1,041 research outputs found
The Rossiter-McLaughlin effect in Exoplanet Research
The Rossiter-McLaughlin effect occurs during a planet's transit. It provides
the main means of measuring the sky-projected spin-orbit angle between a
planet's orbital plane, and its host star's equatorial plane. Observing the
Rossiter-McLaughlin effect is now a near routine procedure. It is an important
element in the orbital characterisation of transiting exoplanets. Measurements
of the spin-orbit angle have revealed a surprising diversity, far from the
placid, Kantian and Laplacian ideals, whereby planets form, and remain, on
orbital planes coincident with their star's equator. This chapter will review a
short history of the Rossiter-McLaughlin effect, how it is modelled, and will
summarise the current state of the field before describing other uses for a
spectroscopic transit, and alternative methods of measuring the spin-orbit
angle.Comment: Review to appear as a chapter in the "Handbook of Exoplanets", ed. H.
Deeg & J.A. Belmont
Learning Interpretable Rules for Multi-label Classification
Multi-label classification (MLC) is a supervised learning problem in which,
contrary to standard multiclass classification, an instance can be associated
with several class labels simultaneously. In this chapter, we advocate a
rule-based approach to multi-label classification. Rule learning algorithms are
often employed when one is not only interested in accurate predictions, but
also requires an interpretable theory that can be understood, analyzed, and
qualitatively evaluated by domain experts. Ideally, by revealing patterns and
regularities contained in the data, a rule-based theory yields new insights in
the application domain. Recently, several authors have started to investigate
how rule-based models can be used for modeling multi-label data. Discussing
this task in detail, we highlight some of the problems that make rule learning
considerably more challenging for MLC than for conventional classification.
While mainly focusing on our own previous work, we also provide a short
overview of related work in this area.Comment: Preprint version. To appear in: Explainable and Interpretable Models
in Computer Vision and Machine Learning. The Springer Series on Challenges in
Machine Learning. Springer (2018). See
http://www.ke.tu-darmstadt.de/bibtex/publications/show/3077 for further
informatio
Transit Photometry as an Exoplanet Discovery Method
Photometry with the transit method has arguably been the most successful
exoplanet discovery method to date. A short overview about the rise of that
method to its present status is given. The method's strength is the rich set of
parameters that can be obtained from transiting planets, in particular in
combination with radial velocity observations; the basic principles of these
parameters are given. The method has however also drawbacks, which are the low
probability that transits appear in randomly oriented planet systems, and the
presence of astrophysical phenomena that may mimic transits and give rise to
false detection positives. In the second part we outline the main factors that
determine the design of transit surveys, such as the size of the survey sample,
the temporal coverage, the detection precision, the sample brightness and the
methods to extract transit events from observed light curves. Lastly, an
overview over past, current and future transit surveys is given. For these
surveys we indicate their basic instrument configuration and their planet
catch, including the ranges of planet sizes and stellar magnitudes that were
encountered. Current and future transit detection experiments concentrate
primarily on bright or special targets, and we expect that the transit method
remains a principal driver of exoplanet science, through new discoveries to be
made and through the development of new generations of instruments.Comment: Review chapte
Moderate and heavy metabolic stress interval training improve arterial stiffness and heart rate dynamics in humans
Traditional continuous aerobic exercise training attenuates age-related increases of arterial stiffness, however, training studies have not determined whether metabolic stress impacts these favourable effects. Twenty untrained healthy participants (n = 11 heavy metabolic stress interval training, n = 9 moderate metabolic stress interval training) completed 6 weeks of moderate or heavy intensity interval training matched for total work and exercise duration. Carotid artery stiffness, blood pressure contour analysis, and linear and non-linear heart rate variability were assessed before and following training. Overall, carotid arterial stiffness was reduced (p 0.05). This study demonstrates the effectiveness of interval training at improving arterial stiffness and autonomic function, however, the metabolic stress was not a mediator of this effect. In addition, these changes were also independent of improvements in aerobic capacity, which were only induced by training that involved a high metabolic stress
Yes, research can inform health policy; but can we bridge the 'Do-Knowing It's Been Done' gap?
Copyright @ 2011 Hanney and Gonzalez.Provisional Abstract: This editorial introduces a new Supplement in Health Research Policy and Systems and highlighs the importance of assessing the impact of health research by examining whether we can move from 'Know-Do' to 'Do-Knowing It's Been Done'This article is made available through the Brunel Open Access publishing fund
The signature of orbital motion from the dayside of the planet tau Bootis b
The giant planet orbiting tau Bootis was among the first extrasolar planets
to be discovered through the reflex motion of its host star. It is one of the
brightest known and most nearby planets with an orbital period of just a few
days. Over the course of more than a decade, measurements of its orbital
inclination have been announced and refuted, and have subsequently remained
elusive until now. Here we report on the detection of carbon monoxide
absorption in the thermal day-side spectrum of tau Bootis b. At a spectral
resolution of R~100,000, we trace the change in the radial velocity of the
planet over a large range in phase, determining an orbital inclination of
i=44.5+-1.5 degrees and a true planet mass of 5.95+-0.28 MJup. This result
extends atmospheric characterisation to non-transiting planets. The strong
absorption signal points to an atmosphere with a temperature that is decreasing
towards higher altitudes. This is a stark contrast to the temperature inversion
invoked for other highly irradiated planets, and supports models in which the
absorbing compounds believed to cause such atmospheric inversions are destroyed
by the ultraviolet emission from the active host star.Comment: To appear in the June 28 issue of Nature: main article +
supplementary informatio
SPECULOOS exoplanet search and its prototype on TRAPPIST
One of the most significant goals of modern science is establishing whether
life exists around other suns. The most direct path towards its achievement is
the detection and atmospheric characterization of terrestrial exoplanets with
potentially habitable surface conditions. The nearest ultracool dwarfs (UCDs),
i.e. very-low-mass stars and brown dwarfs with effective temperatures lower
than 2700 K, represent a unique opportunity to reach this goal within the next
decade. The potential of the transit method for detecting potentially habitable
Earth-sized planets around these objects is drastically increased compared to
Earth-Sun analogs. Furthermore, only a terrestrial planet transiting a nearby
UCD would be amenable for a thorough atmospheric characterization, including
the search for possible biosignatures, with near-future facilities such as the
James Webb Space Telescope. In this chapter, we first describe the physical
properties of UCDs as well as the unique potential they offer for the detection
of potentially habitable Earth-sized planets suitable for atmospheric
characterization. Then, we present the SPECULOOS ground-based transit survey,
that will search for Earth-sized planets transiting the nearest UCDs, as well
as its prototype survey on the TRAPPIST telescopes. We conclude by discussing
the prospects offered by the recent detection by this prototype survey of a
system of seven temperate Earth-sized planets transiting a nearby UCD,
TRAPPIST-1.Comment: Submitted as a chapter in the "Handbook of Exoplanets" (editors: H.
Deeg & J.A. Belmonte; Section Editor: N. Narita). 16 pages, 4 figure
Efficient Performance of Electrostatic Spray-Deposited TiO2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation
A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm-2) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm-2). When SHI irradiation of oxygen ions of fluence 1 × 1013 ions/cm2 was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs
A description of a knowledge broker role implemented as part of a randomized controlled trial evaluating three knowledge translation strategies
<p>Abstract</p> <p>Background</p> <p>A knowledge broker (KB) is a popular knowledge translation and exchange (KTE) strategy emerging in Canada to promote interaction between researchers and end users, as well as to develop capacity for evidence-informed decision making. A KB provides a link between research producers and end users by developing a mutual understanding of goals and cultures, collaborates with end users to identify issues and problems for which solutions are required, and facilitates the identification, access, assessment, interpretation, and translation of research evidence into local policy and practice. Knowledge-brokering can be carried out by individuals, groups and/or organizations, as well as entire countries. In each case, the KB is linked with a group of end users and focuses on promoting the integration of the best available evidence into policy and practice-related decisions.</p> <p>Methods</p> <p>A KB intervention comprised one of three KTE interventions evaluated in a randomized controlled trial.</p> <p>Results</p> <p>KB activities were classified into the following categories: initial and ongoing needs assessments; scanning the horizon; knowledge management; KTE; network development, maintenance, and facilitation; facilitation of individual capacity development in evidence informed decision making; and g) facilitation of and support for organizational change.</p> <p>Conclusion</p> <p>As the KB role developed during this study, central themes that emerged as particularly important included relationship development, ongoing support, customized approaches, and opportunities for individual and organizational capacity development. The novelty of the KB role in public health provides a unique opportunity to assess the need for and reaction to the role and its associated activities. Future research should include studies to evaluate the effectiveness of KBs in different settings and among different health care professionals, and to explore the optimal preparation and training of KBs, as well as the identification of the personality characteristics most closely associated with KB effectiveness. Studies should also seek to better understand which combination of KB activities are associated with optimal evidence-informed decision making outcomes, and whether the combination changes in different settings and among different health care decision makers.</p
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