Capture Region Research Articles

Kinetics and prey capture by a paddling jellyfish: three-dimensional simulation and Lagrangian coherent structure analysis

Abstract

Fixed-Time Cooperative Relay Tracking in Multiagent Surveillance Networks

This paper is concerned with the fixed-time cooperative relay tracking control problem for a set of planar agents in a surveillance network. The plane is partitioned into multiple “capture regions” by using the Voronoi partition according to agents’ positions. Once an evader enters into a new capture region, one agent of the tracer team stops and the tracking mission is relayed to another one who is in charge of the new region. As a result, an impulsive model is proposed to describe the problem and a distributed fixed-time cooperative relay control strategy is provided that is not dependent on initial condition. Numerical simulations are provided to demonstrate the validness of the cooperative relay tracking scheme.

Microfluidic assay of antiplatelet agents for inhibition of shear-induced platelet adhesion and activation.

We have developed a microfluidic system to perfuse whole blood through a flow channel with an upstream stenotic region and a downstream protein capture region. This flow-based system was used to assay how effectively antiplatelet agents suppress shear-induced platelet adhesion and activation downstream of the stenotic region. Microcontact printing was used to covalently attach one of three platelet binding proteins [fibrinogen, collagen, or von Willebrand factor (vWf)] to the surface of the downstream capture region. Whole blood with an antiplatelet agent was transiently exposed to an upstream high wall shear rate (either 4860 s-1 or 11 560 s-1), and subsequently flowed over the downstream capture region where the platelet adhesion was measured. Several antiplatelet agents (acetylsalicylic acid, tirofiban, eptifibatide, anti-vWf, and anti-GPIbα) were evaluated for their efficacy in attenuating downstream adhesion. Following antibody blocking of vWf or GPIbα, downstream platelet activation was also assessed in perfused blood by flow cytometry using two activation markers (active GPIIb/IIIa and P-selectin). Acetylsalicylic acid demonstrated its inability to diminish shear-induced platelet adhesion to all three binding proteins. GPIIb/IIIa inhibitors (tirofiban and eptifibatide) significantly reduced platelet adhesion to fibrinogen. Antibody blocking of vWf or GPIbα effectively diminished platelet adhesion to all three capture proteins as well as platelet activation in perfused blood, indicating an essential role of vWf-GPIbα interaction in mediating shear-induced platelet aggregation.

A Novel Proportional Navigation Based Method for Robotic Interception Planning With Final Velocity Control

This paper presents a new method for robot interception planning based on the proportional navigation. Guidance laws are basically developed for aerospace applications where a pursuer impacts a target using these methods, however in the robotic application it is required to have a smooth grasp between the robot and the goal. In this method, a new term is considered for longitude axis to have the control on the final approaching velocity. The proposed method not only ensures the position and velocity match (also referred to as rendezvous) but also can be used to set the final closing velocity to any desired value. Approaching velocity can be zero for grasping the goal or a specific known velocity for hitting it in a controlled manner. It is shown that the capture region of the proposed approach is wider that other proportional navigation based methods. The proposed method is implemented on Qbot-2 and its performance is experimentally validated.

A Numerical Investigation of the Vibration Effect on Interactions in a Gas Bubble Ensemble and Solid Particles in a Liquid

Abstract—It is known that linearly polarized translational vibrations can multiply the capture cross section of deposited solid particles by a single gas bubble suspended in a liquid. This fact is of great theoretical and practical importance for using vibrations to intensify the flotation process, which, however, involves multiple rising bubbles. The present work studied the capture of solid particles by a gas bubble ensemble in liquid exposed to high-frequency small amplitude vibrations in two-dimensional formulation numerically. The numerical solution was obtained using ANSYS Fluent software. The obtained fields of the averaged and pulsating components of the flow velocity were then processed by our own code in order to calculate the trajectories of small particles from a “cloud” located in the computational domain. The description of forces acting on the particle took the added mass of the fluid, gravity, the Archimedean force, Stokes force, Basset force, and the vibrational force due to the inhomogeneity of the pulsating field into account. The calculations were performed for millimeter air bubbles in water with particle characteristics significant for the flotation process. The influence of vibrations is shown to be significantly attenuated within the bubble ensemble due to the “screening” effect, which peaks at the highest vibration frequency and depends weakly on the distance between the bubbles. However, vibrations of a lesser frequency, at which the gas in bubbles is compressible, are still able to penetrate deep into the liquid volume at a sufficient excitation intensity, and thereby increase the particle capture region.

Optimal Solution of a Target Defense Game with Two defenders and a Faster Intrude

A target defense game with two defenders and a faster intruder is solved based on the classic differential game theory. In the game, the intruder seeks to enter a circular target area, while the defenders endeavor to capture it outside of the target. Under the faster intruder assumption, the game has two phases, where the optimal trajectories are straight and curved, respectively. In the second phase, a peculiar phenomenon exists where the intruder moves at the edge of one defender’s capture region, yet this defender cannot force capture. Because of this, the terminal states of the game are singular, therefore the standard method of integrating optimal trajectories from terminal states is not applicable. The way to circumvent this singularity is to solve the optimal trajectories of a two-player game between the intruder and the closer defender, and assemble them with the trajectory of the other defender. The key contribution of this paper is the solution of the intruder-closer-defender subgame against a circular target area. In the vector field of the optimal trajectories, two singular surfaces and a singular point are observed. Each singular surface indicates a discontinuity in the closer defender’s control, while the singular point represents a situation where the target is successfully protected by a single defender. The complete solution of the two-defender game is solved based on the result of the intruder-closer-defender subgame. The proposed solution is verified through a special case where the capture range is zero. This verification also presents a simpler approach of solving the zero capture range problem.

Skin tone on mobile displays under different ambient lighting

This experiment was aimed to study the preference of mobile phone facial images captured under different simulated ambient lightings. The experiment was carried out by assessing the preference of images for two facial images under 11 lightings (5 correlated colour temperature levels at 2 illuminances plus a dark condition). Forty-five images were processed via CAT02 chromatic adaptation transform to simulate the pictures captured under different light environments. The results revealed that the preferred capture region was between 6500 and 8000K around -0.05 Duv. Furthermore, it was found that the preferred skin tones of all the 45 rendered had good agreement under all the ambient lightings of viewing, i.e.to have mean values of L*, Cab*, hab of [76.3 25.1, 46.4°] units under D65/10 o conditions.

Effects of elapsed time on downstream platelet adhesion following transient exposure to elevated upstream shear forces

Transient exposure to elevated shear forces is known to prime platelets for enhanced downstream adhesion, but how far downstream these priming effects persist is not known. In the present study, the platelet capture regions, prepared by immobilizing fibrinogen, collagen, or von Willebrand factor, were placed at three different distances from the upstream stenotic region to vary the elapsed time of circulating platelets downstream. Platelet adhesion increased with the increase of upstream wall shear rates from 1620 s−1 to 11,560 s−1 for all three downstream proteins, but only the adhesion to fibrinogen increased significantly with the distance between the upstream stenotic region and the downstream capture region. In contrast, platelet adhesion to downstream collagen remained essentially independent on the distance and the adhesion to von Willebrand factor marginally increased with the distance after transient platelet exposure to upstream wall shear rates of 2145 s−1 and 11,560 s−1. The results implied that the activation of fibrinogen receptor GPIIb/IIIa by transient exposure to high upstream wall shear rates progresses in a time-dependent manner during the downstream flow of platelets. The highly elevated upstream wall shear rate of 11,560 s−1 altered the morphology of many platelets adhered to downstream fibrinogen from their native ellipsoidal to spread circular form. The platelet shape analysis showed that longer periods of post-stenotic flow increased the surface coverage fraction of ellipsoidal platelet population and decreased the surface coverage fraction of fully spread platelets on fibrinogen for both transiently elevated upstream wall shear rates.

A new strategy to capture single biological micro particles at the interface between a water film and substrate by ultrasonic tweezers

Controlled capture of single biological micro particles, with effective capture function, little heat damage to and good stability of captured samples simultaneously, has been a technological challenge in the area of micro manipulation. This paper presents an ultrasonic tweezers based new strategy to meet the challenge. In the strategy, being different from the other ultrasonic methods, the MMP (micro manipulating probe), which vibrates elliptically, is in contact with the substrate. Single yeast cells with a diameter of 3–7 μm and Chlorella vulgaris powders with a diameter of 2–10 μm near the MMP can be sucked onto the MMP’s tip. The captured particle can be transferred to a desired location at the interface between the water film and substrate by moving the ultrasonic tweezers. The temperature rise in the capture region is less than 0.1 °C, and the sucking distance can be up to 20 μm. The captured particle is in contact with the MMP’s tip, which results in a good stability of the captured particle. The experiments also show that it is possible to use multiple MMPs to individually capture single cells. The finite element analyses indicate that acoustic radiation force generated by the ultrasonic field around the MMP is responsible for the capture. Moreover, the effects of the orthogonal vibration components, tilt angle and length of the MMP on the capture capability are clarified.

Effects of Elapsed Time on Downstream Platelet Adhesion Following Exposure to Transiently Elevated Upstream Shear Forces

Transient exposure to elevated shear forces pre-activates platelets for enhanced downstream adhesion, but how far downstream these priming effects persist is not known. We found that platelet adhesion to downstream capture region containing one of the three immobilized platelet binding proteins: fibrinogen, collagen, or von Willebrand factor, changed after platelets flowed through an upstream stenotic region. These platelet capture regions were placed at three different distances from the upstream stenotic region. Platelet adhesion increased with the increase of upstream wall shear rates from 1620 s-1 to 11560 s-1 for all three proteins, but only the adhesion to fibrinogen increased significantly with the distance between the upstream stenotic region and downstream capture region. Platelet adhesion to collagen remained essentially independent on the distance and adhesion to von Willebrand factor marginally increased with the distance after transient platelet exposure to higher upstream shear rates. The results implied that the activation of fibrinogen receptor GPIIb/IIIa by transient exposure to high upstream wall shear rates progresses in a time-dependent manner during the flow of platelets to the downstream capture regions. The highly elevated upstream wall shear rate of 11560 s-1 altered the morphology of many platelets adhered to downstream fibrinogen from their native ellipsoidal to spread circular form. The platelet shape analysis showed that longest periods of post-stenotic flow increased the surface coverage fraction of ellipsoidal platelet population and decreased the surface coverage fraction of fully spread platelets on fibrinogen after both elevated upstream wall shear rates.

Effect of fluorine substituents on benzothiadiazole-based D-π-A'-π-A photosensitizers for dye-sensitized solar cells.

Two D–π–A′–π–A organic dyes with triazatruxene (TAT) as the electron donor, thiophene as the π-spacer, benzoic acid as the anchor group, and benzothiadiazole (BT) or difluorobenzo[c][1,2,5]thiadiazole (DFBT) as the additional acceptor, namely LS101 and LS102, respectively, were applied to dye-sensitized solar cells (DSSCs). As fluorine substituents are usually strong electron-withdrawing groups, introducing two fluorine atoms into BT was expected to strengthen the electron-withdrawing ability of the auxiliary acceptor, resulting in DSSCs with a broader light capture region and further improved power conversion efficiency (PCE). Fluorine is the smallest electron-withdrawing group with an induction effect, but can also act as an electron-donating group owing to its conjugation effect. When the conjugation effect is dominant, the electron-withdrawing ability of additional acceptor DFBT decreases instead. Accordingly, the band gap of LS102 was broadened and the UV-vis absorption spectrum was blue-shifted. In the end, DSSCs based on LS101 achieved a champion PCE of 10.2% (Jsc = 15.1 mA cm−2, Voc = 966 mV, FF = 70.1%) while that based on LS102 gave a PCE of only 8.6% (Jsc = 13.4 mA cm−2, Voc = 934 mV, FF = 69.1%) under standard AM 1.5G solar irradiation (100 mW cm−2) with Co2+/Co3+ as the electrolyte.

Capturability of a Sliding-Mode Guidance Law With Finite-Time Convergence

Using the Lyapunov-like approach, the capturability of a recently proposed sliding-mode guidance law, which is used for exoatmospheric interception and can guide the line-of-sight (LOS) angular rate to converge to zero or its small neighborhood in a finite time, is thoroughly analyzed. The target is assumed to have an arbitrary but upper-bounded maneuvering acceleration. A more realistic definition of capture is considered. The upper bound of the commanded acceleration is obtained and so is the capture region. The new theoretical findings are extended to the three-dimensional space with the help of the rotating LOS coordinate system.

Recurrent inflammatory disease caused by a heterozygous mutation in CD48

Recurrent inflammatory disease caused by a heterozygous mutation in CD48

Study of a Transportation Process of Dust Particles in the Plasma of Radio Frequency Discharge

This paper presents the results of studies of dust formations in a radio frequency (RF) discharge plasma. In particular, the behavior of dust clouds in various types of traps was investigated. The experiments were carried out in argon plasma with the following discharge parameters: gas pressure of 0.02–0.6 Torr and discharge power of 1–50 W. Two types of the ring were used as a trap—“closed” and “nonclosed.” It was found that by changing the discharge parameters and using a different type of trap, it is possible to control the capture region of dust formations, and therefore, manipulate the extraction of dust particles by mass (size, in the case of monodispersity of particles). It has been observed that at a lower gas pressure the dust cloud is less affected by the traps; moreover, the wider the edge opening of “nonclosed” ring trap, the more efficient the process of extracting dust particles. The results of this paper can be useful for practical application in the processes of separation and extraction of dust particles from a plasma crystal, the study of particle interactions, and the manipulation of individual particles, etc.

Capturability of Impact-Angle Control Composite Guidance Law Considering Field-of-View Limit

A capture region of the composite guidance law is analyzed for a missile equipped with a strapdown seeker. The composite guidance law consists of a deviated pure pursuit guidance law and a pure proportional navigation guidance law to perform impact-angle control. The range of the field-of-view limit restricts the performance of the guidance law, which reduces the capture region. Based on the characteristics of the guidance law, the range of the achievable impact angle is investigated by considering the collision condition and the field-of-view limit. It is shown that the capture region is represented in terms of the relative initial position and terminal flight-path angle. Numerical simulations are performed to investigate the properties of the proposed capture region of the composite guidance law.

High‐Performance Inverted Perovskite Solar Cells by Reducing Electron Capture Region for Electron Transport Layers

The power conversion efficiency (PCE) of inverted perovskite solar cells (i‐PSCs) is lower than that of the normal structures. The low efficiency is mainly ascribed to the inferior properties of commonly used [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) electron transport layers (ETLs) such as complexity in achieving high‐quality films, low electron mobility, imperfect energy level for electron extraction, and large electron capture region. Herein, the bulk heterojunction (BHJ) ETLs composed of PCBM and polymers are developed. The electron mobility of the BHJ film is enhanced by more than three times compared with PCBM, leading to efficient electron extraction. The electron capture region of the BHJ film decreases to 1.20 × 10−18 from 3.70 × 10−17 cm−3 for PCBM due to increased relative permittivity, which reduces the trap‐assistant recombination at the interface. Meanwhile, the devices with BHJ exhibit good stability regardless of illumination and dark storage conditions owing to the more hydrophobic BHJ films and full coverage of perovskite surface, which effectively prevent the moisture permeation into the perovskite devices. It is believed that this breakthrough provides a suitable approach to improve the efficiency and stability of i‐PSCs.

Stable Efficiency Exceeding 20.6% for Inverted Perovskite Solar Cells through Polymer-Optimized PCBM Electron-Transport Layers.

Fullerene derivative, such as [6,6]-phenyl C61 butyric acid methyl ester (PCBM), is widely used as an electron-transport layer (ETL) in inverted perovskite solar cell (PSC). However, its low electron mobility, complexity in achieving quality film formation, and severe nonradiative recombination at perovskite/PCBM interface due to the large electron capture region, lead tolower efficiency for inverted PSCs compared to the normal structures. Herein, we demonstrate an effective and practical strategy to overcome these challenges. Conjugated n-type polymeric materials are mixed together with PCBM to form a homogeneous bulk-mixed (HBM) continuous film with high electron mobility and suitable energy level. HBM film is found to completely cap the perovskite surface to enhance the electron extraction. The critical electron capture radius of the HBM decreases to 12.52 nm from 14.89 nm of PCBM due to the large relative permittivity, resulting in reduced nonradiative recombination at perovskite/HBM interface. The efficiency of inverted PSCs with HBM ETLs exceeds 20.6% with a high fill factor of 0.82. Further, the stability of devices is improved owing to the high hydrophobicity of the HBM ETLs. Under ambient air condition after 45 days, the efficiency of inverted PSCs based on HBM remains 80% of the initial value. This is significantly higher than the control devices which retain only 48% of the initial value under similar aging conditions. We believe these breakthroughs in improving efficiency and stability of inverted PSCs will expedite their transition.

24. Identification of recurrent, non-coding mutations across breast cancer molecular subtypes

Many studies have attempted pan-cancer analyses in order to identify recurrent coding mutations, but few have explored non-coding space, and often the results do not extend to breast cancer. While some breast cancer specific studies have identified significantly mutated promoters, they have often failed to incorporate transcriptome data to assess the impact and relevance of mutations on gene expression within tumors (Nik-Zainal et al. 2016, Rheinbay et al. 2017). In order to address this issue, we have compiled a data set consisting of 458 breast cancer tumor/normal pairs. Mutations have been identified with whole genome, exome, or custom capture sequencing and expression with transcriptome sequencing or microarray. The custom (regulome) capture reagent covers regions assembled from regulatory databases, 5’ untranslated regions, 500 bases upstream and downstream of transcription start sites, and 50,000 bases upstream and downstream of 178 genes that have been implicated as being important in breast cancer (Lesurf et al. 2016). While this custom capture region is similar in size to an exome, it has advantages over WGS and exome sequencing. It provides deep sequence coverage of regulatory regions, including GC-rich promoter regions, where WGS often produces insufficient coverage. After extensive filtering, our preliminary analysis revealed significant mutation clustering within the noncoding space of RMRP, WDR74, as noted in previous studies, as well as ∼50 other genes not previously reported. The significance of these mutations, based on recurrence, transcriptome changes, and molecular subtype relationships will be presented.

Numerical Study of Enhancement of Positive Dielectrophoresis Particle Trapping in Electrode-Multilayered Microfluidic Device.

Enhancement of positive dielectrophoresis (pDEP) particle trapping by a co-occurring fluid flow under an ac electric field in an electrode-multilayered microfluidic device is investigated by three-dimensional particle-fluid flow simulations. The particle motion near one cross section of the microfluidic device is simulated under a zero flow condition by the Eulerian-Lagrangian method incorporating the ac electrothermal effect, thermal buoyancy, and dielectrophoresis. The mean trapping rate under the steady state Rm is evaluated from the simulated number of trapped particles Ntrap for 54 cases with four parameters: electrode excitation pattern, medium conductivity σ, applied voltage ϕe, and the real part of the Clausius-Mossotti factor Re[K(ω)]. The simulated pDEP velocity in the upper part of the flow channel is validated by an experiment using cell suspension and is fitted so that the non-dimensional velocity error is within 15% of a typical velocity of pDEP. The mean trapping rate Rm is greatly increased by the fluid flow only in the high conductivity and high voltage cases. Regardless of the electrode excitation pattern, Rm increased almost proportionally to the inflow rate into the capture region, where the pDEP force is effective. From a fitted equation of the results, the increase of Rm when Re[K(ω)] = 0.1 to 0.5 is found to be about 20% to 30% of the number of particles transported into the capture regions. The results quantify the enhancement of pDEP trapping by the fluid flow occurring under practical conditions in the device.

Active Sampling-based Data-driven Reachability Verification for Proportional Navigation Guidance Law

Abstract Reachability verification for the capture region of missile guidance law is conducted. It is challenging to analytically obtain the precise capture region especially when the guaranteed interception is needed against moving evader. Therefore, the capture region of a guidance law is usually shown through numerical simulations, which requires heavy computation. In this paper, an active sampling-based reachability verification is performed based on numerical simulation. Proportional navigation guidance is considered as a guidance law, and the capture region is obtained while the computational burden is alleviated relatively. The prediction error of the active sampling-based approach is compared with that of the conventional random sampling-based approach.