122 research outputs found
A Physical Model for z~2 Dust Obscured Galaxies
We present a physical model for the origin of z~2 Dust-Obscured Galaxies
(DOGs), a class of high-redshift ULIRGs selected at 24 micron which are
particularly optically faint (24/R>1000). By combining N-body/SPH simulations
of high redshift galaxy evolution with 3D polychromatic dust radiative transfer
models, we find that luminous DOGs (with F24 > 0.3 mJy at z~2 are well-modeled
as extreme gas-rich mergers in massive (~5x10^12-10^13 Msun) halos, with
elevated star formation rates (~500-1000 Msun/yr) and/or significant AGN growth
(Mdot > 0.5 Msun/yr), whereas less luminous DOGs are more diverse in nature. At
final coalescence, merger-driven DOGs transition from being starburst dominated
to AGN dominated, evolving from a "bump" to a power-law shaped mid-IR (IRAC)
spectral energy distribution (SED). After the DOG phase, the galaxy settles
back to exhibiting a "bump" SED with bluer colors and lower star formation
rates. While canonically power-law galaxies are associated with being
AGN-dominated, we find that the power-law mid-IR SED can owe both to direct AGN
contribution, as well as to a heavily dust obscured stellar bump at times that
the galaxy is starburst dominated. Thus power-law galaxies can be either
starburst or AGN dominated. Less luminous DOGs can be well-represented either
by mergers, or by massive ($M_{\rm baryon} ~5x10^11 Msun) secularly evolving
gas-rich disc galaxies (with SFR > 50 Msun/yr). By utilising similar models as
those employed in the SMG formation study of Narayanan et al. (2010), we
investigate the connection between DOGs and SMGs. We find that the most heavily
star-forming merger driven DOGs can be selected as Submillimetre Galaxies
(SMGs), while both merger-driven and secularly evolving DOGs typically satisfy
the BzK selection criteria.Comment: Accepted by MNRAS; major changes include better description of
dependency on ISM specification and updated models allowing dust to evolve
with metallicity
Submillimeter Follow-up of WISE-Selected Hyperluminous Galaxies
We have used the Caltech Submillimeter Observatory (CSO) to follow-up a
sample of WISE-selected, hyperluminous galaxies, so called W1W2-dropout
galaxies. This is a rare (~ 1000 all-sky) population of galaxies at high
redshift (peaks at z=2-3), that are faint or undetected by WISE at 3.4 and 4.6
um, yet are clearly detected at 12 and 22 um. The optical spectra of most of
these galaxies show significant AGN activity. We observed 14 high-redshift (z >
1.7) W1W2-dropout galaxies with SHARC-II at 350 to 850 um, with 9 detections;
and observed 18 with Bolocam at 1.1 mm, with five detections. Warm Spitzer
follow-up of 25 targets at 3.6 and 4.5 um, as well as optical spectra of 12
targets are also presented in the paper. Combining WISE data with observations
from warm Spitzer and CSO, we constructed their mid-IR to millimeter spectral
energy distributions (SEDs). These SEDs have a consistent shape, showing
significantly higher mid-IR to submm ratios than other galaxy templates,
suggesting a hotter dust temperature. We estimate their dust temperatures to be
60-120 K using a single-temperature model. Their infrared luminosities are well
over 10^{13} Lsun. These SEDs are not well fitted with existing galaxy
templates, suggesting they are a new population with very high luminosity and
hot dust. They are likely among the most luminous galaxies in the Universe. We
argue that they are extreme cases of luminous, hot dust-obscured galaxies
(DOGs), possibly representing a short evolutionary phase during galaxy merging
and evolution. A better understanding of their long-wavelength properties needs
ALMA as well as Herschel data.Comment: Will be Published on Sep 1, 2012 by Ap
Cognitive and neural processes in non-clinical auditory hallucinations
BACKGROUND: The nosological status of auditory hallucinations in non-clinical samples is unclear. AIMS: To investigate the functional neural basis of non-clinical hallucinations. METHOD: After selection from 1206 people, 68 participants of high, medium and low hallucination proneness completed a task designed to elicit verbal hallucinatory phenomena under conditions of stimulus degradation. Eight subjects who reported hearing a voice when none was present repeated the task during functional imaging. RESULTS: During the signal detection task, the high hallucination-prone participants reported a voice to be present when it was not (false alarms) significantly more often than the average or low participants (P<0.03, d.f.=2). On functional magnetic resonance imaging, patterns of activation during these false alarms showed activation in the superior and middle temporal cortex (P<0.001). CONCLUSIONS: Auditory hallucinatory experiences reported in non-clinical samples appear to be mediated by similar patterns of cerebral activation as found during hallucinations in schizophrenia
Iatrogenic Bowel Injury Following Minimally Invasive Lateral Approach to the Lumbar Spine: A Retrospective Analysis of 3 Cases.
Study Design: Retrospective cohort study.
Objective: Anterior approaches are often used during lumbar interbody fusion procedures. Visceral injuries (bowel injuries) are rare but represent a primary risk during anterior approaches to the lumbar spine. Left untreated, these injuries can result in significant complications. The aim of this study was to investigate the presentation and management of bowel injury cases following anterior approaches to the lumbar spine to raise the surgeon\u27s awareness of this rare complication.
Methods: All direct anterior, oblique anterior, and transpsoas lumbar interbody fusion surgeries performed at our institution between 2012 and 2016 were analyzed retrospectively. Charts were screened for cases requiring return to the operating room owing to a suspected bowel injury and details of the case were extracted for illustrative purposes.
Results: A total of 775 anterior lumbar surgeries were conducted at a single tertiary care institution between July 2012 and June 2017. A total of 590 transpsoas lumbar interbody fusion (TPIF) surgeries were performed. Four patients, each having undergone TPIF, were suspected of bowel injury and underwent an exploratory laparotomy. At surgery, 3 patients were confirmed to have a bowel injury, giving a procedure-specific incidence of 0.51% and overall incidence of 0.39%. Among the 3 confirmed bowel injury cases, average delay between surgery and visceral injury diagnosis was 4.7 days (range 3-7 days).
Conclusions: We noted abdominal pain, distention, and fever as the most common findings in the setting of a visceral injury. A high index of suspicion and computed tomography imaging remain critical for identifying postoperative bowel injuries
Clustering of Dust-Obscured Galaxies at z ~ 2
We present the angular autocorrelation function of 2603 dust-obscured
galaxies (DOGs) in the Bootes field of the NOAO Deep Wide-Field Survey. DOGs
are red, obscured galaxies, defined as having R-[24] \ge 14 (F_24/F_R \ga
1000). Spectroscopy indicates that they are located at 1.5 \la z \la 2.5. We
find strong clustering, with r_0 = 7.40^{+1.27}_{-0.84} Mpc/h for the full F_24
> 0.3 mJy sample. The clustering and space density of the DOGs are consistent
with those of submillimeter galaxies, suggestive of a connection between these
populations. We find evidence for luminosity-dependent clustering, with the
correlation length increasing to r_0 = 12.97^{+4.26}_{-2.64} Mpc/h for brighter
(F_24 > 0.6 mJy) DOGs. Bright DOGs also reside in richer environments than
fainter ones, suggesting these subsamples may not be drawn from the same parent
population. The clustering amplitudes imply average halo masses of log M =
12.2^{+0.3}_{-0.2} Msun for the full DOG sample, rising to log M =
13.0^{+0.4}_{-0.3} Msun for brighter DOGs. In a biased structure formation
scenario, the full DOG sample will, on average, evolve into ~ 3 L* present-day
galaxies, whereas the most luminous DOGs may evolve into brightest cluster
galaxies.Comment: ApJL in press; 4 pages, 3 figures, 1 tabl
Tephra without borders: Far-reaching clues into past explosive eruptions
This review is intended to highlight recent exciting advances in the study of distal (>100 km from the source) tephra and cryptotephra deposits and their potential application for volcanology. Geochemical correlations of tephra between proximal and distal locations have extended the geographical distribution of tephra over tens of millions square kilometers. Such correlations embark on the potential to reappraise volume and magnitude estimates of known eruptions. Cryptotephra investigations in marine, lake and ice-core records also give rise to continuous chronicles of large explosive eruptions many of which were hitherto unknown. Tephra preservation within distal ice sheets and varved lake sediments permit precise dating of parent eruptions and provide new insight into the frequency of eruptions. Recent advances in analytical methods permit an examination of magmatic processes and the evolution of the whole volcanic belts at distances of hundreds and thousands of kilometers from source. Distal tephrochronology has much to offer volcanology and has the potential to significantly contribute to our understanding of sizes, recurrence intervals and geochemical make-up of the large explosive eruptions
Metabolic power in hurling with respect to position and halves of match-play.
The current investigation compared the metabolic power and energetic characteristics in team sports with respect to positional lines and halves of match-play. Global positioning system (GPS) technology data were collected from 22 elite competitive hurling matches over a 3-season period. A total of 250 complete match-files were recorded with players split into positional groups of full-back; half-back; midfield; half-forward; full-forward. Raw GPS data were exported into a customized spreadsheet that provided estimations of metabolic power and speed variables across match-play events (average metabolic power [Pmet], high metabolic load distance [HMLD], total distance, relative distance, high-speed distance, maximal speed, accelerations, and deceleration). Pmet, HMLD, total, relative and high-speed distance were 8.9 ± 1.6 W·kg-1, 1457 ± 349 m, 7506 ± 1364 m, 107 ± 20 m·min-1 and 1169 ± 260 m respectively. Half-backs, midfielders and half-forwards outperformed full-backs (Effect Size [ES] = 1.03, 1.22 and 2.07 respectively), and full-forwards in Pmet (Effect Size [ES] = 1.70, 2.07 and 1.28 respectively), and HMLD (full-backs: ES = -1.23, -1.37 and -0.84 respectively, and full-forwards: ES = -1.77, -2.00 and -1.38 respectively). Half-backs (ES = -0.60), midfielders (ES = -0.81), and half-forwards (ES = -0.74) experienced a second-half temporal decrement in HMLD. The current investigation demonstrates that metabolic power may increase our understanding of the match-play demands placed on elite hurling players. Coaches may utilize these findings to construct training drills that replicate match-play demands
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