2,895 research outputs found
A Strategy for Efficiently Collecting Aerosol Condensate Using Silica Fibers: Application to Carbonyl Emissions from E-Cigarettes
Analyzing harmful constituents in e-cigarette aerosols typically involves adopting a methodology used for analyzing tobacco smoke. Cambridge filter pads (CFP) are the basis of numerous protocols for analyzing the various classes of compounds representing 93 harmful and potentially harmful constituents identified in tobacco smoke by the FDA. This paper describes a simplified method for trapping the low volatility components of e-cigarette aerosols using a single trapping procedure followed by physical extraction. The trap is a plug of amorphous silica fibers (0.75 g of 4 Όm diameter) within a 10 mL syringe inserted between the e-cigarette mouthpiece and the pump of the vaping machine. The method is evaluated for emissions from three generations of e-cigarette device (Kangertech CE4, EVOD, and Subox Mini-C). On average, the silica wool traps about 94% of the vaporized liquid mass in the three devices and higher levels of condensate is retained before reaching saturation compared with CFP. The condensate is then physically extracted from the silica wool plug using a centrifuge. Condensate is then available for use directly in multiple analytical procedures or toxicological experiments. The method is tested by comparison with published analyses of carbonyls, among the most potent toxicants and carcinogens in e-cigarette emissions. Ranges for HPLC-DAD analyses of carbonyl-DNPH derivatives in a laboratory formulation of e-liquid are formaldehyde (0.182 ± 0.023 to 9.896 ± 0.709 Όg puff-1), acetaldehyde (0.059 ± 0.005 to 0.791 ± 0.073 Όg puff-1), and propionaldehyde (0.008 ± 0.0001 to 0.033 ± 0.023 Όg puff-1); other carbonyls are identified and quantified. Carbonyl concentrations are also consistent with published experiments showing marked increases with variable power settings (10W to 50W). Compared with CFPs, e-cigarette aerosol collection by silica wool requires only one vaping session for multiple analyte groups, traps more condensate per puff, and collects more condensate before saturation
One size doesnât fit all: the influence of supervisorsâ power tactics and subordinatesâ need for cognitive closure on burnout and stress
The present research investigated the notion of fit between supervisorsâ power tactics and subordinatesâ need for cognitive closure (NFCC) on subordinatesâ burnout and stress. Subordinates who tend to avoid ambiguity (high NFCC) were expected to experience relatively less burnout (Study 1) and stress (Study 2) if their supervisors utilize harsh (controlling and unequivocal) power tactics and more burnout and stress if their supervisors utilize soft (autonomy-supportive and equivocal) power tactics. In contrast, it was expected that subordinates who avoid firm and binding conclusions (low NFCC) would experience relatively less burnout and stress if their supervisors use soft power tactics and more burnout and stress if they use harsh power tactics. Two studies conducted in diverse organizational settings supported these hypotheses. Collectively, these results support the conclusion that soft (vs. harsh) power tactics are not always associated with better (vs. worse) organizational outcomes. Theoretical and practical implications for organizations are discussed
Multiphysics simulation of corona discharge induced ionic wind
Ionic wind devices or electrostatic fluid accelerators are becoming of
increasing interest as tools for thermal management, in particular for
semiconductor devices. In this work, we present a numerical model for
predicting the performance of such devices, whose main benefit is the ability
to accurately predict the amount of charge injected at the corona electrode.
Our multiphysics numerical model consists of a highly nonlinear strongly
coupled set of PDEs including the Navier-Stokes equations for fluid flow,
Poisson's equation for electrostatic potential, charge continuity and heat
transfer equations. To solve this system we employ a staggered solution
algorithm that generalizes Gummel's algorithm for charge transport in
semiconductors. Predictions of our simulations are validated by comparison with
experimental measurements and are shown to closely match. Finally, our
simulation tool is used to estimate the effectiveness of the design of an
electrohydrodynamic cooling apparatus for power electronics applications.Comment: 24 pages, 17 figure
HAT-P-49b: A 1.7 M_J Planet Transiting a Bright 1.5 M_S F-Star
We report the discovery of the transiting extrasolar planet HAT-P-49b. The
planet transits the bright (V = 10.3) slightly evolved F-star HD 340099 with a
mass of 1.54M_S and a radius of 1.83 R_S. HAT-P-49b is orbiting one of the 25
brightest stars to host a transiting planet which makes this a favorable
candidate for detailed follow-up. This system is an especially strong target
for Rossiter- McLaughlin follow-up due to the fast rotation of the host star,
16 km/s. The planetary companion has a period of 2.6915 d, mass of 1.73 M_J and
radius of 1.41 R_J. The planetary characteristics are consistent with that of a
classical hot Jupiter but we note that this is the fourth most massive star to
host a transiting planet with both M_p and R_p well determined.Comment: Accepted to the Astronomical Journa
HAT-P-55b: A Hot Jupiter Transiting a Sun-like Star
We report the discovery of a new transiting extrasolar planet, HAT-P-55b. The
planet orbits a V = 13.207 +/- 0.039 sun-like star with a mass of 1.013 +/-
0.037 solar masses, a radius of 1.011 +/- 0.036 solar radii and a metallicity
of -0.03 +/- 0.08. The planet itself is a typical hot Jupiter with a period of
3.5852467 +/- 0.0000064 days, a mass of 0.582 +/- 0.056 Jupiter masses and a
radius of 1.182 +/- 0.055 Jupiter radii. This discovery adds to the increasing
sample of transiting planets with measured bulk densities, which is needed to
put constraints on models of planetary structure and formation theories.Comment: 7 pages, 4 figures, accepted for publication in PAS
HAT-P-57b: A Short-Period Giant Planet Transiting A Bright Rapidly Rotating A8V Star Confirmed Via Doppler Tomography
We present the discovery of HAT-P-57b, a P = 2.4653 day transiting planet
around a V = 10.465 +- 0.029 mag, Teff = 7500 +- 250 K main sequence A8V star
with a projected rotation velocity of v sin i = 102.1 +- 1.3 km s^-1. We
measure the radius of the planet to be R = 1.413 +- 0.054 R_J and, based on RV
observations, place a 95% confidence upper limit on its mass of M < 1.85 M_J .
Based on theoretical stellar evolution models, the host star has a mass and
radius of 1.47 +- 0.12 M_sun, and 1.500 +- 0.050 R_sun, respectively.
Spectroscopic observations made with Keck-I/HIRES during a partial transit
event show the Doppler shadow of HAT-P-57b moving across the average spectral
line profile of HAT-P- 57, confirming the object as a planetary system. We use
these observations, together with analytic formulae that we derive for the line
profile distortions, to determine the projected angle between the spin axis of
HAT-P-57 and the orbital axis of HAT-P-57b. The data permit two possible
solutions, with -16.7 deg < lambda < 3.3 deg or 27.6 deg < lambda < 57.4 deg at
95% confidence, and with relative probabilities for the two modes of 26% and
74%, respectively. Adaptive optics imaging with MMT/Clio2 reveals an object
located 2.7" from HAT-P-57 consisting of two point sources separated in turn
from each other by 0.22". The H and L -band magnitudes of the companion stars
are consistent with their being physically associated with HAT-P-57, in which
case they are stars of mass 0.61 +- 0.10 M_sun and 0.53 +- 0.08 M_sun. HAT-P-57
is the most rapidly rotating star, and only the fourth main sequence A star,
known to host a transiting planet.Comment: 18 pages, 14 figures, 5 tables, accepted for publication in A
HAT-P-44b, HAT-P-45b, and HAT-P-46b: Three Transiting Hot Jupiters in Possible Multi-Planet Systems
We report the discovery by the HATNet survey of three new transiting
extrasolar planets orbiting moderately bright (V=13.2, 12.8 and 11.9) stars.
The planets have orbital periods of 4.3012, 3.1290, and 4.4631 days, masses of
0.39, 0.89, and 0.49 Mjup, and radii of 1.28, 1.43, and 1.28 Rjup. The stellar
hosts have masses of 0.94, 1.26, and 1.28 Msun. Each system shows significant
systematic variations in its residual radial velocities indicating the possible
presence of additional components. Based on its Bayesian evidence, the
preferred model for HAT-P-44 consists of two planets, including the transiting
component, with the outer planet having a period of 220 d and a minimum mass of
1.6 Mjup. Due to aliasing we cannot rule out an alternative solution for the
outer planet having a period of 438 d and a minimum mass of 3.7 Mjup. For
HAT-P-45 at present there is not enough data to justify the additional free
parameters included in a multi-planet model, in this case a single-planet
solution is preferred, but the required jitter of 22.5 +- 6.3 m/s is relatively
high for a star of this type. For HAT-P-46 the preferred solution includes a
second planet having a period of 78 d and a minimum mass of 2.0 Mjup, however
the preference for this model over a single-planet model is not very strong.
While substantial uncertainties remain as to the presence and/or properties of
the outer planetary companions in these systems, the inner transiting planets
are well characterized with measured properties that are fairly robust against
changes in the assumed models for the outer planets. Continued RV monitoring is
necessary to fully characterize these three planetary systems, the properties
of which may have important implications for understanding the formation of hot
Jupiters.Comment: 21 pages, 10 figures, 14 tables, submitted to A
HAT-P-56b: An inflated massive Hot Jupiter transiting a bright F star followed up with K2 Campaign 0 observations
We report the discovery of HAT-P-56b by the HATNet survey, an inflated hot
Jupiter transiting a bright F type star in Field 0 of NASA's K2 mission. We
combine ground-based discovery and follow-up light curves with high precision
photometry from K2, as well as ground-based radial velocities from TRES on the
FLWO 1.5m telescope to determine the physical properties of this system.
HAT-P-56b has a mass of , radius of , and transits its host
star on a near-grazing orbit with a period of 2.7908 d. The radius of HAT-P-56b
is among the largest known for a planet with . The host star has a
V-band magnitude of 10.9, mass of 1.30 , and radius of 1.43 .
The periodogram of the K2 light curve suggests the star is a Dor
variable. HAT-P-56b is an example of a ground-based discovery of a transiting
planet, where space-based observations greatly improve the confidence in the
confirmation of its planetary nature, and also improve the accuracy of the
planetary parameters.Comment: 13 pages, 11 figures, accepted by A
Automated optical identification of a large complete northern hemisphere sample of flat spectrum radio sources with S_6cm > 200 mJy
This paper describes the automated optical APM identification of radio
sources from the Jodrell Bank - VLA Astrometric Survey (JVAS), as used for the
search for distant radio-loud quasars. The sample has been used to investigate
possible relations between optical and radio properties of flat spectrum radio
sources. From the 915 sources in the sample, 756 have an optical APM
identification at a red (e) and/or blue (o) plate,resulting in an
identification fraction of 83% with a completeness and reliability of 98% and
99% respectively. About 20% are optically identified with extended APM objects
on the red plates, e.g. galaxies. However the distinction between galaxies and
quasars can not be done properly near the magnitude limit of the POSS-I plates.
The identification fraction appears to decrease from >90% for sources with a 5
GHz flux density of >1 Jy, to <80% for sources at 0.2 Jy. The identification
fraction, in particular that for unresolved quasars, is found to be lower for
sources with steeper radio spectra. In agreement with previous studies, we find
that the quasars at low radio flux density levels also tend to have fainter
optical magnitudes, although there is a large spread. In addition, objects with
a steep radio-to-optical spectral index are found to be mainly highly polarised
quasars, supporting the idea that in these objects the polarised synchrotron
component is more prominent. It is shown that the large spread in
radio-to-optical spectral index is possibly caused by source to source
variations in the Doppler boosting of the synchrotron component [Abridged].Comment: LaTex, 17 pages, 5 gif figures, 4 tables. Accepted for publication in
MNRAS. High resolution figures can be found at http://www.roe.ac.uk/~ignas
HAT-P-50b, HAT-P-51b, HAT-P-52b, and HAT-P-53b: Three Transiting Hot Jupiters and a Transiting Hot Saturn From the HATNet Survey
We report the discovery and characterization of four transiting exoplanets by
the HATNet survey. The planet HAT-P-50b has a mass of 1.35 M_J and a radius of
1.29 R_J, and orbits a bright (V = 11.8 mag) M = 1.27 M_sun, R = 1.70 R_sun
star every P = 3.1220 days. The planet HAT-P-51b has a mass of 0.31 M_J and a
radius of 1.29 R_J, and orbits a V = 13.4 mag, M = 0.98 M_sun, R = 1.04 R_sun
star with a period of P = 4.2180 days. The planet HAT-P-52b has a mass of 0.82
M_J and a radius of 1.01 R_J, and orbits a V = 14.1 mag, M = 0.89 M_sun, R =
0.89 R_sun star with a period of P = 2.7536 days. The planet HAT-P-53b has a
mass of 1.48 M_J and a radius of 1.32 R_J, and orbits a V = 13.7 mag, M = 1.09
M_sun, R = 1.21 R_sun star with a period of P = 1.9616 days. All four planets
are consistent with having circular orbits and have masses and radii measured
to better than 10% precision. The low stellar jitter and favorable R_P/R_star
ratio for HAT-P-51 make it a promising target for measuring the
Rossiter-McLaughlin effect for a Saturn-mass planet.Comment: Submitted to AJ. 20 pages, 9 figures, 5 tables. Data available at
http://hatnet.org
- âŠ