517 research outputs found
The effects of extended public transport operating hours and venue lockout policies on drinking-related harms in Melbourne, Australia: Results from SimDrink, an agent-based simulation model.
Background: The late-night accessibility of entertainment precincts is a contributing factor to acute drinking-related harms. Using computer simulation we test the effects of improved public transport (PT) and venue lockouts on verbal aggression, consumption-related harms and transport-related harms among a population of young adults engaging in heavy drinking in Melbourne. Methods: Using an agent-based model we implemented: a two-hour PT extension/24-hour PT; 1 am/3 am venue lockouts; and combinations of both. Outcomes determined for outer-urban (OU) and inner-city (IC) residents were: the number of incidents of verbal aggression inside public and private venues; the number of people ejected from public venues for being intoxicated; and the percentage of people experiencing verbal aggression, consumption-related harms and transport-related harms. Results: All-night PT reduced verbal aggression in the model by 21% but displaced some incidents among OU residents from private to public settings. Comparatively, 1 am lockouts reduced verbal aggression in the model by 19% but led to IC residents spending more time in private rather than public venues where their consumption-related harms increased. Extending PT by 2 h had similar outcomes to 24-hour PT except with fewer incidents of verbal aggression displaced. Although 3 am lockouts were inferior to 1 am lockouts, when modelled in combination with any extension of PT both policies were similar. Conclusions: A two-hour extension of PT is likely to be more effective in reducing verbal aggression and consumption-related harms than venue lockouts. Modelling a further extension of PT to 24 h had minimal additional benefits but the potential to displace incidents of verbal aggression among OU residents from private to public venues
Enhancing our understanding of short-term rental activity: a daily scrape-based approach for Airbnb listings
The growth of the online short-term rental market, facilitated by platforms such as Airbnb, has added to pressure on cities’ housing supply. Without detailed data on activity levels, it is difficult to design and evaluate appropriate policy interventions. Up until now, the data sources and methods used to derive activity measures have not provided the detail and rigour needed to robustly carry out these tasks. This paper demonstrates an approach based on daily scrapes of the calendars of Airbnb listings. We provide a systematic interpretation of types of calendar activity derived from these scrapes and define a set of indicators of listing activity levels. We exploit a unique period in short-term rental markets during the UK’s first COVID-19 lockdown to demonstrate the value of this approach
K2 Discovers a Busy Bee: An Unusual Transiting Neptune Found in the Beehive Cluster
Open clusters have been the focus of several exoplanet surveys but only a few
planets have so far been discovered. The \emph{Kepler} spacecraft revealed an
abundance of small planets around small, cool stars, therefore, such cluster
members are prime targets for exoplanet transit searches. Kepler's new mission,
K2, is targeting several open clusters and star-forming regions around the
ecliptic to search for transiting planets around their low-mass constituents.
Here, we report the discovery of the first transiting planet in the
intermediate-age (800 Myr) Beehive cluster (Praesepe). K2-95 is a faint
() dwarf from K2's Campaign 5
with an effective temperature of , approximately
solar metallicity and a radius of . We
detected a transiting planet with a radius of and an orbital period of 10.134 days. We combined photometry,
medium/high-resolution spectroscopy, adaptive optics/speckle imaging and
archival survey images to rule out any false positive detection scenarios,
validate the planet, and further characterize the system. The planet's radius
is very unusual as M-dwarf field stars rarely have Neptune-sized transiting
planets. The comparatively large radius of K2-95b is consistent with the other
recently discovered cluster planets K2-25b (Hyades) and K2-33b (Upper
Scorpius), indicating systematic differences in their evolutionary states or
formation. These discoveries from K2 provide a snapshot of planet formation and
evolution in cluster environments and thus make excellent laboratories to test
differences between field-star and cluster planet populations.Comment: 14 pages, 8 figues. Accepted for publication in A
Broadband CPW-based impedance-transformed Josephson parametric amplifier
Quantum-limited Josephson parametric amplifiers play a pivotal role in
advancing the field of circuit quantum electrodynamics by enabling the fast and
high-fidelity measurement of weak microwave signals. Therefore, it is necessary
to develop robust parametric amplifiers with low noise, broad bandwidth, and
reduced design complexity for microwave detection. However, current broadband
parametric amplifiers either have degraded noise performance or rely on complex
designs. Here, we present a device based on the broadband impedance-transformed
Josephson parametric amplifier (IMPA) that integrates a horn-like coplanar
waveguide (CPW) transmission line, which significantly decreases the design and
fabrication complexity, while keeping comparable performance. The device shows
an instantaneous bandwidth of 700(200) MHz for 15(20) dB gain with an average
saturation power of -110 dBm and near quantum-limited added noise. The
operating frequency can be tuned over 1.4 GHz using an external flux bias. We
further demonstrate the negligible back-action from our device on a transmon
qubit. The amplification performance and simplicity of our device promise its
wide adaptation in quantum metrology, quantum communication, and quantum
information processing.Comment: 11 pages, 8 figure
Revisiting the HIP 41378 System with K2 and Spitzer
We present new observations of the multiplanet system HIP 41378, a bright star (V = 8.9, K s = 7.7) with five known transiting planets. Previous K2 observations showed multiple transits of two Neptune-sized bodies and single transits of three larger planets (R P = 0.33R J , 0.47R J , 0.88R J ). K2 recently observed the system again in Campaign 18 (C18). We observe one new transit each of two of the larger planets d/f, giving maximal orbital periods of 1114/1084 days, as well as integer divisions of these values down to a lower limit of about 50 days. We use all available photometry to determine the eccentricity distributions of HIP 41378 d & f, finding that periods lesssim300 days require non-zero eccentricity. We check for overlapping orbits of planets d and f to constrain their mutual periods, finding that short periods (P < 300 days) for planet f are disfavored. We also observe transits of planets b and c with Spitzer/Infrared Array Camera (IRAC), which we combine with the K2 observations to search for transit timing variations (TTVs). We find a linear ephemeris for planet b, but see a significant TTV signal for planet c. The ability to recover the two smaller planets with Spitzer shows that this fascinating system will continue to be detectable with Spitzer, CHEOPS, TESS, and other observatories, allowing us to precisely determine the periods of d and f, characterize the TTVs of planet c, recover the transits of planet e, and further enhance our view of this remarkable dynamical laboratory
Exoplanets around Low-mass Stars Unveiled by K2
We present the detection and follow-up observations of planetary candidates
around low-mass stars observed by the K2 mission. Based on light-curve
analysis, adaptive-optics imaging, and optical spectroscopy at low and high
resolution (including radial velocity measurements), we validate 16 planets
around 12 low-mass stars observed during K2 campaigns 5-10. Among the 16
planets, 12 are newly validated, with orbital periods ranging from 0.96-33
days. For one of the planets (K2-151b) we present ground-based transit
photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf
planets together with the validated or confirmed planets found previously, we
investigate the dependence of planet radius on stellar insolation and
metallicity [Fe/H]. We confirm that for periods days, planets
with a radius are less common than planets with a
radius between 1-2. We also see a hint of the "radius valley"
between 1.5 and 2 that has been seen for close-in planets around
FGK stars. These features in the radius/period distribution could be attributed
to photoevaporation of planetary envelopes by high-energy photons from the host
star, as they have for FGK stars. For the M dwarfs, though, the features are
not as well defined, and we cannot rule out other explanations such as
atmospheric loss from internal planetary heat sources, or truncation of the
protoplanetary disk. There also appears to be a relation between planet size
and metallicity: those few planets larger than about 3 are found
around the most metal-rich M dwarfs.Comment: 29 pages, 21 figures, 6 tables, Accepted in Astronomical Journa
Three Small Planets Transiting a Hyades Star
We present the discovery of three small planets transiting K2-136 (LP 358
348, EPIC 247589423), a late K dwarf in the Hyades. The planets have orbital
periods of , , and
days, and radii of , , and , respectively. With an age of
600-800 Myr, these planets are some of the smallest and youngest transiting
planets known. Due to the relatively bright (J=9.1) host star, the planets are
compelling targets for future characterization via radial velocity mass
measurements and transmission spectroscopy. As the first known star with
multiple transiting planets in a cluster, the system should be helpful for
testing theories of planet formation and migration.Comment: Accepted to The Astronomical Journa
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