86 research outputs found
The Stellar Kinematics of Void Dwarf Galaxies Using KCWI
Dwarf galaxies located in extremely under-dense cosmic voids are excellent
test-beds for disentangling the effects of large-scale environment on galaxy
formation and evolution. We present integral field spectroscopy for low-mass
galaxies () located inside (N=21) and
outside (N=9) cosmic voids using the Keck Cosmic Web Imager (KCWI). Using
measurements of stellar line-of-sight rotational velocity
and velocity dispersion , we test the tidal stirring
hypothesis, which posits that dwarf spheroidal galaxies are formed through
tidal interactions with more massive host galaxies. We measure low values of
for our sample of isolated dwarf
galaxies, and we find no trend between and
distance from a massive galaxy out to
Mpc. These suggest that dwarf galaxies can become dispersion-supported "puffy"
systems even in the absence of environmental effects like tidal interactions.
We also find indications of an upward trend between
and galaxy stellar mass, perhaps implying
that stellar disk formation depends on mass rather than environment. Although
some of our conclusions may be slightly modified by systematic effects, our
main result still holds: that isolated low-mass galaxies may form and remain as
puffy systems rather than the dynamically cold disks predicted by classical
galaxy formation theory.Comment: 19 pages including references; submitted to ApJ. Code used for
analysis and figures can be found here:
https://github.com/mdlreyes/void-dwarf-analysi
Evidence for Sub-Chandrasekhar Type Ia Supernovae from Stellar Abundances in Dwarf Galaxies
There is no consensus on the progenitors of Type Ia supernovae (SNe Ia) despite their importance for cosmology and chemical evolution. We address this question using our previously published catalogs of Mg, Si, Ca, Cr, Fe, Co, and Ni abundances in dwarf galaxy satellites of the Milky Way (MW) to constrain the mass at which the white dwarf (WD) explodes during a typical SN Ia. We fit a simple bi-linear model to the evolution of [X/Fe] with [Fe/H], where X represents each of the elements mentioned above. We use the evolution of [Mg/Fe] coupled with theoretical supernova yields to isolate what fraction of the elements originated in SNe Ia. Then, we infer the [X/Fe] yield of SNe Ia for all of the elements except Mg. We compare these observationally inferred yields to recent theoretical predictions for two classes of Chandrasekhar-mass (M_(Ch)) SN Ia as well as sub-M_(Ch) SNe Ia. Most of the inferred SN Ia yields are consistent with all of the theoretical models, but [Ni/Fe] is consistent only with sub-M_(Ch) models. We conclude that the dominant type of SN Ia in ancient dwarf galaxies is the explosion of a sub-M_(Ch) WD. The MW and dwarf galaxies with extended star formation histories have higher [Ni/Fe] abundances, which could indicate that the dominant class of SN Ia is different for galaxies where star formation lasted for at least several Gyr
Evidence for Sub-Chandrasekhar Type Ia Supernovae from Stellar Abundances in Dwarf Galaxies
There is no consensus on the progenitors of Type Ia supernovae (SNe Ia) despite their importance for cosmology and chemical evolution. We address this question using our previously published catalogs of Mg, Si, Ca, Cr, Fe, Co, and Ni abundances in dwarf galaxy satellites of the Milky Way (MW) to constrain the mass at which the white dwarf (WD) explodes during a typical SN Ia. We fit a simple bi-linear model to the evolution of [X/Fe] with [Fe/H], where X represents each of the elements mentioned above. We use the evolution of [Mg/Fe] coupled with theoretical supernova yields to isolate what fraction of the elements originated in SNe Ia. Then, we infer the [X/Fe] yield of SNe Ia for all of the elements except Mg. We compare these observationally inferred yields to recent theoretical predictions for two classes of Chandrasekhar-mass (M_(Ch)) SN Ia as well as sub-M_(Ch) SNe Ia. Most of the inferred SN Ia yields are consistent with all of the theoretical models, but [Ni/Fe] is consistent only with sub-M_(Ch) models. We conclude that the dominant type of SN Ia in ancient dwarf galaxies is the explosion of a sub-M_(Ch) WD. The MW and dwarf galaxies with extended star formation histories have higher [Ni/Fe] abundances, which could indicate that the dominant class of SN Ia is different for galaxies where star formation lasted for at least several Gyr
Development of an International Odor Identification Test for Children: The Universal Sniff Test
Objective: To assess olfactory function in children and to create and validate an odor identification test to diagnose olfactory dysfunction in children, which we called the Universal Sniff (U-Sniff) test. Study design: This is a multicenter study involving 19 countries. The U-Sniff test was developed in 3 phases including 1760 children age 5-7 years. Phase 1: identification of potentially recognizable odors; phase 2: selection of odorants for the odor identification test; and phase 3: evaluation of the test and acquisition of normative data. Test—retest reliability was evaluated in a subgroup of children (n = 27), and the test was validated using children with congenital anosmia (n = 14). Results: Twelve odors were familiar to children and, therefore, included in the U-Sniff test. Children scored a mean ± SD of 9.88 ± 1.80 points out of 12. Normative data was obtained and reported for each country. The U-Sniff test demonstrated a high test—retest reliability (r27 = 0.83, P < .001) and enabled discrimination between normosmia and children with congenital anosmia with a sensitivity of 100% and specificity of 86%. Conclusions: The U-Sniff is a valid and reliable method of testing olfaction in children and can be used internationally
A Novel Tumor-Promoting Function Residing in the 5′ Non-coding Region of vascular endothelial growth factor mRNA
Shigetada Teshima-Kondo and colleagues find that cancer cells have a survival system that is regulated by vegf mRNA and that vegf mRNA and its protein may synergistically promote the malignancy of tumor cells
Development of a core outcome set for therapeutic studies in eosinophilic esophagitis (COREOS)
BACKGROUND
End points used to determine treatment efficacy in eosinophilic esophagitis (EoE) have evolved over time. With multiple novel therapies in development for EoE, harmonization of outcomes measures will facilitate evidence synthesis and appraisal when comparing different treatments.
OBJECTIVE
We sought to develop a core outcome set (COS) for controlled and observational studies of pharmacologic and diet interventions in adult and pediatric patients with EoE.
METHODS
Candidate outcomes were generated from systematic literature reviews and patient engagement interviews and surveys. Consensus was established using an iterative Delphi process, with items voted on using a 9-point Likert scale and with feedback from other participants to allow score refinement. Consensus meetings were held to ratify the outcome domains of importance and the core outcome measures. Stakeholders were recruited internationally and included adult and pediatric gastroenterologists, allergists, dieticians, pathologists, psychologists, researchers, and methodologists.
RESULTS
The COS consists of 4 outcome domains for controlled and observational studies: histopathology, endoscopy, patient-reported symptoms, and EoE-specific quality of life. A total of 69 stakeholders (response rate 95.8%) prioritized 42 outcomes in a 2-round Delphi process, and the final ratification meeting generated consensus on 33 outcome measures. These included measurement of the peak eosinophil count, Eosinophilic Esophagitis Histology Scoring System, Eosinophilic Esophagitis Endoscopic Reference Score, and patient-reported measures of dysphagia and quality of life.
CONCLUSIONS
This interdisciplinary collaboration involving global stakeholders has produced a COS that can be applied to adult and pediatric studies of pharmacologic and diet therapies for EoE and will facilitate meaningful treatment comparisons and improve the quality of data synthesis
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