Ultrafast Pulses
Ultrafast Pulses - Related Videos
01:16
Pulse
0 Views •
2024
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...
01:05
Pulse
0 Views •
2024
The pulse is one of the most fundamental physiological indicators of the body's cardiovascular health. It is the rhythmic expansion and contraction of the arterial walls in response to the pressure generated by the heart's pumping action. Pulse Rate and its Significance Pulse rate, often measured in beats per minute (bpm), reflects the heart rate (HR), which is influenced by numerous factors such as stress, physical activity, and hormonal changes. A normal resting adult pulse rate falls between...
05:57
Blood Flow Imaging with Ultrafast Doppler
0 Views •
Cited by 10 •
2020
This protocol shows how to apply ultrafast ultrasound Doppler imaging to quantify blood flows. After a 1 s long acquisition, the experimenter has access to a movie of the full field of view with axial velocity values for each pixel every ≈0.3 ms (depending on the ultrasound time of flight).
01:17
NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
0 Views •
2024
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.
01:20
Regulation of Pulse
0 Views •
2024
Pulse regulation involves physiological mechanisms that ensure adequate blood flow throughout the body. The heartbeat, regulated by the autonomic nervous system, is influenced by hormonal balance, physical activity, and emotional state. Autonomic Nervous System, or ANS: ANS regulates heart rate and pulse involuntarily through the sinoatrial node, the heart's pacemaker. The sympathetic branch speeds up the pulse rate during stress or physical activity by releasing norepinephrine. The...
FAQs
The focal region becomes selective because nonlinear absorption increases sharply where photon density is sufficiently high. Outside that focus, the energy does not reach the same absorption conditions, so exposure is reduced. In bioengineering, this spatial dependence allows researchers to confine excitation or material modification to a chosen three-dimensional location rather than affecting the entire optical path.
Pulse duration, wavelength, repetition rate, and fluence provide the main control variables. Adjusting them changes how energy is delivered and helps researchers tune imaging contrast, fabrication accuracy, and tissue response. These parameters should therefore be selected according to whether the goal is localized excitation, precise material processing, or controlled interaction with biological tissue.
Very brief energy delivery creates high peak intensity while restricting the time available for heat to diffuse. This combination supports localized effects at the target region and can reduce unintended thermal influence nearby. For bioengineering applications, controlling this balance is important when researchers seek precision in tissue interaction, imaging, microsurgery, or biomaterial processing.
A typical setup begins by focusing the laser pulse at the intended location, then selecting pulse duration, wavelength, repetition rate, and fluence for the desired response. Researchers can use these settings to control where energy is deposited and how strongly the sample responds. The resulting configuration is matched to imaging, fabrication, surgery, or tissue-focused experiments.
Multiphoton microscopy uses the high photon density at the focus to drive excitation through nonlinear absorption. Because this condition is concentrated in a localized region, researchers can obtain three-dimensional spatial control and tune imaging contrast while reducing excitation outside the focal area. Pulse parameters help determine the balance between useful imaging signal and the tissue response.
In microsurgery, focused pulses can localize energy deposition to support precision intervention. In photopolymerization, the same focal control can initiate material modification only where the required photon density is reached. These applications use the spatial selectivity of nonlinear absorption to improve control over the treated region, supporting both biological manipulation and fabrication of biomaterial structures.
Their combination of high peak intensity, limited heat diffusion, and adjustable delivery conditions supports precise interactions with biological materials. Researchers can vary wavelength, repetition rate, fluence, and pulse duration to influence fabrication accuracy or tissue response. This flexibility connects the technique to biomaterial processing as well as imaging and microsurgical workflows.