The MKID Exoplanet Camera for Subaru SCExAO Walter, Alexander B.; Fruitwala, Neelay; Steiger, Sarah ...
Publications of the Astronomical Society of the Pacific,
12/2020, Letnik:
132, Številka:
1018
Journal Article
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Odprti dostop
We present the MKID Exoplanet Camera (MEC), a z through J band (800-1400 nm) integral field spectrograph located behind The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) at the Subaru ...Telescope on Maunakea that utilizes Microwave Kinetic Inductance Detectors (MKIDs) as the enabling technology for high contrast imaging. MEC is the first permanently deployed near-infrared MKID instrument and is designed to operate both as an IFU, and as a focal plane wavefront sensor in a multi-kHz feedback loop with SCExAO. The read noise free, fast time domain information attainable by MKIDs allows for the direct probing of fast speckle fluctuations that currently limit the performance of most high contrast imaging systems on the ground and will help MEC achieve its ultimate goal of reaching contrasts of 10−7 at 2 λ/D. Here we outline the instrument details of MEC including the hardware, firmware, and data reduction and analysis pipeline. We then discuss MEC's current on-sky performance and end with future upgrades and plans.
Abstract
We report the direct imaging discovery of a low-mass companion to the nearby accelerating A star, HIP 109427, with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument ...coupled with the Microwave Kinetic Inductance Detector Exoplanet Camera (MEC) and CHARIS integral field spectrograph. CHARIS data reduced with reference star point spread function (PSF) subtraction yield 1.1–2.4
μ
m spectra. MEC reveals the companion in
Y
and
J
band at a comparable signal-to-noise ratio using stochastic speckle discrimination, with no PSF subtraction techniques. Combined with complementary follow-up
L
p
photometry from Keck/NIRC2, the SCExAO data favors a spectral type, effective temperature, and luminosity of M4–M5.5, 3000–3200 K, and
log
10
(
L
/
L
⊙
)
=
−
2.28
−
0.04
+
0.04
, respectively. Relative astrometry of HIP 109427 B from SCExAO/CHARIS and Keck/NIRC2, and complementary Gaia–Hipparcos absolute astrometry of the primary favor a semimajor axis of 6.55
+3.0
−0.48
au, an eccentricity of
0.54
−
0.15
+
0.28
, an inclination of
66.7
−
14
+
8.5
degrees, and a dynamical mass of
0.280
−
0.059
+
0.18
M
⊙
. This work shows the potential for extreme AO systems to utilize speckle statistics in addition to widely used postprocessing methods to directly image faint companions to nearby stars near the telescope diffraction limit.
Influenza is thought to be communicated from person to person by multiple pathways. However, the relative importance of different routes of influenza transmission is unclear. To better understand the ...potential for the airborne spread of influenza, we measured the amount and size of aerosol particles containing influenza virus that were produced by coughing. Subjects were recruited from patients presenting at a student health clinic with influenza-like symptoms. Nasopharyngeal swabs were collected from the volunteers and they were asked to cough three times into a spirometer. After each cough, the cough-generated aerosol was collected using a NIOSH two-stage bioaerosol cyclone sampler or an SKC BioSampler. The amount of influenza viral RNA contained in the samplers was analyzed using quantitative real-time reverse-transcription PCR (qPCR) targeting the matrix gene M1. For half of the subjects, viral plaque assays were performed on the nasopharyngeal swabs and cough aerosol samples to determine if viable virus was present. Fifty-eight subjects were tested, of whom 47 were positive for influenza virus by qPCR. Influenza viral RNA was detected in coughs from 38 of these subjects (81%). Thirty-five percent of the influenza RNA was contained in particles>4 µm in aerodynamic diameter, while 23% was in particles 1 to 4 µm and 42% in particles<1 µm. Viable influenza virus was detected in the cough aerosols from 2 of 21 subjects with influenza. These results show that coughing by influenza patients emits aerosol particles containing influenza virus and that much of the viral RNA is contained within particles in the respirable size range. The results support the idea that the airborne route may be a pathway for influenza transmission, especially in the immediate vicinity of an influenza patient. Further research is needed on the viability of airborne influenza viruses and the risk of transmission.
Abstract
We introduce a new framework for point-spread function subtraction based on the spatiotemporal variation of speckle noise in high-contrast imaging data where the sampling timescale is faster ...than the speckle evolution timescale. One way that space–time covariance arises in the pupil is as atmospheric layers translate across the telescope aperture and create small, time-varying perturbations in the phase of the incoming wavefront. The propagation of this field to the focal plane preserves some of that space–time covariance. To utilize this covariance, our new approach uses a Karhunen–Loève transform on an image sequence, as opposed to a set of single reference images as in previous applications of Karhunen–Loève Image Processing (KLIP) for high-contrast imaging. With the recent development of photon-counting detectors, such as microwave kinetic inductance detectors, this technique now has the potential to improve contrast when used as a post-processing step. Preliminary testing on simulated data shows this technique can improve contrast by at least 10%–20% from the original image, with significant potential for further improvement. For certain choices of parameters, this algorithm may provide larger contrast gains than spatial-only KLIP.
Animal and human studies indicate that electrical stimulation of dorsal root ganglion (DRG) neurons may modulate neuropathic pain signals. ACCURATE, a pivotal, prospective, multicenter, randomized ...comparative effectiveness trial, was conducted in 152 subjects diagnosed with complex regional pain syndrome or causalgia in the lower extremities. Subjects received neurostimulation of the DRG or dorsal column (spinal cord stimulation, SCS). The primary end point was a composite of safety and efficacy at 3 months, and subjects were assessed through 12 months for long-term outcomes and adverse events. The predefined primary composite end point of treatment success was met for subjects with a permanent implant who reported 50% or greater decrease in visual analog scale score from preimplant baseline and who did not report any stimulation-related neurological deficits. No subjects reported stimulation-related neurological deficits. The percentage of subjects receiving ≥50% pain relief and treatment success was greater in the DRG arm (81.2%) than in the SCS arm (55.7%, P < 0.001) at 3 months. Device-related and serious adverse events were not different between the 2 groups. Dorsal root ganglion stimulation also demonstrated greater improvements in quality of life and psychological disposition. Finally, subjects using DRG stimulation reported less postural variation in paresthesia (P < 0.001) and reduced extraneous stimulation in nonpainful areas (P = 0.014), indicating DRG stimulation provided more targeted therapy to painful parts of the lower extremities. As the largest prospective, randomized comparative effectiveness trial to date, the results show that DRG stimulation provided a higher rate of treatment success with less postural variation in paresthesia intensity compared to SCS.
Background. Considerable controversy exists with regard to whether influenza virus and respiratory syncytial virus (RSV) are spread by the inhalation of infectious airborne particles and about the ...importance of this route, compared with droplet or contact transmission. Methods. Airborne particles were collected in an urgent care clinic with use of stationary and personal aerosol samplers. The amounts of airborne influenza A, influenza B, and RSV RNA were determined using real-time quantitative polymerase chain reaction. Health care workers and patients participating in the study were tested for influenza. Results. Seventeen percent of the stationary samplers contained influenza A RNA, 1% contained influenza B RNA, and 32% contained RSV RNA. Nineteen percent of the personal samplers contained influenza A RNA, none contained influenza B RNA, and 38% contained RSV RNA. The number of samplers containing influenza RNA correlated well with the number and location of patients with influenza (r=0.77). Forty-two percent of the influenza A RNA was in particles ⩽4.1 µm in aerodynamic diameter, and 9% of the RSV RNA was in particles ⩽4.1 µm. Conclusions. Airborne particles containing influenza and RSV RNA were detected throughout a health care facility. The particles were small enough to remain airborne for an extended time and to be inhaled deeply into the respiratory tract. These results support the possibility that influenza and RSV can be transmitted by the airborne route and suggest that further investigation of the potential of these particles to transmit infection is warranted.
The question of whether influenza is transmitted to a significant degree by aerosols remains controversial, in part, because little is known about the quantity and size of potentially infectious ...airborne particles produced by people with influenza. In this study, the size and amount of aerosol particles produced by nine subjects during coughing were measured while they had influenza and after they had recovered, using a laser aerosol particle spectrometer with a size range of 0.35 to 10 μm. Individuals with influenza produce a significantly greater volume of aerosol when ill compared with afterward (p = 0.0143). When the patients had influenza, their average cough aerosol volume was 38.3 picoliters (pL) of particles per cough (SD 43.7); after patients recovered, the average volume was 26.4 pL per cough (SD 45.6). The number of particles produced per cough was also higher when subjects had influenza (average 75,400 particles/cough, SD 97,300) compared with afterward (average 52,200, SD 98,600), although the difference did not reach statistical significance (p = 0.1042). The average number of particles expelled per cough varied widely from patient to patient, ranging from 900 to 302,200 particles/cough while subjects had influenza and 1100 to 308,600 particles/cough after recovery. When the subjects had influenza, an average of 63% of each subject's cough aerosol particle volume in the detection range was in the respirable size fraction (SD 22%), indicating that these particles could reach the alveolar region of the lungs if inhaled by another person. This enhancement in aerosol generation during illness may play an important role in influenza transmission and suggests that a better understanding of this phenomenon is needed to predict the production and dissemination of influenza-laden aerosols by people infected with this virus.
Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resources: a PDF file of demographic information, influenza test results, and volume and peak flow rate during each cough and a PDF file containing number and size of aerosol particles produced.
Abstract
We present the Microwave Kinetic Inductance Detector (MKID) Pipeline, which is a general use science data pipeline for the reduction and analysis of ultraviolet, optical, and infrared MKID ...data sets. This paper provides an introduction to the nature of MKID data sets, it gives an overview of the calibration steps that are included in the pipeline, and it introduces the implementation of the software.
Background. Severe H1N1 influenza can be lethal in otherwise healthy individuals and can have features of reactive hemophagocytic lymphohistiocytosis (HLH). HLH is associated with mutations in ...lymphocyte cytolytic pathway genes, which have not been previously explored in H1N1 influenza. Methods. Sixteen cases of fatal influenza A(H1N1) infection, 81% with histopathologic hemophagocytosis, were identified and analyzed for clinical and laboratory features of HLH, using modified HLH-2004 and macrophage activation syndrome (MAS) criteria. Fourteen specimens were subject to whole-exome sequencing. Sequence alignment and variant filtering detected HLH gene mutations and potential disease-causing variants. Cytolytic function of the PRF1 p.A91V mutation was tested in lentiviral-transduced NK-92 natural killer (NK) cells. Results. Despite several lacking variables, cases of influenza A(H1N1) infection met 44% and 81% of modified HLH-2004 and MAS criteria, respectively. Five subjects (36%) carried one of 3 heterozygous LYST mutations, 2 of whom also possessed the p.A91V PRF1 mutation, which was shown to decrease NK cell cytolytic function. Several patients also carried rare variants in other genes previously observed in MAS. Conclusions. This cohort of fatal influenza A(H1N1) infections confirms the presence of hemophagocytosis and HLH pathology. Moreover, the high percentage of HLH gene mutations suggests they are risk factors for mortality among individuals with influenza A(H1N1) infection.
Abstract
We present the direct imaging discovery of a low-mass companion to the nearby accelerating F star, HIP 5319, using SCExAO coupled with the CHARIS, VAMPIRES, and MEC instruments in addition ...to Keck/NIRC2 imaging. CHARIS
JHK
(1.1–2.4
μ
m) spectroscopic data combined with VAMPIRES 750 nm, MEC
Y
, and NIRC2
L
p
photometry is best matched by an M3–M7 object with an effective temperature of
T
= 3200 K and surface gravity log(
g
) = 5.5. Using the relative astrometry for HIP 5319 B from CHARIS and NIRC2, and absolute astrometry for the primary from Gaia and Hipparcos, and adopting a log-normal prior assumption for the companion mass, we measure a dynamical mass for HIP 5319 B of
31
−
11
+
35
M
J
, a semimajor axis of
18.6
−
4.1
+
10
au, an inclination of
69.4
−
15
+
5.6
degrees, and an eccentricity of
0.42
−
0.29
+
0.39
. However, using an alternate prior for our dynamical model yields a much higher mass of
128
−
88
+
127
M
J
. Using data taken with the LCOGT NRES instrument we also show that the primary HIP 5319 A is a single star in contrast to previous characterizations of the system as a spectroscopic binary. This work underscores the importance of assumed priors in dynamical models for companions detected with imaging and astrometry, and the need to have an updated inventory of system measurements.
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