Mobile Formation Coordination and Tracking Control for Multiple Non-holonomic Vehicles

This paper addresses forward motion control for trajectory tracking and mobile formation coordination for a group of non-holonomic vehicles on SE(2). Firstly, by constructing an intermediate attitude variable which involves vehicles' position information and desired attitude, the translational and rotational control inputs are designed in two stages to solve the trajectory tracking problem. Secondly, the coordination relationships of relative positions and headings are explored thoroughly for a group of non-holonomic vehicles to maintain a mobile formation with rigid body motion constraints. We prove that, except for the cases of parallel formation and translational straight line formation, a mobile formation with strict rigid-body motion can be achieved if and only if the ratios of linear speed to angular speed for each individual vehicle are constants. Motion properties for mobile formation with weak rigid-body motion are also demonstrated. Thereafter, based on the proposed trajectory tracking approach, a distributed mobile formation control law is designed under a directed tree graph. The performance of the proposed controllers is validated by both numerical simulations and experiments

Effectiveness of 10 polymorphic microsatellite markers for parentage and pedigree analysis in plateau pika (Ochotona curzoniae)

<p>Abstract</p> <p>Background</p> <p>The plateau pika <it>(Ochotona curzoniae) </it>is an underground-dwelling mammal, native to the Tibetan plateau of China. A set of 10 polymorphic microsatellite loci has been developed earlier. Its reliability for parentage assignment has been tested in a plateau pika population. Two family groups with a known pedigree were used to validate the power of this set of markers.</p> <p>Results</p> <p>The error in parentage assignment using a combination of these 10 loci was very low as indicated by their power of discrimination (0.803 - 0.932), power of exclusion (0.351 - 0.887), and an effectiveness of the combined probability of exclusion in parentage assignment of 99.999%.</p> <p>Conclusion</p> <p>All the offspring of a family could be assigned to their biological mother; and their father or relatives could also be identified. This set of markers therefore provides a powerful and efficient tool for parentage assignment and other population analyses in the plateau pika.</p

Symmetry-Preserving Program Representations for Learning Code Semantics

Large Language Models (LLMs) have shown promise in automated program reasoning, a crucial aspect of many security tasks. However, existing LLM architectures for code are often borrowed from other domains like natural language processing, raising concerns about their generalization and robustness to unseen code. A key generalization challenge is to incorporate the knowledge of code semantics, including control and data flow, into the LLM architectures. Drawing inspiration from examples of convolution layers exploiting translation symmetry, we explore how code symmetries can enhance LLM architectures for program analysis and modeling. We present a rigorous group-theoretic framework that formally defines code symmetries as semantics-preserving transformations and provides techniques for precisely reasoning about symmetry preservation within LLM architectures. Using this framework, we introduce a novel variant of self-attention that preserves program symmetries, demonstrating its effectiveness in generalization and robustness through detailed experimental evaluations across different binary and source code analysis tasks. Overall, our code symmetry framework offers rigorous and powerful reasoning techniques that can guide the future development of specialized LLMs for code and advance LLM-guided program reasoning tasks

Individualist–Collectivist Differences in Climate Change Inaction: The Role of Perceived Intractability

The willingness to take action against climate change may be shaped by cultural orientations. The present study investigated individualist–collectivist differences in climate change inaction as well as the mediating role of perceived intractability. In Study 1, a survey of 182 undergraduates showed that greater perceived intractability of climate change was significantly related to a lower frequency of climate-friendly actions in the preceding 6 months. In Study 2, participants who were exposed to information concerning the intractability of climate change (experimental group, n = 98) reported a significantly greater perceived intractability of climate change and lower intention to assume a low-carbon lifestyle than those presented with neutral information (control group, n = 83). Based on Studies 1 and 2, participants with collectivist or individualist orientations were recruited from a pool of Chinese undergraduate students in Study 3. We found that participants with a more individualist orientation (n = 62) are more subject to perceived intractability, and less likely to take climate-friendly action than those with a more collectivist orientation (n = 94), and individualist/collectivist status affects climate change inaction through perceived intractability as mediator. The implications of these findings are discussed in relation to the promotion of public engagement with climate change by mitigating perceived intractability

A Novel mRNA Delivery Strategy Employing Adenovirus Piggyback mRNA Binders via Catcher/Tag Molecular Glue

mRNA-based therapeutics open a new era for the prevention and treatment of a wide range of diseases. However, existing mRNA delivery vehicles have limited repertoires for dendritic cell targeting and intranasal administration which are two paramount delivery pathways of significant advantages for treating cancer and infectious respiratory diseases. Adenovirus (Ad) with well-deciphered viral genomes and intensive-studied structure biology has been developed for DCs-targeted cancer vaccines and intranasal COVID vaccines. In light of these virtues, Ad presents as the “off-the-shelf” tool possessing well-defined manufacturable capabilities and translatable feasibility that perfectly complements the current limitations of mRNA delivery. In this study, we developed a novel “Ad piggyback protamine (AdPro)” mRNA delivery platform built upon the utilization of Catcher/Tag molecular glue to accomplish specific anchoring protamine to hexon locales of Ad capsid at a molecular precision level. Our pilot study manifested that “AdPro” was a potent mRNA delivery vehicle and integration of Catcher/Tag technology enabled us to manipulate the construction process with great precision, offering the opportunity to engineer other capsid proteins to equip Ad with both mRNA delivery and cell targeting ability. Further investigation may consider evaluating other mRNA constructs, such as circRNA, or other advanced mRNA binders, such as RALA to optimize the delivery efficiency as well as genetically engineering Ads fiber protein with cell targeting ligands while retaining the SpyTag-incorporated hexon as the mRNA binders anchoring site to develop the multi-functional delivery platform

Pairwise-Based Hierarchical Gating Networks for Sequential Recommendation

The sequential pattern behind users’ behaviors indicates the importance of exploring the transition relationships among adjacent items in next-item recommendation task. Most existing methods based on Markov Chains or deep learning architecture have demonstrated their superiority in sequential recommendation scenario, but they have not been well-studied at a range of problems: First, the influence strength of items that the user just access might be different since not all items are equally important for modeling user’s preferences. Second, the user might assign various interests to certain parts of items, as what often attracts users is a specific feature or aspect of an item. Third, many methods ignore the complex item relations in user’s previous actions. In this paper, we present a novel recommendation approach with gating mechanism and encoding module to address above problems. Specifically, the pair-wise encoding layer is first introduced to build 3-way tensor for modeling the relationships among items in user interact histories. We also apply two gating layers to filter useful information and capture user’s short-term preference from aspect-level and item-level. We also follow the similar sprits to model user’s long-term preference by integrating user latent embeddings. Empirical results on three public datasets show that our method achieves effective improvements over the state-of-the-art sequence-based models

Full state tracking and formation control for under-actuated VTOL UAVs

In this paper, a coupled-attitude based trajectory tracking scheme is proposed to track both the position and attitude of under-actuated unmanned aerial vehicles, and its application on formation control is further demonstrated. An intermediate attitude which is composed of the desired attitude and position information is designed in a two-stage framework, wherein the first stage is the controller design of a translational subsystem and the second stage is that of an attitude subsystem. By virtue of the intermediate attitude, trajectory tracking which includes both attitude and position is realized. The proposed intermediate attitude can be viewed as a bridge connecting the position and attitude motion, and it is a new approach for both single and multiple under-actuated rigid bodies’ control. Based on the approach of coupled-attitude-based trajectory tracking, both the set point stabilization and formation tracking tasks for under-actuated vertical takeoff and landing vehicles over a directed acyclic graph can be achieved. The performances of the proposed control laws are illustrated through numerical simulations.Published versio

Mobile Formation Coordination and Tracking Control for Multiple Nonholonomic Vehicles

This article addresses forward motion control for trajectory tracking and mobile formation coordination for a group of nonholonomic vehicles on SE(2). First, by constructing an intermediate attitude variable which involves vehicles' position information and desired attitude, the translational and rotational control inputs are designed in two stages to solve the trajectory tracking problem. Second, the coordination relationships of relative positions and headings are explored thoroughly for a group of nonholonomic vehicles to maintain a mobile formation with rigid-body motion constraints. We prove that, except for the cases of parallel formation and translational straight line formation, a mobile formation with strict rigid-body motion can be achieved if and only if the ratios of linear speed to angular speed for each individual vehicle are constants. Motion properties for mobile formation with weak rigid-body motion are also demonstrated. Thereafter, based on the proposed trajectory tracking approach, a distributed mobile formation control law is designed under a directed tree graph. The performance of the proposed controllers is validated by both numerical simulations and experiments