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Fast Sensing of Double-Dot Charge Arrangement and Spin State with a Radio-Frequency Sensor Quantum Dot
Single-shot measurement of the charge arrangement and spin state of a double quantum dot are reported with measurement times down to 100 ns. Sensing uses radio-frequency reflectometry of a proximal quantum dot in the Coulomb blockade regime. The sensor quantum dot is up to 30 times more sensitive than a comparable quantum point-contact sensor and yields three times greater signal to noise in rf single-shot measurements. Numerical modeling is qualitatively consistent with experiment and shows that the improved sensitivity of the sensor quantum dot results from reduced lifetime broadening and screening.PhysicsOther Research Uni
Gravitational Microlensing Event Statistics for the Zwicky Transient Facility
Microlensing surveys have discovered thousands of events with almost all
events discovered within the Galactic bulge or toward the Magellanic clouds.
The Zwicky Transient Facility (ZTF), while not designed to be a microlensing
campaign, is an optical time-domain survey that observes the entire northern
sky every few nights including the Galactic plane. ZTF observes
stars in g-band and r-band and can significantly contribute to the observed
microlensing population. We predict that ZTF will observe 1100
microlensing events in three years of observing within degrees
latitude of the Galactic plane, with 500 events in the outer Galaxy
(). This yield increases to 1400 (800) events
by combining every three ZTF exposures, 1800 (900) events if ZTF
observes for a total of five years, and 2400 (1300) events for a
five year survey with post-processing image stacking. Using the microlensing
modeling software PopSyCLE, we compare the microlensing populations in the
Galactic bulge and the outer Galaxy. We also present an analysis of the
microlensing event ZTF18abhxjmj to demonstrate how to leverage these population
statistics in event modeling. ZTF will constrain Galactic structure, stellar
populations, and primordial black holes through photometric microlensing.Comment: 19 pages, 13 figures, 5 tables, accepted to ApJ (6/4/2020),
microlensing simulation catalogs available at
https://portal.nersc.gov/project/uLens/Galactic_Microlensing_Distribution
The Impact of Initial-Final Mass Relations on Black Hole Microlensing
Uncertainty in the initial-final mass relation (IFMR) has long been a problem
in understanding the final stages of massive star evolution. One of the major
challenges of constraining the IFMR is the difficulty of measuring the mass of
non-luminous remnant objects (i.e. neutron stars and black holes).
Gravitational wave detectors have opened the possibility of finding large
numbers of compact objects in other galaxies, but all in merging binary
systems. Gravitational lensing experiments using astrometry and photometry are
capable of finding compact objects, both isolated and in binaries, in the Milky
Way. In this work we improve the PopSyCLE microlensing simulation code in order
to explore the possibility of constraining the IFMR using the Milky Way
microlensing population. We predict that the Roman Space Telescope's
microlensing survey will likely be able to distinguish different IFMRs based on
the differences at the long end of the Einstein crossing time distribution and
the small end of the microlensing parallax distribution, assuming the small
() microlensing parallaxes characteristic of black hole
lenses are able to be measured accurately. We emphasize that future
microlensing surveys need to be capable of characterizing events with small
microlensing parallaxes in order to place the most meaningful constraints on
the IFMR.Comment: 24 pages, 17 figures Accepted to Ap
Near-infrared and Millimeter-wavelength Observations of Mol 160: A Massive Young Protostellar Core
We have discovered two compact sources of shocked H2 2.12-micron emission
coincident with Mol 160 (IRAS 23385+6053), a massive star-forming core thought
to be a precursor to an ultracompact HII region. The 2.12-micron sources lie
within 2" (0.05 pc) of a millimeter-wavelength continuum peak where the column
density is >= 10e24 cm. We estimate that the ratio of molecular hydrogen
luminosity to bolometric luminosity is > 0.2%, indicating a high ratio of
mechanical to radiant luminosity. CS J=2-1 and HCO J=1-0 observations with
CARMA indicate that the protostellar molecular core has a peculiar velocity of
~ 2 km s with respect to its parent molecular cloud. We also observed 95
GHz CH3OH J=8$-7 Class I maser emission from several locations within the core.
Comparison with previous observations of 44-GHz CH3OH maser emission shows the
maser sources have a high mean ratio of 95-GHz to 44-GHz intensity. Our
observations strengthen the case that Mol 160 (IRAS 23385+6053) is a rapidly
accreting massive protostellar system in a very early phase of its evolution.Comment: 47 pages, 8 figures, 2 tables, accepted for publication in ApJ, 7 Dec
201
Long-term nitrofurantoin:an analysis of complication awareness, monitoring, and pulmonary injury cases
BACKGROUND: Long-term nitrofurantoin (NF) treatment can result in pulmonary and hepatic injury. Current guidelines do not outline the type or frequency of monitoring required for detection of these injuries. AIM: To assess 1) awareness of NF complications among prescribers; 2) monitoring practice; and 3) to describe the pulmonary sequelae of NF-related complications. DESIGN & SETTING: Evaluation of prescribing habits by questionnaires and review of GP databases, and case-note review in secondary care. METHOD: The following study procedures were undertaken: 1) an electronic questionnaire was distributed to prescribers, interrogating prescribing and monitoring practices, and awareness of complications; 2) an analysis was undertaken (June–July 2020) of NF monitoring among GPs in the local clinical commissioning group (CCG); and 3) a case review was carried out of patients diagnosed with NF-induced interstitial lung disease (NFILD) at the interstitial lung disease (ILD) centre (2014–2020). RESULTS: A total of 125 prescribers of long-term NF responded to the questionnaire (82.4% GPs; 12.0% urologists). Many were unaware of the potential for liver (42.4%) and lung (28.0%) complications; 40.8% and 52.8% never monitored for these, respectively. Only 53.3% of urologists believed themselves responsible for arranging monitoring, while nearly all GPs believed this to be the prescriber’s responsibility (94.2%). One-third of all responders considered current British National Formulary (BNF) guidelines 'not at all sufficient/clear', with mean clarity scoring of 2.2/5. Among patients with NFILD (n = 46), NF had been prescribed most often (69.6%) for treatment of recurrent UTI and 58.6% (n = 27) were prescribed for >6 months. On withdrawal of the medication 61.4% displayed resolution (completely or minimal fibrosis), while 15.9% of patients had progressive lung fibrosis. CONCLUSION: NF can cause marked or irreversible lung complications and there is currently a shortfall in awareness and monitoring. Existing monitoring guidelines should be augmented
A Reanalysis of Public Galactic Bulge Gravitational Microlensing Events from OGLE-III and IV
Modern surveys of gravitational microlensing events have progressed to
detecting thousands per year. Surveys are capable of probing Galactic
structure, stellar evolution, lens populations, black hole physics, and the
nature of dark matter. One of the key avenues for doing this is studying the
microlensing Einstein radius crossing time distribution (). However,
systematics in individual light curves as well as over-simplistic modeling can
lead to biased results. To address this, we developed a model to simultaneously
handle the microlensing parallax due to Earth's motion, systematic instrumental
effects, and unlensed stellar variability with a Gaussian Process model. We
used light curves for nearly 10,000 OGLE-III and IV Milky Way bulge
microlensing events and fit each with our model. We also developed a forward
model approach to infer the timescale distribution by forward modeling from the
data rather than using point estimates from individual events. We find that
modeling the variability in the baseline removes a source of significant bias
in individual events, and previous analyses over-estimated the number of long
timescale ( days) events due to their over simplistic models ignoring
parallax effects and stellar variability. We use our fits to identify hundreds
of events that are likely black holes.Comment: Submitted version, in review, 33 pages, 18 figures, MCMC posterior
samples available by publisher after acceptanc
GROWTH on S190510g: DECam Observation Planning and Follow-Up of a Distant Binary Neutron Star Merger Candidate
The first two months of the third Advanced LIGO and Virgo observing run (2019 April–May) showed that distant gravitational-wave (GW) events can now be readily detected. Three candidate mergers containing neutron stars (NS) were reported in a span of 15 days, all likely located more than 100 Mpc away. However, distant events such as the three new NS mergers are likely to be coarsely localized, which highlights the importance of facilities and scheduling systems that enable deep observations over hundreds to thousands of square degrees to detect the electromagnetic counterparts. On 2019 May 10 02:59:39.292 UT the GW candidate S190510g was discovered and initially classified as a binary neutron star (BNS) merger with 98% probability. The GW event was localized within an area of 3462 deg^2, later refined to 1166 deg^2 (90%) at a distance of 227 ± 92 Mpc. We triggered Target-of-Opportunity observations with the Dark Energy Camera (DECam), a wide-field optical imager mounted at the prime focus of the 4 m Blanco Telescope at Cerro Tololo Inter-American Observatory in Chile. This Letter describes our DECam observations and our real-time analysis results, focusing in particular on the design and implementation of the observing strategy. Within 24 hr of the merger time, we observed 65% of the total enclosed probability of the final skymap with an observing efficiency of 94%. We identified and publicly announced 13 candidate counterparts. S190510g was reclassified 1.7 days after the merger, after our observations were completed, with a "BNS merger" probability reduced from 98% to 42% in favor of a "terrestrial classification
Long-rising Type II Supernovae in the Zwicky Transient Facility Census of the Local Universe
SN 1987A was an unusual hydrogen-rich core-collapse supernova originating
from a blue supergiant star. Similar blue supergiant explosions remain a small
family of events, and are broadly characterized by their long rises to peak.
The Zwicky Transient Facility (ZTF) Census of the Local Universe (CLU)
experiment aims to construct a spectroscopically complete sample of transients
occurring in galaxies from the CLU galaxy catalog. We identify 13 long-rising
(>40 days) Type II supernovae from the volume-limited CLU experiment during a
3.5 year period from June 2018 to December 2021, approximately doubling the
previously known number of these events. We present photometric and
spectroscopic data of these 13 events, finding peak r-band absolute magnitudes
ranging from -15.6 to -17.5 mag and the tentative detection of Ba II lines in 9
events. Using our CLU sample of events, we derive a long-rising Type II
supernova rate of Mpc yr,
1.4% of the total core-collapse supernova rate. This is the first
volumetric rate of these events estimated from a large, systematic,
volume-limited experiment.Comment: 32 pages, 17 figures, 5 tables. Submitted to Ap
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