110 research outputs found
Seasons Fall 2018 Volume 47 Number 3
Highlights : Thompson-Morris Plot Restoration Complete Botany for Beginners Preserving Our Tree Canopy Three Great Native Trees ArbNet Accreditationhttps://repository.upenn.edu/morrisarboretum_seasons/1000/thumbnail.jp
PON1 status does not influence cholinesterase activity in Egyptian agricultural workers exposed to chlorpyrifos.
Animal studies have shown that paraoxonase 1 (PON1) genotype can influence susceptibility to the organophosphorus pesticide chlorpyrifos (CPF). However, Monte Carlo analysis suggests that PON1 genotype may not affect CPF-related toxicity at low exposure conditions in humans. The current study sought to determine the influence of PON1 genotype on the activity of blood cholinesterase as well as the effect of CPF exposure on serum PON1 in workers occupationally exposed to CPF. Saliva, blood and urine were collected from agricultural workers (n=120) from Egypt's Menoufia Governorate to determine PON1 genotype, blood cholinesterase activity, serum PON1 activity towards chlorpyrifos-oxon (CPOase) and paraoxon (POase), and urinary levels of the CPF metabolite 3,5,6-trichloro-2-pyridinol (TCPy). The PON1 55 (P≤0.05) but not the PON1 192 genotype had a significant effect on CPOase activity. However, both the PON1 55 (P≤0.05) and PON1 192 (P≤0.001) genotypes had a significant effect on POase activity. Workers had significantly inhibited AChE and BuChE after CPF application; however, neither CPOase activity nor POase activity was associated with ChE depression when adjusted for CPF exposure (as determined by urinary TCPy levels) and stratified by PON1 genotype. CPOase and POase activity were also generally unaffected by CPF exposure although there were alterations in activity within specific genotype groups. Together, these results suggest that workers retained the capacity to detoxify chlorpyrifos-oxon under the exposure conditions experienced by this study population regardless of PON1 genotype and activity and that effects of CPF exposure on PON1 activity are minimal
Low Mass Companions for Five Solar-Type Stars from the Magellan Planet Search Program
We report low mass companions orbiting five Solar-type stars that have
emerged from the Magellan precision Doppler velocity survey, with minimum
(Msini) masses ranging from 1.2 to 25 Mjup. These nearby target stars range
from mildly metal-poor to metal-rich, and appear to have low chromospheric
activity. The companions to the brightest two of these stars have previously
been reported from the CORALIE survey. Four of these companions (HD 48265-b, HD
143361-b, HD 28185-b, HD 111232-b) are low-mass Jupiter-like planets in
eccentric intermediate and long-period orbits. On the other hand, the companion
to HD 43848 appears to be a long period brown dwarf in a very eccentric orbit.Comment: Accepted for publication on ApJ, 26 pages, 10 figures, 7 table
A Six-Planet System Around the Star HD 34445
We present a new precision radial velocity dataset that reveals a
multi-planet system orbiting the G0V star HD 34445. Our 18-year span consists
of 333 precision radial velocity observations, 56 of which were previously
published, and 277 which are new data from Keck Observatory, Magellan at Las
Campanas Observatory, and the Automated Planet Finder at Lick Observatory.
These data indicate the presence of six planet candidates in Keplerian motion
about the host star with periods of 1057, 215, 118, 49, 677, and 5700 days, and
minimum masses of 0.63, 0.17, 0.1, 0.05, 0.12 and 0.38 Jupiter masses
respectively. The HD 34445 planetary system, with its high degree of
multiplicity, its long orbital periods, and its induced stellar radial velocity
half-amplitudes in the range is fundamentally unlike either our own solar system (in which only
Jupiter and Saturn induce significant reflex velocities for the Sun), or the
Kepler multiple-transiting systems (which tend to have much more compact
orbital configurations)Comment: 10 pages, 11 figure
The test case of HD26965: difficulties disentangling weak Doppler signals from stellar activity
We report the discovery of a radial velocity signal that can be interpreted
as a planetary-mass candidate orbiting the K dwarf HD26965, with an orbital
period of 42.3640.015 days, or alternatively, as the presence of residual,
uncorrected rotational activity in the data. Observations include data from
HIRES, PFS, CHIRON, and HARPS, where 1,111 measurements were made over 16
years. Our best solution for HD26965 is consistent with a super-Earth that
has a minimum mass of 6.920.79 M orbiting at a distance of
0.2150.008 AU from its host star. We have analyzed the correlation between
spectral activity indicators and the radial velocities from each instrument,
showing moderate correlations that we include in our model. From this analysis,
we recover a 38 day signal, which matches some literature values of the
stellar rotation period. However, from independent Mt. Wilson HK data for this
star, we find evidence for a significant 42 day signal after subtraction of
longer period magnetic cycles, casting doubt on the planetary hypothesis for
this period. Although our statistical model strongly suggests that the 42-day
signal is Doppler in origin, we conclude that the residual effects of stellar
rotation are difficult to fully model and remove from this dataset,
highlighting the difficulties to disentangle small planetary signals and
photospheric noise, particularly when the orbital periods are close to the
rotation period of the star. This study serves as an excellent test case for
future works that aim to detect small planets orbiting `Sun-like' stars using
radial velocity measurements.Comment: 16 pages, 10 figures, 13 tables, accepted for publication in A
MagAO Imaging of Long-period Objects (MILO). I. A Benchmark M Dwarf Companion Exciting a Massive Planet around the Sun-like Star HD 7449
We present high-contrast Magellan adaptive optics (MagAO) images of HD 7449,
a Sun-like star with one planet and a long-term radial velocity (RV) trend. We
unambiguously detect the source of the long-term trend from 0.6-2.15 \microns
~at a separation of \about 0\fasec 54. We use the object's colors and spectral
energy distribution to show that it is most likely an M4-M5 dwarf (mass \about
0.1-0.2 \msun) at the same distance as the primary and is therefore likely
bound. We also present new RVs measured with the Magellan/MIKE and PFS
spectrometers and compile these with archival data from CORALIE and HARPS. We
use a new Markov chain Monte Carlo procedure to constrain both the mass ( \msun ~at 99 confidence) and semimajor axis (\about 18 AU) of the M
dwarf companion (HD 7449B). We also refine the parameters of the known massive
planet (HD 7449Ab), finding that its minimum mass is
\mj, its semimajor axis is AU, and its eccentricity is
. We use N-body simulations to constrain the eccentricity
of HD 7449B to 0.5. The M dwarf may be inducing Kozai oscillations
on the planet, explaining its high eccentricity. If this is the case and its
orbit was initially circular, the mass of the planet would need to be
1.5 \mj. This demonstrates that strong constraints on known planets
can be made using direct observations of otherwise undetectable long-period
companions.Comment: Corrected planet mass error (7.8 Mj --> 1.09 Mj, in agreement with
previous studies
DOPPLER MONITORING OF THE WASP-47 MULTIPLANET SYSTEM
We present precise Doppler observations of WASP-47, a transiting planetary system featuring a hot Jupiter with both inner and outer planetary companions. This system has an unusual architecture and also provides a rare opportunity to measure planet masses in two different ways: the Doppler method, and the analysis of transit-timing variations (TTV). Based on the new Doppler data, obtained with the Planet Finder Spectrograph on the Magellan/Clay 6.5 m telescope, the mass of the hot Jupiter is 370 ± 29[subscript ⊕]. This is consistent with the previous Doppler determination as well as the TTV determination. For the inner planet WASP-47e, the Doppler data lead to a mass of 12.2 ± 3.7[subscript ⊕], in agreement with the TTV-based upper limit of <22 M[subscript ⊕] (95% confidence). For the outer planet WASP-47d, the Doppler mass constraint of 10.4 ± 8.4[subscript ⊕] is consistent with the TTV-based measurement of $15.2[+6.7 over -7.6] M[subscript ⊕].United States. National Aeronautics and Space Administration (Origins Program Grant NNX11AG85G
Doppler monitoring of the WASP-47 multiplanet system
We present precise Doppler observations of WASP-47, a transiting planetary system featuring a hot Jupiter with both inner and outer planetary companions. This system has an unusual architecture and also provides a rare opportunity to measure planet masses in two different ways: the Doppler method, and the analysis of transit-timing variations (TTV). Based on the new Doppler data, obtained with the Planet Finder Spectrograph on the Magellan/Clay 6.5 m telescope, the mass of the hot Jupiter is 370+/- 29M⊕. This is consistent with the previous Doppler determination as well as the TTV determination. For the inner planet WASP-47e, the Doppler data lead to a mass of 12.2 +/-3.7 M⊕ in agreement with the TTV-based upper limit of <22 M⊕ (95% confidence). For the outer planet WASP-47d, the Doppler mass constraint of 10.4 +/- 8.4 M⊕ is consistent with the TTV-based measurement of 15.2 -7.6 to +6.7 M
Analysis of the 24-Hour Activity Cycle: An illustration examining the association with cognitive function in the Adult Changes in Thought (ACT) Study
The 24-hour activity cycle (24HAC) is a new paradigm for studying activity
behaviors in relation to health outcomes. This approach captures the
interrelatedness of the daily time spent in physical activity (PA), sedentary
behavior (SB), and sleep. We illustrate and compare the use of three popular
approaches, namely isotemporal substitution model (ISM), compositional data
analysis (CoDA), and latent profile analysis (LPA) for modeling outcome
associations with the 24HAC. We apply these approaches to assess an association
with a cognitive outcome, measured by CASI item response theory (IRT) score, in
a cohort of 1034 older adults (mean [range] age = 77 [65-100]; 55.8% female;
90% White) who were part of the Adult Changes in Thought (ACT) Activity
Monitoring (ACT-AM) sub-study. PA and SB were assessed with thigh-worn activPAL
accelerometers for 7 days. We highlight differences in assumptions between the
three approaches, discuss statistical challenges, and provide guidance on
interpretation and selecting an appropriate approach. ISM is easiest to apply
and interpret; however, the typical ISM model assumes a linear association.
CoDA specifies a non-linear association through isometric logratio
transformations that are more challenging to apply and interpret. LPA can
classify individuals into groups with similar time-use patterns. Inference on
associations of latent profiles with health outcomes need to account for the
uncertainty of the LPA classifications which is often ignored. The selection of
the most appropriate method should be guided by the scientific questions of
interest and the applicability of each model's assumptions. The analytic
results did not suggest that less time spent on SB and more in PA was
associated with better cognitive function. Further research is needed into the
health implications of the distinct 24HAC patterns identified in this cohort.Comment: 51 pages, 11 tables, 8 figure
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