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This paper presents polycarbonate negative topographies used as substrates for the templated self- assembly of microsphere-based microrobots. This approach protects primary structures from damage during molding and de-molding, providing high fidelity negatives of arrays for assembly via templated assembly by selective removal (TASR). We show that reducing the surface energy mismatch between the microspheres and substrate results in yield increases up to 790%. This work addresses yield-related challenges of multicomponent microsystem assembly with existing PDMS-based templated assembly methods. The application of this technology in DNA microswimmer fabrication is demonstrated. 

Magnetically-actuated swimming microrobots are an emerging tool for navigating and manipulating materials in confined spaces. Recent work has demonstrated that it is possible to build such systems at the micro and nanoscales using polymer microspheres, magnetic particles and DNA nanotechnology. However, while these materials enable an unprecedented ability to build at small scales, such systems often demonstrate significant polydispersity resulting from both the material variations and the assembly process itself. This variability makes it difficult to predict, let alone optimize, the direction or magnitude of microswimmer velocity from design parameters such as link shape or aspect ratio. To isolate questions of a swimmer's design from variations in its physical dimensions, we present a novel experimental platform using two-photon polymerization to build a two-link, buoyant milliswimmer with a fully customizable shape and integrated flexible linker (the swimmer is underactuated, enabling asymmetric cyclic motion and net translation). Our approach enables us to control both swimming direction and repeatability of swimmer performance. These studies provide ground truth data revealing that neither the first order nor second order models currently capture the key features of milliswimmer performance. We therefore use our experimental platform to develop design guidelines for tuning the swimming speeds, and we identify the following three approaches for increasing speed: (1) tuning the actuation frequency for a fixed aspect ratio, (2) adjusting the aspect ratio given a desired range of operating frequencies, and (3) using the weaker value of linker stiffness from among the values that we tested, while still maintaining a robust connection between the links. We also find experimentally that spherical two-link swimmers with dissimilar link diameters achieve net velocities comparable to swimmers with cylindrical links, but that two-link spherical swimmers of equal diameter do not. 

Runtime verificationis a lightweight method for monitoring the formal specification of a system during its execution. It has recently been shown that a given state predicate can be monitored consistently by a set of crash-prone asynchronousdistributedmonitors observing the system, only if each monitor can emit verdicts taken from alarge enoughfinite set. We revisit this impossibility result in the concrete context of linear-time logic (ltl) semantics for runtime verification, that is, when the correctness of the system is specified by anltlformula on its execution traces. First, we show that monitors synthesized based on the 4-valued semantics ofltl(rv-ltl) may result in inconsistent distributed monitoring, even for some simpleltlformulas. More generally, given anyltlformula φ, we relate the number of different verdicts required by the monitors for consistently monitoring φ, with a specific structural characteristic of φ called itsalternation number. Specifically, we show that, for everyk ≥ 0, there is anltlformula φ with alternation number kthat cannot be verified at runtime by distributed monitors emitting verdicts from a set of cardinality smaller thank+ 1. On the positive side, we define a family of logics, calleddistributedltl(abbreviated asdltl), parameterized byk≥ 0, which refinesrv-ltlby incorporating2k+ 4 truth values. Our main contribution is to show that, for everyk≥ 0, everyltlformula φ with alternation number kcan be consistently monitored by distributed monitors, each running an automaton based on a (2 ⌈k/2 ⌉ +4)-valued logic taken from thedltlfamily. 

In this paper, we address the growing visibility of people who reject gender categories and identify as neither women nor men. We begin with a brief overview of how we conceptualize gender as a social structure. We use this theoretical framework to theorize how the increased visibility of people who reject the gender binary influence how we understand the gender structure, social change, and social justice. While we offer no empirical analysis in this article, we do draw upon interviews with 120 non-binary people in three metropolitan areas in the United States and interviews that are in process in Italy and Spain. We discuss the possibility that those who reject gender categories may increase freedom from gendered expectations for everyone, but also the possibility of backlash to increased visibility of gender non-conformity. We conclude the paper with an argument that the future of feminism as a social movement should be aimed at liberation from gender itself. 

Abstract Snake venoms are complex mixtures of toxic proteins that hold significant medical, pharmacological and evolutionary interest. To better understand the genetic diversity underlying snake venoms, we developed VenomCap, a novel exon‐capture probe set targeting toxin‐coding genes from a wide range of elapid snakes, with a particular focus on the ecologically diverse and medically important subfamily Hydrophiinae. We tested the capture success of VenomCap across 24 species, representing all major elapid lineages. We included snake phylogenomic probes in the VenomCap capture set, allowing us to compare capture performance between venom and phylogenomic loci and to infer elapid phylogenetic relationships. We demonstrated VenomCap's ability to recover exons from ~1500 target markers, representing a total of 24 known venom gene families, which includes the dominant gene families found in elapid venoms. We find that VenomCap's capture results are robust across all elapids sampled, and especially among hydrophiines, with respect to measures of target capture success (target loci matched, sensitivity, specificity and missing data). As a cost‐effective and efficient alternative to full genome sequencing, VenomCap can dramatically accelerate the sequencing and analysis of venom gene families. Overall, our tool offers a model for genomic studies on snake venom gene diversity and evolution that can be expanded for comprehensive comparisons across the other families of venomous snakes. 

Methods for state estimation that rely on visual information are challenging on legged robots due to rapid changes in the viewing angle of onboard cameras. In this work, we show that by leveraging structure in the way that the robot locomotes, the accuracy of visual-inertial SLAM in these challenging scenarios can be increased. We present a method that takes advantage of the underlying periodic predictability often present in the motion of legged robots to improve the performance of the feature tracking module within a visual-inertial SLAM system. Our method performs multi-session SLAM on a single robot, where each session is responsible for mapping during a distinct portion of the robot’s gait cycle. Our method produces lower absolute trajectory error than several state-of-the-art methods for visual-inertial SLAM in both a simulated environment and on data collected on a quadrupedal robot executing dynamic gaits. On real-world bounding gaits, our median trajectory error was less than 35% of the error of the next best estimate provided by state-of-the-art methods.