Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Gradient and Del Operator01:14

Gradient and Del Operator

3.5K
In mathematics and physics, the gradient and del operator are fundamental concepts used to describe the behavior of functions and fields in space. The gradient is a mathematical operator that gives both the magnitude and direction of the maximum spatial rate of change. Consider a person standing on a mountain. The slope of the mountain at any given point is not defined unless it is quantified in a particular direction. For this reason, a "directional derivative" is defined, which is a vector...
3.5K
What is an Electrochemical Gradient?01:26

What is an Electrochemical Gradient?

119.2K
Adenosine triphosphate, or ATP, is considered the primary energy source in cells. However, energy can also be stored in the electrochemical gradient of an ion across the plasma membrane, which is determined by two factors: its chemical and electrical gradients.
The chemical gradient relies on differences in the abundance of a substance on the outside versus the inside of a cell and flows from areas of high to low ion concentration. In contrast, the electrical gradient revolves around an...
119.2K
Transient and Steady-state Response01:24

Transient and Steady-state Response

305
In control systems, test signals are essential for evaluating performance under various conditions. The ramp function is effective for systems undergoing gradual changes, while the step function is suitable for assessing systems facing sudden disturbances. For systems subjected to shock inputs, the impulse function is the most appropriate test signal.
These test signals are integral in designing control systems to exhibit two key performance aspects: transient response and steady-state...
305
Temperature Dependence on Reaction Rate02:55

Temperature Dependence on Reaction Rate

84.4K
The Collision Theory
Atoms, molecules, or ions must collide before they can react with each other. Atoms must be close together to form chemical bonds. This premise is the basis for a theory that explains many observations regarding chemical kinetics, including factors affecting reaction rates.
The collision theory is based on the postulates that (i) the reaction rate is proportional to the rate of reactant collisions, (ii) the reacting species collide in an orientation allowing contact between...
84.4K
Voltammetry: Factors Affecting Measurements01:21

Voltammetry: Factors Affecting Measurements

220
A current produced due to the redox reactions of the analyte at the working and auxiliary electrodes is called a faradaic current. The reaction can be divided into two types. The current generated due to the reduction of the analyte is called cathodic current, and it carries a positive charge. In contrast, the current produced by analyte oxidation is known as an anodic current, and it has a negative charge. The applied potential at the working electrode determines the faradaic current flow, and...
220
Temperature Measurement Sites01:14

Temperature Measurement Sites

2.3K
A thermometer measures body temperature. The common sites for measuring body temperature are the oral cavity, axillary region, temporal artery, and skin surface, such as the forehead, abdomen, and axilla. True core body temperature is assessed in the rectum, tympanic membrane, pulmonary artery, esophagus, and urinary bladder.
Oral: When assessing oral temperature, the thermometer tip should be placed under the tongue in the posterior sublingual pocket. It offers accurate readings and can be...
2.3K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Prospective Head Motion Correction in T1- and T2-Weighted Long Echo Train Sequences Using Servo Navigation.

Magnetic resonance in medicine·2026
Same author

Direct MRI of collagen.

eLife·2026
Same author

The sinking dynamics of a solid intruder in concentrated cornstarch suspensions studied using ultra-fast magnetic resonance imaging.

Soft matter·2026
Same author

Core-shell particles with tailored magnetic susceptibility for signal-efficient magnetic resonance imaging of granular systems.

Journal of magnetic resonance (San Diego, Calif. : 1997)·2026
Same author

Autonomy for MRI Field Cameras: Synchronization, Self-Calibration, and Sequence Detection.

Magnetic resonance in medicine·2026
Same author

Motion- and Field-Robust Mesoscopic Whole-Brain <math><semantics><mrow><msubsup><mi>T</mi> <mn>2</mn> <mo>*</mo></msubsup></mrow> <annotation>$$ {T}_2^{\ast } $$</annotation></semantics></math> -Weighted Imaging at 7 and 11.7 T Using Servo Navigation.

Magnetic resonance in medicine·2026

Related Experiment Video

Updated: Oct 9, 2025

A Temperature Gradient Assay to Determine Thermal Preferences of Drosophila Larvae
08:59

A Temperature Gradient Assay to Determine Thermal Preferences of Drosophila Larvae

Published on: June 25, 2018

7.8K

Thermal variation in gradient response: measurement and modeling.

Jennifer Nussbaum1, Benjamin E Dietrich1, Bertram J Wilm1

  • 1Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland.

Magnetic Resonance in Medicine
|December 21, 2021
PubMed
Summary

Gradient heating in MRI violates time invariance. A new thermal extension of linear time-invariant (LTI) models, using temperature sensing, recovers LTI utility for accurate gradient response modeling.

Keywords:
GIRFgradient impulse responselinear time-invariant (LTI) systemstemperature dependencetransfer function

More Related Videos

Dual-mode Imaging of Cutaneous Tissue Oxygenation and Vascular Function
11:35

Dual-mode Imaging of Cutaneous Tissue Oxygenation and Vascular Function

Published on: December 8, 2010

16.7K
A Gusseted Thermogradient Table to Control Soil Temperatures for Evaluating Plant Growth and Monitoring Soil Processes
07:40

A Gusseted Thermogradient Table to Control Soil Temperatures for Evaluating Plant Growth and Monitoring Soil Processes

Published on: October 22, 2016

12.1K

Related Experiment Videos

Last Updated: Oct 9, 2025

A Temperature Gradient Assay to Determine Thermal Preferences of Drosophila Larvae
08:59

A Temperature Gradient Assay to Determine Thermal Preferences of Drosophila Larvae

Published on: June 25, 2018

7.8K
Dual-mode Imaging of Cutaneous Tissue Oxygenation and Vascular Function
11:35

Dual-mode Imaging of Cutaneous Tissue Oxygenation and Vascular Function

Published on: December 8, 2010

16.7K
A Gusseted Thermogradient Table to Control Soil Temperatures for Evaluating Plant Growth and Monitoring Soil Processes
07:40

A Gusseted Thermogradient Table to Control Soil Temperatures for Evaluating Plant Growth and Monitoring Soil Processes

Published on: October 22, 2016

12.1K

Area of Science:

  • Magnetic Resonance Imaging (MRI)
  • Physics
  • Engineering

Background:

  • Linear time-invariant (LTI) models accurately describe MRI gradient dynamics.
  • Gradient system heating introduces time-varying behavior, violating LTI assumptions.
  • Understanding thermal effects is crucial for maintaining MRI performance.

Purpose of the Study:

  • To investigate the impact of gradient system heating on MRI transfer functions.
  • To develop a thermal extension of LTI models to account for heating effects.
  • To assess the performance of thermal modeling for gradient dynamics.

Main Methods:

  • Applied high-amplitude DC and AC waveforms to a clinical MR system to induce heating.
  • Measured transfer functions during system cooldown.
  • Monitored gradient temperatures using an array of sensors.
  • Developed local and global linear models relating temperature to transfer functions.

Main Results:

  • Observed significant thermal effects on time-resolved transfer functions, linked to eddy currents and mechanical resonances.
  • Demonstrated that thermal modeling effectively captures these heating-induced changes.
  • Identified well-placed temperature sensors and sufficient training data as critical for model accuracy.

Conclusions:

  • Gradient heating alters system response, breaking time invariance.
  • A linear thermal extension of LTI models, incorporating temperature sensing and training, can restore the utility of LTI modeling.
  • This approach offers a practical solution for managing thermal variations in MRI gradient systems.