48 research outputs found
TB99: Flora of Oxford County, Maine
This is a study of the vascular plants occurring in Oxford County, Maine. Plants with vascular or conductive tissue (kingdom Plantae, division Tracheophyta) include the ferns and their allies (horsetails and lycopods) and the seed-bearing plants. Our aim has been to determine which plants occur in the county and, based on herbarium collections and observations, their habitat preferences, frequency of occurrence, and geographic distribution. We have also endeavored to explain the nature of the flora first in terms of the various factors which influence its composition and second by grouping the plants into the most important natural associations.https://digitalcommons.library.umaine.edu/aes_techbulletin/1106/thumbnail.jp
Novel verbal fluency scores and structural brain imaging for prediction of cognitive outcome in mild cognitive impairment
AbstractIntroductionThe objective of this study was to assess the utility of novel verbal fluency scores for predicting conversion from mild cognitive impairment (MCI) to clinical Alzheimer's disease (AD).MethodVerbal fluency lists (animals, vegetables, F, A, and S) from 107 MCI patients and 51 cognitively normal controls were transcribed into electronic text files and automatically scored with traditional raw scores and five types of novel scores computed using methods from machine learning and natural language processing. Additional scores were derived from structural MRI scans: region of interest measures of hippocampal and ventricular volumes and gray matter scores derived from performing ICA on measures of cortical thickness. Over 4 years of follow-up, 24 MCI patients converted to AD. Using conversion as the outcome variable, ensemble classifiers were constructed by training classifiers on the individual groups of scores and then entering predictions from the primary classifiers into regularized logistic regression models. Receiver operating characteristic curves were plotted, and the area under the curve (AUC) was measured for classifiers trained with five groups of available variables.ResultsClassifiers trained with novel scores outperformed those trained with raw scores (AUC 0.872 vs 0.735; PÂ <Â .05 by DeLong test). Addition of structural brain measurements did not improve performance based on novel scores alone.ConclusionThe brevity and cost profile of verbal fluency tasks recommends their use for clinical decision making. The word lists generated are a rich source of information for predicting outcomes in MCI. Further work is needed to assess the utility of verbal fluency for early AD
The K2-3 system revisited: testing photoevaporation and core-powered mass loss with three small planets spanning the radius valley
Multi-planet systems orbiting M dwarfs provide valuable tests of theories of
small planet formation and evolution. K2-3 is an early M dwarf hosting three
small exoplanets (1.5-2.0 Earth radii) at distances of 0.07-0.20 AU. We measure
the high-energy spectrum of K2-3 with HST/COS and XMM-Newton, and use
empirically-driven estimates of Ly-alpha and extreme ultraviolet flux. We use
EXOFASTv2 to jointly fit radial velocity, transit, and SED data. This
constrains the K2-3 planet radii to 4% uncertainty and the masses of K2-3b and
c to 13% and 30%, respectively; K2-3d is not detected in RV measurements. K2-3b
and c are consistent with rocky cores surrounded by solar composition envelopes
(mass fractions of 0.36% and 0.07%), H2O envelopes (55% and 16%), or a mixture
of both. However, based on the high-energy output and estimated age of K2-3, it
is unlikely that K2-3b and c retain solar composition atmospheres. We pass the
planet parameters and high-energy stellar spectrum to atmospheric models.
Dialing the high-energy spectrum up and down by a factor of 10 produces
significant changes in trace molecule abundances, but not at a level detectable
with transmission spectroscopy. Though the K2-3 planets span the small planet
radius valley, the observed system architecture cannot be readily explained by
photoevaporation or core-powered mass loss. We instead propose 1) the K2-3
planets are all volatile-rich, with K2-3d having a lower density than typical
of super-Earths, and/or 2) the K2-3 planet architecture results from more
stochastic processes such as planet formation, planet migration, and impact
erosion.Comment: 15 pages, 7 figure, published in AJ, HLSPs at
https://archive.stsci.edu/hlsp/mstarpanspe
KELT-1b: A Strongly Irradiated, Highly Inflated, Short Period, 27 Jupiter-mass Companion Transiting a mid-F Star
We present the discovery of KELT-1b, the first transiting low-mass companion
from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North)
survey. The V=10.7 primary is a mildly evolved, solar-metallicity, mid-F star.
The companion is a low-mass brown dwarf or super-massive planet with mass of
27.23+/-0.50 MJ and radius of 1.110+0.037-0.024 RJ, on a very short period
(P=1.21750007) circular orbit. KELT-1b receives a large amount of stellar
insolation, with an equilibrium temperature assuming zero albedo and perfect
redistribution of 2422 K. Upper limits on the secondary eclipse depth indicate
that either the companion must have a non-zero albedo, or it must experience
some energy redistribution. Comparison with standard evolutionary models for
brown dwarfs suggests that the radius of KELT-1b is significantly inflated.
Adaptive optics imaging reveals a candidate stellar companion to KELT-1, which
is consistent with an M dwarf if bound. The projected spin-orbit alignment
angle is consistent with zero stellar obliquity, and the vsini of the primary
is consistent with tidal synchronization. Given the extreme parameters of the
KELT-1 system, we expect it to provide an important testbed for theories of the
emplacement and evolution of short-period companions, and theories of tidal
dissipation and irradiated brown dwarf atmospheres.Comment: 30 pages, 19 figures. Submitted to Ap
KELT-2Ab: A Hot Jupiter Transiting the Bright (V=8.77) Primary Star of a Binary System
We report the discovery of KELT-2Ab, a hot Jupiter transiting the bright
(V=8.77) primary star of the HD 42176 binary system. The host is a slightly
evolved late F-star likely in the very short-lived "blue-hook" stage of
evolution, with \teff=6148\pm48{\rm K}, and
\feh=0.034\pm0.78. The inferred stellar mass is
\msun\ and the star has a relatively large radius
of \rsun. The planet is a typical hot Jupiter with
period days and a mass of \mj\ and
radius of \rj. This is mildly inflated as compared
to models of irradiated giant planets at the 4 Gyr age of the system.
KELT-2A is the third brightest star with a transiting planet identified by
ground-based transit surveys, and the ninth brightest star overall with a
transiting planet. KELT-2Ab's mass and radius are unique among the subset of
planets with host stars, and therefore increases the diversity of bright
benchmark systems. We also measure the relative motion of KELT-2A and -2B over
a baseline of 38 years, robustly demonstrating for the first time that the
stars are bound. This allows us to infer that KELT-2B is an early K-dwarf. We
hypothesize that through the eccentric Kozai mechanism KELT-2B may have
emplaced KELT-2Ab in its current orbit. This scenario is potentially testable
with Rossiter-McLaughlin measurements, which should have an amplitude of
44 m s.Comment: 9 pages, 2 tables, 4 figures. A short video describing this paper is
available at http://www.youtube.com/watch?v=wVS8lnkXXlE. Revised to reflect
the ApJL version. Note that figure 4 is not in the ApJL versio
B844: Checklist of the Vascular Plants of Maine Third Revision
This is the third revision of the Checklist of Vascular Plants of Maine. Like its predecessors, it lists all ferns and related plants, conifers, and flowering plants native and naturalized in Maine and records their county-level distribution in the state. The first Check- list (Ogden et al. 1948) was based on specimens in herbaria at the University of Maine (hereafter referred to as MAINE), Portland Society of Natural History, New England Botanical Club, Gray Herbarium of Harvard University, and the private collection of Glen D. Chamberlain of Presque Isle, Maine (now part of MAINE). Bean et al. (1966) revised the checklist to include additions to the flora and update the nomenclature to follow Fernald (1950). Richards et al. (1983) added many new state and county records in the second revision.
The purpose of this revision is twofold. First, we have included many new county and state records. Since Richards et al. (1983) there has been considerable collecting in Maine, much of it directed at searching for new state and county records in relatively neglected regions of the state. Second, there have been numerous changes in the scientific names of Maine plants since Fernald (1950), the nomenclatural basis of Richards et al. (1983). We have largely followed Kartesz\u27s (1994) nomenclature (see Taxonomy and Nomenclature section). Recent work on rare plants and establishment of an official list of endangered and threatened plants in Maine (Dibble et al. 1989; Maine State Planning Office 1990) also motivate updating the known distribution and taxonomy of Maine\u27s flora.https://digitalcommons.library.umaine.edu/aes_bulletin/1121/thumbnail.jp
A Cautionary Tale: MARVELS Brown Dwarf Candidate Reveals Itself To Be A Very Long Period, Highly Eccentric Spectroscopic Stellar Binary
We report the discovery of a highly eccentric, double-lined spectroscopic
binary star system (TYC 3010-1494-1), comprising two solar-type stars that we
had initially identified as a single star with a brown dwarf companion. At the
moderate resolving power of the MARVELS spectrograph and the spectrographs used
for subsequent radial-velocity (RV) measurements (R ~ <30,000), this particular
stellar binary mimics a single-lined binary with an RV signal that would be
induced by a brown dwarf companion (Msin(i)~50 M_Jup) to a solar-type primary.
At least three properties of this system allow it to masquerade as a single
star with a very low-mass companion: its large eccentricity (e~0.8), its
relatively long period (P~238 days), and the approximately perpendicular
orientation of the semi-major axis with respect to the line of sight (omega~189
degrees). As a result of these properties, for ~95% of the orbit the two sets
of stellar spectral lines are completely blended, and the RV measurements based
on centroiding on the apparently single-lined spectrum is very well fit by an
orbit solution indicative of a brown dwarf companion on a more circular orbit
(e~0.3). Only during the ~5% of the orbit near periastron passage does the
true, double-lined nature and large RV amplitude of ~15 km/s reveal itself. The
discovery of this binary system is an important lesson for RV surveys searching
for substellar companions; at a given resolution and observing cadence, a
survey will be susceptible to these kinds of astrophysical false positives for
a range of orbital parameters. Finally, for surveys like MARVELS that lack the
resolution for a useful line bisector analysis, it is imperative to monitor the
peak of the cross-correlation function for suspicious changes in width or
shape, so that such false positives can be flagged during the candidate vetting
process.Comment: 16 pages, 11 figures, 6 table
Very Low-Mass Stellar and Substellar Companions to Solar-Like Stars from MARVELS I: A Low Mass Ratio Stellar Companion to TYC 4110-01037-1 in a 79-day Orbit
TYC 4110-01037-1 has a low-mass stellar companion, whose small mass ratio and
short orbital period are atypical amongst solar-like (Teff ~< 6000 K) binary
systems. Our analysis of TYC 4110-01037-1 reveals it to be a moderately aged
(~<5 Gyr) solar-like star having a mass of 1.07 +/- 0.08 MSun and radius of
0.99 +/- 0.18 RSun. We analyze 32 radial velocity measurements from the
SDSS-III MARVELS survey as well as 6 supporting radial velocity measurements
from the SARG spectrograph on the 3.6m TNG telescope obtained over a period of
~2 years. The best Keplerian orbital fit parameters were found to have a period
of 78.994 +/- 0.012 days, an eccentricity of 0.1095 +/- 0.0023, and a
semi-amplitude of 4199 +/- 11 m/s. We determine the minimum companion mass (if
sin i = 1) to be 97.7 +/- 5.8 MJup. The system's companion to host star mass
ratio, >0.087 +/- 0.003, places it at the lowest end of observed values for
short period stellar companions to solar-like (Teff ~< 6000 K) stars. One
possible way to create such a system would be if a triple-component stellar
multiple broke up into a short period, low q binary during the cluster
dispersal phase of its lifetime. A candidate tertiary body has been identified
in the system via single-epoch, high contrast imagery. If this object is
confirmed to be co-moving, we estimate it would be a dM4 star. We present these
results in the context of our larger-scale effort to constrain the statistics
of low mass stellar and brown dwarf companions to FGK-type stars via the
MARVELS survey.Comment: 22 pages; accepted in A
Toward estimating the impact of changes in immigrants' insurance eligibility on hospital expenditures for uncompensated care
BACKGROUND: The Personal Responsibility and Work Opportunity Reconciliation Act (PRWORA) of 1996 gave states the option to withdraw Medicaid coverage of nonemergency care from most legal immigrants. Our goal was to assess the effect of PRWORA on hospital uncompensated care in the United States. METHODS: We collected the following state-level data for the period from 1994 through 1999: foreign-born, noncitizen population and health uninsurance rates (US Census Current Population Survey); percentage of teaching hospitals (American Hospital Association Annual Survey of Hospitals); and each state's decision whether to implement the PRWORA Medicaid bar for legal permanent residents or to continue offering nonemergency Medicaid coverage using state-only funds (Urban Institute). We modeled uncompensated care expenditures by state (also from the Annual Survey of Hospitals) in both univariate and multivariable regression analyses. RESULTS: When measured at the state level, there was no significant relationship between uncompensated care expenditures and states' percentage of noncitizen immigrants. Uninsurance rates were the only significant factor in predicting uncompensated hospital care expenditures by state. CONCLUSIONS: Reducing the number of uninsured patients would most surely reduce hospital expenditures for uncompensated care. However, data limitations hampered our efforts to obtain a monetary estimate of hospitals' financial losses due specifically to the immigrant eligibility changes in PRWORA. Quantifying the impact of these provisions on hospitals will require better data sources