Categorical information influences conscious perception: An interaction between object-substitution masking and repetition blindness

The visual system is constantly bombarded with dynamic input. In this context, the creation of enduring object representations presents a particular challenge. We used object-substitution masking (OSM) as a tool to probe these processes. In particular, we examined the effect of target-like stimulus repetitions on OSM. In visual crowding, the presentation of a physically identical stimulus to the target reduces crowding and improves target perception, whereas in spatial repetition blindness, the presentation of a stimulus that belongs to the same category (type) as the target impairs perception. Across two experiments, we found an interaction between spatial repetition blindness and OSM, such that repeating a same-type stimulus as the target increased masking magnitude relative to presentation of a different-type stimulus. These results are discussed in the context of the formation of object files. Moreover, the fact that the inducer only had to belong to the same "type" as the target in order to exacerbate masking, without necessarily being physically identical to the target, has important implications for our understanding of OSM per se. That is, our results show the target is processed to a categorical level in OSM despite effective masking and, strikingly, demonstrate that this category-level content directly influences whether or not the target is perceived, not just performance on another task (as in priming).This research was supported by an Australian Research Council (ARC) Discovery Early Career Research Award (DE140101734) awarded to S.C.G., and an ARC Discovery Project (DP110104553) grant awarded to M.E, and a UK Medical Research Council (MRC) Career Development Award to J.A.G. The authors thank Reuben Rideaux for assistance with the data collection

Contact and Friction of Nano-Asperities: Effects of Adsorbed Monolayers

Molecular dynamics simulations are used to study contact between a rigid, nonadhesive, spherical tip with radius of order 30nm and a flat elastic substrate covered with a fluid monolayer of adsorbed chain molecules. Previous studies of bare surfaces showed that the atomic scale deviations from a sphere that are present on any tip constructed from discrete atoms lead to significant deviations from continuum theory and dramatic variability in friction forces. Introducing an adsorbed monolayer leads to larger deviations from continuum theory, but decreases the variations between tips with different atomic structure. Although the film is fluid, it remains in the contact and behaves qualitatively like a thin elastic coating except for certain tips at high loads. Measures of the contact area based on the moments or outer limits of the pressure distribution and on counting contacting atoms are compared. The number of tip atoms making contact in a time interval grows as a power of the interval when the film is present and logarithmically with the interval for bare surfaces. Friction is measured by displacing the tip at a constant velocity or pulling the tip with a spring. Both static and kinetic friction rise linearly with load at small loads. Transitions in the state of the film lead to nonlinear behavior at large loads. The friction is less clearly correlated with contact area than load.Comment: RevTex4, 17 pages, 13 figure

Partisanship, Propaganda and Post-Truth Politics: Quantifying Impact in Online Debate

The recent past has highlighted the influential role of social networks and online media in shaping public debate on current affairs and political issues. This paper is focused on studying the role of politically-motivated actors and their strategies for influencing and manipulating public opinion online: partisan media, state-backed propaganda, and post-truth politics. In particular, we present quantitative research on the presence and impact of these three `Ps' in online Twitter debates in two contexts: (i) the run up to the UK EU membership referendum (`Brexit'); and (ii) the information operations of Russia-backed online troll accounts. We first compare the impact of highly partisan versus mainstream media during the Brexit referendum, specifically comparing tweets by half a million `leave' and `remain' supporters. Next, online propaganda strategies are examined, specifically left- and right-wing troll accounts. Lastly, we study the impact of misleading claims made by the political leaders of the leave and remain campaigns. This is then compared to the impact of the Russia-backed partisan media and propaganda accounts during the referendum. In particular, just two of the many misleading claims made by politicians during the referendum were found to be cited in 4.6 times more tweets than the 7,103 tweets related to Russia Today and Sputnik and in 10.2 times more tweets than the 3,200 Brexit-related tweets by the Russian troll accounts.Comment: This is now published in the Journal of Web Science. Please cite accordingly. https://webscience-journal.net/webscience/article/view/8

Shoot yield drives phosphorus use efficiency in Brassica oleracea and correlates with root architecture traits

The environmental and financial costs of using inorganic phosphate fertilizers to maintain crop yield and quality are high. Breeding crops that acquire and use phosphorus (P) more efficiently could reduce these costs. The variation in shoot P concentration (shoot-P) and various measures of P use efficiency (PUE) were quantified among 355 Brassica oleracea L. accessions, 74 current commercial cultivars, and 90 doubled haploid (DH) mapping lines from a reference genetic mapping population. Accessions were grown at two or more external P concentrations in glasshouse experiments; commercial and DH accessions were also grown in replicated field experiments. Within the substantial species-wide diversity observed for shoot-P and various measures of PUE in B. oleracea, current commercial cultivars have greater PUE than would be expected by chance. This may be a consequence of breeding for increased yield, which is a significant component of most measures of PUE, or early establishment. Root development and architecture correlate with PUE; in particular, lateral root number, length, and growth rate. Significant quantitative trait loci associated with shoot-P and PUE occur on chromosomes C3 and C7. These data provide information to initiate breeding programmes to improve PUE in B. oleracea

Impact of Lumacaftor/Ivacaftor on Pulmonary Exacerbation Rates in Members with Cystic Fibrosis in a Medicaid Population

This poster gives an overview of pulmonary exacerbation rates pre- and post-initiation of Lumacaftor/Ivacaftor (LUM/IVA) in Massachusetts\u27 Medicaid program. Pulmonary disease is one of the leading causes of morbidity and mortality among patients with cystic fibrosis. LUM/IVA has been effective in improving pulmonary outcomes in two observational studies, but before this study, there had been no published data evaluating real-world outcomes for Medicaid patients receiving this therapy. This poster on the impact of a drug for patients with cystic fibrosis was shared during the 2018 Academy of Managed Care Pharmacy Managed Care & Specialty Pharmacy Annual Meeting and awarded a gold ribbon. The poster abstracts were evaluated on relevance, originality, quality, bias and clarity. Only 20 percent of submitted abstracts were honored with awards

Experimental evidence of non-Amontons behaviour at a multicontact interface

We report on normal stress field measurements at the multicontact interface between a rough elastomeric film and a smooth glass sphere under normal load, using an original MEMS-based stress sensing device. These measurements are compared to Finite Elements Method calculations with boundary conditions obeying locally Amontons' rigid-plastic-like friction law with a uniform friction coefficient. In dry contact conditions, significant deviations are observed which decrease with increasing load. In lubricated conditions, the measured profile recovers almost perfectly the predicted profile. These results are interpreted as a consequence of the finite compliance of the multicontact interface, a mechanism which is not taken into account in Amontons' law

Elastic contact between self-affine surfaces: Comparison of numerical stress and contact correlation functions with analytic predictions

Contact between an elastic manifold and a rigid substrate with a self-affine fractal surface is reinvestigated with Green's function molecular dynamics. Stress and contact autocorrelation functions (ACFs) are found to decrease algebraically. A rationale is provided for the observed similarity in the exponents for stress and contact ACFs. Both exponents differ substantially from analytic predictions over the range of Hurst roughness exponents studied. The effect of increasing the range of interactions from a hard sphere repulsion to exponential decay is analyzed. Results for exponential interactions are accurately described by recent systematic corrections to Persson's contact mechanics theory. The relation between the area of simply connected contact patches and the normal force is also studied. Below a threshold size the contact area and force are consistent with Hertzian contact mechanics, while area and force are linearly related in larger contact patches.Comment: 12 pages, 9 figure