We perform high-resolution, non-invasive, deep-tissue imaging of the mouse neocortex using multiphoton microscopy with a high repetition rate optical parametric amplifier laser source tunable between =1,100 and 1,400 nm. By combining the high repetition rate (511 kHz) and high pulse energy (400 nJ) of our amplifier laser system, we demonstrate imaging of vasculature labeled with Texas Red and Indocyanine Green, and neurons expressing tdTomato and yellow fluorescent protein. We measure the blood flow speed of a single capillary at a depth of 1.2 mm, and image vasculature to a depth of 1.53 mm with fine axial steps (5 m) and reasonable acquisition times. The high image quality enabled analysis of vascular morphology at depths to 1.45 mm.
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http://dx.doi.org/10.1364/BOE.8.003470 | DOI Listing |
Am J Physiol Cell Physiol
December 2024
Muscle Health Research Centre, School of Kinesiology & Health Science, Faculty of Health, York University, Toronto, ON, Canada.
High-load resistance exercise (>60% of 1-repetition maximum) is a well-known stimulus to enhance skeletal muscle hypertrophy with chronic training. However, studies have intriguingly shown that low-load resistance exercise training (RET) (≤60% of 1-repetition maximum) can lead to similar increases in skeletal muscle hypertrophy as compared to high-load RET. This has raised questions about the underlying mechanisms for eliciting the hypertrophic response with low-load RET.
View Article and Find Full Text PDFLaser Photon Rev
October 2024
Harvard Medical School, Boston, MA 02114, USA; Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Cardiology, Erasmus Medical Center, Rotterdam GD3015, The Netherlands; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
Photoacoustic microscopy (PAM) is a high-resolution and non-invasive imaging modality that provides optical absorption contrast. By employing dual- or multiple-wavelength excitation, PAM extends its capabilities to offer valuable spectroscopic information. To achieve efficient multispectral PAM imaging, an essential requirement is a light source characterized by a high repetition rate and switching rate, a ≈microjoule pulse energy, and a ≈nanosecond pulse duration.
View Article and Find Full Text PDFAtten Percept Psychophys
December 2024
Department of Psychological and Brain Sciences, University of Delaware, Newark, DE, 19716-2577, USA.
In the attentional blink paradigm, participants attempt to identify two targets appearing in a rapidly presented stream of distractors. Report accuracy is typically high for the first target (T1) while identification of the second target (T2) is impaired when it follows within about 200-400 ms of T1. An important question is whether T2 is processed to a semantic level even when participants are unaware of its identity.
View Article and Find Full Text PDFWe report on continuous high-harmonic generation (HHG) at 1 kHz repetition rate from a liquid-sheet plasma mirror driven by relativistic-intensity near-single-cycle light transients. Through precise control of both the surface plasma density gradient and the driving light waveform, we can produce highly stable and reproducible extreme ultraviolet spectral quasi-continua, expected to correspond to the generation of stable kHz-trains of isolated attosecond pulses in the time domain. This confirms the exciting potential of liquid-sheet targets as one of the building blocks of future high-power attosecond lasers.
View Article and Find Full Text PDFTransverse mode instability (TMI) significantly limits the power scaling of ytterbium-doped fiber lasers. In this Letter, what we believe to be a novel TMI mitigation strategy is proposed and demonstrated in a bidirectional output fiber laser. On the basis of the continuous wave (CW) pump, integrating a quasi-continuous wave (QCW) pump can effectively improve the TMI threshold of the system.
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