Time evolution of intrinsic alignments of galaxies

Intrinsic alignments (IA), correlations between the intrinsic shapes and orientations of galaxies on the sky, are both a significant systematic in weak lensing and a probe of the effect of large-scale structure on galactic structure and angular momentum. In the era of precision cosmology, it is thus especially important to model IA with high accuracy. Efforts to use cosmological perturbation theory to model the dependence of IA on the large-scale structure have thus far been relatively successful; however, extant models do not consistently account for time evolution. In particular, advection of galaxies due to peculiar velocities alters the impact of IA, because galaxy positions when observed are generally different from their positions at the epoch when IA is believed to be set. In this work, we evolve the galaxy IA from the time of galaxy formation to the time at which they are observed, including the effects of this advection, and show how this process naturally leads to a dependence of IA on the velocity shear. We calculate the galaxy-galaxy-IA bispectrum to tree level (in the linear matter density) in terms of the evolved IA coefficients. We then discuss the implications for weak lensing systematics as well as for studies of galaxy formation and evolution. We find that considering advection introduces nonlocality into the bispectrum, and that the degree of nonlocality represents the memory of a galaxy's path from the time of its formation to the time of observation. We discuss how this result can be used to constrain the redshift at which IA is determined and provide Fisher estimation for the relevant measurements using the example of SDSS-BOSS.Comment: 30 pages, 5 figures, 2 table

Preliminary design of a mobile lunar power supply

A preliminary design for a Stirling isotope power system for use as a mobile lunar power supply is presented. Performance and mass of the components required for the system are estimated. These estimates are based on power requirements and the operating environment. Optimizations routines are used to determine minimum mass operational points. Shielding for the isotope system are given as a function of the allowed dose, distance from the source, and the time spent near the source. The technologies used in the power conversion and radiator systems are taken from ongoing research in the Civil Space Technology Initiative (CSTI) program

Improving Tracer Particle Surface Properties for Wind Tunnel Research

The surface properties of micron size polystyrene latex microspheres (PSLs) modified with quaternary alkylammonium (QA) surfactants were investigated, with a focus on the relationship between surface chemistry and adhesion. These investigations were motivated by the need to develop non-fouling tracer particles for wind tunnel studies. The goals were to relate the work of adhesion between particles and substrates to the type and amount of QA modifier in order to optimize the performance of PSL tracers. Surfactant-free emulsion polymerization (SFEP) can produce PSLs for wind tunnel tracers. Covalentlybound charged groups (derived from the initiator) stabilize PSL surfaces in water. This work used PSLs with anionic surface groups. Previous studies indicated that surface-bound charged groups on PSLs have a significant impact on their interfacial energy. Modifying charged surface groups therefore offers a method to modulate PSL interfacial properties. In this work, PSLs and films were modified by adsorption of QA surfactants

CHAP Enhances Versatility in Colloidal Probe Fabrication

A colloidal probe, comprising a colloidal particle attached to an atomic force microscope cantilever, is employed to measure directly interaction forces between the particle and a surface. It is possible to change or even destroy a particle while attaching it to a cantilever, thus limiting the types of systems to which the colloidal probe technique may be applied. Here we present the Controlled Heating and Alignment Platform (CHAP) for fabricating colloidal probes without altering the original characteristics of the attached particle. The CHAP applies heat directly to the atomic force microscope chip to rapidly and precisely control cantilever temperature. This minimizes particle heating and enables control over the viscosity of thermoplastic adhesive, to prevent it from contaminating the particle surface. 3D-printed components made the CHAP compatible with standard optical microscopes and streamlined the fabrication process while increasing the platforms versatility. Using the CHAP with a thermoplastic wax adhesive, colloidal probes were fabricated using polystyrene and silica particles between 0.7 and 40 m in diameter. We characterized the properties and interactions of the adhesive and particles, as well as the properties of the completed probes, to demonstrate the retention of particle features throughout fabrication. Pull-off tests with CHAPs probes measured adhesive force values in the expected ranges and demonstrated that particles were firmly attached to the cantilevers

Improving nanopore read accuracy with the R2C2 method enables the sequencing of highly multiplexed full-length single-cell cDNA.

High-throughput short-read sequencing has revolutionized how transcriptomes are quantified and annotated. However, while Illumina short-read sequencers can be used to analyze entire transcriptomes down to the level of individual splicing events with great accuracy, they fall short of analyzing how these individual events are combined into complete RNA transcript isoforms. Because of this shortfall, long-distance information is required to complement short-read sequencing to analyze transcriptomes on the level of full-length RNA transcript isoforms. While long-read sequencing technology can provide this long-distance information, there are issues with both Pacific Biosciences (PacBio) and Oxford Nanopore Technologies (ONT) long-read sequencing technologies that prevent their widespread adoption. Briefly, PacBio sequencers produce low numbers of reads with high accuracy, while ONT sequencers produce higher numbers of reads with lower accuracy. Here, we introduce and validate a long-read ONT-based sequencing method. At the same cost, our Rolling Circle Amplification to Concatemeric Consensus (R2C2) method generates more accurate reads of full-length RNA transcript isoforms than any other available long-read sequencing method. These reads can then be used to generate isoform-level transcriptomes for both genome annotation and differential expression analysis in bulk or single-cell samples

Throw the Book at Them: Why the FTC Needs to Get Tough with Influencers

The Federal Trade Commission is an administrative agency that has traditionally been aggressive when deploying its delegated authority. At the core of these actions is the FTC’s interpretive definition of deception as based upon a reasonable consumer standard. Specifically, the commission has regularly used Section 5(a) of the FTC Act, in tandem with its interpretive definition of deception, as a sword in a variety of contexts, including enforcement actions for deceptive advertising, endorsements, and claim substantiation against a range of industries. These include successfully brought actions or consent decrees obtained in enforcement proceedings against powerful economic entities, including Google and Facebook. Yet, in one area, the FTC has been reluctant to engage in the hard tactics it regularly deploys in other areas. The Commission has struggled to employ a coherent enforcement strategy for deceptive practices by Social Media Influencers. The Commission has taken significant steps towards deception and disclosure enforcement for influencers, including publication of a set of guidelines for disclosure. However, with the exception of a series of warning letters sent to high profile influencers in April of 2017, the Commission has not engaged in a significant enforcement action—choosing instead to launch an inquiry in February 2020 to review the disclosure guidelines. As empirical research demonstrates that consumers do not understand the nature of the influencer process, this Article argues that the FTC should employ a commitment to a robust enforcement stance. The FTC’s failure to “make an example” of high-profile influencers or to take a hardline approach with influencers, as the Commission did with native advertising online, represents a parting with the manner with which the Commissions has traditionally enforced the deception standard in endorsement ads. This departure, this Article argues, is undermining the FTC’s consumer protections