A system for the determination of planar force vectors from spontaneously active chicken embryos

2014 ◽  
Vol 112 (9) ◽  
pp. 2349-2356 ◽  
Author(s):  
Andrew A. Sharp ◽  
Blake W. Cain ◽  
Joanna Pakiraih ◽  
James L. Williams
Keyword(s):  
Model Systems ◽  
Force Measurements ◽  
Force Vector ◽  
Chicken Embryos ◽  
Computational Program ◽  
Embryonic Motility ◽  
Measuring Force ◽  
Vector Magnitude ◽  
Force Vectors

Generally, a combination of kinematic, electromyographic (EMG), and force measurements are used to understand how an organism generates and controls movement. The chicken embryo has been a very useful model system for understanding the early stages of embryonic motility in vertebrates. Unfortunately, the size and delicate nature of embryos makes studies of motility during embryogenesis very challenging. Both kinematic and EMG recordings have been achieved in embryonic chickens, but two-dimensional force vector recordings have not. Here, we describe a dual-axis system for measuring force generated by the leg of embryonic chickens. The system employs two strain gauges to measure planar forces oriented with the plane of motion of the leg. This system responds to forces according to the principles of Pythagorean geometry, which allows a simple computational program to determine the force vector (magnitude and direction) generated during spontaneous motor activity. The system is able to determine force vectors for forces >0.5 mN accurately and allows for simultaneous kinematic and EMG recordings. This sensitivity is sufficient for force vector measurements encompassing most embryonic leg movements in midstage chicken embryos allowing for a more complete understanding of embryonic motility. Variations on this system are discussed to enable nonideal or alternative sensor arrangements and to allow for translation of this approach to other delicate model systems.

Casimir forces and vacuum energy

2017 ◽  
Author(s):  
Serge Reynaud ◽  
Astrid Lambrecht
Keyword(s):  
Casimir Force ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Thermal Fluctuations ◽  
Model Systems ◽  
Vacuum Field ◽  
Force Measurements ◽  
Casimir Forces ◽  
Current State ◽  
Field Fluctuations

The Casimir force is an effect of quantum vacuum field fluctuations, with applications in many domains of physics. The ideal expression obtained by Casimir, valid for perfect plane mirrors at zero temperature, has to be modified to take into account the effects of the optical properties of mirrors, thermal fluctuations, and geometry. After a general introduction to the Casimir force and a description of the current state of the art for Casimir force measurements and their comparison with theory, this chapter presents pedagogical treatments of the main features of the theory of Casimir forces for one-dimensional model systems and for mirrors in three-dimensional space.

Experimental and Theoretical Rotordynamic Characteristics of a Hybrid Journal Bearing

1997 ◽  
Vol 119 (1) ◽  
pp. 132-141 ◽  
Author(s):  
J. T. Sawicki ◽  
R. J. Capaldi ◽  
M. L. Adams
Keyword(s):  
Journal Bearing ◽  
Operating Conditions ◽  
Dynamic Force ◽  
Test Results ◽  
Force Measurements ◽  
Lubrication Equation ◽  
Load Cells ◽  
Theoretical Predictions ◽  
Stiffness And Damping

This paper describes an experimental and theoretical investigation of a four-pocket, oil-fed, orifice-compensated hydrostatic bearing including the hybrid effects of journal rotation. The test apparatus incorporates a double-spool-shaft spindle which permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit, for both forward and backward whirling. This configuration yields data that enables determination of the full linear anisotropic rotordynamic model. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Theoretical predictions are made for the same configuration and operating conditions as the test matrix using a finite-difference solver of Reynolds lubrication equation. The computational results agree well with test results, theoretical predictions of stiffness and damping coefficients are typically within thirty percent of the experimental results.

Determination of Substrate/Ligand Binding Constants from Electromotrive Force Measurements

2008 ◽  
Vol 37 (4) ◽  
pp. 519-526 ◽  
Author(s):  
M. Lopez-Lopez ◽  
P. Lopez-Cornejo ◽  
A. García ◽  
F. Sanchez
Keyword(s):  
Ligand Binding ◽  
Binding Constants ◽  
Force Measurements

scholarly journals Determination of beam characteristics by its vibration measurement

1995 ◽  
Vol 17 (3) ◽  
pp. 27-38
Author(s):  
Nguyen Cao Menh ◽  
Tran Trong Toan
Keyword(s):  
Inverse Problem ◽  
Analytical Method ◽  
Transverse Vibration ◽  
Vibration Measurement ◽  
Computational Program ◽  
Beam Characteristics ◽  
Free Beam

On the basis of analyzing the transverse vibration of a clamped-free beam, in this paper an inverse problem is investigated. The analytical method· and computational program me have been presented for determination of the length of the beam when vibrations at some points on the beam with external distribution excitation or vibration at one point with some excited frequencies are measured. The obtained results from the illustration examples described in the paper give us the procedure for selecting one solution in multi-solution inverse problem.

scholarly journals 5′,8-Cyclopurine Lesions in DNA Damage: Chemical, Analytical, Biological, and Diagnostic Significance

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 513 ◽  
Author(s):  
Chryssostomos Chatgilialoglu ◽  
Carla Ferreri ◽  
Nicholas E. Geacintov ◽  
Marios G. Krokidis ◽  
Yuan Liu ◽  
...  
Keyword(s):  
Genetic Instability ◽  
Model Systems ◽  
Diagnostic Significance ◽  
Purine Base ◽  
Repair Mechanisms ◽  
Cellular Dna ◽  
Radical Attack ◽  
Molecular Library

Purine 5′,8-cyclo-2′-deoxynucleosides (cPu) are tandem-type lesions observed among the DNA purine modifications and identified in mammalian cellular DNA in vivo. These lesions can be present in two diasteroisomeric forms, 5′R and 5′S, for each 2′-deoxyadenosine and 2′-deoxyguanosine moiety. They are generated exclusively by hydroxyl radical attack to 2′-deoxyribose units generating C5′ radicals, followed by cyclization with the C8 position of the purine base. This review describes the main recent achievements in the preparation of the cPu molecular library for analytical and DNA synthesis applications for the studies of the enzymatic recognition and repair mechanisms, their impact on transcription and genetic instability, quantitative determination of the levels of lesions in various types of cells and animal model systems, and relationships between the levels of lesions and human health, disease, and aging, as well as the defining of the detection limits and quantification protocols.

scholarly journals A rapid spectrophotometric determination of imidacloprid in selected commercial formulations in the presence of 6-chloronicotinic acid

2009 ◽  
Vol 74 (12) ◽  
pp. 1455-1465 ◽  
Author(s):  
Valéria Guzsvány ◽  
Zsigmond Papp ◽  
Sanja Lazic ◽  
Ferenc Gaál ◽  
Luka Bjelica ◽  
...  
Keyword(s):  
Spectrophotometric Method ◽  
High Performance ◽  
High Performance Liquid Chromatographic ◽  
Model Systems ◽  
Zero Crossing ◽  
Spectrophotometric Methods ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Liquid Chromatographic

A simple first-order derivative spectrophotometric method was developed for the simultaneous determination of imidacloprid and 6-chloronicotinic acid (6-CNA). By using the zero-crossing approach, imidacloprid was determined at 249 nm and 6-CNA at 236 nm with detection limits of 0.32 and 0.17 ?g mL-1, respectively, and relative standard deviations not exceeding 1.2 % in the case of model systems. The proposed method was applied for the determination of imidacloprid and 6-CNA in commercial formulations. A conventional spectrophotometric method (at 270 nm) was also employed for the determination of the content of imidacloprid in the same commercial formulations. The results of the developed spectrophotometric methods were in good agreement with those obtained by the high-performance liquid chromatographic method.

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