Miracle-dz/UniFAR-FTUs huggingface dataset:
Robustness analysis of unmanned helicopter flight control law using μ-analysis techniques

This paper mainly describes a method based on structured singular value (μ) for analyzing the robustness of unmanned helicopter flight control system. The helicopter is a complex controlled system with static instability, non-linearity, multi-variables and strong coupling. In this paper, based on the introduction of basic theory of LFT and μ-analysis, the X-Unmanned Helicopter(X-UMH) is chosen as an example. In order to analyze the stability robustness in terms of the standard clearance criteria, a method to convert the classical simultaneous gain and phase margin requirements with a multiplicative uncertainty on the plant is studied. The Model-following control system (MFCS) was introduced to design the helicopter flight control law. The flight envelope could be cleared continuously in the condition with simultaneously varying uncertain parameters. The results of simulation results indicate the feasibility and effectiveness of the methods.
The Role of Water in Activation Mechanism of Human N-Formyl Peptide Receptor 1 (FPR1) Based on Molecular Dynamics Simulations

The Formyl Peptide Receptor 1 (FPR1) is an important chemotaxis receptor involved in various aspects of host defense and inflammatory processes. We constructed a model of FPR1 using as a novel template the chemokine receptor CXCR4 from the same branch of the phylogenetic tree of G-protein-coupled receptors. The previously employed template of rhodopsin contained a bulge at the extracellular part of TM2 which directly influenced binding of ligands. We also conducted molecular dynamics (MD) simulations of FPR1 in the apo form as well as in a form complexed with the agonist fMLF and the antagonist tBocMLF in the model membrane. During all MD simulation of the fMLF-FPR1 complex a water molecule transiently bridged the hydrogen bond between W2546.48 and N1083.35 in the middle of the receptor. We also observed a change in the cytoplasmic part of FPR1 of a rotamer of the Y3017.53 residue (tyrosine rotamer switch). This effect facilitated movement of more water molecules toward the receptor center. Such rotamer of Y3017.53 was not observed in any crystal structures of GPCRs which can suggest that this state is temporarily formed to pass the water molecules during the activation process. The presence of a distance between agonist and residues R2015.38 and R2055.42 on helix TM5 may suggest that the activation of FPR1 is similar to the activation of β-adrenergic receptors since their agonists are separated from serine residues on helix TM5. The removal of water molecules bridging these interactions in FPR1 can result in shrinking of the binding site during activation similarly to the shrinking observed in β-ARs. The number of GPCR crystal structures with agonists is still scarce so the designing of new ligands with agonistic properties is hampered, therefore homology modeling and docking can provide suitable models. Additionally, the MD simulations can be beneficial to outline the mechanisms of receptor activation and the agonist/antagonist sensing.
Chemical Defense Against Different Marine Herbivores: Are Amphipods Insect Equivalents?

The Structurally similar diterpenoid alcohols pachydictyol-A and dictyol-E are produced by the brown seaweed Dictyota dichotoma. This seaweed and several related species that also produce these compounds are known to be relatively low preference foods for tropical fishes and urchins. We evaluated the effect of various concentrations of these compounds on feeding by the three common types of herbivores that co-occur with Dictyota in coastal North Carolina. Fish (Diplodus holbrooki), sea urchins (Arbacia punctulata), and a mixed species group of gammarid amphipods were offered pieces of the palatable seaweed Gracilaria tikvahiae coated with either (1) dictyol-E or pachydictyol-A dissolved in diethyl ether or (2) diethyl ether alone. Dictyol-E significantly reduced consumption by fish and urchins at concentrations of 0.5 and 1.0% of algal dry mass, but had no effect on amphipod grazing. Pachydictyol-A significantly reduced fish grazing at the relatively high concentrations of 1.0 and 1.3% of plant dry mass; at 0.5% it tended to decrease grazing, but the effect was not significant (P = .07). Pachydictyol-A had no effect on urchin grazing and significantly increased amphipod grazing. When Pachydictyol-A was fed to fish as 1.0% of food dry mass, their growth rate was reduced by a significant 48%. In feeding preference experiments with several seaweeds, Dictyota ranks low for fish and urchins but high for amphipods. This is consistent with the hypothesis that the secondary metabolites produced by Dictyota play a major role in determining its susceptibility to herbivores. The ability of amphipods to circumvent the chemical defenses (Dictyota, and the fact that the two species of algae most readily consumed by amphipods (Codium and Dictyota) were the two species least readily consumed by fish, suggest that predation and herbivory by fishes may be major factors selecting for amphipods that can live on, and eat, seaweeds that are unpalatable to fishes. Amphipods that fed on Dictyota did not appear to sequester the Dictyota metabolites; when exposed to fish predation, Dictyota-fed amphipods were eaten as readily as amphipods that had fed on an alga with no defensive chemistry. Tubicolous amphipods and other small marine herbivores that may spend significant portions of their lives on only a few plants my be under very different evolutionary constraints than the larger, more mobile herbivores that commonly moved between many plants. Several characteristics of these smaller, less mobile, and much less studied, marine herbivores suggest that they may be ecologically similar to terrestrial insects and may play a large, but presently unappreciated, role in structuring marine plant communities.
A Comparison of Two Approaches for Vision and Self-Localization on a Mobile Robot

This paper considers two approaches to the problem of vision and self-localization on a mobile robot. In the first approach, the perceptual processing is primarily bottom-up, with visual object recognition entirely preceding localization. In the second, significant top-down information is incorporated, with vision and localization being intertwined. That is, the processing of vision is highly dependent on the robot's estimate of its location. The two approaches are implemented and tested on a Sony Aibo ERS-7 robot, localizing as it walks through a color-coded test-bed domain. This paper's contributions are an exposition of two different approaches to vision and localization on a mobile robot, an empirical comparison of the two methods, and a discussion of the relative advantages of each method.
A tutorial for competent memetic algorithms: model, taxonomy, and design issues

The combination of evolutionary algorithms with local search was named "memetic algorithms" (MAs) (Moscato, 1989). These methods are inspired by models of natural systems that combine the evolutionary adaptation of a population with individual learning within the lifetimes of its members. Additionally, MAs are inspired by Richard Dawkin's concept of a meme, which represents a unit of cultural evolution that can exhibit local refinement (Dawkins, 1976). In the case of MA's, "memes" refer to the strategies (e.g., local refinement, perturbation, or constructive methods, etc.) that are employed to improve individuals. In this paper, we review some works on the application of MAs to well-known combinatorial optimization problems, and place them in a framework defined by a general syntactic model. This model provides us with a classification scheme based on a computable index D, which facilitates algorithmic comparisons and suggests areas for future research. Also, by having an abstract model for this class of metaheuristics, it is possible to explore their design space and better understand their behavior from a theoretical standpoint. We illustrate the theoretical and practical relevance of this model and taxonomy for MAs in the context of a discussion of important design issues that must be addressed to produce effective and efficient MAs.
Robot kinematic calibration with plane constraints based on POE formula

Utilizing plane constraints, a linear kinematic calibration algorithm is proposed for industrial robots based on local frame representation of the POE (Product-of-Exponential) formula. Different from conventional calibration methods which need expensive measurement equipment, the proposed method only needs a laser range finder mounted onto the robot end-effector and several predefined planes fixed to the base. As it suffices to lump all the kinematic errors into the initial poses of the local coordinate frames, the error model derived from the plane constraints is significantly simplified. An iterative least square algorithm is employed to identify the kinematic errors of the robot. Simulation results demonstrate the effectiveness of the proposed calibration method.
Cascade and triangular source coding with side information at the first two nodes

We consider the cascade and triangular rate-distortion problem where side information is known to the source encoder and to the first user but not to the second user. We characterize the rate-distortion region for these problems. For the quadratic Gaussian case, we show that it suffices to consider jointly Gaussian distributions, a fact that leads to an explicit solution.
Improving Species Diversity and Biomass Estimates of Tropical Dry Forests Using Airborne LiDAR

The spatial distribution of plant diversity and biomass informs management decisions to maintain biodiversity and carbon stocks in tropical forests. Optical remotely sensed data is often used for supporting such activities; however, it is difficult to estimate these variables in areas of high biomass. New technologies, such as airborne LiDAR, have been used to overcome such limitations. LiDAR has been increasingly used to map carbon stocks in tropical forests, but has rarely been used to estimate plant species diversity. In this study, we first evaluated the effect of using different plot sizes and plot designs on improving the prediction accuracy of species richness and biomass from LiDAR metrics using multiple linear regression. Second, we developed a general model to predict species richness and biomass from LiDAR metrics for two different types of tropical dry forest using regression analysis. Third, we evaluated the relative roles of vegetation structure and habitat heterogeneity in explaining the observed patterns of biodiversity and biomass, using variation partition analysis and LiDAR metrics. The results showed that with increasing plot size, there is an increase of the accuracy of biomass estimations. In contrast, for species richness, the inclusion of different habitat conditions (cluster of four plots over an area of 1.0 ha) provides better estimations. We also show that models of plant diversity and biomass can be derived from small footprint LiDAR at both local and regional scales. Finally, we found that a large portion of the variation in species richness can be exclusively attributed to habitat heterogeneity, while biomass was mainly explained by vegetation structure.
Age-related changes in dentate gyrus cell numbers, neurogenesis, and associations with cognitive impairments in the rhesus monkey

The generation of new neurons in the adult mammalian brain is well-established for the hippocampal dentate gyrus (DG). However, the role of neurogenesis in hippocampal function and cognition, how it changes in aging, and the mechanisms underlying this are yet to be elucidated in the monkey brain. To address this, we investigated adult neurogenesis in the DG of 42 rhesus monkeys (39 cognitively tested) ranging in age from young adult to the elderly. We report here that there is an age-related decline in proliferation and a delayed development of adult neuronal phenotype. Additionally, we show that many of the new neurons survive throughout the lifetime of the animal and may contribute to a modest increase in total neuron number in the granule cell layer of the DG over the adult life span. Lastly, we find that measures of decreased adult neurogenesis are only modestly predictive of age-related cognitive impairment.
Involvement of Multiple Transporters in the Hepatobiliary Transport of Rosuvastatin

Rosuvastatin is an HMG-CoA reductase inhibitor and one of the most hydrophilic among the commercially available statins. It is efficiently accumulated in the liver and excreted into the bile in an unchanged form in rats, suggesting that hepatic transporters play a major role in its clearance. Therefore, we investigated the transporters responsible for the hepatic uptake and biliary excretion of rosuvastatin. Uptake studies revealed that human organic anion transporting polypeptide (OATP) 1B1, OATP1B3, and OATP2B1 accept rosuvastatin as a substrate. Among the OATP family transporters, OATP1B1 contributes predominantly to the hepatic uptake of rosuvastatin, as estimated with the previously published relative activity factor method, and OATP1B3 is also partly involved. Significant vectorial basal-to-apical transport was observed in OATP1B1/multidrug resistance-associated protein 2 (MRP2), OATP1B1/multidrug resistance protein 1 (MDR1), and OATP1B1/breast cancer resistance protein (BCRP) double transfectants compared with that in an OATP1B1 single transfectant or in vector-transfected control cells. The ATP-dependent uptake of rosuvastatin by human BCRP-expressing membrane vesicles was significantly higher than the uptake by green fluorescent protein-expressing control vesicles, suggesting that MRP2, MDR1, and BCRP can transport rosuvastatin. Under in vivo conditions, the biliary excretion clearances based on the intrahepatic concentration of the parent rosuvastatin in Eisai hyperbilirubinemic rats and Bcrp1 knockout mice were reduced to 53% and 12% of those in the control Sprague-Dawley rats and FVB mice, respectively, indicating that rat Mrp2 and mouse Bcrp1 are both partly involved in the biliary excretion of rosuvastatin. These results suggest that multiple transporters are involved in the hepatic uptake and efflux of rosuvastatin.
Direction finding of nonstationary signals using a time-frequency Hough transform

We consider the problem of direction finding for nonstationary signals impinging on an array of sensors. Making use of a time-frequency representation of the data, we are able to exploit the non-stationary nature of the source signals. We employ a generalized Hough transform to estimate the time-frequency signature of each source. The proposed method also allows direction finding when there are more sources than the number of array sensors.
Probabilistic Clustering of White Matter Fibre Bundles using Regression Mixtures

We present a novel approach for probabilistic clustering of white matter fibre pathways using curve-based regression mixture modelling techniques in 3D curve space. The clustering algorithm is based on a principled method for probabilistic modelling of a set of fibre trajectories as individual sequences of points generated from a finite mixture model consisting of multivariate polynomial regression model components. Unsupervised learning is carried out using maximum likelihood principles. Specifically, conditional mixture is used together with an EM algorithm to estimate cluster membership. The result of clustering is a probabilistic assignment of fibre trajectories to each cluster and an estimate of cluster parameters. A statistical model is calculated for each clustered fibre bundle using fitted parameters of the probabilistic clustering. We illustrate the potential of our clustering approach on synthetic and real data.
Structure and mechanical properties of Octopus vulgaris suckers

In this study, we investigate the morphology and mechanical features of Octopus vulgaris suckers, which may serve as a model for the creation of a new generation of attachment devices. Octopus suckers attach to a wide range of substrates in wet conditions, including rough surfaces. This amazing feature is made possible by the sucker's tissues, which are pliable to the substrate profile. Previous studies have described a peculiar internal structure that plays a fundamental role in the attachment and detachment processes of the sucker. In this work, we present a mechanical characterization of the tissues involved in the attachment process, which was performed using microindentation tests. We evaluated the elasticity modulus and viscoelastic parameters of the natural tissues (E ∼ 10 kPa) and measured the mechanical properties of some artificial materials that have previously been used in soft robotics. Such a comparison of biological prototypes and artificial material that mimics octopus-sucker tissue is crucial for the design of innovative artificial suction cups for use in wet environments. We conclude that the properties of the common elastomers that are generally used in soft robotics are quite dissimilar to the properties of biological suckers.
Exosomes: Implications in HIV-1 Pathogenesis

Exosomes are membranous nanovesicles of endocytic origin that carry host and pathogen derived genomic, proteomic, and lipid cargos. Exosomes are secreted by most cell types into the extracellular milieu and are subsequently internalized by recipient cells. Upon internalization, exosomes condition recipient cells by donating their cargos and/or activating various signal transduction pathways, consequently regulating physiological and pathophysiological processes. The role of exosomes in viral pathogenesis, especially human immunodeficiency virus type 1 [HIV-1] is beginning to unravel. Recent research reports suggest that exosomes from various sources play important but different roles in the pathogenesis of HIV-1. From these reports, it appears that the source of exosomes is the defining factor for the exosomal effect on HIV-1. In this review, we will describe how HIV-1 infection is modulated by exosomes and in turn how exosomes are targeted by HIV-1 factors. Finally, we will discuss potentially emerging therapeutic options based on exosomal cargos that may have promise in preventing HIV-1 transmission.
The Add-on Impact of Mobile Applications in Learning Strategies: A Review Study

Mobile devices are more powerful and portable nowadays with plenty of useful tools for assisting people handle daily life. With the advance of mobile technology, the issue of mobile learning has been widely investigated in e-learning research. Many researches consider it is important to integrate pedagogical and technical strengths of mobile technology into learning environments. This review study focuses on the investigation of add-on impact of mobile applications in learning strategies. We surveyed recent researches including context awareness, pedagogical strategy-enhanced learning scenarios, as well as collaborative and socially networked mobile learning. Through this review study, essential characteristics of mobile learning were identified and discussed. With the essential characteristics, we emphasized on the add-on impact of mobile learning and elaborated mobile learning model in learning strategies.
Toward ecosystem-based coastal areas and fisheries management in the Coral Triangle : integrated strategies and guidance

The CTI Integration Guide, entitled “Moving Toward Ecosystem-based Coastal Area and Fisheries Management in the Coral Triangle: Integrated Strategies and Guidance” is intended to help marine and coastal managers, conservation practitioners, and their network of partners including government officials, communities, funders, economic investors, and other stakeholders work toward ecosystem-based management (EBM) by identifying integrated strategies that can be implemented through FACT SHEET: INTEGRATION GUIDE
Evaluating the Sustainability of Harvest Among Northern Common Eiders Somateria Mollissima Borealis in Greenland and Canada

Sustainable harvest, the extraction of game without affecting population viability, is a desirable approach to the use of wildlife. However, overharvest has been responsible for the decline of many wildlife populations globally, so there is an urgent need to balance human requirements while avoiding the severe depletion of wild populations. Northern common eiders Somateria mollissima borealis are heavily hunted in Canada and Greenland, but the effect of this intensive harvest has not been examined. We developed a population model to investigate the sustainability of the reported harvest, which consisted of two wintering areas in Greenland and Atlantic Canada and three breeding populations. The model indicated that harvest in Atlantic Canada was sustainable, but a number of conditions could lead to slow declines. In contrast, the annual winter harvest of 55,000–70,000 eiders reported during 1993–2000 in Greenland was not sustainable, and this conclusion held under a wide range of alternate conditions. The model indicated that harvest during late winter may have a greater effect on populations than harvest in early winter. We further refined the model to assume that at some low population level the success of hunters would decline and that harvest became a function of population size (a rate). This scenario had the expected and undesirable result of stabilizing populations at very low levels. Overall, our model suggests that the high harvest reported in Greenland during 1993–2000 endangers the sustainable use of the northern common eider population and that management actions are required. Common eider harvest levels in Greenland should be reduced by at least 40% of the 1993–2000 levels to stop projected declines, and allow for recovery of the decimated Greenland breeding population. Encouragingly, new hunting regulations were introduced in Greenland in 2002–2004, and harvest levels appear to be decreasing. If these harvest reductions continue, our population model could be used to re-evaluate the status of populations in the two countries.