15 research outputs found
Development Tests of a Cryogenic Filter Wheel Assembly for the NIRCam Instrument
The James Webb Space Telescope is an infrared-optimized space telescope scheduled for launch in 201 3. Its 6.5-m diameter primary mirror will collect light from some of the first galaxies formed after the big bang. The Near Infrared camera (NIRCam) will detect the first light from these galaxies, provide the necessary tools for studying the formation of stars, aid in discovering planets around other stars, and adjust the wave front error on the primary mirror (Fig. 1). The instrument and its complement of mechanisms and optics will operate at a cryogenic temperature of 35 K. This paper describes tests and test results of the NIRCam Filter Wheel assembly prototype
Discovery and Follow-up Observations of the Young Type Ia Supernova 2016coj
The Type~Ia supernova (SN~Ia) 2016coj in NGC 4125 (redshift ) was
discovered by the Lick Observatory Supernova Search 4.9 days after the fitted
first-light time (FFLT; 11.1 days before -band maximum). Our first detection
(pre-discovery) is merely day after the FFLT, making SN 2016coj one
of the earliest known detections of a SN Ia. A spectrum was taken only 3.7 hr
after discovery (5.0 days after the FFLT) and classified as a normal SN Ia. We
performed high-quality photometry, low- and high-resolution spectroscopy, and
spectropolarimetry, finding that SN 2016coj is a spectroscopically normal SN
Ia, but with a high velocity of \ion{Si}{2} 6355 (\,\kms\
around peak brightness). The \ion{Si}{2} 6355 velocity evolution can
be well fit by a broken-power-law function for up to a month after the FFLT. SN
2016coj has a normal peak luminosity ( mag), and it
reaches a -band maximum \about16.0~d after the FFLT. We estimate there to be
low host-galaxy extinction based on the absence of Na~I~D absorption lines in
our low- and high-resolution spectra. The spectropolarimetric data exhibit weak
polarization in the continuum, but the \ion{Si}{2} line polarization is quite
strong () at peak brightness.Comment: Submitte
North Pacific Surgical Association A predictive model of early mortality in trauma patients
Abstract BACKGROUND: Rapid thrombelastography (rTEG) is a real-time whole-blood viscoelastic coagulation assay. We hypothesized that admission rTEG and clinical data are independent predictors of trauma-related mortality. METHODS: Prospective observational data (patient demographics, admission vital signs, laboratory studies, and injury characteristics) from trauma patients enrolled within 6 hours of injury were collected. Mann-Whitney U test and analysis of variance test assessed significance (P % .05). Logistic regression analyses determined the association of the studied variables with 24-hour mortality. RESULTS: Seven hundred ninety-five trauma patients were enrolled, of which 55 died within 24 hours of admission. Admission variables which independently predicted 24-hour mortality were as follows: Glasgow Coma Scale %8, hemoglobin ,11 g/dL, international normalized ratio .1.5, Ly30 .8%, and penetrating injury (P , .05). This 5-variable model's area under the receiver operator characteristic curve was .88. The Hosmer-Lemeshow goodness-of-fit test was .90. CONCLUSIONS: This 5-variable model provides a rapid prediction of 24-hour mortality. The inclusion of rTEG Ly30 demonstrates the association of fibrinolysis with outcome and may support the early use of antifibrinolytic therapies
The origin and evolution of the normal Type Ia SN 2018aoz with infant-phase reddening and excess emission
SN~2018aoz is a Type Ia SN with a -band plateau and excess emission in the
infant-phase light curves 1 day after first light, evidencing an
over-density of surface iron-peak elements as shown in our previous study.
Here, we advance the constraints on the nature and origin of SN~2018aoz based
on its evolution until the nebular phase. Near-peak spectroscopic features show
the SN is intermediate between two subtypes of normal Type Ia: Core-Normal and
Broad-Line. The excess emission could have contributions from the radioactive
decay of surface iron-peak elements as well as ejecta interaction with either
the binary companion or a small torus of circumstellar material. Nebular-phase
limits on H and He~I favour a white dwarf companion, consistent with
the small companion size constrained by the low early SN luminosity, while the
absence of [O~I] and He~I disfavours a violent merger of the progenitor. Of the
two main explosion mechanisms proposed to explain the distribution of surface
iron-peak elements in SN~2018aoz, the asymmetric Chandrasekhar-mass explosion
is less consistent with the progenitor constraints and the observed blueshifts
of nebular-phase [Fe~II] and [Ni~II]. The helium-shell double-detonation
explosion is compatible with the observed lack of C spectral features, but
current 1-D models are incompatible with the infant-phase excess emission,
color, and absence of nebular-phase [Ca~II]. Although
the explosion processes of SN~2018aoz still need to be more precisely
understood, the same processes could produce a significant fraction of Type Ia
SNe that appear normal after 1 day.Comment: Submitted for publication in ApJ. 35 pages, 16 figures, 7 table
Early Spectroscopy and Dense Circumstellar Medium Interaction in SN~2023ixf
We present the optical spectroscopic evolution of SN~2023ixf seen in
sub-night cadence spectra from 1.18 to 14 days after explosion. We identify
high-ionization emission features, signatures of interaction with material
surrounding the progenitor star, that fade over the first 7 days, with rapid
evolution between spectra observed within the same night. We compare the
emission lines present and their relative strength to those of other supernovae
with early interaction, finding a close match to SN~2020pni and SN~2017ahn in
the first spectrum and SN~2014G at later epochs. To physically interpret our
observations we compare them to CMFGEN models with confined, dense
circumstellar material around a red supergiant progenitor from the literature.
We find that very few models reproduce the blended \NC{} emission lines
observed in the first few spectra and their rapid disappearance thereafter,
making this a unique diagnostic. From the best models, we find a mass-loss rate
of \mlunit{}, which far exceeds the mass-loss rate for any
steady wind, especially for a red supergiant in the initial mass range of the
detected progenitor. These mass-loss rates are, however, similar to rates
inferred for other supernovae with early circumstellar interaction. Using the
phase when the narrow emission features disappear, we calculate an outer dense
radius of circumstellar material and a mean circumstellar material density
of . This is consistent with the
lower limit on the outer radius of the circumstellar material we calculate from
the peak \Halpha{} emission flux, .Comment: Submitted to ApJ
Ischaemic conditioning and targeting reperfusion injury: a 30 year voyage of discovery
To commemorate the auspicious occasion of the 30th anniversary of IPC, leading pioneers in the field of cardioprotection gathered in Barcelona in May 2016 to review and discuss the history of IPC, its evolution to IPost and RIC, myocardial reperfusion injury as a therapeutic target, and future targets and strategies for cardioprotection. This article provides an overview of the major topics discussed at this special meeting and underscores the huge importance and impact, the discovery of IPC has made in the field of cardiovascular research
Early Spectroscopy and Dense Circumstellar Medium Interaction in SN 2023ixf
We present the optical spectroscopic evolution of SN 2023ixf seen in subnight cadence spectra from 1.18 to 15 days after explosion. We identify high-ionization emission features, signatures of interaction with material surrounding the progenitor star, that fade over the first 7 days, with rapid evolution between spectra observed within the same night. We compare the emission lines present and their relative strength to those of other supernovae with early interaction, finding a close match to SN 2020pni and SN 2017ahn in the first spectrum and SN 2014G at later epochs. To physically interpret our observations, we compare them to CMFGEN models with confined, dense circumstellar material around a red supergiant (RSG) progenitor from the literature. We find that very few models reproduce the blended N iii ( λλ 4634.0,4640.6)/C iii ( λλ 4647.5,4650.0) emission lines observed in the first few spectra and their rapid disappearance thereafter, making this a unique diagnostic. From the best models, we find a mass-loss rate of 10 ^−3 –10 ^−2 M _⊙ yr ^−1 , which far exceeds the mass-loss rate for any steady wind, especially for an RSG in the initial mass range of the detected progenitor. These mass-loss rates are, however, similar to rates inferred for other supernovae with early circumstellar interaction. Using the phase when the narrow emission features disappear, we calculate an outer dense radius of circumstellar material R _CSM,out ≈ 5 × 10 ^14 cm, and a mean circumstellar material density of ρ = 5.6 × 10 ^−14 g cm ^−3 . This is consistent with the lower limit on the outer radius of the circumstellar material we calculate from the peak H α emission flux, R _CSM,out ≳ 9 × 10 ^13 cm