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Related Concept Videos

NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences01:17

NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences

A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
Pulse rhythm01:30

Pulse rhythm

Pulse rhythm refers to the pattern of pulsations within specific intervals, offering valuable insights into the regularity or irregularity of the heart's beats as observed through the pattern of pulsation within specific intervals. A regular pulse exhibits a consistent heart rate with uniform waveforms and pulsation force, variations of which can be classified as normal, weak, or bounding.
Conversely, an irregular pulse pattern is termed dysrhythmia, stemming from disruptions in cardiac muscle...
Atomic Nuclei: Larmor Precession Frequency01:11

Atomic Nuclei: Larmor Precession Frequency

The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession, and the angular frequency...
¹H NMR Signal Multiplicity: Splitting Patterns01:13

¹H NMR Signal Multiplicity: Splitting Patterns

When protons A and X are coupled, their nuclear spin energy levels are slightly modified. This is because the energy required to excite proton A to a spin state parallel to proton X is slightly different from the energy required for it to become anti-parallel to spin X. Consequently, there are two possible excitation frequencies for A (A1 and A2), depending on the spin state of X, and vice versa. The mutual nature of coupling implies that the difference between frequencies A1 and A2, indicated...
Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule01:10

Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule

In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1  triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the others.
Pulse01:16

Pulse

When the heart pumps blood out, arterial elastic fibers play a crucial role in sustaining a high-pressure gradient. They expand to accommodate the received blood and then recoil - a process known as the pulse that can be either manually palpated or electronically quantified. Despite a reduction in its effect with increased distance from the heart, elements of the pulse's systolic and diastolic components persist, observable even at the arteriole level.
The pulse serves as a clinical indicator...

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Related Experiment Video

Updated: Jul 12, 2026

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
11:19

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels

Published on: July 4, 2016

Pulse structure of four pulsars.

F D Drake, H D Craft

    Science (New York, N.Y.)
    |May 17, 1968
    PubMed
    Summary

    This study analyzes the pulse structure of four pulsars, revealing consistent subpulse shapes across different periods. The findings align with models of radio emission from expanding, exponentially decaying spheres.

    Area of Science:

    • Astronomy and Astrophysics
    • Radio Astronomy

    Background:

    • Pulsars are rapidly rotating neutron stars emitting beams of electromagnetic radiation.
    • Understanding pulsar pulse structure is key to probing their emission mechanisms and physical properties.

    Purpose of the Study:

    • To characterize and compare the pulse structures of four known pulsars.
    • To investigate the underlying physical mechanisms responsible for observed pulsar emission patterns.

    Main Methods:

    • Analysis of observational data from four pulsars with varying periods.
    • Detailed examination of pulse widths, subpulse characteristics, and pulse shapes.

    Main Results:

    • Longest period pulsars (approx. 38 ms pulsewidth) exhibit three subpulses.

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    Pure Shift Nuclear Magnetic Resonance: a New Tool for Plant Metabolomics
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    A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
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    A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

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    Related Experiment Videos

    Last Updated: Jul 12, 2026

    Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
    11:19

    Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels

    Published on: July 4, 2016

    Pure Shift Nuclear Magnetic Resonance: a New Tool for Plant Metabolomics
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    A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
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  • A medium period pulsar shows two pulses separated by ~23 ms.
  • The short-period pulsar emits single, constant-shaped pulses.
  • First subpulses across all pulsars share a similar, consistent shape.

    • Conclusions:

    • The observed first subpulse shape supports theoretical models of radio emission from a spherically expanding disturbance.
    • Exponential decay of radio emission after excitation is consistent with the observed pulse shapes.