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Shreya Majumdar

Publications and source records attributed to Shreya Majumdar.

2 recordsLinked to original sources

Sight, smell and more: What cues do free-ranging dogs use for decision-making while scavenging?

Finding food is a fundamental activity for survival of all living organisms. Free-ranging dogs have been known to use their olfaction to assess the quality and type of available food but their use of visual ability in foraging is not well-documented. In the current study, we seek to remedy that by testing free-ranging dogs in a food-based choice test. We tested whether the dogs implemented hierarchical or synergistic usage of cues while finding food. We found limited prioritization of olfactory cues over visual cues in dichromatic choice tests but in phases with similar perceptual elements, the sensory choice was not clear. Furthermore, free-ranging dogs display a dynamic decision-making in unpredictable urban environments adopting a good-enough strategy during foraging. They prefer speed over accuracy, settling for intermediate quality food if their preferred food item is not available. These dogs also displayed left-bias during food choice. In multi-sensorial, natural setting multiple modulators like environmental noise, risk, and internal perceptual elements apart from food cues seem to be affecting the decision-making in dogs.

q-bio.NC↗

Frequency and Abundance of Binary sUpermassive bLack holes from Optical Variability Surveys (FABULOVS): Hubble Space Telescope Imaging of Radial-Velocity Selected Binary Candidates

Sub-parsec (sub-pc) binary supermassive black holes (BSBHs) should be common from galaxy mergers, yet direct evidence has been elusive. We present HST/WFC3IR F160W imaging for a sample of 8 candidate sub-pc BSBHs at redshifts z~0.1--0.5, as well as cross-comparison with a sample of ordinary quasars with archival HST/WFC3 IR F160W images. These 8 candidate sub-pc BSBHs were identified from multi-epoch spectroscopic surveys of quasars (including both typical quasars and those with single-peaked velocity-offset broad lines). whose broad H$β$ lines are significantly offset (by ~< a few hundred km/s) from the systemic redshifts. We directly test the prediction that the host galaxies of BSBHs would have a higher fraction of disturbed morphologies and younger stellar bulges from recent interactions than those of control quasars. After careful subtraction of the central quasar light, our candidate BSBH hosts show a statistically undifferentiated distribution of host asymmetry, indicative of a similar fraction of recent mergers. While a significantly larger sample is needed to place this result on a much firmer statistical ground, it opens questions as to the timescale differences between galaxy merger and BSBH formation, or the efficacy of the radial-velocity-shift--based selection of sub-pc BSBH candidates.

astro-ph.GA↗