The nature of Garner interference: The role of uncertainty, information, and variation in the breakdown in selective attention

The popular measure of Garner Interference specifies the detriment to performance with the task-relevant attribute in the presence of a randomly varying distractor. But is irrelevant variation per se responsible for this breakdown of selective attention as the traditional account suggests? In this study we identified an overlooked alternative account – increased irrelevant information – which threatens the validity of the variation interpretation. We designed a new condition within the Garner paradigm, Roving Baseline, which allowed for dissociating the separate and combined contributions of information and variation at both macro and micro levels of analysis. A third account, increased number of stimuli or stimulus uncertainty, was also considered as well as the rival interpretations of configural processing and change detection. Our conceptual assay was complemented by a pair of dedicated experiments that included the novel Roving Baseline condition. The results of the theoretical analysis and of the experiments converged on supporting variability as the source of Garner interference. We found no evidence for an influence of information or of stimulus uncertainty. Our study thus adds further support for W. R. Garner's original intuition when designing the paradigm and the interference bearing his name

Scaling behavior in steady-state contractile actomyosin network flow

Contractile actomyosin network flows are crucial for many cellular processes including cell division and motility, morphogenesis and transport. How local remodeling of actin architecture tunes stress production and dissipation and regulates large-scale network flow remains poorly understood. Here, we generate contractile actomyosin networks with rapid turnover in vitro, by encapsulating cytoplasmic Xenopus egg extracts into cell-sized 'water-in-oil' droplets. Within minutes, the networks reach a dynamic steady-state with continuous inward flow. The networks exhibit homogenous, density-independent contraction for a wide range of physiological conditions, indicating that the myosin-generated stress driving contraction is proportional to the effective network viscosity. We further find that the contraction rate approximately scales with the network turnover rate, but this relation breaks down in the presence of excessive crosslinking or branching. Our findings suggest that cells use diverse biochemical mechanisms to generate robust, yet tunable, actin flows by regulating two parameters: turnover rate and network geometry

SDSS-IV MaNGA: Identification of active galactic nuclei in optical integral field unit surveys

In this paper, we investigate 2727 galaxies observed by MaNGA as of June 2016 to develop spatially resolved techniques for identifying signatures of active galactic nuclei (AGN). We identify 303 AGN candidates. The additional spatial dimension imposes challenges in identifying AGN due to contamination from diffuse ionized gas, extra-planar gas and photoionization by hot stars. We show that the combination of spatially-resolved line diagnostic diagrams and additional cuts on H$\alpha$ surface brighness and H$\alpha$ equivalent width can distinguish between AGN-like signatures and high-metallicity galaxies with LINER-like spectra. Low mass galaxies with high specific star formation rates are particularly difficult to diagnose and routinely show diagnostic line ratios outside of the standard star-formation locus. We develop a new diagnostic -- the distance from the standard diagnostic line in the line-ratios space -- to evaluate the significance of the deviation from the star-formation locus. We find 173 galaxies that would not have been selected as AGN candidates based on single-fibre spectral measurements but exhibit photoionization signatures suggestive of AGN activity in the MaNGA resolved observations, underscoring the power of large integral field unit (IFU) surveys. A complete census of these new AGN candidates is necessary to understand their nature and probe the complex co-evolution of supermassive black holes and their hosts.Comment: 18 pages, 11 figures, accepted to MNRA

TraumAID: AI Support in the Management of Multiple Trauma

This paper outlines the particular demands that multiple trauma makes on systems designed to provide appropriate decision support, and the ways that these demands are currently being met in our system, TraumAID. The demands follow from: (1) the nature of trauma and the procedures used in its diagnosis, (2) the need to adjust diagnostic and therapeutic procedures to available resource levels, (3) the role of anatomy in trauma and the need for anatomical reasoning, (4) the role of non-specialists in managing trauma, and (5) the competing demands of multiple injuries and the consequent need for planning. We believe that these demands are not unique to multiple trauma, so that the paper may be of general interest to expert system research and development

TraumAID: Reasoning and Planning in the Initial Definitive Management of Multiple Injuries

The TraumAID system has been designed to provide computerized decision support to optimize the initial definitive management of acutely injured patients after resuscitation and stabilization. The currently deployed system, TraumAID 1.0, addresses penetrating injuries to the abdomen and to the chest. Our experience with TraumAID 1.0 has demonstrated some major deficiencies in rule-based reasoners that are faced with problems of both diagnosis and treatment. To address these deficiencies, we have redesigned the system (TraumAID 2.0), factoring it into two modules: (1) a rule-based reasoner embodying the knowledge and logical machinery needed to link clinical evidence to diagnostic and therapeutic goals, and (2) a planner embodying the global knowledge and logical machinery needed to create a plan that addresses combinations of goals. After describing TraumAID 2.0, we discuss an extension of the TraumAID interface (critique mode interaction) that may improve its acceptability in a clinical setting. We close with a brief discussion of management support in resource-limited environments, which is an important issue in the time-critical context of multiple trauma

SDSS-IV MaNGA: Variations in the N/O -- O/H relation bias metallicity gradient measurements

In this paper we use strong line calibrations of N/O and O/H in MaNGA spaxel data to explore the systematics introduced by variations in N/O on various strong-line metallicity diagnostics. We find radial variations in N/O at fixed O/H which correlate with total galaxy stellar-mass; and which can induce $\sim 40 \%$ systematic uncertainties in oxygen abundance gradients when nitrogen-dependent abundance calibrations are used. Empirically, we find that these differences are associated with variation in the local star formation efficiency, as predicted by recent chemical evolution models for galaxies, but we cannot rule out other processes such as radial migration and the accretion of passive dwarf galaxies also playing a role.Comment: 8 pages, 4 figures. Submitted to ApJL. All comments are welcom

Centering and symmetry breaking in confined contracting actomyosin networks

Centering and decentering of cellular components is essential for internal organization of cells and their ability to perform basic cellular functions such as division and motility. How cells achieve proper localization of their components is still not well-understood, especially in large cells such as oocytes. Here, we study actin-based positioning mechanisms in artificial cells with persistently contracting actomyosin networks, generated by encapsulating cytoplasmic Xenopus egg extracts into cell-sized water-in-oil droplets. We observe size-dependent localization of the contraction center, with a symmetric configuration in larger cells and a polar one in smaller cells. In the symmetric state, the contraction center is actively centered, via a hydrodynamic mechanism based on Darcy friction between the contracting network and the surrounding cytoplasm. During symmetry breaking, transient attachments to the cell boundary drive the contraction center to a polar location near the droplet boundary. Our findings demonstrate a robust, yet tunable, mechanism for subcellular localization

HI Rich but Low Star Formation galaxies in MaNGA: Physical Properties and Comparison to Control Samples

Gas rich galaxies are typically star-forming. We make use of HI-MaNGA, a program of HI follow-up for the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey of the Sloan Digital Sky Surveys to construct a sample of unusual neutral hydrogen (HI, 21cm) rich galaxies which have low Star Formation Rates (SFRs); using infra-red color from the Wide-field Infrared Survey Explorer (WISE) as a proxy for specific SFR. Out of a set of 1575 MaNGA galaxies with HI-MaNGA detections, we find 83 (5%) meet our selection criteria to be HI rich with low SFR. We construct two stellar mass-matched control samples: HI rich galaxies with typical SFR (High SF Control) and HI poor galaxies with low SFR (Low HI Control). We investigate the properties of each of these samples, comparing physical parameters such as ionization state maps, stellar and ionized gas velocity and dispersion, environment measures, metallicity, and morphology to search for the reasons why these unusual HI rich galaxies are not forming stars. We find evidence for recent external accretion of gas in some galaxies (via high counter-rotating fractions), along with some evidence for AGN feedback (from a high cLIER and/or red geyser fraction), and bar quenching (via an enhanced strong bar fraction). Some galaxies in the sample are consistent with simply having their HI in a high angular momentum, large radius, low density disc. We conclude that no single physical process can explain all HI rich, low SFR galaxies.Comment: 15 pages, in press MNRAS. v2 following corrections noticed in proof

Galaxy Zoo: Kinematics of strongly and weakly barred galaxies

We study the bar pattern speeds and corotation radii of 225 barred galaxies, using IFU data from MaNGA and the Tremaine-Weinberg method. Our sample, which is divided between strongly and weakly barred galaxies identified via Galaxy Zoo, is the largest that this method has been applied to. We find lower pattern speeds for strongly barred galaxies than for weakly barred galaxies. As simulations show that the pattern speed decreases as the bar exchanges angular momentum with its host, these results suggest that strong bars are more evolved than weak bars. Interestingly, the corotation radius is not different between weakly and strongly barred galaxies, despite being proportional to bar length. We also find that the corotation radius is significantly different between quenching and star forming galaxies. Additionally, we find that strongly barred galaxies have significantly lower values for R, the ratio between the corotation radius and the bar radius, than weakly barred galaxies, despite a big overlap in both distributions. This ratio classifies bars into ultrafast bars (R < 1.0; 11% of our sample), fast bars (1.0 < R < 1.4; 27%) and slow bars (R > 1.4; 62%). Simulations show that R is correlated with the bar formation mechanism, so our results suggest that strong bars are more likely to be formed by different mechanisms than weak bars. Finally, we find a lower fraction of ultrafast bars than most other studies, which decreases the recently claimed tension with {\Lambda}CDM. However, the median value of R is still lower than what is predicted by simulations.Comment: 20 pages, 16 figure

SDSS-IV MaNGA: Evidence for enriched accretion onto satellite galaxies in dense environments

We investigate the environmental dependence of the local gas-phase metallicity in a sample of star-forming galaxies from the MaNGA survey. Satellite galaxies with stellar masses in the range $910^{10.5} \, \mathrm{M_{\odot}}$) centrals are $\sim 0.1 \, \mathrm{dex}$ more metal rich than satellites of low-mass ($M_{*} < 10^{10} \, \mathrm{M_{\odot}}$) centrals, controlling for local stellar mass surface density and gas fraction. Fitting a gas-regulator model to the spaxel data, we are able to account for variations in the local gas fraction, stellar mass surface density and local escape velocity-dependent outflows. We find that the best explanation for the metallicity differences is the variation in the average metallicity of accreted gas between different environments that depends on the stellar mass of the dominant galaxies in each halo. This is interpreted as evidence for the exchange of enriched gas between galaxies in dense environments that is predicted by recent simulations