2,494 research outputs found
Theoretical Elastic Stress Distributions Arising from Discontinuities and Edge Loads in Several Shell-Type Structures
The deformation and complete stress distribution are determined for each of the following edge loaded thin shells of revolution: (1) a right circular cylinder, (2) a frustum of a right circular cone, and (3) a portion of a sphere. The locations of the maximum circumferential and meridional stresses on both the inner and outer surfaces are also found. The basic equations for the above were selected from the published literature on the subject and expanded to produce to resultant-stress equations in closed from where practicable to do so. Equations are also developed for the discontinuity shear force and bending moment at each of the following junction: (1) axial change of thickness in a circular cylinder, (2) axial change of thickness in a cone, (3) change of thickness in a portion of a sphere, (4) a cylinder and a cone, (5) a cylinder and a portion of a sphere(6) a cylinder and a flat head, and (7) a cone and a portion of a sphere
An Expert System Approach to Audit Planning and Evaluation in the Belief-Function Framework
This is the author's final draft. The publisher's version is available from:
Intrinsic Optical and Electronic Properties from Quantitative Analysis of Plasmonic Semiconductor Nanocrystal Ensemble Optical Extinction
The optical extinction spectra arising from localized surface plasmon
resonance in doped semiconductor nanocrystals (NCs) have intensities and
lineshapes determined by free charge carrier concentrations and the various
mechanisms for damping the oscillation of those free carriers. However, these
intrinsic properties are convoluted by heterogeneous broadening when measuring
spectra of ensembles. We reveal that the traditional Drude approximation is not
equipped to fit spectra from a heterogeneous ensemble of doped semiconductor
NCs and produces fit results that violate Mie scattering theory. The
heterogeneous ensemble Drude approximation (HEDA) model rectifies this issue by
accounting for ensemble heterogeneity and near-surface depletion. The HEDA
model is applied to tin-doped indium oxide NCs for a range of sizes and doping
levels but we expect it can be employed for any isotropic plasmonic particles
in the quasistatic regime. It captures individual NC optical properties and
their contributions to the ensemble spectra thereby enabling the analysis of
intrinsic NC properties from an ensemble measurement. Quality factors for the
average NC in each ensemble are quantified and found to be notably higher than
those of the ensemble. Carrier mobility and conductivity derived from HEDA fits
matches that measured in the bulk thin film literature
The declining representativeness of the British party system, and why it matters
In a recent article, Michael Laver has explained âWhy Vote-Seeking Parties May Make Voters Miserableâ. His model shows that, while ideological convergence may boost congruence between governments and the median voter, it can reduce congruence between the party system and the electorate as a whole. Specifically, convergence can increase the mean distance between voters and their nearest party. In this article we show that this captures the reality of todayâs British party system. Policy scale placements in British Election Studies from 1987 to 2010 confirm that the pronounced convergence during the past decade has left the Conservatives and Labour closer together than would be optimal in terms of minimising the policy distance between the average voter and the nearest major party. We go on to demonstrate that this comes at a cost. Respondents who perceive themselves as further away from one of the major parties in the system tend to score lower on satisfaction with democracy. In short, vote-seeking parties have left the British party system less representative of the ideological diversity in the electorate, and thus made at least some British voters miserable
HATNet Field G205: Follow-Up Observations of 28 Transiting-Planet candidates and Confirmation of the Planet HAT-P-8b
We report the identification of 32 transiting-planet candidates in HATNet
field G205. We describe the procedures that we have used to follow up these
candidates with spectroscopic and photometric observations, and we present a
status report on our interpretation of the 28 candidates for which we have
follow-up observations. Eight are eclipsing binaries with orbital solutions
whose periods are consistent with their photometric ephemerides; two of these
spectroscopic orbits are singled-lined and six are double-lined. For one of the
candidates, a nearby but fainter eclipsing binary proved to be the source for
the HATNet light curve, due to blending in the HATNet images. Four of the
candidates were found to be rotating more rapidly than vsini = 50 km/s and were
not pursued further. Thirteen of the candidates showed no significant velocity
variation at the level of 0.5 to 1.0 km/s . Seven of these were eventually
withdrawn as photometric false alarms based on an independent reanalysis using
more sophisticated tools. Of the remaining six, one was put aside because a
close visual companion proved to be a spectroscopic binary, and two were not
followed up because the host stars were judged to be too large. Two of the
remaining candidates are members of a visual binary, one of which was
previously confirmed as the first HATNet transiting planet, HAT-P-1b. In this
paper we confirm that the last of this set of candidates is also a a transiting
planet, which we designate HAT-P-8b, with mass Mp = 1.52 +/- 0.18/0.16 Mjup,
radius Rp = 1.50 +/- 0.08/0.06 Rjup, and photometric period P = 3.076320 +/-
0.000004 days. HAT-P-8b has an inflated radius for its mass, and a large mass
for its period. The host star is a solar-metallicity F dwarf, with mass M* =
1.28 +/- 0.04 Msun and Rp = 1.58 +/- 0.08/0.06 Rsun.Comment: 16 pages, 6 figures, 13 table
Refined stellar, orbital and planetary parameters of the eccentric HAT-P-2 planetary system
We present refined parameters for the extrasolar planetary system HAT-P-2
(also known as HD 147506), based on new radial velocity and photometric data.
HAT-P-2b is a transiting extrasolar planet that exhibits an eccentric orbit. We
present a detailed analysis of the planetary and stellar parameters, yielding
consistent results for the mass and radius of the star, better constraints on
the orbital eccentricity, and refined planetary parameters. The improved
parameters for the host star are M_star = 1.36 +/- 0.04 M_sun and R_star = 1.64
+/- 0.08 R_sun, while the planet has a mass of M_p = 9.09 +/- 0.24 M_Jup and
radius of R_p = 1.16 +/- 0.08 R_Jup. The refined transit epoch and period for
the planet are E = 2,454,387.49375 +/- 0.00074 (BJD) and P = 5.6334729 +/-
0.0000061 (days), and the orbital eccentricity and argument of periastron are e
= 0.5171 +/- 0.0033 and omega = 185.22 +/- 0.95 degrees. These orbital elements
allow us to predict the timings of secondary eclipses with a reasonable
accuracy of ~15 minutes. We also discuss the effects of this significant
eccentricity including the characterization of the asymmetry in the transit
light curve. Simple formulae are presented for the above, and these, in turn,
can be used to constrain the orbital eccentricity using purely photometric
data. These will be particularly useful for very high precision, space-borne
observations of transiting planets.Comment: Revised version, accepted for publication in MNRAS, 11 pages, 6
figure
Effect of mammographic screening from age 40 years on breast cancer mortality (UK Age trial):final results of a randomised, controlled trial
Copyright © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.BACKGROUND: The appropriate age range for breast cancer screening remains a matter of debate. We aimed to estimate the effect of mammographic screening at ages 40-48 years on breast cancer mortality. METHODS: We did a randomised, controlled trial involving 23 breast screening units across Great Britain. We randomly assigned women aged 39-41 years, using individual randomisation, stratified by general practice, in a 1:2 ratio, to yearly mammographic screening from the year of inclusion in the trial up to and including the calendar year that they reached age 48 years (intervention group), or to standard care of no screening until the invitation to their first National Health Service Breast Screening Programme (NHSBSP) screen at approximately age 50 years (control group). Women in the intervention group were recruited by postal invitation. Women in the control group were unaware of the study. The primary endpoint was mortality from breast cancers (with breast cancer coded as the underlying cause of death) diagnosed during the intervention period, before the participant's first NHSBSP screen. To study the timing of the mortality effect, we analysed the results in different follow-up periods. Women were included in the primary comparison regardless of compliance with randomisation status (intention-to-treat analysis). This Article reports on long-term follow-up analysis. The trial is registered with the ISRCTN registry, ISRCTN24647151. FINDINGS: 160â921 women were recruited between Oct 14, 1990, and Sept 24, 1997. 53â883 women (33·5%) were randomly assigned to the intervention group and 106â953 (66·5%) to the control group. Between randomisation and Feb 28, 2017, women were followed up for a median of 22·8 years (IQR 21·8-24·0). We observed a significant reduction in breast cancer mortality at 10 years of follow-up, with 83 breast cancer deaths in the intervention group versus 219 in the control group (relative rate [RR] 0·75 [95% CI 0·58-0·97]; p=0·029). No significant reduction was observed thereafter, with 126 deaths versus 255 deaths occurring after more than 10 years of follow-up (RR 0·98 [0·79-1·22]; p=0·86). INTERPRETATION: Yearly mammography before age 50 years, commencing at age 40 or 41 years, was associated with a relative reduction in breast cancer mortality, which was attenuated after 10 years, although the absolute reduction remained constant. Reducing the lower age limit for screening from 50 to 40 years could potentially reduce breast cancer mortality. FUNDING: National Institute for Health Research Health Technology Assessment programme.Peer reviewe
The Transit Ingress and the Tilted Orbit of the Extraordinarily Eccentric Exoplanet HD 80606b
We present the results of a transcontinental campaign to observe the 2009
June 5 transit of the exoplanet HD 80606b. We report the first detection of the
transit ingress, revealing the transit duration to be 11.64 +/- 0.25 hr and
allowing more robust determinations of the system parameters. Keck spectra
obtained at midtransit exhibit an anomalous blueshift, giving definitive
evidence that the stellar spin axis and planetary orbital axis are misaligned.
The Keck data show that the projected spin-orbit angle is between 32-87 deg
with 68.3% confidence and between 14-142 deg with 99.73% confidence. Thus the
orbit of this planet is not only highly eccentric (e=0.93), but is also tilted
away from the equatorial plane of its parent star. A large tilt had been
predicted, based on the idea that the planet's eccentric orbit was caused by
the Kozai mechanism. Independently of the theory, it is noteworthy that all 3
exoplanetary systems with known spin-orbit misalignments have massive planets
on eccentric orbits, suggesting that those systems migrate differently than
lower-mass planets on circular orbits.Comment: ApJ, in press [13 pg
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