377 research outputs found
Spectral Energy Distributions of M81 Globular Clusters in BATC Multicolor Survey
In this paper, we give the spectral energy distributions of 42 M81 globular
clusters in 13 intermediate-band filters from 4000 to 10000 A, using the CCD
images of M81 observed as part of the BATC multicolor survey of the Sky. The
BATC multicolor filter system is specifically designed to exclude most of the
bright and variable night-sky emission lines including the OH forest. Hence, it
can present accurate SEDs of the observed objects. These spectral energy
distributions are low-resolution spectra, and can reflect the stellar
populations of the globular clusters. This paper confirms the conclusions of
Schroder et al. that, M81 contains clusters as young as a few Gyrs, which also
were observed in both M31 and M33Comment: Accepted for Publication in PASP, 10 pages, 3 figure
The Mid-Infrared Fundamental Plane of Early-Type Galaxies
Three observables of early-type galaxies - size (), surface brightness
(), and velocity dispersion () - form a tight planar
correlation known as the fundamental plane (FP), which has provided great
insights into the galaxy formation and the evolution processes. However, the FP
has been found to be tilted against the simple virial expectation, prompting
debates on its origin. In order to investigate the contribution of systematic
stellar population variation to the FP tilt, we study here the FP relations of
early-type galaxies in mid-infrared (MIR) which may represent the stellar mass
well. We examined the wavelength dependence of the FP coefficients, and
in , using a sample of 56
early-type galaxies for which visible (V-band), near-infrared (K-band), and MIR
(Spitzer IRAC, 3.6--8.0m) data are available. We find that the coefficient
increases as a function of wavelength as , while the coefficient reaches the closest to -1 at 3.6--5.8m.
When applied to the visible FP coefficients derived from a larger sample of
nearby early-type galaxies, we get the FP relation with (1.6--1.8,-0.9) at 3.6m. Our result suggests that the stellar population
effect can explain more than half of the FP tilt, closing the gap between the
virial expectation and the optical FP. The reduction in the FP tilt is
reflected in the dynamical mass-to-light ratio, , dependence on
which decreases toward 3.6--5.8m, suggesting that the MIR light better
represents mass than the shorter wavelengths.Comment: 5 pages, 3 figures, to appear in ApJ
Pantallas (no tan) planas : imaginarios tecnológicos en la formación docente inicial
En el presente trabajo analizamos el imaginario que construyen lo/as ingresantes a las carreras de formación docente inicial sobre las tecnologías digitales y sus alcances retomando emergentes de una experiencia que llevamos adelante en marzo de 2022 en el Instituto Superior de Formación Docente N°19 de la ciudad de Mar del Plata. El enfoque teórico que consideramos hace hincapié en las tecnologías e infraestructuras digitales desde una perspectiva sociotécnica, vinculándolas con prácticas y disposiciones sociales de una forma compleja y no determinista. Hablamos de digitalidad o cultura digital desde un prisma que permite dar cuenta de transformaciones en el mapa de las infraestructuras de la cultura y condensar modos de pensar, de sentir, de decir, de hacer y de ser que tienen características singulares. Consideramos que las formas de subjetivación que la cotidianeidad digital promueve performan y a su vez son producto de un proceso de fuertes cambios sociales, culturales y de la subjetividad. Este proceso es estudiado desde muy diversas perspectivas y llega a ser considerado como rasgo de una mutación antropológica. Situándonos como docentes-productores de conocimiento, construimos un corpus de análisis derivado de esas experiencias áulicas, sobre el cual trabajamos a partir de aportes de la metodología cualitativa. Los emergentes de ese proceso interpretativo, mediados por algunos de los debates teóricos que presentamos, sustentan las reflexiones de ese trabajo. Con estas experiencias buscamos pensar, frente a la omnipresencia de algoritmos y lógicas comerciales que organizan buena parte del entorno tecnocultural, qué posibilidades dejamos a la curiosidad, al deseo y a lo nuevo, y cómo damos lugar a instancias de análisis, reflexión y posicionamiento en el espacio escolar.Fil: Colombo, Laura. Universidad Tecnológica Nacional.Fil: Bressan, David. Universidad Nacional de Mar del Plata.Fil: Ayciriet, Federico . Universidad Nacional de Mar del Plata
Maize chlorotic mottle virus exhibits low divergence between differentiated regional sub-populations.
Maize chlorotic mottle virus has been rapidly spreading around the globe over the past decade. The interactions of maize chlorotic mottle virus with Potyviridae viruses causes an aggressive synergistic viral condition - maize lethal necrosis, which can cause total yield loss. Maize production in sub-Saharan Africa, where it is the most important cereal, is threatened by the arrival of maize lethal necrosis. We obtained maize chlorotic mottle virus genome sequences from across East Africa and for the first time from Ecuador and Hawaii, and constructed a phylogeny which highlights the similarity of Chinese to African isolates, and Ecuadorian to Hawaiian isolates. We used a measure of clustering, the adjusted Rand index, to extract region-specific SNPs and coding variation that can be used for diagnostics. The population genetics analysis we performed shows that the majority of sequence diversity is partitioned between populations, with diversity extremely low within China and East Africa
Multiwavelength Observations of the Low Metallicity Blue Compact Dwarf Galaxy SBS 0335-052
New infrared and millimeter observations from Keck, Palomar, ISO, and OVRO
and archival data from the NRAO VLA and IRAS are presented for the low
metallicity blue compact dwarf galaxy SBS 0335-052. Mid-infrared imaging shows
this young star-forming system is compact (0.31"; 80 pc) at 12.5 microns. The
large Br-gamma equivalent width (235 Angstroms) measured from integral field
spectroscopy is indicative of a ~5 Myr starburst. The central source appears to
be optically thin in emission, containing both a warm (~80 K) and a hot (~210
K) dust component, and the overall interstellar radiation field is quite
intense, about 10,000 times the intensity in the solar neighborhood. CO
emission is not detected, though the galaxy shows an extremely high global H I
gas-to-dust mass ratio, high even for blue compact dwarfs. Finally, the
galaxy's mid-infrared-to-optical and mid-to-near-infrared luminosity ratios are
quite high, whereas its far-infrared-to-radio and far-infrared-to-optical flux
ratios are surprisingly similar to what is seen in normal star-forming
galaxies. The relatively high bolometric infrared-to-radio ratio is more easily
understood in the context of such a young system with negligible nonthermal
radio continuum emission. These new lines of evidence may outline features
common to primordial galaxies found at high redshift.Comment: 28 pages including 6 figures; accepted for publication in the
Astronomical Journa
The Black Hole Mass Function across Cosmic Time. II. Heavy Seeds and (Super)Massive Black Holes
This is the second paper in a series aimed at modeling the black hole (BH) mass function from the stellar to the (super)massive regime. In the present work, we focus on (super)massive BHs and provide an ab initio computation of their mass function across cosmic time. We consider two main mechanisms to grow the central BH that are expected to cooperate in the high-redshift star-forming progenitors of local massive galaxies. The first is the gaseous dynamical friction process, which can cause the migration toward the nuclear regions of stellar mass BHs originated during the intense bursts of star formation in the gas-rich host progenitor galaxy and the buildup of a central heavy BH seed, M• ∼ 103−5 M⊙, within short timescales of ≲some 107 yr. The second mechanism is the standard Eddington-type gas disk accretion onto the heavy BH seed through which the central BH can become (super)massive, M• ∼ 106−10 M⊙, within the typical star formation duration, ≲1 Gyr, of the host. We validate our semiempirical approach by reproducing the observed redshift-dependent bolometric AGN luminosity functions and Eddington ratio distributions and the relationship between the star formation and the bolometric luminosity of the accreting central BH. We then derive the relic (super)massive BH mass function at different redshifts via a generalized continuity equation approach and compare it with present observational estimates. Finally, we reconstruct the overall BH mass function from the stellar to the (super)massive regime over more than 10 orders of magnitudes in BH mass
Clozapine prescription trends in Brazil in the last decade
Objective: Clozapine is a second-generation antipsychotic indicated for treatment-resistant schizophrenia. Studies in several countries have shown a low rate of clozapine use despite the fact that approximately 30% of schizophrenia cases are treatment-resistant. In Brazil, few studies have addressed the frequency and variety of antipsychotic use in individuals diagnosed with schizophrenia (ICD F20). The objective of this study was to measure the rates of clozapine use in this population in the last decade using Brazilian Ministry of Health data. Methods: Prescriptions made between 2010 and 2020 in all 26 states and the Federal District registered at the Outpatient Information System Database from the Brazilian Health System (SIASUS) were evaluated. Results: A total of 25,143,524 prescriptions were recorded in this period, with clozapine representing 8.86% of all antipsychotics. The most frequently prescribed antipsychotic for patients with schizophrenia was olanzapine (35.8%), followed by quetiapine (27.5%). From 2010 to 2020, the rate of clozapine prescriptions in Brazil increased from 7.2% to 10.9%. Conclusions: Despite a slight increase in prescriptions in the last decade, clozapine is still underutilized in Brazil
INFLAMMATORY BOWEL DISEASE AND EXTRAINTESTINAL MANIFESTATIONS
Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, are chronic and recurrent inflammatory diseases. Although the typical symptoms are localized in the gastrointestinal tract, there are also extraintestinal manifestations (EIMs) associated with IBD, probably caused by immune reactions secondary to the pathology of origin. Anybody can be affected by EIMs, which can be dermatological, pulmonary, ocular, musculoskeletal, hepatobiliary and neurological, et al. This represents a therapeutic challenge for clinicians, who must first establish a diagnostic and then a multidisciplinary therapeutic path, in order to guarantee an optimal quality of life for the patient
Chemical evolution of the intra-cluster medium
The high metallicity of the intra-cluster medium (ICM) is generally
interpreted on the base of the galactic wind scenario for elliptical galaxies.
In this framework, we develop a toy-model to follow the chemical evolution of
the ICM, formulated in analogy to chemical models for individual galaxies. The
model computes the galaxy formation history (GFH) of cluster galaxies,
connecting the final luminosity function (LF) to the corresponding metal
enrichment history of the ICM. The observed LF can be reproduced with a smooth,
Madau-plot like GFH peaking at z~ 1-2, plus a "burst" of formation of dwarf
galaxies at high redshift. The model is used to test the response of the
predicted metal content and abundance evolution of the ICM to varying input
galactic models. The chemical enrichment is computed from "galactic yields"
based on models of elliptical galaxies with a variable initial mass function
(IMF), favouring the formation of massive stars at high redshift and/or in more
massive galaxies. For a given final galactic luminosity, these model
ellipticals eject into the ICM a larger quantity of gas and of metals than do
standard models based on the Salpeter IMF. However, a scenario in which the IMF
varies with redshift as a consequence of the effect of the the cosmic
background temperature on the Jeans mass scale, appears to be too mild to
account for the observed metal production in clusters. The high
iron-mass-to-luminosity-ratio of the ICM can be reproduced only by assuming a
more dramatic variation of the typical stellar mass, in line with other recent
findings. The mass in the wind-ejected gas is predicted to exceed the mass in
galaxies by a factor of 1.5-2 and to constitute roughly half of the
intra-cluster gas.Comment: 25 pages, 17 figures, accepted for publication in A&
Mid-IR Luminosities and UV/Optical Star Formation Rates at z<1.4
UV continuum and mid-IR emission constitute two widely used star formation
indicators at intermediate and high redshifts. We study 2430 galaxies with
z<1.4 in the Extended Groth Strip with MIPS 24 mic observations from FIDEL,
spectroscopy from DEEP2, and UV, optical, and near-IR photometry from AEGIS.
The data are coupled with stellar population models and Bayesian SED fitting to
estimate dust-corrected SFRs. In order to probe the dust heating from stellar
populations of various ages, the derived SFRs were averaged over various
timescales--from 100 Myr for "current" SFR to 1--3 Gyr for long-timescale SFRs.
These SED-based UV/optical SFRs are compared to total infrared luminosities
extrapolated from 24 mic observations. We find that for the blue, actively star
forming galaxies the correlation between the IR luminosity and the UV/optical
SFR shows a decrease in scatter when going from shorter to longer SFR-averaging
timescales. We interpret this as the greater role of intermediate age stellar
populations in heating the dust than what is typically assumed. This holds over
the entire redshift range. Many so-called green valley galaxies are simply
dust-obscured actively star-forming galaxies. However, there exist 24
mic-detected galaxies, some with L>10^11 L_sun, yet with little current star
formation. For them a reasonable amount of dust absorption of stellar light is
sufficient to produce the observed levels of IR. In our sample optical and
X-ray AGNs do not contribute on average more than ~50% to the mid-IR
luminosity, and we see no evidence for a large population of "IR excess"
galaxies (Abridged).Comment: Accepted for publication in ApJ. Content identical to arXiv version
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