scholarly journals Dynamic Analysis and Simulation of an Optically Levitated Rotating Ellipsoid Rotor in Liquid Medium

2021 ◽  
Author(s):  
Qi Zhu ◽  
Nan Li ◽  
Heming Su ◽  
Wenqiang Li ◽  
Huizhu Hu

AbstractOptical trap, a circularly polarized laser beam can levitate and control the rotation of microspheres in liquid medium with high stiffness. Trapping force performs as confinement while the trapped particle can be analog to a liquid floated gyroscope with three degree-of-freedom. In this work, we analyzed the feasibility of applying optically levitated rotor in the system. We presented the dynamic analysis and simulation of an ellipsoid micron particle. The precession motion and nutation motion of a rotating ellipsoid probe particle in optical tweezers were performed. We also analyzed the attitude changes of an optically levitated ellipsoid when there was variation of the external torque caused by deviation of the incident light that was provided. Furthermore, the trail path of the rotational axis vertex and the stabilization process of a particle of different ellipticities were simulated. We compared the movement tendencies of particles of different shapes and analyzed the selection criteria of ellipsoid rotor. These analytical formulae and simulation results are applicable to the analysis of the rotational motion of particles in optical tweezers, especially to the future research of the gyroscope effect.

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 570
Author(s):  
Alexander B. Stilgoe ◽  
Declan J. Armstrong ◽  
Halina Rubinsztein-Dunlop

The trap stiffness us the key property in using optical tweezers as a force transducer. Force reconstruction via maximum-likelihood-estimator analysis (FORMA) determines the optical trap stiffness based on estimation of the particle velocity from statistical trajectories. Using a modification of this technique, we determine the trap stiffness for a two micron particle within 2 ms to a precision of ∼10% using camera measurements at 10 kfps with the contribution of pixel noise to the signal being larger the level Brownian motion. This is done by observing a particle fall into an optical trap once at a high stiffness. This type of calibration is attractive, as it avoids the use of a nanopositioning stage, which makes it ideal for systems of large numbers of particles, e.g., micro-fluidics or active matter systems.


2016 ◽  
Vol 45 (9) ◽  
pp. 0918003
Author(s):  
王施相 Wang Shixiang ◽  
郭 劲 Guo Jin ◽  
甘新基 Gan Xinji ◽  
王挺峰 Wang Tingfeng

2016 ◽  
Vol 45 (9) ◽  
pp. 918003
Author(s):  
王施相 Wang Shixiang ◽  
郭 劲 Guo Jin ◽  
甘新基 Gan Xinji ◽  
王挺峰 Wang Tingfeng

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Huoyin Zhang ◽  
Shiyunmeng Zhang ◽  
Jiachen Lu ◽  
Yi Lei ◽  
Hong Li

AbstractPrevious studies in humans have shown that brain regions activating social exclusion overlap with those related to attention. However, in the context of social exclusion, how does behavioral monitoring affect individual behavior? In this study, we used the Cyberball game to induce the social exclusion effect in a group of participants. To explore the influence of social exclusion on the attention network, we administered the Attention Network Test (ANT) and compared results for the three subsystems of the attention network (orienting, alerting, and executive control) between exclusion (N = 60) and inclusion (N = 60) groups. Compared with the inclusion group, the exclusion group showed shorter overall response time and better executive control performance, but no significant differences in orienting or alerting. The excluded individuals showed a stronger ability to detect and control conflicts. It appears that social exclusion does not always exert a negative influence on individuals. In future research, attention to network can be used as indicators of social exclusion. This may further reveal how social exclusion affects individuals' psychosomatic mechanisms.


2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Kendall A. Johnson ◽  
Clive H. Bock ◽  
Phillip M. Brannen

Abstract Background Phony peach disease (PPD) is caused by the plant pathogenic bacterium Xylella fastidiosa subsp. multiplex (Xfm). Historically, the disease has caused severe yield loss in Georgia and elsewhere in the southeastern United States, with millions of PPD trees being removed from peach orchards over the last century. The disease remains a production constraint, and management options are few. Limited research has been conducted on PPD since the 1980s, but the advent of new technologies offers the opportunity for new, foundational research to form a basis for informed management of PPD in the U.S. Furthermore, considering the global threat of Xylella to many plant species, preventing import of Xfm to other regions, particularly where peach is grown, should be considered an important phytosanitary endeavor. Main topics We review PPD, its history and impact on peach production, and the eradication efforts that were conducted for 42 years. Additionally, we review the current knowledge of the pathogen, Xfm, and how that knowledge relates to our understanding of the peach—Xylella pathosystem, including the epidemiology of the disease and consideration of the vectors. Methods used to detect the pathogen in peach are discussed, and ramifications of detection in relation to management and control of PPD are considered. Control options for PPD are limited. Our current knowledge of the pathogen diversity and disease epidemiology are described, and based on this, some potential areas for future research are also considered. Conclusion There is a lack of recent foundational research on PPD and the associated strain of Xfm. More research is needed to reduce the impact of this pathogen on peach production in the southeastern U.S., and, should it spread internationally, wherever peaches are grown.


2018 ◽  
Vol 184 ◽  
pp. 02006
Author(s):  
Mariana Ratiu ◽  
Alexandru Rus ◽  
Monica Loredana Balas

In this paper, we present the first steps in the process of the modeling in ADAMS MBS of MSC software of the mechanical system of an articulated robot, with six revolute joints. The geometric 3D CAD model of the robot, identical to the real model, in the PARASOLID format, is imported into ADAMS/View and then are presented the necessary steps for building the kinematic model of the robot. We conducted this work, in order to help us in our future research, which will consist of kinematic and dynamic analysis and optimization of the robot motion.


2008 ◽  
Vol 17 (04) ◽  
pp. 387-394 ◽  
Author(s):  
XIUDONG SUN ◽  
XUECONG LI ◽  
JIANLONG ZHANG

Orientating manipulations of cylindrical particles were performed by optical tweezers. Vertical and horizontal manipulations of Escherichia coli (E. coli) were carried out by changing the trapping depth and the focused laser beam shape. It was found that carbon nanotubes bundles (CNTBs) could be rotated in the linear polarized optical trap until it orientated its long axis along the linear polarization direction of the laser beam. However, E.coli could not be orientated in this way. Corresponding mechanisms were discussed based on the anisomeric electric characters of CNTBs. These orientation technologies of cylindrical objects with optical trap have potential applications in assembling nano-electric devices.


1997 ◽  
Vol 31 (11) ◽  
pp. 1360-1369 ◽  
Author(s):  
Edyta J Frackiewicz ◽  
John J Sramek ◽  
John M Herrera ◽  
Neil M Kurtz ◽  
Neal R Cutler

OBJECTIVE: To review the data generated by studies examining interethnic/racial differences in response to antipsychotics. DATA SOURCES: A MEDLINE search (1966-19%) identified all articles examining differences in antipsychotic response among Caucasians, Asians, Hispanics, and African-Americans, as well as articles evaluating postulated mechanisms for these differences. STUDY SELECTION: All abstracts, studies, and review articles were evaluated. DATA SYNTHESIS: Ethnic/racial differences in response to antipsychotic medications have been reported and may be due to genetics, kinetic variations, dietary or environmental factors, or variations in the prescribing practices of clinicians. Studies suggest that Asians may respond to lower doses of antipsychotics due to pharmacokinetic and pharmacodynamic differences. Research relevant to African-Americans is limited, but some studies suggest that differences in this group may be due to clinician biases and prescribing practices, rather than to pharmacokinetic or pharmacodynamic variability. CONCLUSIONS: Future research directed at validating the hypotheses that different ethnic/racial groups show variations in response to antipsychotics should focus on homogenous ethnic groups, use recent advances in pharmacogenetic testing, and control for such variables as observer bias, gender, disease chronicity, dietary and environmental factors, and exposure to enzyme-inducing and -inhibiting agents. Clinicians should be aware that potential interethnic/racial differences in pharmacodynamics and pharmacokinetics may exist that can alter response to antipsychotics.


Author(s):  
Ramanjit Kaur ◽  
Abhishek Mewada ◽  
Vikas Veeranna ◽  
Sandip Zalawadiya ◽  
Krithi Ramesh ◽  
...  

Background Diabetes mellitus (DM) is a major cause of overall mortality even with optimal control. We sought to explore the association of novel biomarkers with mortality in a nationally representative cohort of adults based on DM status and control. Methods Adults (aged >20 years) in the National Health and Nutrition Examination Survey ( NHANES ) 1999-2008 we subdivided into four groups: no DM, Controlled DM, Uncontrolled DM and Evidence of DM but no formal diagnosis. Cox-proportional hazard analysis was performed to determine the association between novel biomarkers and mortality across the subgroups. Results Red cell distribution width (RDW) and homocysteine remained significant predictors of mortality beyond traditional risk factors (for age, sex, race, body mass index, hypertension, dyslipidemia, smoking and additionally for hemoglobin, mean corpuscular volume and nutritional factor deficiencies) across all the DM subgroups in comparison to the other biomarkers. (Table 1). Conclusion RDW and homocysteine predict mortality irrespective of the diabetes status. These may be the potential targets for future research to ascertain the exact pathophysiologic mechanism.


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