A Note on D1-D5 Entropy and Geometric Quantization

We quantize the space of 2-charge fuzzballs in IIB supergravity on $K3$. The resulting entropy precisely matches the D1-D5 black hole entropy, including a specific numerical coefficient. A partial match (ie., a smaller coefficient) was found by Rychkov a decade ago using the Lunin-Mathur subclass of solutions - we use a simple observation to generalize his approach to the full moduli space of $K3$ fuzzballs, filling a small gap in the literature.Comment: v2,3: minor corrections to a footnote and acknowledgments, v1 is the JHEP versio

Chiral Higher Spin Gravity

We construct a candidate for the most general chiral higher spin theory with AdS$_3$ boundary conditions. In the Chern-Simons language, on the left it has the Drinfeld-Sokolov reduced form, but on the right all charges and chemical potentials are turned on. Altogether (for the spin-3 case) these are $19$ functions. Despite this, we show that the resulting metric has the form of the "most general" AdS$_3$ boundary conditions discussed by Grumiller and Riegler. The asymptotic symmetry algebra is a product of a $\mathcal{W}_3$ algebra on the left and an affine $sl(3)_k$ current algebra on the right, as desired. The metric and higher spin fields depend on all the $19$ functions. We compare our work with previous results in the literature.Comment: v2: refs added, minor correction

A Neumann Boundary Term for Gravity

The Gibbons-Hawking-York (GHY) boundary term makes the Dirichlet problem for gravity well defined, but no such general term seems to be known for Neumann boundary conditions. In this paper, we view Neumann {\em not} as fixing the normal derivative of the metric ("velocity") at the boundary, but as fixing the functional derivative of the action with respect to the boundary metric ("momentum"). This leads directly to a new boundary term for gravity: the trace of the extrinsic curvature with a specific dimension-dependent coefficient. In three dimensions this boundary term reduces to a "one-half" GHY term noted in the literature previously, and we observe that our action translates precisely to the Chern-Simons action with no extra boundary terms. In four dimensions the boundary term vanishes, giving a natural Neumann interpretation to the standard Einstein-Hilbert action without boundary terms. We argue that in light of AdS/CFT, ours is a natural approach for defining a "microcanonical" path integral for gravity in the spirit of the (pre-AdS/CFT) work of Brown and York.Comment: v3: emphasized that a covariant notion of Neumann boundary condition inevitably leads to our boundary term. v4: more ref

A Grassmann Path From AdS_3 to Flat Space

We show that interpreting the inverse AdS_3 radius 1/l as a Grassmann variable results in a formal map from gravity in AdS_3 to gravity in flat space. The underlying reason for this is the fact that ISO(2,1) is the Inonu-Wigner contraction of SO(2,2). We show how this works for the Chern-Simons actions, demonstrate how the general (Banados) solution in AdS_3 maps to the general flat space solution, and how the Killing vectors, charges and the Virasoro algebra in the Brown-Henneaux case map to the corresponding quantities in the BMS_3 case. Our results straightforwardly generalize to the higher spin case: the recently constructed flat space higher spin theories emerge automatically in this approach from their AdS counterparts. We conclude with a discussion of singularity resolution in the BMS gauge as an application.Comment: 20 pages, 1 figure; v2: many refs added, minor changes, v3: typos fixed, one more ref added, JHEP versio

3D Gravity, Chern-Simons and Higher Spins: A Mini Introduction

These are notes of introductory lectures on (a) elements of 2+1 dimensional gravity, (b) some aspects of its relation to Chern-Simons theory, (c) its generalization to couple higher spins, and (d) cosmic singularity resolution as an application in the context of flat space higher spin theory. A knowledge of the Einstein-Hilbert action, classical non-Abelian gauge theory and some (negotiable amount of) maturity are the only pre-requisites.Comment: 23 pages, Based on talks/lectures by CK at Goteborg, Tehran and Bangkok. v2:acknowledgments and references added, v3:published versio

Higher Spin Cosmology

We construct cosmological solutions of higher spin gravity in 2+1 dimensional de Sitter space. We show that a consistent thermodynamics can be obtained for their horizons by demanding appropriate holonomy conditions. This is equivalent to demanding the integrability of the Euclidean boundary CFT partition function, and reduces to Gibbons-Hawking thermodynamics in the spin-2 case. By using a prescription of Maldacena, we relate the thermodynamics of these solutions to those of higher spin black holes in AdS_3.Comment: 21 pages, v2: many typos fixed, refs added, v3: minor corrections/improvements, Phys. Rev. D version, v4: one more re

Security, Privacy and Steganographic Analysis of FaceApp and TikTo

Article originally published in International Journal of Computer Science and SecuritySmartphone applications (Apps) can be addictive for users due to their uniqueness, ease-of-use, trendiness, and growing popularity. The addition of Artificial Intelligence (AI) into their functionality has rapidly gained popularity with smartphone users. Over the years, very few smartphone Apps have quickly gained immense popularity like FaceApp and TikTok. FaceApp boasts of using AI to transform photos of human faces using its powerful facial recognition capabilities. FaceApp has been the target of ensuing backlash against it driving the market for a number of other similar yet lesser-known clones into the top ranks of the App stores. TikTok offers video editing and sharing of short video clips whereby making them charming, funny, cringe-inducing, and addictive to the younger generation. FaceApp and TikTok have been the targets of the media, privacy watchdogs, and governments over worries of privacy, ethnicity filters, data misuse, anti-forensics, and security. In this paper, the authors forensically review FaceApp and TikTok Apps from the Android Play Store, for their data ownership, data management, privacy concerns, steganographic use, and overall security posture

Speckle pattern analysis of security holograms and related foils for quality assessment and authentication.

A speckle pattern is produced by the mutual interference of a set of coherent wavefronts. Speckle patterns typically occur in diffuse reflections of monochromatic light such a laser light. When a rough surface is illuminated by a coherent light is imaged, a speckle pattern is observed in the image plane. This study involves the quality assessment and authentication of security holograms and its related foils by analyzing the speckle pattern generated from the specimen itself. Speckle pattern from various type of security holograms and foils are taken. By processing the image of the speckle pattern, the size of the speckles is analyzed using MATLAB software. By evaluating the size of the speckle generated, the feasibility of analyzing the quality and authenticity of the security hologram is assessed. The paper discusses about the experimental setup, image capturing, and processing method and the result obtained in detail

Real Time Data Downlink Device for Live Telemetry from Instrumented Vehicles

Real Time Data Downlink Device (RTDD) for Live Telemetry from Instrumented Vehicles Avinash Muthu Krishnan1, Marc D. Compere1, Kevin A. Adkins2 1 Department of Mechanical Engineering, Embry-Riddle Aeronautical University 2 Department of Aeronautical Science, Embry-Riddle Aeronautical University This paper presents a microcontroller and communications design that delivers real-time telemetry data over the cellular network from vehicles instrumented for scientific or engineering purposes. The Real Time Data Downlink (RTDD) device is being designed for atmospheric data collection on an aerial platform. While this application specifically pertains to the atmospheric sciences, the data collection technique is broadly applicable to ground, surface, or aerial platform data collection. The RTDD is implemented on four DJI Matrice-100 quadcopters that transmit real time position, wind speed, pressure, temperature and humidity over the cellular network. Each vehicle writes sensor data locally while simultaneously transmitting data samples to a data collection computer for real time experiment monitoring. The data collection computer runs an open-sourced software called the Mobility Virtual Environment (MoVE). MoVE aggregates all incoming data streams from each vehicle to provide a comprehensive picture of the scenario with a live 2D map display of all vehicles and a browser-based table to present the data. The RTDD provides real time data thus ensuring complete mission execution and confirmation of sensor performance. Therefore, the RTDD is a critical component of the instrumented aircraft and an overall successful multi-vehicle data collection effort

New Air Quality Measurement Method: Low-Cost Sensors on UAV’s

With the rapid industrialization and the current status of climate change, air pollution has become a global concern. However, detecting atmospheric pollutants is costly, time-consuming, and cumbersome. Currently, the Environmental Protection Agency (US EPA) utilizes filter-based techniques in their federal reference and federal equivalent methods (FRM and FEM, respectively) to measure ground-based particulate matter (PM) levels in the atmosphere. Recently, the development of low-cost sensors has helped in combatting the high cost associated with acquiring these measurements. These sensors allow for PM concentrations to be measured at high resolutions. Due to their surface mounted nature, the EPA’s methods are limited in measuring the concentrations of PM at the ground-level. Hence, they lack the ability of determining the concentrations at various altitudes, which is important in characterizing the origin and the formation pathway of such pollutants. To address these shortcomings, we propose placing multiple low-cost sensors on Unmanned Aerial Vehicles (UAVs) to measure the concentrations of PM in Daytona Beach, FL. Sampling will be conducted seasonally, and the PM concentrations will be compared to their counterpart observations obtained using the EPA’s methods. The findings of this study should aid in the development of low-cost air pollution sensors that can be hosted on UAVs. This work promises to be advantageous in detecting air pollutants in both congested and remote areas