, possibly due to the presence
of optically thick dust. The diagnostics we present provide a promising tool to
find and characterize AGNs from z=0 to z=3 with low and medium-resolution
near-IR spectrographs in future surveys.Comment: Paper accepted for publication in A&A on 05/09/2023. Three public
Github repositories include: (1) a table with emission line measurements for
the paper sample : https://github.com/Anthony96/Line_measurements_nearIR ,
Cloudy emission line predictions for star-forming galaxies and AGN models :
https://github.com/Anthony96/star-forming_models ,
https://github.com/Anthony96/AGN_model
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