1,234 research outputs found
Evolution of Subjective Hurricane Risk Perceptions: A Bayesian Approach
This paper studies how individuals update subjective risk perceptions in response to hurricane track forecast information, using a unique data set from an event market, the Hurricane Futures Market (HFM). We derive a theoretical Bayesian framework which predicts how traders update their perceptions of the probability of a hurricane making landfall in a certain range of coastline. Our results suggest that traders behave in a way consistent with Bayesian updating but this behavior is based on the perceived quality of the information received.risk perceptions, learning, Bayesian learning, event markets, prediction markets, favorite-longshot bias, hurricanes
Tropical cyclone rainbands can trigger meteotsunamis
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Shi, L., Olabarrieta, M., Nolan, D. S., & Warner, J. C. Tropical cyclone rainbands can trigger meteotsunamis. Nature Communications, 11(1), (2020): 678, doi:10.1038/s41467-020-14423-9.Tropical cyclones are one of the most destructive natural hazards and much of the damage and casualties they cause are flood-related. Accurate characterization and prediction of total water levels during extreme storms is necessary to minimize coastal impacts. While meteotsunamis are known to influence water levels and to produce severe consequences, their impacts during tropical cyclones are underappreciated. This study demonstrates that meteotsunami waves commonly occur during tropical cyclones, and that they can contribute significantly to total water levels. We use an idealized coupled ocean–atmosphere–wave numerical model to analyze tropical cyclone-induced meteotsunami generation and propagation mechanisms. We show that the most extreme meteotsunami events are triggered by inherent features of the structure of tropical cyclones: inner and outer spiral rainbands. While outer distant spiral rainbands produce single-peak meteotsunami waves, inner spiral rainbands trigger longer lasting wave trains on the front side of the tropical cyclones.We thank all the developers of COAWST, ROMS, WRF, and SWAN models. D.N. was supported by NSF grant AGS-1654831. We would like to thank Dr. K. Bagamian for her editorial and writing suggestions. We would like to thank Dr. A. Aretxabaleta for the internal US Geological Survey internal revision and suggestions
The ages of quasar host galaxies
We present the results of fitting deep off-nuclear optical spectroscopy of
radio-quiet quasars, radio-loud quasars and radio galaxies at z ~ 0.2 with
evolutionary synthesis models of galaxy evolution. Our aim was to determine the
age of the dynamically dominant stellar populations in the hos t galaxies of
these three classes of powerful AGN. Some of our spectra display residual
nuclear contamination at the shortest wavelengths, but the detailed quality of
the fits longward of the 4000A break provide unequivocal proof, if further
proof were needed, that quasars lie in massive galaxies with (at least at z ~
0.2) evolved stellar populations. By fitting a two-component model we have
separated the very blue (starburst and/or AGN contamination) from the redder
underlying spectral energy distribution, and find that the hosts of all three
classes of AGN are dominated by old stars of age 8 - 14 Gyr. If the blue
component is attributed to young stars, we find that, at most, 1% of the
baryonic mass of these galaxies is involved in star-formation activity at the
epoch of observation. These results strongly support the conclusion reached by
McLure et al. (1999) that the host galaxies of luminous quasars are massive
ellipticals which formed prior to the peak epoch of quasar activity at z ~ 2.5.Comment: 24 pages, LaTeX, uses MNRAS style file, incorporates 19 postscript
figures, final version, to be published in MNRA
A Possible Bifurcation in Atmospheres of Strongly Irradiated Stars and Planets
We show that under certain circumstances the differences between the
absorption mean and Planck mean opacities can lead to multiple solutions for an
LTE atmospheric structure. Since the absorption and Planck mean opacities are
not expected to differ significantly in the usual case of radiative
equilibrium, non-irradiated atmospheres, the most interesting situations where
the effect may play a role are strongly irradiated stars and planets, and also
possibly structures where there is a significant deposition of mechanical
energy, such as stellar chromospheres and accretion disks. We have presented an
illustrative example of a strongly irradiated giant planet where the
bifurcation effect is predicted to occur for a certain range of distances from
the star.Comment: 22 pages, 6 figures, submitted to Ap
The Impact of Dry Midlevel Air on Hurricane Intensity in Idealized Simulations with No Mean Flow
This study examines the potential negative influences of dry midlevel air on the development of tropical cyclones (specifically, its role in enhancing cold downdraft activity and suppressing storm development). The Weather Research and Forecasting model is used to construct two sets of idealized simulations of hurricane development in environments with different configurations of dry air. The first set of simulations begins with dry air located north of the vortex center by distances ranging from 0 to 270 km, whereas the second set of simulations begins with dry air completely surrounding the vortex, but with moist envelopes in the vortex core ranging in size from 0 to 150 km in radius. No impact of the dry air is seen for dry layers located more than 270 km north of the initial vortex center (approximately 3 times the initial radius of maximum wind). When the dry air is initially closer to the vortex center, it suppresses convective development where it entrains into the storm circulation, leading to increasingly asymmetric convection and slower storm development. The presence of dry air throughout the domain, including the vortex center, substantially slows storm development. However, the presence of a moist envelope around the vortex center eliminates the deleterious impact on storm intensity. Instead, storm size is significantly reduced. The simulations suggest that dry air slows intensification only when it is located very close to the vortex core at early times. When it does slow storm development, it does so primarily by inducing outward- moving convective asymmetries that temporarily shift latent heating radially outward away from the high-vorticity inner core
HIV-1 Evolutionary Patterns Associated with Metastatic Kaposi's Sarcoma during AIDS.
Kaposi's sarcoma (KS) in HIV-infected individuals can have a wide range of clinical outcomes, from indolent skin tumors to a life-threatening visceral cancer. KS tumors contain endothelial-related cells and inflammatory cells that may be HIV-infected. In this study we tested if HIV evolutionary patterns distinguish KS tumor relatedness and progression. Multisite autopsies from participants who died from HIV-AIDS with KS prior to the availability of antiretroviral therapy were identified at the AIDS and Cancer Specimen Resource (ACSR). Two patients (KS1 and KS2) died predominantly from non-KS-associated disease and KS3 died due to aggressive and metastatic KS within one month of diagnosis. Skin and visceral tumor and nontumor autopsy tissues were obtained (n = 12). Single genome sequencing was used to amplify HIV RNA and DNA, which was present in all tumors. Independent HIV tumor clades in phylogenies differentiated KS1 and KS2 from KS3, whose sequences were interrelated by both phylogeny and selection. HIV compartmentalization was confirmed in KS1 and KS2 tumors; however, in KS3, no compartmentalization was observed among sampled tissues. While the sample size is small, the HIV evolutionary patterns observed in all patients suggest an interplay between tumor cells and HIV-infected cells which provides a selective advantage and could promote KS progression
Spatially Resolved Stellar Populations of Eight GOODS-South AGN at z~1
We present a pilot study of the stellar populations of 8 AGN hosts at z~1 and
compare to (1) lower redshift samples and (2) a sample of nonactive galaxies of
similar redshift. We utilize K' images in the GOODS South field obtained with
the laser guide star adaptive optics (LGSAO) system at Keck Observatory. We
combine this K' data with B, V, i, and z imaging from the ACS on HST to give
multi-color photometry at a matched spatial resolution better than 100 mas in
all bands. The hosts harbor AGN as inferred from their high X-ray luminosities
(L_X > 10^42 ergs/s) or mid-IR colors. We find a correlation between the
presence of younger stellar populations and the strength of the AGN, as
measured with [OIII] line luminosity or X-ray (2-10 keV) luminosity. This
finding is consistent with similar studies at lower redshift. Of the three Type
II galaxies, two are disk galaxies and one is of irregular type, while in the
Type I sample there only one disk-like source and four sources with smooth,
elliptical/spheroidal morphologies. In addition, the mid-IR SEDs of the strong
Type II AGN indicate that they are excited to LIRG (Luminous InfraRed Galaxy)
status via galactic starbursting, while the strong Type I AGN are excited to
LIRG status via hot dust surrounding the central AGN. This supports the notion
that the obscured nature of Type II AGN at z~1 is connected with global
starbursting and that they may be extincted by kpc-scale dusty features that
are byproducts of this starbursting.Comment: 56 pages, 39 figures, accepted to A
A Project Based Approach to Statistics and Data Science
In an increasingly data-driven world, facility with statistics is more
important than ever for our students. At institutions without a statistician,
it often falls to the mathematics faculty to teach statistics courses. This
paper presents a model that a mathematician asked to teach statistics can
follow. This model entails connecting with faculty from numerous departments on
campus to develop a list of topics, building a repository of real-world
datasets from these faculty, and creating projects where students interface
with these datasets to write lab reports aimed at consumers of statistics in
other disciplines. The end result is students who are well prepared for
interdisciplinary research, who are accustomed to coping with the
idiosyncrasies of real data, and who have sharpened their technical writing and
speaking skills
Dermatological conditions in intensive care: a secondary analysis of the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database
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