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関連する概念動画

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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関連する実験動画

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

4つのパルサーのパルス構造です.

F D Drake, H D Craft

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

    この研究では,4つのパルサーのパルス構造を分析し,異なる期間間で一貫したサブパルス形を明らかにしました. この発見は,膨張し,指数関数的に衰退する球体からの無線放射のモデルと一致しています.

    科学分野:

    • 天文学と天体物理学について
    • ラジオ天文学 ラジオ天文学

    背景:

    • パルサーは,電磁放射線のビームを放射する,急速に回転する中性子星です.
    • パルサーのパルス構造を理解することは,パルサーの放出機構と物理的性質を調査するための鍵です.

    研究 の 目的:

    • 4つの既知のパルサーのパルス構造を特徴付け,比較する.
    • 観測されたパルサー発射パターンの背後にある物理的メカニズムを調査する.

    主な方法:

    • 周期が異なる4つのパルサーからの観測データの分析.
    • パルス幅,サブパルス特性,パルス形状の詳細な調査.

    主要な成果:

    • 最も長い周期パルサー (約. 38msのパルス幅) は,3つのサブパルスを示します.
    • 中期パルサーは,2つのパルスを約23 msで隔てています.
    • 短周期パルサーは,単一の,定数形のパルスを放出します.
    • すべてのパルサーの間の最初のサブパルスは,似たような,一貫した形状を共有しています.

    結論:

    • 観測された最初のサブパルス形は,球状に膨張する干渉からの無線放射の理論的モデルをサポートしています.

    さらに関連する動画

    Pure Shift Nuclear Magnetic Resonance: a New Tool for Plant Metabolomics
    13:16

    Pure Shift Nuclear Magnetic Resonance: a New Tool for Plant Metabolomics

    Published on: July 31, 2021

    A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
    07:56

    A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

    Published on: September 5, 2019

    関連する実験動画

    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
    13:16

    Pure Shift Nuclear Magnetic Resonance: a New Tool for Plant Metabolomics

    Published on: July 31, 2021

    A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
    07:56

    A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

    Published on: September 5, 2019

  • エキサイテーション後の無線放射の指数分解は,観測されたパルス形と一致しています.