126 research outputs found
Newer Surveillance Data Extends Our Understanding of the Niche of \u3ci\u3eRickettsia montanensis\u3c/i\u3e (Rickettsiales: Rickettsiaceae) Infection of the American Dog Tick (Acari: Ixodidae) in the United States
Background: Understanding the geographic distribution of Rickettsia montanensis infections in Dermacentor variabilis is important for tick-borne disease management in the United States, as both a tick-borne agent of interest and a potential confounder in surveillance of other rickettsial diseases. Two previous studies modeled niche suitability for D. variabilis with and without R. montanensis, from 2002-2012, indicating that the D. variabilis niche overestimates the infected niche. This study updates these, adding data since 2012.
Methods: Newer surveillance and testing data were used to update Species Distribution Models (SDMs) of D. variabilis, and R. montanensis infected D. variabilis, in the United States. Using random forest (RF) models, found to perform best in previous work, we updated the SDMs and compared them with prior results. Warrenâs I niche overlap metric was used to compare between predicted suitability for all ticks and âpathogen positive nicheâ models across datasets.
Results: Warrenâs I indicated \u3c 2% change in predicted niche, and there was no change in order of importance of environmental predictors, for D. variabilis or R. montanensis positive niche. The updated D. variabilis niche model overpredicted suitability compared to the updated R. montanensis positive niche in key peripheral parts of the range, but slightly underpredicted through the northern and midwestern parts of the range. This reinforces previous findings of a more constrained pathogen-positive niche than predicted by D. variabilis records alone.
Conclusions: The consistency of predicted niche suitability for D. variabilis in the United States, with the addition of nearly a decade of new data, corroborates this is a species with generalist habitat requirements. Yet a slight shift in updated niche distribution, even of low suitability, included more southern areas, pointing to a need for continued and extended monitoring and surveillance. This further underscores the importance of revisiting vector and vector-borne disease distribution maps
Galaxy classification: deep learning on the OTELO and COSMOS databases
Context. The accurate classification of hundreds of thousands of galaxies
observed in modern deep surveys is imperative if we want to understand the
universe and its evolution. Aims. Here, we report the use of machine learning
techniques to classify early- and late-type galaxies in the OTELO and COSMOS
databases using optical and infrared photometry and available shape parameters:
either the Sersic index or the concentration index. Methods. We used three
classification methods for the OTELO database: 1) u-r color separation , 2)
linear discriminant analysis using u-r and a shape parameter classification,
and 3) a deep neural network using the r magnitude, several colors, and a shape
parameter. We analyzed the performance of each method by sample bootstrapping
and tested the performance of our neural network architecture using COSMOS
data. Results. The accuracy achieved by the deep neural network is greater than
that of the other classification methods, and it can also operate with missing
data. Our neural network architecture is able to classify both OTELO and COSMOS
datasets regardless of small differences in the photometric bands used in each
catalog. Conclusions. In this study we show that the use of deep neural
networks is a robust method to mine the cataloged dataComment: 20 pages, 10 tables, 14 figures, Astronomy and Astrophysics (in
press
The OTELO survey. A case study of [O III]4959,5007 emitters at <z> = 0.83
The OTELO survey is a very deep, blind exploration of a selected region of
the Extended Groth Strip and is designed for finding emission-line sources
(ELSs). The survey design, observations, data reduction, astrometry, and
photometry, as well as the correlation with ancillary data used to obtain a
final catalogue, including photo-z estimates and a preliminary selection of
ELS, were described in a previous contribution. Here, we aim to determine the
main properties and luminosity function (LF) of the [O III] ELS sample of OTELO
as a scientific demonstration of its capabilities, advantages, and
complementarity with respect to other surveys. The selection and analysis
procedures of ELS candidates obtained using tunable filter (TF) pseudo-spectra
are described. We performed simulations in the parameter space of the survey to
obtain emission-line detection probabilities. Relevant characteristics of [O
III] emitters and the LF([O III]), including the main selection biases and
uncertainties, are presented. A total of 184 sources were confirmed as [O III]
emitters at a mean redshift z=0.83. The minimum detectable line flux and
equivalent width (EW) in this ELS sample are 5 10 erg
s cm and 6 \AA, respectively. We are able to constrain the
faint-end slope () of the observed LF([O III]) at
z=0.83. This LF reaches values that are approximately ten times lower than
those from other surveys. The vast majority (84\%) of the morphologically
classified [O III] ELSs are disc-like sources, and 87\% of this sample is
comprised of galaxies with stellar masses of M 10
M.Comment: v1: 16 pages, 6 figures. Accepted in Astronomy \& Astrophysics. v2:
Author added in metadat
The OTELO survey: the star formation rate evolution of low-mass galaxies
We present the analysis of a sample of \ha\,, \hb\ and \oii\ emission line
galaxies from the \otelo\ survey, with masses typically below log(M_*/M_\sun)
\sim 9.4 and redshifts between and 1.43. We study the star
formation rate, star formation rate density, and number density and their
evolution with redshift. We obtain a robust estimate of the specific star
formation rate -- stellar mass relation based on the lowest mass sample
published so far. We also determine a flat trend of the star formation rate
density and number density with redshift. Our results suggest a scenario of no
evolution of the number density of galaxies, regardless of their masses, up to
redshift . This implies a gradual change of the relative importance
of the star forming processes, from high-mass galaxies to low-mass galaxies,
with decreasing redshift. We also find little or no variation of the star
formation rate density in the redshift range of .Comment: 8 pages, 3 figures, accepted for publication in ApJ letter
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