1,813 research outputs found
An Introduction to Celestial Mechanics
Includes bibliography.Mode of access: Internet
Modeling Multi-Wavelength Stellar Astrometry. II. Determining Absolute Inclinations, Gravity Darkening Coefficients, and Spot Parameters of Single Stars with SIM Lite
We present a novel technique to determine the absolute inclination of single
stars using multi-wavelength sub-milliarcsecond astrometry. The technique
exploits the effect of gravity darkening, which causes a wavelength-dependent
astrometric displacement parallel to a star's projected rotation axis. We find
this effect is clearly detectable using SIM Lite for various giant stars and
rapid rotators, and present detailed models for multiple systems using the
REFLUX code. We also explore the multi-wavelength astrometric reflex motion
induced by spots on single stars. We find that it should be possible to
determine spot size, relative temperature, and some positional information for
both giant and nearby main-sequence stars utilizing multi-wavelength SIM Lite
data. This data will be extremely useful in stellar and exoplanet astrophysics,
as well as supporting the primary SIM Lite mission through proper
multi-wavelength calibration of the giant star astrometric reference frame, and
reduction of noise introduced by starspots when searching for extrasolar
planets.Comment: 8 pages, 7 figures, 4 tables. Accepted for publication in the
Astrophysical Journa
The Written Description Requirement
It is now well accepted that this provision of the 1952 Patent Act (Patent Act) includes a written description requirement that is separate and distinct from the enablement requirement. Thus, a specification may enable one of ordinary skill to make or use a claimed invention, but still not adequately describe the invention in a way that the public knows that the inventor was in possession of the claimed invention at the time of filing the application. For example, a patent specification that discloses various patterns of eight wooden shingles, does not necessarily provide written description for a claim amendment that recites “at least six shingles,” even though the specification would enable one so inclined to construct a panel of at least six wooden shingles. However, it was not entirely clear from the language of the Patent Act itself that there was a written description requirement separate and distinct from the enablement requirement. The well-accepted understanding that these are separate and distinct requirements flows from judicial decisions, and not the text of the Patent Act itself
Shrinking binary and planetary orbits by Kozai cycles with tidal friction
At least two arguments suggest that the orbits of a large fraction of binary
stars and extrasolar planets shrank by 1-2 orders of magnitude after formation:
(i) the physical radius of a star shrinks by a large factor from birth to the
main sequence, yet many main-sequence stars have companions orbiting only a few
stellar radii away, and (ii) in current theories of planet formation, the
region within ~0.1 AU of a protostar is too hot and rarefied for a Jupiter-mass
planet to form, yet many "hot Jupiters" are observed at such distances. We
investigate orbital shrinkage by the combined effects of secular perturbations
from a distant companion star (Kozai oscillations) and tidal friction. We
integrate the relevant equations of motion to predict the distribution of
orbital elements produced by this process. Binary stars with orbital periods of
0.1 to 10 days, with a median of ~2 d, are produced from binaries with much
longer periods (10 d to 10^5 d), consistent with observations indicating that
most or all short-period binaries have distant companions (tertiaries). We also
make two new testable predictions: (1) For periods between 3 and 10 d, the
distribution of the mutual inclination between the inner binary and the
tertiary orbit should peak strongly near 40 deg and 140 deg. (2) Extrasolar
planets whose host stars have a distant binary companion may also undergo this
process, in which case the orbit of the resulting hot Jupiter will typically be
misaligned with the equator of its host star.Comment: Submitted to ApJ; 18 pages, 10 figure
Observability of the General Relativistic Precession of Periastra in Exoplanets
The general relativistic precession rate of periastra in close-in exoplanets
can be orders of magnitude larger than the magnitude of the same effect for
Mercury. The realization that some of the close-in exoplanets have significant
eccentricities raises the possibility that this precession might be detectable.
We explore in this work the observability of the periastra precession using
radial velocity and transit light curve observations. Our analysis is
independent of the source of precession, which can also have significant
contributions due to additional planets and tidal deformations. We find that
precession of the periastra of the magnitude expected from general relativity
can be detectable in timescales of <~ 10 years with current observational
capabilities by measuring the change in the primary transit duration or in the
time difference between primary and secondary transits. Radial velocity curves
alone would be able to detect this precession for super-massive, close-in
exoplanets orbiting inactive stars if they have ~100 datapoints at each of two
epochs separated by ~20 years. We show that the contribution to the precession
by tidal deformations may dominate the total precession in cases where the
relativistic precession is detectable. Studies of transit durations with Kepler
might need to take into account effects arising from the general relativistic
and tidal induced precession of periastra for systems containing close-in,
eccentric exoplanets. Such studies may be able to detect additional planets
with masses comparable to that of Earth by detecting secular variations in the
transit duration induced by the changing longitude of periastron.Comment: 13 pages, 5 figures. Accepted for publication in Ap
On a new observable for measuring the Lense-Thirring effect with Satellite Laser Ranging
In this paper we present a rather extensive error budget for the difference
of the perigees of a pair of supplementary SLR satellites aimed to the
detection of the Lense-Thirring effect.Comment: LaTex2e, 14 pages, 1 table, no figures. Some changes and additions to
the abstract, Introduction and Conclusions. References updated, typos
corrected. Equation corrected. To appear in General Relativity and
Gravitatio
An exploratory study looking at the relationship marketing techniques used in the music festival industry
There are current issues and trends in the music festival
market, which may affect the success of an event, and market saturation
is at the forefront of these issues. Previous literature, maintaining
the need for a marketing approach to festivals, identifi es the need
for maintaining strong stakeholder relationships in order to succeed
in a business environment; attention has been focused to the theory
of relationship marketing (RM) because of the recognition that this
practice is complementary to the marketing of festivals. The very nature
of the music festival as an annual, usually, 4-day event means that
effective marketing is needed to keep connections with the consumer
throughout the year. This article focuses on the RM techniques
utilised within the music festival industry from the viewpoint of the
festival organiser in an attempt to establish how festival organisations
value and monitor organisational relationships. This article explores
the extent to which these relationships are valued and managed;
furthermore, the variations between these intricate relationships
are considered by focusing on those held with the organisation ’ s
consumers and sponsors, the results of which have provided the
ability to establish the importance and relevance of RM to the industry
and further identify the marketing communication methods employed
to establish and maintain such relationships. In-depth, convergent
interviews have been conducted with a segment of music festival
organisers from a range of events. The results have been integrated
with the study of current literature to best exemplify these issues. It
has been established that RM has a strong role in today ’ s commercial
and independent music festival industry; technological advances are
enabling the organiser to support online relationships further and
increase consumer loyalty. There is a need to expand the research
further because of the complexity of organisational relationships and
the varying categories of festivals
Association Between Risk-of-Bias Assessments and Results of Randomized Trials in Cochrane Reviews: The ROBES Meta-Epidemiologic Study.
Flaws in the design of randomized trials may bias intervention effect estimates and increase between-trial heterogeneity. Empirical evidence suggests that these problems are greatest for subjectively assessed outcomes. For the Risk of Bias in Evidence Synthesis (ROBES) Study, we extracted risk-of-bias judgements (for sequence generation, allocation concealment, blinding, and incomplete data) from a large collection of meta-analyses published in the Cochrane Library (issue 4; April 2011). We categorized outcome measures as mortality, other objective outcome, or subjective outcome, and we estimated associations of bias judgements with intervention effect estimates using Bayesian hierarchical models. Among 2,443 randomized trials in 228 meta-analyses, intervention effect estimates were, on average, exaggerated in trials with high or unclear (versus low) risk-of-bias judgements for sequence generation (ratio of odds ratios (ROR) = 0.91, 95% credible interval (CrI): 0.86, 0.98), allocation concealment (ROR = 0.92, 95% CrI: 0.86, 0.98), and blinding (ROR = 0.87, 95% CrI: 0.80, 0.93). In contrast to previous work, we did not observe consistently different bias for subjective outcomes compared with mortality. However, we found an increase in between-trial heterogeneity associated with lack of blinding in meta-analyses with subjective outcomes. Inconsistency in criteria for risk-of-bias judgements applied by individual reviewers is a likely limitation of routinely collected bias assessments. Inadequate randomization and lack of blinding may lead to exaggeration of intervention effect estimates in randomized trials
Differences in access and patient outcomes across antiretroviral treatment clinics in the Free State province: A prospective cohort study
Objective. To assess differences in access to antiretroviral treatment (ART) and patient outcomes across public sector treatment facilities in the Free State province, South Africa. Design. Prospective cohort study with retrospective database linkage. We analysed data on patients enrolled in the treatment programme across 36 facilities between May 2004 and December 2007, and assessed percentage initiating ART and percentage dead at 1 year after enrolment. Multivariable logistic regression was used to estimate associations of facility-level and patient-level characteristics with both mortality and treatment status. Results. Of 44 866 patients enrolled, 15 219 initiated treatment within 1 year; 8 778 died within 1 year, 7 286 before accessing ART. Outcomes at 1 year varied greatly across facilities and more variability was explained by facility-level factors than by patient-level factors. The odds of starting treatment within 1 year improved over calendar time. Patients enrolled in facilities with treatment initiation available on site had higher odds of starting treatment and lower odds of death at 1 year compared with those enrolled in facilities that did not offer treatment initiation. Patients were less likely to start treatment if they were male, severely immunosuppressed (CD4 count ≤50 cells/μl), or underweight
- …