Environmental Manipulations Research Articles

A Motion Planning Algorithm for Redundant Manipulators Using Rapidly Exploring Randomized Trees and Artificial Potential Fields

This paper presents a novel motion planner for redundant robotic manipulators by utilizing rapidly exploring randomized trees and artificial potential fields. Rapidly exploring randomized trees and artificial potential fields are two well-known navigational strategies in the robotics industry; however, their potential benefits and synergy when implemented together has been largely unexplored. In the proposed motion planner, rapidly exploring randomized trees is first used to determine a suitable path for the end-effector to follow that maneuvers around all obstacles in the robot's workspace. Once a path has been determined, attractive and repulsive potential fields are implemented at all points along the path and are used in a gradient optimization algorithm to determine joint trajectories to reach the desired location. To supplement the attractive and repulsive potential fields, an orientation field is proposed to minimize the error between the actual end-effector orientation and the desired orientation during joint trajectory planning. The motion planner is examined through both analytical and experimental evaluation using the 7 degrees of freedom Kinova JACO and Kinova Gen3 robotic arms. The conclusions drawn from this work substantiate the efficacy and superiority of the proposed two-stage motion planner for the control of redundant manipulators in obstacle-ridden environments.

Collision-free kinematics for hyper-redundant manipulators in dynamic scenes using optimal velocity obstacles

Hyper-redundant manipulators have been widely used in the complex and cluttered environment for achieving various kinds of tasks. In this article, we present two contributions. First, we provide a novel algorithm of relating forward and backward reaching inverse kinematic algorithm to velocity obstacles. Our optimization-based algorithm simultaneously handles the task space constraints, the joint limit constraints, and the collision-free constraints for hyper-redundant manipulators based on the generalized framework. Second, we present an extension of our inverse kinematic algorithm to collision avoidance for the hyper-redundant manipulators, where the workspaces may have different types of obstacles. We highlight the performance of our algorithm on hyper-redundant manipulators with various degrees of freedom. The results show that our algorithm has made full use of dexterity of hyper-redundant manipulators in complex environments, enhancing the performance and increasing the flexibility.

The influence of cognitive tasks on sensory organization test performance

IntroductionMany static postural tasks requiring vestibular contributions are completed while dual- tasking. ObjectiveWe investigated the influence of dual-tasks on sensory integration for postural control and cognitive performance during the sensory organization test and examined the relationship between cognitive function and dual-task cost during the sensory organization test. MethodsTwenty adults completed single and dual-task versions of the six conditions of the sensory organization test were completed during two visits separated by one week. A subset of 13 participants completed three National Institute of Health (NIH)-toolbox cognitive tests including the Flanker inhibitory control and attention test, dimensional change card sort test and pattern comparison processing speed test. Wilcoxon signed rank tests were used to compare postural sway during single and dual-task sensory organization test. Friedman’s test, with pairwise comparison post-hoc tests, was used to compare single task serial subtraction performance to the 6 dual-task sensory organization test conditions. Spearman’s correlation coefficients were used to assess the relationship between cognitive performance on NIH-toolbox test and postural and cognitive dual-task cost during the sensory organization test. ResultsPerforming a cognitive dual-task during the sensory organization test resulted in a significant increase in postural sway during condition 1 (Z=−3.26, p=0.001, ES=0.73), condition 3 (Z=−2.53, p=0.012, ES=0.56), and condition 6 (Z=−2.02, p=0.044, ES=0.45). Subtraction performance significantly decreased in during condition 6 (Z=−2.479, p=0.011, ES=0.55) compared to single-task. The dimensional change card sort test demonstrated moderate correlations with dual-task cost of serial subtraction performance in condition 5 (dimensional change card sort test: r=−0.62, p=0.02) and condition 6 (dimensional change card sort test: r=−0.56, p=0.04). Pattern comparison processing speed test scores were significantly correlated with dual-task cost of postural control during condition 2. ConclusionPerforming a cognitive task during the sensory organization test resulted in significantly increased postural sway during three conditions, particularly during visual environment manipulation oppose to vestibular and somatosensory manipulation. Cognitive performance decreased during the most complex sensory organization test condition. Additionally, we found participants with poorer executive function had greater dual-task cost during more complex sensory integration demands.

Demographic drivers of Norway rat populations from urban slums in Brazil

The Norway rat is a globally distributed pest, known for its resilience to eradication and control programs. Efficient population control, especially in urban settings, is dependent on knowledge of rat demography and population ecology. We analyzed the relationship between four demographic outcomes, estimated by live-trapping data, and fine-scale environmental features measured at the capture site. Wounds, a proxy for agonistic interactions, were associated with mature individuals. Areas with environmental features favorable to rats, such as open sewers and unpaved earth, were associated with more mature individuals with a better body condition index. The control measures (environmental stressors) are likely to be disrupting the social structure of rat colonies, increasing the frequency and distribution of agonistic interactions, which were common in both sexes and maturity states. The relationship between the favorable environmental conditions and the demographic markers analyzed indicate possible targets for infestation control through environmental manipulation, and could be incorporated into current pest management programs to achieve long-term success. Our study indicate that urban interventions focused on removal of potential resources for rats could be potential long-term solutions by reducing the carrying capacity of the environment.

Bearing fruit: Piloting a novel judgment bias task in an American black bear.

Judgment bias tasks can reveal changes in affect in animals as a function of environmental manipulations such as provision of enrichment. We assessed affect in an American black bear across seasonal changes in availability of a mulberry bush. We used a novel judgment bias task in which the background color of a touchscreen signaled whether the left or right positioned stimulus was correct. The bear learned the conditional rule in which the correct action for the white background (choose left) resulted in three pieces of food and the correct action for the black background (choose right) resulted in one piece of food. On probe trials involving intermediate gray backgrounds, left side responses indicated optimism and right side responses indicated pessimism. Tests took place at the beginning, middle, and end of mulberry season and again nearing the end of the summer and early fall before hibernation. The bear showed the most optimistic responses during the phase involving increased opportunities for foraging on mulberry. A follow-up experiment confirmed that the bear preferred three food items over one food item, suggesting the quantity-based discrimination was in fact salient to this bear. This is the first evidence for conditional discrimination learning in a black bear, validating the task to assess changes in affect.

Recent Advances in Strategies for Improving the Performance of CO2 Reduction Reaction on Single Atom Catalysts

Excessive consumption of fossil fuels gives rise to the increasing emission of carbon dioxide (CO2) in the atmosphere and furthers the ecocrisis. Electrochemical CO2 reduction (ECR) has both functions of dwindling greenhouse gas concentration and converting it into valuable products. Due to the intrinsic chemical inertness of CO2 molecules, the study on efficient and low‐cost catalysts has attracted much attention. Recently isolated atoms, dispersed in stable support, play an important role in decreasing energy barriers of intermediate steps and obtaining target products with high activity and selectivity for ECR. The effective regulation of central atoms or coordination environment is significant to realize the desired performances of ECR with a high efficiency and selectivity. Hence, a comprehensive summary about strategies for improving the performance of ECR on single atom catalysts (SACs) is necessary. Herein, the SACs on various supports are introduced, the methods to design stable SACs are discussed, and the strategies for tuning the performance of ECR on SACs are summarized. The localized environment manipulation is widely used for high‐performance SACs design, including regulating central atoms and coordination environment. Finally, the perspectives are discussed to shed light on the rational design of intriguing SACs for ECR.

Long term effects of early life stress on HPA circuit in rodent models

Adaptation to environmental challenges represents a critical process for survival, requiring the complex integration of information derived from both external cues and internal signals regarding current conditions and previous experiences. The Hypothalamic–pituitary–adrenal axis plays a central role in this process inducing the activation of a neuroendocrine signaling cascade that affects the delicate balance of activity and cross-talk between areas that are involved in sensorial, emotional, and cognitive processing such as the hippocampus, amygdala, Prefrontal Cortex, Ventral Tegmental Area, and dorsal raphe.Early life stress, especially early critical experiences with caregivers, influences the functional and structural organization of these areas, affects these processes in a long-lasting manner and may result in long-term maladaptive and psychopathological outcomes, depending on the complex interaction between genetic and environmental factors.This review summarizes the results of studies that have modeled this early postnatal stress in rodents during the first 2 postnatal weeks, focusing on the long-term effects on molecular and structural alteration in brain areas involved in Hypothalamic–pituitary–adrenal axis function. Moreover, a brief investigation of epigenetic mechanisms and specific genetic targets mediating the long-term effects of these early environmental manipulations and at the basis of differential neurobiological and behavioral effects during adulthood is provided.

Measuring the Effects of Circadian Rhythm-Related Manipulations on Depression-Like Behavior in Rodents: Forced Swim and Tail Suspension Tests.

The forced swim and tail suspension tests are commonly used to determine the effects of circadian-related pharmacological, genetic, and environmental manipulations on depression-like behavior in rodents. Both tests involve scoring immobility of rodents in an inescapable condition. Here we describe how to set up and carry out these tests.

Surprising spatiotemporal stability of a multi-peak fitness landscape revealed by independent field experiments measuring hybrid fitness.

The effect of the environment on fitness in natural populations is a fundamental question in evolutionary biology. However, experimental manipulations of both environment and phenotype at the same time are rare. Thus, the relative importance of the competitive environment versus intrinsic organismal performance in shaping the location, height, and fluidity of fitness peaks and valleys remains largely unknown. Here, we experimentally tested the effect of competitor frequency on the complex fitness landscape driving adaptive radiation of a generalist and two trophic specialist pupfishes, a scale‐eater and molluscivore, endemic to hypersaline lakes on San Salvador Island (SSI), Bahamas. We manipulated phenotypes, by generating 3407 F4/F5 lab‐reared hybrids, and competitive environment, by altering the frequency of rare transgressive hybrids between field enclosures in two independent lake populations. We then tracked hybrid survival and growth rates across these four field enclosures for 3–11 months. In contrast to competitive speciation theory, we found no evidence that the frequency of hybrid phenotypes affected their survival. Instead, we observed a strikingly similar fitness landscape to a previous independent field experiment, each supporting multiple fitness peaks for generalist and molluscivore phenotypes and a large fitness valley isolating the divergent scale‐eater phenotype. These features of the fitness landscape were stable across manipulated competitive environments, multivariate trait axes, and spatiotemporal heterogeneity. We suggest that absolute performance constraints and divergent gene regulatory networks shape macroevolutionary (interspecific) fitness landscapes in addition to microevolutionary (intraspecific) competitive dynamics. This interplay between organism and environment underlies static and dynamic features of the adaptive landscape.

Unseating “State” and “Archive”: Mobility and Manipulation in Past Environments and Present Praxis

AbstractThese concluding reflections assess how the contributors to this special issue intervene in key assumptions that shape the current field of archival studies. As the “archival turn” gains ground, forms of Euro- and state-centrism reappear in scholarship otherwise innovative in its attention to the textual remnants of the past. Here, instead, we explore the methodological stakes involved in defining both the “archive” and the historical power brokers who created and preserved a documentary record in pursuit of their varied social, cultural, economic, and political projects. The essay points to the resurgence of culturalist and civilisational indices for comparative archivistics, and follows the arguments collected in this issue to assert by contrast the often uneven and uneasy regional, administrative, and procedural definitions at work within preserved records. Identifying “mobility” as both a methodological tactic and a historical process, this conclusion presents a fluid rather than fixed textual landscape and presents an alternative frame for investigating preservationist practices.

Many roads to bacterial generalism.

The fundamental niches of bacteria can be defined along many environmental axes, including temperature tolerance and resources consumed, while interactions with other organisms can constrain (e.g. competition) or enlarge (e.g. cross-feeding) realized niches. Organisms are often categorized as generalists or specialists, corresponding to broad or narrow niche requirements, which can then be linked to their functional role in an ecosystem. We show how these terms are applied to bacteria, make predictions about how the type and extent of generalism displayed by an organism relates to its functional potential and discuss the value of collecting different types of generalist bacteria. We believe that new approaches that take advantage of both high-throughput sequencing and environmental manipulation can allow us to understand the many types of generalism found within both cultivated and yet-to-be-cultivated bacteria.

Passivity-Based Gain Independent Control for Transparent Sensing of Remote Environment

Teleoperated robots are traditionally used for extended human sensing and manipulation of remote environment. Though controllers have already been proposed in the literature to achieve stability and transparency in the system, their implementation becomes limited because of the complexities in tuning the gains. The objective of this paper is to propose novel controllers, which ensure the system stability and transparency irrespective of the controller gains. The proposed controllers are also shown to accommodate varying time-delays, during which the stability and transparency usually conflict each other. The non-linear tool of passivity analysis is used to demonstrate that the proposed controllers achieve the desired objectives. In addition to the proposed controllers, a torque based sensing is utilized to enhance the transparent sensing of the remote environment, which readily facilitates disturbance rejection for the proposed controllers. Therefore, the proposed methodology (combination of both the controller and sensing method) helps the user in accurately sensing the remote environment and concurrently maintaining global asymptotic stability for any arbitrary choice of controller gains. Experiments carried on a five-bar teleoperation system demonstrate global asymptotic stability and transparent sensing even under time varying delays, and with a much wider range of feedback gains.

Impact of in vitro embryo culture and transfer on blood pressure regulation in the adolescent lamb.

Nutrition during the periconceptional period influences postnatal cardiovascular health. We determined whether in vitro embryo culture and transfer, which are manipulations of the nutritional environment during the periconceptional period, dysregulate postnatal blood pressure and blood pressure regulatory mechanisms. Embryos were either transferred to an intermediate recipient ewe (ET) or cultured in vitro in the absence (IVC) or presence of human serum (IVCHS) and a methyl donor (IVCHS+M) for 6 days. Basal blood pressure was recorded at 19-20 weeks after birth. Mean arterial pressure (MAP) and heart rate (HR) were measured before and after varying doses of phenylephrine (PE). mRNA expression of signaling molecules involved in blood pressure regulation was measured in the renal artery. Basal MAP did not differ between groups. Baroreflex sensitivity, set point, and upper plateau were also maintained in all groups after PE stimulation. Adrenergic receptors alpha-1A (αAR1A), alpha-1B (αAR1B), and angiotensin II receptor type 1 (AT1R) mRNA expression were not different from controls in the renal artery. These results suggest there is no programmed effect of ET or IVC on basal blood pressure or the baroreflex control mechanisms in adolescence, but future studies are required to determine the impact of ET and IVC on these mechanisms later in the life course when developmental programming effects may be unmasked by age.

Early Life Experience Shapes Male Behavior and Social Networks in Drosophila

Living in a group creates a complex and dynamic environment in which behavior of individuals is influenced by and affects the behavior of others. Although social interaction and group living are fundamental adaptations exhibited by many organisms, little is known about how prior social experience, internal states, and group composition shape behavior in groups. Here, we present an analytical framework for studying the interplay between social experience and group interaction in Drosophila melanogaster. We simplified the complexity of interactions in a group using a series of experiments in which we controlled the social experience and motivational states of individuals to compare behavioral patterns and social networks of groups under different conditions. We show that social enrichment promotes the formation of distinct group structure that is characterized by high network modularity, high inter-individual and inter-group variance, high inter-individual coordination, and stable social clusters. Using environmental and genetic manipulations, we show that visual cues and cVA-sensing neurons are necessary for the expression of social interaction and network structure in groups. Finally, we explored the formation of group behavior and structure in heterogenous groups composed of flies with distinct internal states and documented emergent structures that are beyond the sum of the individuals that constitute it. Our results demonstrate that fruit flies exhibit complex and dynamic social structures that are modulated by the experience and composition of different individuals within the group. This paves the path for using simple model organisms to dissect the neurobiology of behavior in complex social environments.

Habitat features and colony characteristics influencing ant personality and its fitness consequences.

Several factors can influence individual and group behavioral variation that can have important fitness consequences. In this study, we tested how two habitat types (seminatural meadows and meadows invaded by Solidago plants) and factors like colony and worker size and nest density influence behavioral (activity, meanderness, exploration, aggression, and nest displacement) variation on different levels of the social organization of Myrmica rubra ants and how these might affect the colony productivity. We assumed that the factors within the two habitat types exert different selective pressures on individual and colony behavioral variation that affects colony productivity. Our results showed individual-/colony-specific expression of both mean and residual behavioral variation of the studied behavioral traits. Although habitat type did not have any direct effect, habitat-dependent factors, like colony size and nest density influenced the individual mean and residual variation of several traits. We also found personality at the individual-level and at the colony level. Exploration positively influenced the total- and worker production in both habitats. Worker aggression influenced all the productivity parameters in seminatural meadows, whereas activity had a positive effect on the worker and total production in invaded meadows. Our results suggest that habitat type, through its environmental characteristics, can affect different behavioral traits both at the individual and colony level and that those with the strongest effect on colony productivity primarily shape the personality of individuals. Our results highlight the need for complex environmental manipulations to fully understand the effects shaping behavior and reproduction in colony-living species.

A Tilting-Rotor Unmanned Aerial Vehicle for Enhanced Aerial Locomotion and Manipulation Capabilities: Design, Control, and Applications

In this article, a novel multirotor unmanned aerial vehicle (UAV) is proposed for enhanced locomotion and manipulation in unstructured environments. The vehicle has a tilting-rotor architecture. Specifically, two pairs of rotors are mounted on two independently controlled tilting arms placed at two sides of the vehicle, forming an “H” configuration. Such a structure endows the vehicle with more degrees of freedom, improving the maneuverability without sacrificing energy efficiency at the cost of only two additional servos compared to traditional quadcopters. Based on this architecture, a dual-level adaptive robust control is developed to cope with inertial parametric uncertainties and uncertain nonlinearities for accurate motion tracking. To resolve the redundancy in actuation, a thrust force optimization problem minimizing power consumption while achieving the desired body force wrench is formulated and solved precisely and efficiently. With the novel design and control, the proposed aerial vehicle is capable of achieving superior maneuverability, better stability and motion accuracy in the presence of uncertainties, as well as improved power efficiency compared to traditional UAVs when performing dexterous aerial locomotion and manipulation. To demonstrate the advantage of the proposed new UAV design and control in real applications, we conduct four challenging experiments on aerial locomotion and manipulation: circular trajectory tracking, passing through a narrow tunnel, picking up an object from a cluttered shelf, and aerial hole drilling. Experimental results validate the applicability of the proposed innovation.

There's no place like home? Return to the home cage triggers dopamine release in the mouse nucleus accumbens

Various stimuli have been employed as reinforcers in preclinical rodent models to elucidate the underpinnings of reward at a molecular and circuit level, with the release of dopamine (DA) in the nucleus accumbens (NAc) as a well-replicated, physiological correlate. Many factors, however, including strain differences, sex, prior stress, and reinforcer administration protocols can influence reward responding and DA release. Although previous evidence indicates that access to the home cage can be an effective reinforcer in behavioral tasks, whether this simple environmental manipulation can trigger DA release in the NAc has not been demonstrated. Here, using fiber photometric recordings of in vivo NAc dopamine release from a genetically-encoded DA sensor, we show that the movement of animals from the home cage to a clear, polycarbonate recording chamber evokes little to no DA release following initial exposure whereas returning animals from the recording chamber to a clean, home-like cage or to the home cage robustly triggers the release of DA, comparable in size to that observed with a 10 mg/kg i.p. Cocaine injection in the recording chamber. Although DA release can be evoked in moving mice to a clean cage, this release was significantly augmented when moving animals from the clean cage to the home cage. Our data provide direct evidence that home cage return from a foreign environment results in a biochemical change consistent with that of a rewarding stimulus. This simple environmental manipulation provides a minimally invasive approach to study the reward circuitry underlying an ethologically relevant reinforcer, return to the safe confines of “home”. The home cage – DA release paradigm may also represent a biomarker-driven paradigm for the evaluation of genetic and experiential events that underlie anhedonic states, characteristic of major mood disorders, and to present new opportunities to identify their treatments.

Low-Resistance silver bromide electrodes for recording fast ion channel kinetics under voltage clamp conditions

BackgroundTwo-electrode voltage clamp is a widely used technique for studying ionic currents. However, fast activation kinetics of ion channels are disguised by the capacitive transient during voltage clamp of Xenopus oocytes. The limiting factors of clamp performance include, but are not limited to, amplifier gain, membrane capacitance, and micropipette resistance. Previous work has focused on increasing amplifier gain (e.g.; high performing two-electrode amplifiers) or reducing the membrane capacitance (e.g.; the cut-open technique). New methodThe use of an Ag-AgBr electrode with saturated KBr solution to reduce micropipette resistance. ResultsThe conductivity of 4 M KBr was 37 % higher compared to 3 M KCl and the micropipette resistance was reduced by 19 % when 4 M KBr was used, compared to the standard 3 M KCl solution. Micropipette resistances correlated positively with capacitive transient durations. Neither the current-voltage relationship of the voltage-gated sodium channel, Nav1.7, nor Xenopus oocyte stability were affected by bromide ions. Comparison with existing methodsThe de facto standard for two-electrode voltage clamp is 3 M KCl and Ag-AgCl electrodes, which are associated an unnecessarily high micropipette resistance. Elsewise, cut-open voltage clamp techniques are technically demanding and require manipulation of the intracellular environment. ConclusionsThe use of an Ag-AgBr electrode with saturated KBr as micropipette solution reduces the capacitive transient in two-electrode voltage clamp recordings. Moreover, the exchange of chloride against bromide ions does not seem to affect oocyte physiology and ion channel kinetics.

Learning an end-to-end spatial grasp generation and refinement algorithm from simulation

Novel object grasping is an important technology for robot manipulation in unstructured environments. For most of current works, a grasp sampling process is required to obtain grasp candidates, combined with a local feature extractor using deep learning. However, this pipeline is time–cost, especially when grasp points are sparse such as at the edge of a bowl. To tackle this problem, our algorithm takes the whole sparse point clouds as the input and requires no sampling or search process. Our work is combined with two steps. The first step is to predict poses, categories and scores (qualities) based on a SPH3D-GCN network. The second step is an iterative grasp pose refinement, which is to refine the best grasp generated in the first step. The whole weight sizes for these two steps are only about 0.81M and 0.52M, which takes about 73 ms for a whole prediction process including an iterative grasp pose refinement using a GeForce 840M GPU. Moreover, to generate training data of multi-object scene, a single-object dataset (79 objects from YCB object set, 23.7k grasps) and a multi-object dataset (20k point clouds with annotations and masks) combined with thin structures grasp planning are generated. Our experiment shows our work gets 76.67% success rate and 94.44% completion rate, which performs better than current state-of-the-art works.

Blockchain-based eHealth system for auditable EHRs manipulation in cloud environments

The development of cloud-assisted electronic health system effectively addresses the drawbacks of traditional medical management system. However, some challenging problems such as security and privacy in data storage and sharing cannot be ignored. First, it is difficult to ensure the integrity of electronic health records (EHRs) during the data outsourcing process. Second, it is difficult to guarantee the privacy and traceability of EHRs during the data sharing process. In this paper, a blockchain-based eHealth system called BCES is proposed to ensure that the manipulation of EHRs can be audited. In BCES, each legitimate query manipulation of data consumers, together with each legitimate outsourcing manipulation of hospitals, will be written into the blockchain as a transaction for permanent storage, which ensures the traceability. At the same time, the attributes-based proxy re-encryption is adopted to achieve fine-grained access control of medical data, and any behavior that threatens the integrity of EHRs will be discovered by the auditor. Due to the traceable and tamper-resistant characteristic of blockchain, any entity that had an illegal manipulation of EHRs will be held accountable to the evidence of our constructed Proof-Chain. Finally, security analysis and performance evaluation demonstrate that this scheme is secure and efficient.