976 research outputs found
The Role of Cyclone Activity in Snow Accumulation on Arctic Sea Ice
Identifying the mechanisms controlling the timing and magnitude of snow accumulation on sea ice is crucial for understanding snows net effect on the surface energy budget and sea-ice mass balance. Here, we analyze the role of cyclone activity on the seasonal buildup of snow on Arctic sea ice using model, satellite, and in situ data over 19792016. On average, 44% of the variability in monthly snow accumulation was controlled by cyclone snowfall and 29% by sea-ice freeze-up. However, there were strong spatio-temporal differences. Cyclone snowfall comprised ~50% of total snowfall in the Pacific compared to 83% in the Atlantic. While cyclones are stronger in the Atlantic, Pacific snow accumulation is more sensitive to cyclone strength. These findings highlight the heterogeneity in atmosphere-snow-ice interactions across the Arctic, and emphasize the need to scrutinize mechanisms governing cyclone activity to better understand their effects on the Arctic snow-ice system with anthropogenic warming
Female Salix viminalis are more severely infected by Melampsora spp. but neither sex experiences associational effects
Associational effects of plant genotype or species on plant biotic interactions are common, not least for disease spread, but associational effects of plant sex on interactions have largely been ignored. Sex in dioecious plants can affect biotic interactions with herbivores and pollinators; however, its effects on plant-pathogen interactions are understudied and associational effects are unknown. In a replicated field experiment, we assessed Melampsora spp. leaf rust infection in monosexual and mixed sex plots of dioecious Salix viminalis L. to determine whether plant sex has either direct or associational effects on infection severity. We found no differences in Melampsora spp. infection severity among sexual monocultures and mixtures in our field experiment. However, female plants were overall more severely infected. In addition, we surveyed previous studies of infection in S. viminalis clones and reevaluated the studies after we assigned sex to the clones. We found that females were generally more severely infected, as in our field study. Similarly, in a survey of studies on sexbiased infection in dioecious plants, we found more female-biased infections in plant-pathogen pairs. We conclude that there was no evidence for associational plant sex effects of neighboring conspecifics for either females or males on infection severity. Instead, plant sex effects on infection act at an individual plant level. Our findings also suggest that female plants may in general be more severely affected by fungal pathogens than males
Neural correlates of eye contact and social function in autism spectrum disorder
Reluctance to make eye contact during natural interactions is a central diagnostic criterion for autism spectrum disorder (ASD). However, the underlying neural correlates for eye contacts in ASD are unknown, and diagnostic biomarkers are active areas of investigation. Here, neuroimaging, eye-tracking, and pupillometry data were acquired simultaneously using two-person functional near-infrared spectroscopy (fNIRS) during live "in-person" eye-to-eye contact and eye-gaze at a video face for typically-developed (TD) and participants with ASD to identify the neural correlates of live eye-to-eye contact in both groups. Comparisons between ASD and TD showed decreased right dorsal-parietal activity and increased right ventral temporal-parietal activity for ASD during live eye-to-eye contact (p≤0.05, FDR-corrected) and reduced cross-brain coherence consistent with atypical neural systems for live eye contact. Hypoactivity of right dorsal-parietal regions during eye contact in ASD was further associated with gold standard measures of social performance by the correlation of neural responses and individual measures of: ADOS-2, Autism Diagnostic Observation Schedule, 2nd Edition (r = -0.76, -0.92 and -0.77); and SRS-2, Social Responsiveness Scale, Second Edition (r = -0.58). The findings indicate that as categorized social ability decreases, neural responses to real eye-contact in the right dorsal parietal region also decrease consistent with a neural correlate for social characteristics in ASD
Dissecting the main sequence: AGN activity and bulge growth in the local Universe
Local galaxies from the Sloan Digital Sky Survey (SDSS) are used to provide additional support
for an evolutionary pathway in which active galactic nucleus activity is associated with star
formation quenching. Composite, Seyfert 2, and LINER galaxies account for ∼60 per cent of
all star formation in massive galaxies (M > 1010.5 M). Inclusion of these galaxies results in a
‘turnover’ in the star formation rate and stellar mass (SFR−M) relation for massive galaxies.
Our analysis shows that bulge growth has already occurred in the most massive galaxies (M >
1010.5 M), and bulges continue to grow as galaxies quench and redden, (g − r) = 0.5→0.75.
Significant bulge growth is also occurring in low mass starburst galaxies (M < 1010.5 M)
at 0.5 dex above the ‘main sequence’ (MS), where we find an increase in B/T from 0.1→0.3
and bluer colours, (g − r) < 0.25 compared to low-mass galaxies on the MS.Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department
of Energy, the National Aeronautics and Space Administration,
the Japanese Monbukagakusho, the Max Planck Society, and the
Higher Education Funding Council for England. The SDSS web
site is http://www.sdss.org/. DS would like to thank the Distinguished Visitor Program at the Research School for Astronomy
and Astrophysics, Australian National University for their generous support while in residence at the Mount Stromlo Observatory,
Weston Creek, ACT. CM and DS also acknowledge support from
National Science Foundation grant number 1716994. The work of
DS was performed in part at the Aspen Center for Physics, which
is supported by National Science Foundation grant PHY-1607611
Beyond Spheroids and Discs: Classifications of CANDELS Galaxy Structure at 1.4 < z < 2 via Principal Component Analysis
Important but rare and subtle processes driving galaxy morphology and
star-formation may be missed by traditional spiral, elliptical, irregular or
S\'ersic bulge/disk classifications. To overcome this limitation, we use a
principal component analysis of non-parametric morphological indicators
(concentration, asymmetry, Gini coefficient, , multi-mode, intensity
and deviation) measured at rest-frame -band (corresponding to HST/WFC3 F125W
at 1.4 ) galaxy morphologies. Principal component analysis (PCA) quantifies
the correlations between these morphological indicators and determines the
relative importance of each. The first three principal components (PCs) capture
75 per cent of the variance inherent to our sample. We interpret the
first principal component (PC) as bulge strength, the second PC as dominated by
concentration and the third PC as dominated by asymmetry. Both PC1 and PC2
correlate with the visual appearance of a central bulge and predict galaxy
quiescence. PC1 is a better predictor of quenching than stellar mass, as as
good as other structural indicators (S\'ersic-n or compactness). We divide the
PCA results into groups using an agglomerative hierarchical clustering method.
Unlike S\'ersic, this classification scheme separates compact galaxies from
larger, smooth proto-elliptical systems, and star-forming disk-dominated clumpy
galaxies from star-forming bulge-dominated asymmetric galaxies. Distinguishing
between these galaxy structural types in a quantitative manner is an important
step towards understanding the connections between morphology, galaxy assembly
and star-formation.Comment: 31 pages, 24 figures, accepted for publication in MNRA
Patterns of Visual Attention to Faces and Objects in Autism Spectrum Disorder
This study used eye-tracking to examine visual attention to faces and objects in adolescents with autism spectrum disorder (ASD) and typical peers. Point of gaze was recorded during passive viewing of images of human faces, inverted human faces, monkey faces, three-dimensional curvilinear objects, and two-dimensional geometric patterns. Individuals with ASD obtained lower scores on measures of face recognition and social-emotional functioning but exhibited similar patterns of visual attention. In individuals with ASD, face recognition performance was associated with social adaptive function. Results highlight heterogeneity in manifestation of social deficits in ASD and suggest that naturalistic assessments are important for quantifying atypicalities in visual attention
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Brief report: a comparison of the preference for viewing social and non-social movies in typical and autistic adolescents
The recently proposed Social Motivation theory (Chevallier et al., Trends in cognitive sciences 16(4):231–239, 2012) suggests that social difficulties in Autism Spectrum Condition (ASC) might be caused by a difference in the motivation to engage with other people. Here we compared adolescents with (N = 31) and without (N = 37) ASC on the Choose-a-Movie paradigm that measures the social seeking. The results showed a preference for viewing objects over smiling faces in ASC, which is in line with the theory of low social motivation. However, typical adolescents did not show any stimuli preferences, raising questions about developmental changes in social motivation. Age was found to play a significant role in moderating the choice behaviour of the participants. We discuss the implications of these findings in detail
An Assortment of Evolutionary Computation Techniques (AECT) in gaming
© 2020, Springer-Verlag London Ltd., part of Springer Nature. Real-time strategy (RTS) games differ as they persist in varying scenarios and states. These games enable an integrated correspondence of non-player characters (NPCs) to appear as an autodidact in a dynamic environment, thereby resulting in a combined attack of NPCs on human-controlled character (HCC) with maximal damage. This research aims to empower NPCs with intelligent traits. Therefore, we instigate an assortment of ant colony optimization (ACO) with genetic algorithm (GA)-based approach to first-person shooter (FPS) game, i.e., Zombies Redemption (ZR). Eminent NPCs with best-fit genes are elected to spawn NPCs over generations and game levels as yielded by GA. Moreover, NPCs empower ACO to elect an optimal path with diverse incentives and less likelihood of getting shot. The proposed technique ZR is novel as it integrates ACO and GA in FPS games where NPC will use ACO to exploit and optimize its current strategy. GA will be used to share and explore strategy among NPCs. Moreover, it involves an elaboration of the mechanism of evolution through parameter utilization and updation over the generations. ZR is played by 450 players with varying levels having the evolving traits of NPCs and environmental constraints in order to accumulate experimental results. Results revealed improvement in NPCs performance as the game proceeds
Autism diagnosis differentiates neurophysiological responses to faces in adults with tuberous sclerosis complex
- Background: Autism spectrum disorder (ASD) is a common and highly heritable neurodevelopmental disorder that is likely to be the outcome of complex aetiological mechanisms. One strategy to provide insight is to study ASD within tuberous sclerosis complex (TSC), a rare disorder with a high incidence of ASD, but for which the genetic cause is determined. Individuals with ASD consistently demonstrate face processing impairments, but these have not been examined in adults with TSC using event-related potentials (ERPs) that are able to capture distinct temporal stages of processing.
- Methods: For adults with TSC (n = 14), 6 of which had a diagnosis of ASD, and control adults (n = 13) passively viewed upright and inverted human faces with direct or averted gaze, with concurrent EEG recording. Amplitude and latency of the P1 and N170 ERPs were measured.
- Results: Individuals with TSC + ASD exhibited longer N170 latencies to faces compared to typical adults. Typical adults and adults with TSC-only exhibited longer N170 latency to inverted versus upright faces, whereas individuals with TSC + ASD did not show latency differences according to face orientation. In addition, individuals with TSC + ASD showed increased N170 latency to averted compared to direct gaze, which was not demonstrated in typical adults. A reduced lateralization was shown for the TSC + ASD groups on P1 and N170 amplitude.
- Conclusions: The findings suggest that individuals with TSC + ASD may have similar electrophysiological abnormalities to idiopathic ASD and are suggestive of developmental delay. Identifying brain-based markers of ASD that are similar in TSC and idiopathic cases is likely to help elucidate the risk pathways to ASD
Atypical disengagement from faces and its modulation by the control of eye fixation in children with Autism Spectrum Disorder
By using the gap overlap task, we investigated disengagement from faces and objects in children (9–17 years old) with and without autism spectrum disorder (ASD) and its neurophysiological correlates. In typically developing (TD) children, faces elicited larger gap effect, an index of attentional engagement, and larger saccade-related event-related potentials (ERPs), compared to objects. In children with ASD, by contrast, neither gap effect nor ERPs differ between faces and objects. Follow-up experiments demonstrated that instructed fixation on the eyes induces larger gap effect for faces in children with ASD, whereas instructed fixation on the mouth can disrupt larger gap effect in TD children. These results suggest a critical role of eye fixation on attentional engagement to faces in both groups
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