3,196 research outputs found
Different types of response to selection for sex ratio in the flour beetle Tribolium castaneum
International audienc
ChineseâSpanish neural machine translation enhanced with character and word bitmap fonts
Recently, machine translation systems based on neural networks have reached state-of-the-art results for some pairs of languages (e.g., GermanâEnglish). In this paper, we are investigating the performance of neural machine translation in ChineseâSpanish, which is a challenging language pair. Given that the meaning of a Chinese word can be related to its graphical representation, this work aims to enhance neural machine translation by using as input a combination of: words or characters and their corresponding bitmap fonts. The fact of performing the interpretation of every word or character as a bitmap font generates more informed vectorial representations. Best results are obtained when using words plus their bitmap fonts obtaining an improvement (over a competitive neural MT baseline system) of almost six BLEU, five METEOR points and ranked coherently better in the human evaluation.Peer ReviewedPostprint (published version
Attention induced neural response trade-off in retinotopic cortex under load
The effects of perceptual load on visual cortex response to distractors are well established and various phenomena of âinattentional blindnessâ associated with elimination of visual cortex response to unattended distractors, have been documented in tasks of high load. Here we tested an account for these effects in terms of a load-induced trade-off between target and distractor processing in retinotopic visual cortex. Participants were scanned using fMRI while performing a visual-search task and ignoring distractor checkerboards in the periphery. Retinotopic responses to target and distractors were assessed as a function of search load (comparing search set-sizes two, three and five). We found that increased load not only increased activity in frontoparietal network, but also had opposite effects on retinotopic responses to target and distractors. Target-related signals in areas V2âV3 linearly increased, while distractor response linearly decreased, with increased load. Critically, the slopes were equivalent for both load functions, thus demonstrating resource trade-off. Load effects were also found in displays with the same item number in the distractor hemisphere across different set sizes, thus ruling out local intrahemispheric interactions as the cause. Our findings provide new evidence for load theory proposals of attention resource sharing between target and distractor leading to inattentional blindness
High-energy environment of super-Earth 55 Cnc e I: Far-UV chromospheric variability as a possible tracer of planet-induced coronal rain
The irradiation of close-in planets by their star influences their evolution
and might be responsible for a population of ultra-short period planets eroded
to their bare core. In orbit around a bright, nearby G-type star, the
super-Earth 55 Cnc e offers the possibility to address these issues through UV
transit observations. We used the Hubble Space Telescope to observe the transit
in the FUV over 3 epochs in Apr. 2016, Jan. 2017, and Feb. 2017. These
observations reveal significant short- and long-term variability in 55 Cnc
chromospheric emission lines. In the last 2 epochs, we detected a larger flux
in the C III, Si III, and Si IV lines after the planet passed the approaching
quadrature, followed by a flux decrease in the Si IV doublet. In the second
epoch these variations are contemporaneous with flux decreases in the Si II and
C II doublet. All epochs show flux decreases in the N V doublet as well, albeit
at different orbital phases. These flux decreases are consistent with
absorption from optically thin clouds of gas, are mostly localized at low and
redshifted radial velocities in the star rest frame, and occur preferentially
before and during the transit. These 3 points make it unlikely that the
variations are purely stellar, yet we show that the occulting material is also
unlikely to originate from the planet. We tentatively propose that the motion
of 55 Cnc e at the fringes of the stellar corona leads to the formation of a
cool coronal rain. The inhomogeneity and temporal evolution of the stellar
corona would be responsible for the differences between the visits. Additional
variations are detected in the C II doublet in the first epoch and in the O I
triplet in all epochs with a different behavior that points toward intrinsic
stellar variability. Further observations at FUV wavelengths are required to
disentangle between star-planet interactions and the activity of the starComment: 22 pages, 20 figures, accepted for publication in A&
The long egress of GJ~436b's giant exosphere
The M dwarf GJ 436 hosts a transiting warm Neptune known to experience
atmospheric escape. Previous observations revealed the presence of a giant
hydrogen exosphere transiting the star for more than 5 h, and absorbing up to
56% of the flux in the blue wing of the stellar Lyman-{\alpha} line of neutral
hydrogen (H i Ly{\alpha}). The unexpected size of this comet-like exosphere
prevented observing the full transit of its tail. In this Letter, we present
new Ly{\alpha} observations of GJ 436 obtained with the Space Telescope Imaging
Spectrograph (STIS) instrument onboard the Hubble Space Telescope. The
stability of the Ly{\alpha} line over six years allowed us to combine these new
observations with archival data sets, substantially expanding the coverage of
the exospheric transit. Hydrogen atoms in the tail of the exospheric cloud keep
occulting the star for 10-25 h after the transit of the planet, remarkably
confirming a previous prediction based on 3D numerical simulations with the
EVaporating Exoplanet code (EVE). This result strengthens the interpretation
that the exosphere of GJ 436b is shaped by both radiative braking and charge
exchanges with the stellar wind. We further report flux decreases of 15 +/- 2%
and 47 +/- 10% in the red wing of the Ly{\alpha} line and in the line of
ionised silicon (Si iii). Despite some temporal variability possibly linked
with stellar activity, these two signals occur during the exospheric transit
and could be of planetary origin. Follow-up observations will be required to
assess the possibility that the redshifted Ly{\alpha} and Si iii absorption
signatures arise from interactions between the exospheric flow and the magnetic
field of the star.Comment: 10 pages, 7 figures, published in A&
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