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Open-source tools for behavioral video analysis: Setup, methods, and best practices
No full textRecently developed methods for video analysis, especially models for pose estimation and behavior classification, are transforming behavioral quantification to be more precise, scalable, and reproducible in fields such as neuroscience and ethology. These tools overcome long-standing limitations of manual scoring of video frames and traditional ‘center of mass’ tracking algorithms to enable video analysis at scale. The expansion of open-source tools for video acquisition and analysis has led to new experimental approaches to understand behavior. Here, we review currently available open-source tools for video analysis and discuss how to set up these methods for labs new to video recording. We also discuss best practices for developing and using video analysis methods, including community-wide standards and critical needs for the open sharing of datasets and code, more widespread comparisons of video analysis methods, and better documentation for these methods especially for new users. We encourage broader adoption and continued development of these tools, which have tremendous potential for accelerating scientific progress in understanding the brain and behavior
Staggered circular nanoporous graphene converts electromagnetic waves into electricity
No full textHarvesting largely ignored and wasted electromagnetic (EM) energy released by electronic devices and converting it into direct current (DC) electricity is an attractive strategy not only to reduce EM pollution but also address the ever-increasing energy crisis. Here we report the synthesis of nanoparticle-templated graphene with monodisperse and staggered circular nanopores enabling an EM–heat–DC conversion pathway. We experimentally and theoretically demonstrate that this staggered nanoporous structure alters graphene’s electronic and phononic properties by synergistically manipulating its intralayer nanostructures and interlayer interactions. The staggered circular nanoporous graphene exhibits an anomalous combination of properties, which lead to an efficient absorption and conversion of EM waves into heat and in turn an output of DC electricity through the thermoelectric effect. Overall, our results advance the fundamental understanding of the structure–property relationships of ordered nanoporous graphene, providing an effective strategy to reduce EM pollution and generate electric energy
Bacterial Argonaute Proteins Aid Cell Division in the Presence of Topoisomerase Inhibitors in Escherichia coli
No full textProkaryotic Argonaute (pAgo) proteins are guide-dependent nucleases that function in host defense against invaders. Recently, it was shown that TtAgo from Thermus thermophilus also participates in the completion of DNA replication by decatenating chromosomal DNA. Here, we show that two pAgos from cyanobacteria Synechococcus elongatus (SeAgo) and Limnothrix rosea (LrAgo) are active in heterologous Escherichia coli and aid cell division in the presence of the gyrase inhibitor ciprofloxacin, depending on the host double-strand break repair machinery. Both pAgos are preferentially loaded with small guide DNAs (smDNAs) derived from the sites of replication termination. Ciprofloxacin increases the amounts of smDNAs from the termination region and from the sites of genomic DNA cleavage by gyrase, suggesting that smDNA biogenesis depends on DNA replication and is stimulated by gyrase inhibition. Ciprofloxacin enhances asymmetry in the distribution of smDNAs around Chi sites, indicating that it induces double-strand breaks that serve as a source of smDNA during their processing by RecBCD. While active in E. coli, SeAgo does not protect its native host S. elongatus from ciprofloxacin. These results suggest that pAgo nucleases may help to complete replication of chromosomal DNA by promoting chromosome decatenation or participating in the processing of gyrase cleavage sites, and may switch their functional activities depending on the host species
Interpolation Filter Model For Ramanujan Subspace Signals
No full textRamanujan sums have been shown to have interesting applications in signal processing. Ramanujan subspaces, Ramanujan dictionaries, and Ramanujan filter banks are useful in representing and denoising discrete-time periodic signals. In this paper, we theoretically investigate an ideal interpolation filter model for Ramanujan subspace signals wherein an expander ↑ M is followed by the ideal q-th Ramanujan filter C q (e jω ). The output space of this interpolation filter is, in general, only a proper subspace of the q-th Ramanujan subspace Sq. For the special case when M and q are coprime, we prove that the output space is the entire Ramanujan subspace. We also discuss a more general form of this model for the representation of periodic signals, which may have a potential application in denoising periodic signals. When M and q are not coprime, we provide a bound on the dimension of the output space of the interpolation filter. For this general case, we also conjecture that the provided bound in fact equals the dimension of the output space
Interstellar Object Accessibility and Mission Design
No full textInterstellar objects (ISOs) are fascinating and under-explored celestial objects, providing physical laboratories to understand the formation of our solar system and probe the composition and properties of material formed in exoplanetary systems. In this work, we investigate approaches to designing successful flyby missions to ISOs. We have generated trajec-tories to a series of synthetic representative ISOs, simulating a ground campaign to observe the target and resolve its state, and determining the cruise and close approach Δ V required for the encounter. We have developed novel deep learning-driven guidance and control algorithms to enable an accurate flyby of an ISO traveling at velocities over 60 km/s. In this paper, we discuss the accessibility of and mission design to ISOs with varying characteristics, including analysis of state covariance estimation over the course of cruise, handoffs from traditional navigation approaches to novel autonomous navigation for fast flyby regimes, and overall recommendations about preparing for the future in situ exploration of these targets
SPHEREx Preliminary Mission Overview
No full textThe Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) mission is part of the NASA Astrophysics Medium Explorer (MIDEX) program and will perform the first near-infrared all-sky spectral survey from a Low Earth, sun-synchronous, polar orbit. As a space-based observatory, SPHEREx will use spectroscopy to measure hundreds of millions of galaxies and a diversity of astronomical phenomena. With this capability, SPHEREx will produce a three-dimensional map of the universe, which scientists will use to answer questions about the early universe, the history of galaxies, and the prevalence of life-sustaining molecules in planet-forming regions of space. Relying on a robust instrument design with a single observing mode, SPHEREx will map the entire sky four times during its 25-month on-orbit survey period. It will survey the sky in optical, as well as near-infrared light, specifically obtaining near-infrared 0.75−5.0 μm spectra every 6″ over the entire sky. SPHEREx is designed for strong scientific synergies with other missions and observatories, with a resulting goal of a rich legacy archive of data that can be used by the community on numerous scientific investigations. SPHEREx is managed by the Jet Propulsion Laboratory—a division of California Institute of Technology—for NASA's Science Mission Directorate in Washington, DC. The mission's Principal Investigator is based at Caltech, which is also developing the payload in collaboration with JPL. Ball Aerospace is supplying the spacecraft bus. The Korea Astronomy and Space Science Institute (KASI) is an instrument and science partner for the mission. Data will be processed and archived at Caltech's IPAC. In addition to scientists from Caltech, JPL, and KASI, the scientific analysis will include scientists from numerous institutions. This paper provides a preliminary overview of the mission and its concept of operation, as well as an overview of the design of the observatory's spacecraft bus, the instrument, the software architecture, the mission system, and the ground data system. A curated list of key and driving design trade studies are also presented. It is expected that subsequent planned publications will provide intermediate project updates and eventual science results from on-orbit operations
FPGA Implementation of an Adaptive Sweep Algorithm for Spacecraft Radios
No full textSpacecraft communicate with the Deep Space Network (DSN) at a predetermined carrier frequency. However, signals are Doppler shifted away from the original transmitted frequency due to the high orbital velocities of the spacecraft. This paper describes the implementation of an adaptive sweep algorithm on a Xilinx Kintex-7 field-programmable gate array (FPGA). This algorithm estimates the carrier Doppler shift and compensates for it to allow for coherent data demodulation. The algorithm is implemented in MATLAB's Simulink, complied to Verilog using HDL Coder, and run on the FPGA using the FPGA-in-the-loop Wizard. The FPGA implementation has been validated in the presence of noise, by comparing the standard deviation of the Doppler residuals at different signal-to-noise ratios, to values obtained via a theoretical analysis of the carrier synchronization loop. Results indicate excellent agreement and thus validate our implementation. We have also tested the algorithm against flight data obtained from the Lunar Reconnaissance Orbiter (LRO) and the Deep Space Network (DSN), and proven that the algorithm can successfully acquire and track the carrier
Universal time-dependent Ginzburg-Landau theory
No full textWe study the hydrodynamics of superconductors within the framework of Schwinger-Keldysh effective field theory (EFT). We show that in the vicinity of the superconducting phase transition the most general leading-order EFT satisfying the local Kubo-Martin-Schwinger condition is described by a version of the time-dependent Ginzburg-Landau (TDGL) equations augmented with stochastic terms. This version of TDGL is applicable in the gapless regime independent of any microscopic details. Within this approach, it is possible to include systematically the effects of nonuniform temperature and heat conductivity, as well as explicit or spontaneous breaking of time reversal. We also introduce a thermal version of the Josephson relation and use it to construct an exotic hydrodynamics describing a phase of matter where heat can flow without dissipation
Moufang patterns and geometry of information
No full textTechnology of data collection and information transmission is based on various mathematical models of encoding. The words “Geometry of information” refer to such models, whereas the words “Moufang patterns” refer to various sophisticated symmetries appearing naturally in such models.
In this paper, we show that the symmetries of spaces of probability distributions, endowed with their canonical Riemannian metric of information geometry, have the structure of a commutative Moufang loop. We also show that the F-manifold structure on the space of probability distribution can be described in terms of differential
-webs and Malcev algebras. We then present a new construction of (non-commutative) Moufang loops associated to almost-symplectic structures over finite fields, and use them to construct a new class of code loops with associated quantum error-correcting codes and networks of perfect tensors
An electric molecular motor
No full textMacroscopic electric motors continue to have a large impact on almost every aspect of modern society. Consequently, the effort towards developing molecular motors that can be driven by electricity could not be more timely. Here we describe an electric molecular motor based on a [3]catenane, in which two cyclobis(paraquat-p-phenylene)(6) (CBPQT⁴⁺) rings are powered by electricity in solution to circumrotate unidirectionally around a 50-membered loop. The constitution of the loop ensures that both rings undergo highly (85%) unidirectional movement under the guidance of a flashing energy ratchet, whereas the interactions between the two rings give rise to a two-dimensional potential energy surface (PES) similar to that shown by FₒF₁ ATP synthase. The unidirectionality is powered by an oscillating voltage or external modulation of the redox potential. Initially, we focused our attention on the homologous [2]catenane, only to find that the kinetic asymmetry was insufficient to support unidirectional movement of the sole ring. Accordingly, we incorporated a second CBPQT⁴⁺ ring to provide further symmetry breaking by interactions between the two mobile rings. This demonstration of electrically driven continual circumrotatory motion of two rings around a loop in a [3]catenane is free from the production of waste products and represents an important step towards surface-bound electric molecular motors