Microscale Variability of Atrazine and Chloride Leaching Under Field Conditions

1997 ◽  
Vol 11 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Guy A. Chammas ◽  
John L. Hutson ◽  
Jonathan J. Hart ◽  
Joseph M. DiTomaso
Keyword(s):  
Center Of Mass ◽  
Three Dimensional ◽  
Simulation Models ◽  
Field Conditions ◽  
Nonuniform Flow ◽  
High Background ◽  
Sampling Schemes ◽  
Atrazine Concentration ◽  
Herbicide Transport ◽  
Chloride Leaching

Pesticide leaching experiments using widely spaced sampling sites may not adequately characterize chemical leaching behavior such as nonuniform flow between sampling points. We conducted this study to determine the three-dimensional variability of atrazine and chloride movement within a small volume of soil (2,700 cm1) under field conditions. A 1-m2area of Williamson silt loam (coarse-silty, mixed, mesic, Typic Fragiochrept) was sprayed uniformly with atrazine (1.1 kg ai/ha) and chloride (80 kg/ha). We used the Leaching Estimation and Chemistry Model (LEACHM) to simulate chemical movement. After 6.5 cm of rainfall during a 29-d period, we sampled 36 squares (5 by 5 cm) in the central 30- by 30-cm portion of the treated area at six depth increments (0 to 2, 2 to 5, 5 to 10, 10 to 15, 15 to 21, and 21 to 30 cm) and determined atrazine and Cl−concentrations. We recovered 26% of the applied atrazine and 138% of the applied chloride. Low atrazine recovery may have been due to leaching beyond 30 cm and/or degradation while excess chloride recovery is attributed to high background concentrations. Coefficients of variation (CVs) for atrazine significantly increased with depth and ranged from 26 to 353%, while CVs for Cl−were independent of depth and ranged from 32 to 66%. Derived atrazine concentration isograms illustrated highly nonuniform herbicide transport. Although LEACHM overestimated atrazine movement in the upper 15 cm, it was fairly accurate in the lower 15 cm. The overall trend in Cl−flow was adequately predicted, even though the predicted Cl−concentrations were underestimated. LEACHM could not accurately predict nonuniform flow or the variability in solute concentrations between points. However, its prediction of the atrazine center of mass (about 4.7 cm) agreed well with the derived isograms. These findings demonstrate that localized nonideal solute transport may be missed in larger sampling schemes and in simulation models.

Center of Mass Theorem and the Separation of Variables for Two-Body System on a Three-Dimensional Sphere

2020 ◽  
Vol 23 (3) ◽  
pp. 306-311
Author(s):  
Yu. Kurochkin ◽  
Dz. Shoukavy ◽  
I. Boyarina
Keyword(s):  
Constant Curvature ◽  
Jacobi Equation ◽  
Separation Of Variables ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Relative Distance ◽  
Dimensional Sphere ◽  
Body System ◽  
Spaces Of Constant Curvature ◽  
Hamilton Jacobi Equation

The immobility of the center of mass in spaces of constant curvature is postulated based on its definition obtained in [1]. The system of two particles which interact through a potential depending only on the distance between particles on a three-dimensional sphere is considered. The Hamilton-Jacobi equation is formulated and its solutions and trajectory equations are found. It was established that the reduced mass of the system depends on the relative distance.

Dynamics of a composite system in a point source-induced space–time

2021 ◽  
pp. 2150144
Author(s):  
Abdullah Guvendi
Keyword(s):  
Point Source ◽  
Composite System ◽  
Dimensional Space ◽  
Energy Levels ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Space Time ◽  
Spin Coupling ◽  
Quantum Oscillator ◽  
Dimensional Space Time

We investigate the dynamics of a composite system ([Formula: see text]) consisting of an interacting fermion–antifermion pair in the three-dimensional space–time background generated by a static point source. By considering the interaction between the particles as Dirac oscillator coupling, we analyze the effects of space–time topology on the energy of such a [Formula: see text]. To achieve this, we solve the corresponding form of a two-body Dirac equation (fully-covariant) by assuming the center-of-mass of the particles is at rest and locates at the origin of the spatial geometry. Under this assumption, we arrive at a nonperturbative energy spectrum for the system in question. This spectrum includes spin coupling and depends on the angular deficit parameter [Formula: see text] of the geometric background. This provides a suitable basis to determine the effects of the geometric background on the energy of the [Formula: see text] under consideration. Our results show that such a [Formula: see text] behaves like a single quantum oscillator. Then, we analyze the alterations in the energy levels and discuss the limits of the obtained results. We show that the effects of the geometric background on each energy level are not same and there can be degeneracy in the energy levels for small values of the [Formula: see text].

Static and dynamic postural control in long-term microgravity: evidence of a dual adaptation

2001 ◽  
Vol 90 (1) ◽  
pp. 205-215 ◽  
Author(s):  
Guido Baroni ◽  
Alessandra Pedrocchi ◽  
Giancarlo Ferrigno ◽  
Jean Massion ◽  
Antonio Pedotti
Keyword(s):  
Postural Control ◽  
Time Course ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Principal Component ◽  
Movement Analysis ◽  
Trunk Flexion ◽  
Dynamic Movement ◽  
Static Body

The adaptation of dynamic movement-posture coordination during forward trunk bending was investigated in long-term weightlessness. Three-dimensional movement analysis was carried out in two astronauts during a 4-mo microgravity exposure. The principal component analysis was applied to joint-angle kinematics for the assessment of angular synergies. The anteroposterior center of mass (CM) displacement accompanying trunk flexion was also quantified. The results reveal that subjects kept typically terrestrial strategies of movement-posture coordination. The temporary disruption of joint-angular synergies observed at subjects' first in-flight session was promptly recovered when repetitive sessions in flight were analyzed. The CM anteroposterior shift was consistently <3–4 cm, suggesting that subjects could dynamically control the CM position throughout the whole flight. This is in contrast to the observed profound microgravity-induced disruption of the quasi-static body orientation and initial CM positioning. Although this study was based on only two subjects, evidence is provided that static and dynamic postural control might be under two separate mechanisms, adapting with their specific time course to the constraints of microgravity.

A Model of Complexity Levels of Meaning Constitution in Simulation Models of Language Evolution

2011 ◽  
Vol 1 (1) ◽  
pp. 18-38 ◽  
Author(s):  
Andy Lücking ◽  
Alexander Mehler
Keyword(s):  
Physical Properties ◽  
Language Evolution ◽  
Three Dimensional ◽  
Simulation Models ◽  
Context Dependency ◽  
Abstract Objects ◽  
Linguistic Terms ◽  
Left And Right ◽  
Linguistic Categories ◽  
Linguistic Categorization

Currently, some simulative accounts exist within dynamic or evolutionary frameworks that are concerned with the development of linguistic categories within a population of language users. Although these studies mostly emphasize that their models are abstract, the paradigm categorization domain is preferably that of colors. In this paper, the authors argue that color adjectives are special predicates in both linguistic and metaphysical terms: semantically, they are intersective predicates, metaphysically, color properties can be empirically reduced onto purely physical properties. The restriction of categorization simulations to the color paradigm systematically leads to ignoring two ubiquitous features of natural language predicates, namely relativity and context-dependency. Therefore, the models for simulation models of linguistic categories are not able to capture the formation of categories like perspective-dependent predicates ‘left’ and ‘right’, subsective predicates like ‘small’ and ‘big’, or predicates that make reference to abstract objects like ‘I prefer this kind of situation’. The authors develop a three-dimensional grid of ascending complexity that is partitioned according to the semiotic triangle. They also develop a conceptual model in the form of a decision grid by means of which the complexity level of simulation models of linguistic categorization can be assessed in linguistic terms.

scholarly journals The IART System for Race Walking: Experience with World-Class Olympic Race Walkers

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 79
Author(s):  
Teodorico Caporaso ◽  
Stanislao Grazioso ◽  
Dario Panariello ◽  
Giuseppe Di Gironimo ◽  
Antonio Lanzotti
Keyword(s):  
Inertial Sensor ◽  
Center Of Mass ◽  
Field Conditions ◽  
Sequence Classification ◽  
Competition Rules ◽  
Overall Evaluation ◽  
Race Walking ◽  
World Class ◽  
The Subject ◽  
And Training

Race walking is a discipline in which the best chronometric performance is constrained by infringements. Currently, the judgment and training of race walkers is entrusted to subjective observations made by judges. In this paper, with the objective of supporting coaching and judging, we present a wearable inertial sensor system (IART) for the evaluation of performances and infringements in race walking. The system is composed of an inertial sensor positioned close to the center of mass of the subject and a management unit designed for coaches and judges. IART allows: (i) a step sequence classification according to the competition rules; (ii) a customized assessment of elite race walkers based on key performance and infringement indices. The system is experimentally validated in field conditions by nine world-class Olympic race walkers. The results show that IART improves the current evaluation of step sequences and offers a meaningful support for the overall evaluation of the technical gesture.

scholarly journals Numerical Study of the Zero Velocity Surface and Transfer Trajectory of a Circular Restricted Five-Body Problem

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
R. F. Wang ◽  
F. B. Gao
Keyword(s):  
Body Problem ◽  
Numerical Study ◽  
Dimensional Space ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Regular Tetrahedron ◽  
Transfer Trajectory ◽  
Zero Velocity ◽  
Zero Velocity Surfaces ◽  
Zero Velocity Surface

We focus on a type of circular restricted five-body problem in which four primaries with equal masses form a regular tetrahedron configuration and circulate uniformly around the center of mass of the system. The fifth particle, which can be regarded as a small celestial body or probe, obeys the law of gravity determined by the four primaries. The geometric configuration of zero-velocity surfaces of the fifth particle in the three-dimensional space is numerically simulated and addressed. Furthermore, a transfer trajectory of the fifth particle skimming over four primaries then is designed.

scholarly journals Translocation through a narrow pore under a pulling force

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mohammadreza Niknam Hamidabad ◽  
Rouhollah Haji Abdolvahab
Keyword(s):  
Interaction Energy ◽  
External Force ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Major Effect ◽  
Translocation Time ◽  
Polymer Translocation ◽  
Pulling Force ◽  
External Forces ◽  
Polymer Shape

AbstractWe employ a three-dimensional molecular dynamics to simulate a driven polymer translocation through a nanopore by applying an external force, for four pore diameters and two external forces. To see the polymer and pore interaction effects on translocation time, we studied nine interaction energies. Moreover, to better understand the simulation results, we investigate polymer center of mass, shape factor and the monomer spatial distribution through the translocation process. Our results reveal that increasing the polymer-pore interaction energy is accompanied by an increase in the translocation time and decrease in the process rate. Furthermore, for pores with greater diameter, the translocation becomes faster. The shape analysis of the polymer indicates that the polymer shape is highly sensitive to the interaction energy. In great interactions, the monomers come close to the pore from both sides. As a result, the translocation becomes fast at first and slows down at last. Overall, it can be concluded that the external force does not play a major role in the shape and distribution of translocated monomers. However, the interaction energy between monomer and nanopore has a major effect especially on the distribution of translocated monomers on the trans side.

scholarly journals RETARDATION TERMS IN THE ONE-GLUON EXCHANGE POTENTIAL

2001 ◽  
Vol 16 (22) ◽  
pp. 3745-3753 ◽  
Author(s):  
JUN-CHEN SU ◽  
JIAN-XING CHEN
Keyword(s):  
Bound States ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Relativistic Equation ◽  
Previous Literature ◽  
Exchange Potential ◽  
Gluon Exchange ◽  
Mass Frame ◽  
The One ◽  
Exchange Kernel

It is pointed out that the retardation terms given in the original Fermi–Breit potential vanish in the center-of-mass frame. The retarded one-gluon exchange potential is rederived in this paper from the three-dimensional one-gluon exchange kernel which appears in the exact three-dimensional relativistic equation for quark–antiquark bound states. The retardation part of the potential given in the approximation of order p2/m2 is shown to be different from those derived in the previous literature. This part is off-shell and no longer vanishes in the center-of-mass frame.

CONTROL OF ERRORS USING A SIMPLIFIED CLINICAL SETUP FOR MOTION ANALYSIS: ERRORS DUE TO CALIBRATION AND THREE-DIMENSIONAL RECONSTRUCTION

2005 ◽  
Vol 05 (04) ◽  
pp. 491-505 ◽  
Author(s):  
ERIC BERTHONNAUD ◽  
JOANNÈS DIMNET
Keyword(s):  
Motion Analysis ◽  
Center Of Mass ◽  
Force Plate ◽  
Three Dimensional ◽  
Vertical Component ◽  
Calibration Procedure ◽  
Human Movements ◽  
Dimensional Reconstruction ◽  
Analysis Errors ◽  
New System

Different systems of motion analysis have been described. They usually associate several cameras with a force platform. They can analyze very sophisticated human movements. They are, however, expensive and require significant technical formation from users. A new system is proposed for simple and standard clinical applications. It uses only two cameras and a coupled force plate delivering only the vertical component of the patient weight and the location of his center of mass. It is inexpensive, simple to use and delivers accurate results. This is obtained through a strict experimental protocol, and a new method of data treatment which allows the control of errors at each step of the successive calculations. This paper describes the new system, the new calibration procedure and the control of errors.

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