42 research outputs found
Incidence and Risk Factors for Clinically Confirmed secondary bacterial infections in patients hospitalized for coronavirus disease 2019 (COVID-19)
Objective: The true incidence and risk factors for secondary bacterial infections in coronavirus disease 2019 (COVID-19) remains poorly understood. Knowledge of risk factors for secondary infections in hospitalized patients with COVID-19 is necessary to optimally guide selective use of empiric antimicrobial therapy. Design: Single-center retrospective cohort study of symptomatic inpatients admitted for COVID-19 from April 15, 2020, through June 30, 2021. Setting: Academic quaternary-care referral center in Portland, Oregon. Patients: The study included patients who were 18 years or older with a positive severe acute respiratory coronavirus virus 2 (SARS-CoV-2) PCR test up to 10 days prior to admission. Methods: Secondary infections were identified based on clinical, radiographic, and microbiologic data. Logistic regression was used to identify risk factors for secondary infection. We also assessed mortality, length of stay, and empiric antibiotics among those with and without secondary infections. Results: We identified 118 patients for inclusion; 31 (26.3%) had either culture-proven or possible secondary infections among hospitalized patients with COVID-19. Mortality was higher among patients with secondary infections (35.5%) compared to those without secondary infection (4.6%). Empiric antibiotic use on admission was high in both the secondary and no secondary infection groups at 71.0% and 48.3%, respectively. Conclusions: The incidence of secondary bacterial infection was moderate among hospitalized patients with COVID-19. However, a higher proportion of patients received empiric antibiotics regardless of an identifiable secondary infection. Transfer from an outside hospital, baseline immunosuppressant use, and corticosteroid treatment were independent risk factors for secondary infection. Additional studies are needed to validate risk factors and best guide antimicrobial stewardship efforts
Influence of Antibiotic Exposure Intensity on the Risk of Clostridioides Difficile Infection
Antibiotics are a strong risk factor for Clostridioides difficile infection (CDI), and CDI incidence is often measured as an important outcome metric for antimicrobial stewardship interventions aiming to reduce antibiotic use. However, risk of CDI from antibiotics varies by agent and dependent on the intensity (i.e., spectrum and duration) of antibiotic therapy. Thus, the impact of stewardship interventions on CDI incidence is variable, and understanding this risk requires a more granular measure of intensity of therapy than traditionally used measures like days of therapy (DOT)
Self-Reported Cognitive Function and Mental Health Diagnoses among Former Professional American-Style Football Players
Clinical practice strongly relies on patients' self-report. Former professional American-style football players are hesitant to seek help for mental health problems, but may be more willing to report cognitive symptoms. We sought to assess the association between cognitive symptoms and diagnosed mental health problems and quality of life among a cohort of former professional players. In a cross-sectional design, we assessed self-reported cognitive function using items from the Quality of Life in Neurological Disorders (Neuro-QOL) Item Bank. We then compared mental health diagnoses and quality of life, assessed by items from the Patient-Reported Outcome Measurement Information System (PROMIS ®), between former professional players reporting daily problems in cognitive function and former players not reporting daily cognitive problems. Of the 3758 former professional players included in the analysis, 40.0% reported daily problems due to cognitive dysfunction. Former players who reported daily cognitive problems were more likely to also report depression (18.0% vs. 3.3%, odds ratio [OR] = 6.42, 95% confidence interval [CI] [4.90-8.40]) and anxiety (19.1% vs. 4.3%, OR = 5.29, 95% CI [4.14-6.75]) than those without daily cognitive problems. Further, former players reporting daily cognitive problems were more likely to report memory loss and attention deficit(/hyperactivity) disorder and poorer general mental health, lower quality of life, less satisfaction with social activities and relationships, and more emotional problems. These findings highlight the potential of an assessment of cognitive symptoms for identifying former players with mental health, social, and emotional problems
An ALMA survey of submillimetre galaxies in the COSMOS field: The extent of the radio-emitting region revealed by 3 GHz imaging with the Very Large Array
We determine the radio size distribution of a large sample of 152 SMGs in
COSMOS that were detected with ALMA at 1.3 mm. For this purpose, we used the
observations taken by the VLA-COSMOS 3 GHz Large Project. One hundred and
fifteen of the 152 target SMGs were found to have a 3 GHz counterpart. The
median value of the major axis FWHM at 3 GHz is derived to be kpc.
The radio sizes show no evolutionary trend with redshift, or difference between
different galaxy morphologies. We also derived the spectral indices between 1.4
and 3 GHz, and 3 GHz brightness temperatures for the sources, and the median
values were found to be and K. Three of the
target SMGs, which are also detected with the VLBA, show clearly higher
brightness temperatures than the typical values. Although the observed radio
emission appears to be predominantly powered by star formation and supernova
activity, our results provide a strong indication of the presence of an AGN in
the VLBA and X-ray-detected SMG AzTEC/C61. The median radio-emitting size we
have derived is 1.5-3 times larger than the typical FIR dust-emitting sizes of
SMGs, but similar to that of the SMGs' molecular gas component traced through
mid- line emission of CO. The physical conditions of SMGs probably render
the diffusion of cosmic-ray electrons inefficient, and hence an unlikely
process to lead to the observed extended radio sizes. Instead, our results
point towards a scenario where SMGs are driven by galaxy interactions and
mergers. Besides triggering vigorous starbursts, galaxy collisions can also
pull out the magnetised fluids from the interacting disks, and give rise to a
taffy-like synchrotron-emitting bridge. This provides an explanation for the
spatially extended radio emission of SMGs, and can also cause a deviation from
the well-known IR-radio correlation.Comment: 32 pages (incl. 5 appendices), 17 figures, 7 tables; accepted for
publication in A&A; abstract abridged for arXi
DEIMOS spectroscopy of protocluster candidate in COSMOS -- A massive protocluster embedded in a large scale structure?
We present the results of our Keck/DEIMOS spectroscopic follow-up of
candidate galaxies of i-band-dropout protocluster candidate galaxies at
in the COSMOS field. We securely detect Lyman- emission lines
in 14 of the 30 objects targeted, 10 of them being at with a
signal-to-noise ratio of , the remaining galaxies are either
non-detections or interlopers with redshift too different from to be part
of the protocluster. The 10 galaxies at make the protocluster one
of the riches at . The emission lines exhibit asymmetric profiles with
high skewness values ranging from 2.87 to 31.75, with a median of 7.37. This
asymmetry is consistent with them being Ly, resulting in a redshift
range of . Using the spectroscopic redshifts, we re-calculate the
overdensity map for the COSMOS field and find the galaxies to be in a
significant overdensity at the level, with a peak overdensity of
(compared to the previous value of ). The
protocluster galaxies have stellar masses derived from Bagpipes SED fits of
and star formation rates of
, placing them on the main sequence at
this epoch. Using a stellar-to-halo-mass relationship, we estimate the dark
matter halo mass of the most massive halo in the protocluster to be . By comparison with halo mass evolution tracks from
simulations, the protocluster is expected to evolve into a Virgo- or Coma-like
cluster in the present day.Comment: 26 pages, 14 figues, 5 tables, main text is 16 pages, appendix is 10
pages, published in MNRA
COSMOS2020: Identification of High-z Protocluster Candidates in COSMOS
We conduct a systematic search for protocluster candidates at in
the COSMOS field using the recently released COSMOS2020 source catalog. We
select galaxies using a number of selection criteria to obtain a sample of
galaxies that have a high probability of being inside a given redshift bin. We
then apply overdensity analysis to the bins using two density estimators, a
Weighted Adaptive Kernel Estimator and a Weighted Voronoi Tessellation
Estimator. We have found 15 significant () candidate galaxy
overdensities across the redshift range . The majority of the
galaxies appear to be on the galaxy main sequence at their respective epochs.
We use multiple stellar-mass-to-halo-mass conversion methods to obtain a range
of dark matter halo mass estimates for the overdensities in the range of
, at the respective redshifts of the
overdensities. The number and the masses of the halos associated with our
protocluster candidates are consistent with what is expected from the area of a
COSMOS-like survey in a standard CDM cosmology. Through comparison
with simulation, we expect that all the overdensities at will evolve
into a Virgo-/Coma-like clusters at present (i.e., with masses ). Compared to other overdensities identified at
via narrow-band selection techniques, the overdensities presented
appear to have higher stellar masses and star-formation rates.
We compare the evolution in the total star-formation rate and stellar mass
content of the protocluster candidates across the redshift range
and find agreement with the total average star-formation rate from simulations.Comment: 52 pages, 32 figues, 18 tables, main text is 30 pages, appendix is 22
pages, to be published in Ap
JWST and ALMA discern the assembly of structural and obscured components in a high-redshift starburst galaxy
We present observations and analysis of the starburst, PACS-819, at z=1.45
( M), using high-resolution (;
0.8 kpc) ALMA and multi-wavelength JWST images from the COSMOS-Web program.
Dissimilar to HST/ACS images in the rest-frame UV, the redder NIRCam and MIRI
images reveal a smooth central mass concentration and spiral-like features,
atypical for such an intense starburst. Through dynamical modeling of the CO
J=5--4 emission with ALMA, PACS-819 is rotation-dominated thus has a disk-like
nature. However, kinematic anomalies in CO and asymmetric features in the bluer
JWST bands (e.g., F150W) support a more disturbed nature likely due to
interactions. The JWST imaging further enables us to map the distribution of
stellar mass and dust attenuation, thus clarifying the relationships between
different structural components, not discernable in the previous HST images.
The CO J = 5 -- 4 and FIR dust continuum emission are co-spatial with a
heavily-obscured starbursting core (<1 kpc) which is partially surrounded by
much less obscured star-forming structures including a prominent arc, possibly
a tidally-distorted dwarf galaxy, and a clump, either a sign of an ongoing
violent disk instability or a recently accreted low-mass satellite. With
spatially-resolved maps, we find a high molecular gas fraction in the central
area reaching (/) and short depletion times
( 120 Myrs) across the entire system. These
observations provide insights into the complex nature of starbursts in the
distant universe and underscore the wealth of complementary information from
high-resolution observations with both ALMA and JWST.Comment: 18 pages, 12 figures, Submitted to Ap
COSMOS-Web: Intrinsically Luminous z10 Galaxy Candidates Test Early Stellar Mass Assembly
We report the discovery of 15 exceptionally luminous
candidate galaxies discovered in the first 0.28 deg of JWST/NIRCam imaging
from the COSMOS-Web Survey. These sources span rest-frame UV magnitudes of
, and thus constitute the most intrinsically luminous
candidates identified by JWST to-date. Selected via NIRCam imaging
with Hubble ACS/F814W, deep ground-based observations corroborate their
detection and help significantly constrain their photometric redshifts. We
analyze their spectral energy distributions using multiple open-source codes
and evaluate the probability of low-redshift solutions; we conclude that 12/15
(80%) are likely genuine sources and 3/15 (20%) likely
low-redshift contaminants. Three of our candidates push the limits of
early stellar mass assembly: they have estimated stellar masses
, implying an effective stellar baryon fraction of
, where . The assembly of such stellar reservoirs is made
possible due to rapid, burst-driven star formation on timescales 100\,Myr
where the star-formation rate may far outpace the growth of the underlying dark
matter halos. This is supported by the similar volume densities inferred for
galaxies relative to
-- both about Mpc -- implying they live in halos of comparable
mass. At such high redshifts, the duty cycle for starbursts would be of order
unity, which could cause the observed change in the shape of the UVLF from a
double powerlaw to Schechter at . Spectroscopic redshift
confirmation and ensuing constraints of their masses will be critical to
understanding how, and if, such early massive galaxies push the limits of
galaxy formation in CDM.Comment: 30 pages, 9 figures; ApJ submitte
Uncovering a Massive z~7.65 Galaxy Hosting a Heavily Obscured Radio-Loud QSO Candidate in COSMOS-Web
In this letter, we report the discovery of the highest redshift, heavily
obscured, radio-loud QSO candidate selected using JWST NIRCam/MIRI, mid-IR,
sub-mm, and radio imaging in the COSMOS-Web field. Using multi-frequency radio
observations and mid-IR photometry, we identify a powerful, radio-loud (RL),
growing supermassive black hole (SMBH) with significant spectral steepening of
the radio SED ( mJy, ,
, ). In conjunction
with ALMA, deep ground-based observations, ancillary space-based data, and the
unprecedented resolution and sensitivity of JWST, we find no evidence of QSO
contribution to the UV/optical/NIR data and thus infer heavy amounts of
obscuration (N cm). Using the wealth of deep UV
to sub-mm photometric data, we report a singular solution photo-z of
= 7.65 and estimate an extremely massive
host-galaxy (). This
source represents the furthest known obscured RL QSO candidate, and its level
of obscuration aligns with the most representative but observationally scarce
population of QSOs at these epochs.Comment: Submitted to ApJL, Comments welcom
Unveiling the distant Universe: Characterizing Galaxies in the first epoch of COSMOS-Web
We report the identification of 15 galaxy candidates at using the
initial COSMOS-Web JWST observations over 77 arcmin through four NIRCam
filters (F115W, F150W, F277W, F444W) with an overlap with MIRI (F770W) of 8.7
arcmin. We fit the sample using several publicly-available SED fitting and
photometric redshift codes and determine their redshifts between and
(), UV-magnitudes between M =
21.2 and 19.5 (with M) and rest-frame
UV slopes (). These galaxies are, on average, more
luminous than most candidates discovered by JWST so far in the
literature, while exhibiting similar blue colors in their rest-frame UV. The
rest-frame UV slopes derived from SED-fitting are blue ([2.0,
2.7]) without reaching extremely blue values as reported in other recent
studies at these redshifts. The blue color is consistent with models that
suggest the underlying stellar population is not yet fully enriched in metals
like similarly luminous galaxies in the lower redshift Universe. The derived
stellar masses with MM are not in tension with the standard
CDM model and our measurement of the volume density of such UV
luminous galaxies aligns well with previously measured values presented in the
literature at . Our sample of galaxies, although compact, are
significantly resolved.Comment: Submitted to Ap