928 research outputs found
The HARPS search for southern extra-solar planets. XLVII. Five Jupiter-mass planets in long-period orbits, one highly irradiated Neptune, one brown dwarf, and five stellar binaries
Our aim is to detect and characterise long-period companions around main
sequence stars (spectral types late F to early M). We use the RV method to
search for exoplanets around stars. The RV variations are measured with HARPS
at the ESO 3.6 metre telescope. The true mass and inclination of our heavier
companions are provided by astrometry, for which we use proper motions from
Hipparcos and Gaia. Five Jupiter-mass exoplanets are reported to orbit
HIP54597, BD-210397 (x2), HD74698, and HD94771 with 8.9 yr, 5.2 yr, 17.4 yr,
9.4 yr, and 5.9 yr orbits, and to have minimum masses of , , , , and
respectively. HD74698 also hosts a highly irradiated Neptune in a 15 day orbit
with a minimum mass of . The mass of HIP54597 b can
maximally increase by 10% - 30%, the minimum mass of HD74698 c is likely equal
to its true mass, and BD-210397 c has a mass of .
HD62364 hosts a brown dwarf with a true mass of in
an orbit of 14 yr. HD56380B, HD221638B, and HD33473C have minimum masses within
the brown dwarf limits, in orbits of 8.9 yr, 16.6 yr, and 50 yr respectively;
however, astrometric measurements reveal them to be stellar binaries, with
masses of , , and
. The orbits of the stellar binaries HD11938 and
HD61383 are incomplete. The preliminary result for HD61383 is a 0.190
binary in a 39 yr orbit. The secondary of the binary system HD11938
has a mass of 0.33 - which is confirmed by a secondary peak in the
CCF - and a preliminary period of 35 yr. The origin of the 3.0 yr RV signal of
HD3964 is uncertain as it shows entanglement with the magnetic cycle of the
star. We finally report one more star, HD11608, with a magnetic cycle that
mimics a planetary signal.Comment: 22 pages, 32 figures, accepted for publication in A&
Can We Identify Balassa-Samuelson Effects with Measures of Product Variety?
The Balassa-Samuelson hypothesis - i.e. that real exchange rates between each pair of countries increase with the tradables sector productivities ratio between these countries, and decrease with their non-tradables sector productivities ratio - has been one of the most prominent frameworks in open economy macroeconomics for more than forty years. However, empirical studies have often been unable to confirm it. We argue that this might at least in part be due to measurement errors leading to downward-biased estimates. We test the Balassa-Samuelson hypothesis with innovative trade-based vari-ety measures to differentiate between tradables and non-tradables sector productivities that do not suffer from such errors-in-variables. Using a pairwise regression approach, we find stable and very robust Balassa-Samuelson effects over all our specifications
Concurrent starbursts in molecular gas disks within a pair of colliding galaxies at z = 1.52
We report on the discovery of a merger-driven starburst at z = 1.52, PACS-787, based on high signal-to-noise ALMA observations. CO(5-4) and continuum emission (850um) at a spatial resolution of 0.3" reveal two compact (r_1/2 ~ 1 kpc) and interacting molecular gas disks at a separation of 8.6 kpc thus indicative of an early stage in a merger. With a SFR of 991 Msun/yr, this starburst event should occur closer to final coalescence, as usually seen in hydrodynamical simulations. From the CO size, inclination, and velocity profile for both disks, the dynamical mass is calculated through a novel method that incorporates a calibration using simulations of galaxy mergers. Based on the dynamical mass, we measure (1) the molecular gas mass, independent from the CO luminosity, (2) the ratio of the total gas mass and the CO(1 - 0) luminosity (alpha_CO = M_gas/L'_CO(1-0)), and (3) the gas-to-dust ratio, with the latter two being lower than typically assumed. We find that the high star formation, triggered in both galaxies, is caused by a set of optimal conditions: a high gas mass/fraction, a short depletion time (t_depl=85 and 67 Myrs) to convert gas into stars, and the interaction of likely counter-rotating molecular disks that may accelerate the loss of angular momentum. The state of interaction is further established by the detection of diffuse CO and continuum emission, tidal debris that bridges the two nuclei and is associated with stellar emission seen by HST/WFC3. This observation demonstrates the power of ALMA to study the dynamics of galaxy mergers at high redshift
Covert Reorganization of Implicit Task Representations by Slow Wave Sleep
There is evidence that slow wave sleep (SWS) promotes the consolidation of memories that are subserved by mediotemporal- and hippocampo-cortical neural networks. In contrast to implicit memories, explicit memories are accompanied by conscious (attentive and controlled) processing. Awareness at pre-sleep encoding has been recognized as critical for the off-line memory consolidation. The present study elucidated the role of task-dependent cortical activation guided by attentional control at pre-sleep encoding for the consolidation of hippocampus-dependent memories during sleep.A task with a hidden regularity was used (Number Reduction Task, NRT), in which the responses that can be implicitly predicted by the hidden regularity activate hippocampo-cortical networks more strongly than responses that cannot be predicted. Task performance was evaluated before and after early-night sleep, rich in SWS, and late-night sleep, rich in rapid eye movement (REM) sleep. In implicit conditions, slow cortical potentials (SPs) were analyzed to reflect the amount of controlled processing and the localization of activated neural task representations.During implicit learning before sleep, the amount of controlled processing did not differ between unpredictable and predictable responses, nor between early- and late-night sleep groups. A topographic re-distribution of SPs indicating a spatial reorganization occurred only after early, not after late sleep, and only for predictable responses. These SP changes correlated with the amount of SWS and were covert because off-line RT decrease did not differentiate response types or sleep groups.It is concluded that SWS promotes the neural reorganization of task representations that rely on the hippocampal system despite absence of conscious access to these representations.Original neurophysiologic evidence is provided for the role of SWS in the consolidation of memories encoded with hippocampo-cortical interaction before sleep. It is demonstrated that this SWS-mediated mechanism does not depend critically on explicitness at learning nor on the amount of controlled executive processing during pre-sleep encoding
Socio-demographic and practice-oriented factors related to proficiency in problem solving: a lifelong learning perspective
This article explores the relative importance of different socio-demographic and practice-oriented factors that are related to proficiency in problem solving in technology-rich environments (PSTREs) and by extension may be related to complex problem solving (CPS). The empirical analysis focuses on the proficiency measurements of PSTRE made available by the Programme for the International Assessment of Adult Competencies, which is relevant for gaining insight on some of the factors related to CPS. The purpose was to examine the relationship between the broad information processing experience that individuals gather in different contexts over the lifespan, and the chances to develop problem-solving skills that adults receive in different socio-demographic profiles. Results reveal that socio-demographic factors such as age, education and immigration status as well as practice-oriented factors such as ICT use and reading practice at and outside work are strongly related to proficiency
Learners in a Changing Learning Landscape: Reflections from an Instructional Design Perspective
Van Merriënboer, J. J. G., & Stoyanov, S. (2008). Learners in a changing learning landscape: Reflections from an instructional design perspective. In J. Visser & M. Visser-Valfrey (Eds.), Learners in a changing learning landscape: Reflections from a dialogue on new roles and expectations (pp. 69-90). Dordrecht, The Netherlands: Springer.Both learners and teachers find themselves in a learning landscape that is rapidly changing, along with fast societal and technological developments. This paper discusses the new learning landscape from an instructional design perspective. First, with regard to what is learned, people more than ever need flexible problem-solving and reasoning skills allowing them to deal with new, unfamiliar problem situations in their professional and everyday life. Second, with regard to the context in which learning takes place, learning in technology-rich, informal and professional 24/7 settings is becoming general practice. And third, with regard to the learners themselves, they can more often be characterized as lifelong learners who are mature, bring relevant prior knowledge, and have very heterogeneous expectations and perceptions of learning. High-quality instructional design research should focus on the question which instructional methods and media-method combinations are effective, efficient and appealing in this new learning landscape. Some innovative instructional methods that meet this requirement are discussed
Nucleation and crystallization in bio-based immiscible polyester blends
Bio-based thermoplastic polyesters are highly promising materials as they combine interesting thermal and physical properties and in many cases biodegradability. However, sometimes the best property balance can only be achieved by blending in order to improve barrier properties, biodegradability or mechanical properties. Nucleation, crystallization and morphology are key factors that can dominate all these properties in crystallizable biobased polyesters. Therefore, their understanding, prediction and tailoring is essential. In this work, after a brief introduction about immiscible polymer blends, we summarize the crystallization behavior of the most important bio-based (and immiscible) polyester blends, considering examples of double-crystalline components. Even though in some specific blends (e.g., polylactide/polycaprolactone) many efforts have been made to understand the influence of blending on the nucleation, crystallization and morphology of the parent components, there are still many points that have yet to be understood. In the case of other immiscible polyester blends systems, the literature is scarce, opening up opportunities in this environmentally important research topic.The authors would like to acknowledge funding by the BIODEST project ((RISE) H2020-MSCA-RISE-2017-778092
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