566 research outputs found
QRAT+: Generalizing QRAT by a More Powerful QBF Redundancy Property
The QRAT (quantified resolution asymmetric tautology) proof system simulates
virtually all inference rules applied in state of the art quantified Boolean
formula (QBF) reasoning tools. It consists of rules to rewrite a QBF by adding
and deleting clauses and universal literals that have a certain redundancy
property. To check for this redundancy property in QRAT, propositional unit
propagation (UP) is applied to the quantifier free, i.e., propositional part of
the QBF. We generalize the redundancy property in the QRAT system by QBF
specific UP (QUP). QUP extends UP by the universal reduction operation to
eliminate universal literals from clauses. We apply QUP to an abstraction of
the QBF where certain universal quantifiers are converted into existential
ones. This way, we obtain a generalization of QRAT we call QRAT+. The
redundancy property in QRAT+ based on QUP is more powerful than the one in QRAT
based on UP. We report on proof theoretical improvements and experimental
results to illustrate the benefits of QRAT+ for QBF preprocessing.Comment: preprint of a paper to be published at IJCAR 2018, LNCS, Springer,
including appendi
Incremental QBF Solving
We consider the problem of incrementally solving a sequence of quantified
Boolean formulae (QBF). Incremental solving aims at using information learned
from one formula in the process of solving the next formulae in the sequence.
Based on a general overview of the problem and related challenges, we present
an approach to incremental QBF solving which is application-independent and
hence applicable to QBF encodings of arbitrary problems. We implemented this
approach in our incremental search-based QBF solver DepQBF and report on
implementation details. Experimental results illustrate the potential benefits
of incremental solving in QBF-based workflows.Comment: revision (camera-ready, to appear in the proceedings of CP 2014,
LNCS, Springer
Complex organic molecules in low-mass protostars on Solar System scales -- II. Nitrogen-bearing species
The chemical inventory of planets is determined by the physical and chemical
processes that govern the early phases of star formation. The aim is to
investigate N-bearing complex organic molecules towards two Class 0 protostars
(B1-c and S68N) at millimetre wavelengths with ALMA. Next, the results of the
detected N-bearing species are compared with those of O-bearing species for the
same and other sources. ALMA observations in Band 6 ( 1 mm) and Band 5
( 2 mm) are studied at 0.5" resolution, complemented by Band 3
( 3 mm) data in a 2.5" beam. NH2CHO, C2H5CN, HNCO, HN13CO, DNCO,
CH3CN, CH2DCN, and CHD2CN are identified towards the investigated sources.
Their abundances relative to CH3OH and HNCO are similar for the two sources,
with column densities that are typically an order of magnitude lower than those
of O-bearing species. The largest variations, of an order of magnitude, are
seen for NH2CHO abundance ratios with respect to HNCO and CH3OH and do not
correlate with the protostellar luminosity. In addition, within uncertainties,
the N-bearing species have similar excitation temperatures to those of
O-bearing species ( 100 300 K). The similarity of most abundances
with respect to HNCO, including those of CH2DCN and CHD2CN, hints at a shared
chemical history, especially the high D/H ratio in cold regions prior to star
formation. However, some of the variations in abundances may reflect the
sensitivity of the chemistry to local conditions such as temperature (e.g.
NH2CHO), while others may arise from differences in the emitting areas of the
molecules linked to their different binding energies in the ice. The two
sources discussed here add to the small number of sources with such a detailed
chemical analysis on Solar System scales. Future JWST data will allow a direct
comparison between the ice and gas abundances of N-bearing species.Comment: Accepted to A&A, 41 pages, 37 figure
The diverse chemistry of protoplanetary disks as revealed by JWST
Early results from the JWST-MIRI guaranteed time programs on protostars
(JOYS) and disks (MINDS) are presented. Thanks to the increased sensitivity,
spectral and spatial resolution of the MIRI spectrometer, the chemical
inventory of the planet-forming zones in disks can be investigated with
unprecedented detail across stellar mass range and age. Here data are presented
for five disks, four around low-mass stars and one around a very young
high-mass star. The mid-infrared spectra show some similarities but also
significant diversity: some sources are rich in CO2, others in H2O or C2H2. In
one disk around a very low-mass star, booming C2H2 emission provides evidence
for a ``soot'' line at which carbon grains are eroded and sublimated, leading
to a rich hydrocarbon chemistry in which even di-acetylene (C4H2) and benzene
(C6H6) are detected (Tabone et al. 2023). Together, the data point to an active
inner disk gas-phase chemistry that is closely linked to the physical structure
(temperature, snowlines, presence of cavities and dust traps) of the entire
disk and which may result in varying CO2/H2O abundances and high C/O ratios >1
in some cases. Ultimately, this diversity in disk chemistry will also be
reflected in the diversity of the chemical composition of exoplanets.Comment: 17 pages, 8 figures. Author's version of paper submitted to Faraday
Discussions January 18 2023, Accepted March 16 202
How Bodies and Voices Interact in Early Emotion Perception
Successful social communication draws strongly on the correct interpretation of others' body and vocal expressions. Both can provide emotional information and often occur simultaneously. Yet their interplay has hardly been studied. Using electroencephalography, we investigated the temporal development underlying their neural interaction in auditory and visual perception. In particular, we tested whether this interaction qualifies as true integration following multisensory integration principles such as inverse effectiveness. Emotional vocalizations were embedded in either low or high levels of noise and presented with or without video clips of matching emotional body expressions. In both, high and low noise conditions, a reduction in auditory N100 amplitude was observed for audiovisual stimuli. However, only under high noise, the N100 peaked earlier in the audiovisual than the auditory condition, suggesting facilitatory effects as predicted by the inverse effectiveness principle. Similarly, we observed earlier N100 peaks in response to emotional compared to neutral audiovisual stimuli. This was not the case in the unimodal auditory condition. Furthermore, suppression of beta–band oscillations (15–25 Hz) primarily reflecting biological motion perception was modulated 200–400 ms after the vocalization. While larger differences in suppression between audiovisual and audio stimuli in high compared to low noise levels were found for emotional stimuli, no such difference was observed for neutral stimuli. This observation is in accordance with the inverse effectiveness principle and suggests a modulation of integration by emotional content. Overall, results show that ecologically valid, complex stimuli such as joined body and vocal expressions are effectively integrated very early in processing
JOYS+: mid-infrared detection of gas-phase SO emission in a low-mass protostar. The case of NGC 1333 IRAS2A: hot core or accretion shock?
JWST/MIRI has sharpened our infrared eyes toward the star formation process.
This paper presents the first mid-infrared detection of gaseous SO emission
in an embedded low-mass protostellar system. MIRI-MRS observations of the
low-mass protostellar binary NGC 1333 IRAS2A are presented from the JWST
Observations of Young protoStars (JOYS+) program, revealing emission from the
SO asymmetric stretching mode at 7.35 micron. The results are
compared to those derived from high-angular resolution SO data obtained
with ALMA. The SO emission from the band is predominantly located
on au scales around the main component of the binary, IRAS2A1. A
rotational temperature of K is derived from the lines. This is
in good agreement with the rotational temperature derived from pure rotational
lines in the vibrational ground state (i.e., ) with ALMA ( K).
However, the emission of the lines is not in LTE given that the total
number of molecules predicted by a LTE model is found to be a factor
higher than what is derived for the state. This
difference can be explained by a vibrational temperature that is K
higher than the derived rotational temperature of the state. The
brightness temperature derived from the continuum around the band of
SO is K, which confirms that the level is not
collisionally populated but rather infrared pumped by scattered radiation. This
is also consistent with the non-detection of the bending mode at 18-20
micron. Given the rotational temperature, the extent of the emission (
au in radius), and the narrow line widths in the ALMA data (3.5 km/s), the
SO in IRAS2A likely originates from ice sublimation in the central hot core
around the protostar rather than from an accretion shock at the disk-envelope
boundary.Comment: 19 pages, 17 figures, accepted for publication in A&A, abstract
abbreviate
Welding and lung cancer in a pooled analysis of case-control studies.
Several epidemiologic studies have indicated an increased risk of lung cancer among welders. We used the SYNERGY project database to assess welding as a risk factor for developing lung cancer. The database includes data on 15,483 male lung cancer cases and 18,388 male controls from 16 studies in Europe, Canada, China, and New Zealand conducted between 1985 and 2010. Odds ratios and 95% confidence intervals between regular or occasional welding and lung cancer were estimated, with adjustment for smoking, age, study center, and employment in other occupations associated with lung cancer risk. Overall, 568 cases and 427 controls had ever worked as welders and had an odds ratio of developing lung cancer of 1.44 (95% confidence interval: 1.25, 1.67) with the odds ratio increasing for longer duration of welding. In never and light smokers, the odds ratio was 1.96 (95% confidence interval: 1.37, 2.79). The odds ratios were somewhat higher for squamous and small cell lung cancers than for adenocarcinoma. Another 1,994 cases and 1,930 controls had ever worked in occupations with occasional welding. Work in any of these occupations was associated with some elevation of risk, though not as much as observed in regular welders. Our findings lend further support to the hypothesis that welding is associated with an increased risk of lung cancer
Adults' Awareness of Faces Follows Newborns' Looking Preferences
From the first days of life, humans preferentially orient towards upright faces, likely reflecting innate subcortical mechanisms. Here, we show that binocular rivalry can reveal face detection mechanisms in adults that are surprisingly similar to inborn face detection mechanism. We used continuous flash suppression (CFS), a variant of binocular rivalry, to render stimuli invisible at the beginning of each trial and measured the time upright and inverted stimuli needed to overcome such interocular suppression. Critically, specific stimulus properties previously shown to modulate looking preferences in neonates similarly modulated adults' awareness of faces presented during CFS. First, the advantage of upright faces in overcoming CFS was strongly modulated by contrast polarity and direction of illumination. Second, schematic patterns consisting of three dark blobs were suppressed for shorter durations when the arrangement of these blobs respected the face-like configuration of the eyes and the mouth, and this effect was modulated by contrast polarity. No such effects were obtained in a binocular control experiment not involving CFS, suggesting a crucial role for face-sensitive mechanisms operating outside of conscious awareness. These findings indicate that visual awareness of faces in adults is governed by perceptual mechanisms that are sensitive to similar stimulus properties as those modulating newborns' face preferences
Binding binding: Departure points for a different version of the perceptual retouch theory
In the perceptual retouch theory, masking and related microgenetic phenomena were
explained as a result of interaction between specific cortical representational
systems and the non-specific sub-cortical modulation system. Masking appears as
deprivation of sufficient modulation of the consciousness mechanism suffered by
the target-specific signals because of the temporal delay of non-specific
modulation (necessary for conscious representation), which explicates the
later-coming mask information instead of the already decayed target information.
The core of the model envisaged relative magnitudes of EPSPs of single cortical
cells driven by target and mask signals at the moment when the nonspecific,
presynaptic, excitatory input arrives from the thalamus. In the light of the
current evidence about the importance of synchronised activity of specific and
non-specific systems in generating consciousness, the retouch theory requires
perhaps a different view. This article presents some premises for modification
of the retouch theory, where instead of the cumulative presynaptic spike
activities and EPSPs of single cells, the oscillatory activity in the gamma
range of the participating systems is considered and shown to be consistent with
the basic ideas of the retouch theory. In this conceptualisation, O-binding
refers to specific encoding which is based on gamma-band synchronised
oscillations in the activity of specific cortical sensory modules that represent
features and objects; C-binding refers to the gamma-band oscillations in the
activity of the non-specific thalamic systems, which is necessary for the
O-binding based data to become consciously experienced
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