Extracting low-dimensional psychological representations from convolutional neural networks

Deep neural networks are increasingly being used in cognitive modeling as a means of deriving representations for complex stimuli such as images. While the predictive power of these networks is high, it is often not clear whether they also offer useful explanations of the task at hand. Convolutional neural network representations have been shown to be predictive of human similarity judgments for images after appropriate adaptation. However, these high-dimensional representations are difficult to interpret. Here we present a method for reducing these representations to a low-dimensional space which is still predictive of similarity judgments. We show that these low-dimensional representations also provide insightful explanations of factors underlying human similarity judgments.Comment: Accepted to CogSci 202

Urban heritage conservation and rapid urbanization : insights from Surat, India

Currently, heritage is challenged in the Indian city of Surat due to diverse pressures,  including rapid urbanization, increasing housing demand, and socio‐cultural and climate changes.  Where rapid demographic growth of urban areas is happening, heritage is disappearing at an  alarming rate. Despite some efforts from the local government, urban cultural heritage is being  neglected and historic buildings keep being replaced by ordinary concrete buildings at a worryingly  rapid pace. Discussions of challenges and issues of Surat’s urban area is supported by a qualitative  dataset, including in‐depth semi‐structured interviews and focus groups with local policy makers,  planners, and heritage experts, triangulated by observation and a photo‐survey of two historic  areas. Findings from this study reveal a myriad of challenges such as: inadequacy of urban  conservation management policies and processes focused on heritage, absence of skills, training,  and resources amongst decision makers and persistent conflict and competition between heritage  conservation needs and developers’ interests. Furthermore, the values and significance of Surat’s  tangible and intangible heritage is not fully recognized by its citizens and heritage stakeholders. A  crucial opportunity exists for Surat to maximize the potential of heritage and reinforce urban  identity for its present and future generations. Surat’s context is representative of general trends  and conservation challenges and therefore recommendations developed in this study hold the  potential to offer interesting insights to the wider planners and conservationists’ international  community.  This  paper  recommends  thoughtful  integration  of  sustainable  heritage  urban  conservation into local urban development frameworks and the establishment of approaches that  recognize the plurality of heritage values

Optical Spectroscopy of Type Ia Supernovae

We present 432 low-dispersion optical spectra of 32 Type Ia supernovae (SNe Ia) that also have well-calibrated light curves. The coverage ranges from 6 epochs to 36 epochs of spectroscopy. Most of the data were obtained with the 1.5m Tillinghast telescope at the F. L. Whipple Observatory with typical wavelength coverage of 3700-7400A and a resolution of ~7A. The earliest spectra are thirteen days before B-band maximum; two-thirds of the SNe were observed before maximum brightness. Coverage for some SNe continues almost to the nebular phase. The consistency of the method of observation and the technique of reduction makes this an ideal data set for studying the spectroscopic diversity of SNe Ia.Comment: Accepted for publication in the Astronomical Journal, 109 pages (including data table), 44 figures, full resolution figures at http://www.noao.edu/noao/staff/matheson/Iaspec.ps.g

Supersensitive measurement of angular displacements using entangled photons

We show that the use of entangled photons having non-zero orbital angular momentum (OAM) increases the resolution and sensitivity of angular-displacement measurements performed using an interferometer. By employing a 4$\times$4 matrix formulation to study the propagation of entangled OAM modes, we analyze measurement schemes for two and four entangled photons and obtain explicit expressions for the resolution and sensitivity in these schemes. We find that the resolution of angular-displacement measurements scales as $Nl$ while the angular sensitivity increases as $1/(2Nl)$, where $N$ is the number of entangled photons and $l$ the magnitude of the orbital-angular-momentum mode index. These results are an improvement over what could be obtained with $N$ non-entangled photons carrying an orbital angular momentum of $l\hbar$ per photonComment: 6 pages, 3 figure

An alternative construction of B-M and B-T unitals in Desarguesian planes

We present a new construction of non-classical unitals from a classical unital $U$ in $PG(2,q^2)$. The resulting non-classical unitals are B-M unitals. The idea is to find a non-standard model $\Pi$ of $PG(2,q^2)$ with the following three properties: 1. points of $\Pi$ are those of $PG(2,q^2)$; 2. lines of $\Pi$ are certain lines and conics of $PG(2,q^2)$; 3. the points in $U$ form a non-classical B-M unital in $\Pi$. Our construction also works for the B-T unital, provided that conics are replaced by certain algebraic curves of higher degree.Comment: Keywords: unital, desarguesian plane 11 pages; ISSN: 0012-365

Finite Doubly Transitive Affine Planes

AbstractIn this article, we classify the finite affine planes admitting doubly transitive collineation groups