397 research outputs found
A search for transit timing variation
Photometric follow-ups of transiting exoplanets (TEPs) may lead to
discoveries of additional, less massive bodies in extrasolar systems. This is
possible by detecting and then analysing variations in transit timing of
transiting exoplanets. In 2009 we launched an international observing campaign,
the aim of which is to detect and characterise signals of transit timing
variation (TTV) in selected TEPs. The programme is realised by collecting data
from 0.6--2.2-m telescopes spread worldwide at different longitudes. We present
our observing strategy and summarise first results for WASP-3b with evidence
for a 15 Earth-mass perturber in an outer 2:1 orbital resonance.Comment: Poster contribution to Detection and Dynamics of Transiting
Exoplanets (Haute Provence Observatory Colloquium, 23-27 August 2010
Towards the Rosetta Stone of planet formation
Transiting exoplanets (TEPs) observed just about 10 Myrs after formation of
their host systems may serve as the Rosetta Stone for planet formation
theories. They would give strong constraints on several aspects of planet
formation, e.g. time-scales (planet formation would then be possible within 10
Myrs), the radius of the planet could indicate whether planets form by
gravitational collapse (being larger when young) or accretion growth (being
smaller when young). We present a survey, the main goal of which is to find and
then characterise TEPs in very young open clusters.Comment: Poster contribution to Detection and Dynamics of Transiting
Exoplanets (Haute Provence Observatory Colloquium, 23-27 August 2010
DNA origami-based single-molecule force spectroscopy elucidates RNA Polymerase III pre-initiation complex stability
The TATA-binding protein (TBP) and a transcription factor (TF) IIB-like factor are important
constituents of all eukaryotic initiation complexes. The reason for the emergence and
strict requirement of the additional initiation factor Bdp1 in the RNA polymerase (RNAP) III
system, however, remained elusive. A poorly studied aspect in this context is the effect of
DNA strain arising from DNA compaction and transcriptional activity on initiation complex
formation. We made use of a DNA origami-based force clamp to follow the assembly of
human initiation complexes in the RNAP II and RNAP III systems at the single-molecule level
under piconewton forces. We demonstrate that TBP-DNA complexes are force-sensitive and
TFIIB is sufficient to stabilise TBP on a strained promoter. In contrast, Bdp1 is the pivotal
component that ensures stable anchoring of initiation factors, and thus the polymerase itself,
in the RNAP III system. Thereby, we offer an explanation for the crucial role of Bdp1 for the
high transcriptional output of RNAP II
Rethinking Transnational Activism through Regional Perspectives: Reflections, Literatures and Cases
Copyright \ua9 The Author(s), 2024. Published by Cambridge University Press on behalf of the Royal Historical Society. This collectively authored article argues for a regional turn in the historical study of transnational activism. By considering not only pan-regional movements but also examples of borderland contexts, transregional connections and diasporic understandings of \u27region\u27, our discussion identifies fresh possibilities for investigating the evolution and functioning of transnational activism. Based on a Royal Historical Society-funded workshop held at and supported by Northumbria University, the article brings together insights from diverse locations and arenas of contestation. The first part considers literatures on three macro-regional settings - South Asia, Western Europe and Latin America - to illustrate the importance of distinctive regional contexts and constructs in shaping transnational activism and its goals. The second part turns to case studies of transnational activism in and beyond Eastern Europe, West Africa, the Caribbean and East Asia. In doing so, it explores very different notions of the regional to identify how transnational activism has both shaped and been shaped by these ideas. Taken together, the two parts highlight the role of regional identities and projects in challenging inequalities and external domination. Our analysis and examples indicate the possibilities of a regionally rooted approach for writing histories of transnational activism
Constraints on a second planet in the WASP-3 system
There have been previous hints that the transiting planet WASP-3 b is
accompanied by a second planet in a nearby orbit, based on small deviations
from strict periodicity of the observed transits. Here we present 17 precise
radial velocity measurements and 32 transit light curves that were acquired
between 2009 and 2011. These data were used to refine the parameters of the
host star and transiting planet. This has resulted in reduced uncertainties for
the radii and masses of the star and planet. The radial-velocity data and the
transit times show no evidence for an additional planet in the system.
Therefore, we have determined the upper limit on the mass of any hypothetical
second planet, as a function of its orbital period.Comment: Accepted for publication in The Astronomical Journa
Comparison of Different Methods of Automated Landform Classification at the Drainage Basin Scale: Examples from the Southern Italy
In this work, we tested the reliability of two different methods of
automated landform classification (ACL) in three geological domains of the
southern Italian chain with contrasting morphological features. ACL maps
deriving from the TPI-based (topographic position index) algorithm are strictly
dependent to the search input parameters and they are not able to fully capture
landforms of different size. Geomorphons-based classification has shown a
higher potential and can represent a powerful method of ACL, although it
should be improved with the introduction of additional DEM-based parameters
for the extraction of landform classe
Transitioning to molecular diagnostics in pediatric high-grade glioma: Experiences with the 2016 WHO classification of CNS tumors
BACKGROUND:
Pediatric neuro-oncology was profoundly changed in the wake of the 2016 revision of the WHO Classification of Tumors of the Central Nervous System. Practitioners were challenged to quickly adapt to a system of tumor classification redefined by molecular diagnostics.
METHODS:
We designed a 22-question survey studying the impact of the revised WHO classification on pediatric high-grade glioma. The survey collected basic demographics, general attitudes, issues encountered, and opinions on pediatric subtypes. Participant answers were analyzed along socioeconomic lines utilizing the human development index (HDI) of the United Nations and membership in the group of seven (G7) world economic forum.
RESULTS:
Four hundred and sixty-five participants from 53 countries were included, 187 pediatric neurooncologists (40%), 160 neuropathologists (34%), and 118 other experts (26%). When asked about pediatric high-grade glioma entities, participants from very high development countries preferred treating a patient based on genetic findings. Participants from high and medium development countries indicated using traditional histology and tumor location as mainstays for therapeutic decisions. Non-G7 countries tended to regard the introduction of molecularly characterized tumor entities as a problem for daily routine due to lack of resources.
CONCLUSIONS:
Our findings demonstrate an overall greater reliance and favorability to molecular diagnostics among very high development countries. A disparity in resources and access to molecular diagnostics has left some centers unable to classify pediatric high-grade glioma per the WHO classification. The forthcoming edition should strain to abate disparities in molecular diagnostic availability and work toward universal adaptation
Shape modeling technique KOALA validated by ESA Rosetta at (21) Lutetia
We present a comparison of our results from ground-based observations of
asteroid (21) Lutetia with imaging data acquired during the flyby of the
asteroid by the ESA Rosetta mission. This flyby provided a unique opportunity
to evaluate and calibrate our method of determination of size, 3-D shape, and
spin of an asteroid from ground-based observations. We present our 3-D
shape-modeling technique KOALA which is based on multi-dataset inversion. We
compare the results we obtained with KOALA, prior to the flyby, on asteroid
(21) Lutetia with the high-spatial resolution images of the asteroid taken with
the OSIRIS camera on-board the ESA Rosetta spacecraft, during its encounter
with Lutetia. The spin axis determined with KOALA was found to be accurate to
within two degrees, while the KOALA diameter determinations were within 2% of
the Rosetta-derived values. The 3-D shape of the KOALA model is also confirmed
by the spectacular visual agreement between both 3-D shape models (KOALA pre-
and OSIRIS post-flyby). We found a typical deviation of only 2 km at local
scales between the profiles from KOALA predictions and OSIRIS images, resulting
in a volume uncertainty provided by KOALA better than 10%. Radiometric
techniques for the interpretation of thermal infrared data also benefit greatly
from the KOALA shape model: the absolute size and geometric albedo can be
derived with high accuracy, and thermal properties, for example the thermal
inertia, can be determined unambiguously. We consider this to be a validation
of the KOALA method. Because space exploration will remain limited to only a
few objects, KOALA stands as a powerful technique to study a much larger set of
small bodies using Earth-based observations.Comment: 15 pages, 8 figures, 2 tables, accepted for publication in P&S
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