Multiphotonen-Mikroskopie und Laser-Nanochirurgie der Kornea mittels Naher-Infrarot-Nanojoule-Femtosekunden-Laserpulse

Three sub-theses intracorneal multiphoton-mediated optical nanosurgery including flapfree non-invasive intrastromal ablation and flap generation; corneal nonlinear optical histology based on multiphoton microscopy; uses of multiphoton imaging in the femtosecond (fs) laser corneal nanosurgery (nJ) in this work have been studied based on the versatile 80MHz near-infrared (NIR) intense nJ fs lasers emitted from the solid-state Ti: Sapphire laser system with rabbits. The era of laser refractive surgery with the excimer lasers was heralded by the U.S. Food and Drug Administration's approval (FDA) in 1995. Conventional laser corneal refractive surgery (PRK, LASIK) for visual correction based on the high energy ultraviolet (UV) nanosecond excimer laser pulses is now just being challenged due to its disadvantages such as collateral damage outside the focal volume, UV mutation effects and induction of oxidative stress, and microkeratome-related complications. The NIR fs lasers have recently attracted amount attention due to its advantages such as no photon damage outside the focal femtoliter volume and multiphoton absorption without compromising viability. The nanodissection capability of the nJ fs laser pulses has been here confirmed through the histological outcomes of an intratissue fissure without any detrimental effects on overlying layers in the intratissue ablation procedure as well as corneal flap and intrastromal lenticule in the flap generation procedure. The encouraging surgical advances have potential in the treatment of the visual disorders as well as in the ultra-precise ablation of intratissue neoplasia, nanosurgical applications in the subcellular organelle and in developmental biology. Multiphoton microscopy at a high light intensity of MW-GW/cm2 based on the simultaneous absorption of more than one photon is one of the most exciting developments in biomedical imaging. So far, the anatomical micro- and nanostructures of corneal tissue have been extensively studied and reported with conventional histological and electron microscopical methods as well as the confocal one-photon laser scanning microscopy (CLSM). Based on the advantages of multiphoton microscopy such as in-vivo selective displaying of tissue components with subcellular spatial resolution and high contrast, no requirement of cellular and tissue staining or slicing, no out-of-focus photobleaching, improved background discrimination, increased penetration through the biological bulk tissue with NIR light, and no need of pinhole aperture, the excitation of intracellular NAD(P)H/NAD(P)+ in the autofluorescence imaging and the SHG imaging of noncentrosymmetric collagen have been used in this work as novel diagnostic tools for invivo differentiation of corneal layers, for imaging of corneal cells such as epithelial cells, keratocytes and endothelial cells and collagen lamellas. The activated keratocytes (myofibroblasts) have been here as well detected in the wound repair of intrastromal surgery with this nonlinear optical imaging technique. This multiphoton optical imaging technique has potential to become a powerful means in advancing understanding of corneal biomechnics and even cellular reactions in term of laser lesions. The uses of the multiphoton imaging technique has been also proved in this work to be essential for fs nJ cornea surgery such as to determine the surgical interest of region preoperation, to visualize and verify the outcomes of the laser surgery on line

Soliton Molecules and Multisoliton States in Ultrafast Fibre Lasers: Intrinsic Complexes in Dissipative Systems

Benefiting from ultrafast temporal resolution, broadband spectral bandwidth, as well as high peak power, passively mode-locked fibre lasers have attracted growing interest and exhibited great potential from fundamental sciences to industrial and military applications. As a nonlinear system containing complex interactions from gain, loss, nonlinearity, dispersion, etc., ultrafast fibre lasers deliver not only conventional single soliton but also soliton bunching with different types. In analogy to molecules consisting of several atoms in chemistry, soliton molecules (in other words, bound solitons) in fibre lasers are of vital importance for in-depth understanding of the nonlinear interaction mechanism and further exploration for high-capacity fibre-optic communications. In this Review, we summarize the state-of-the-art advances on soliton molecules in ultrafast fibre lasers. A variety of soliton molecules with different numbers of soliton, phase-differences and pulse separations were experimentally observed owing to the flexibility of parameters such as mode-locking techniques and dispersion control. Numerical simulations clearly unravel how different nonlinear interactions contribute to formation of soliton molecules. Analysis of the stability and the underlying physical mechanisms of bound solitons bring important insights to this field. For a complete view of nonlinear optical phenomena in fibre lasers, other dissipative states such as vibrating soliton pairs, soliton rains, rogue waves and coexisting dissipative solitons are also discussed. With development of advanced real-time detection techniques, the internal motion of different pulsing states is anticipated to be characterized, rendering fibre lasers a versatile platform for nonlinear complex dynamics and various practical applications

Temperature Effects on the Unsaturated Permeability of the Densely Compacted GMZ01 Bentonite under Confined Conditions

International audienceIn this study, temperature controlled soil-water retention tests and unsaturated hydraulic conductivity tests for densely compacted Gaomiaozi bentonite - GMZ01 (dry density of 1.70 Mg/m3) were performed under confined conditions. Relevant soil-water retention curves (SWRCs) and unsaturated hydraulic conductivities of GMZ01 at temperatures of 40°C and 60°C were obtained. Based on these results as well as the previously obtained results at 20°C, the influence of temperature on water-retention properties and unsaturated hydraulic conductivity of the densely compacted Gaomiaozi bentonite were investigated. It was observed that: (i) water retention capacity decreases as temperature increases, and the influence of temperature depends on suction; (ii) for all the temperatures tested, the unsaturated hydraulic conductivity decreases slightly in the initial stage of hydration; the value of the hydraulic conductivity becomes constant as hydration progresses and finally, the permeability increases rapidly with suction decreases as saturation is approached; (iii) under confined conditions, the hydraulic conductivity increases as temperature increases, at a decreasing rate with temperature rise. It was also observed that the influence of temperature on the hydraulic conductivity is quite suction-dependent. At high suctions (s > 60 MPa), the temperature effect is mainly due to its influence on water viscosity; by contrast, in the range of low suctions (s < 60 MPa), the temperature effect is related to both the water viscosity and the macro-pores closing phenomenon that is supposed to be temperature dependent

Orthogonal Subspace Learning for Language Model Continual Learning

Benefiting from massive corpora and advanced hardware, large language models (LLMs) exhibit remarkable capabilities in language understanding and generation. However, their performance degrades in scenarios where multiple tasks are encountered sequentially, also known as catastrophic forgetting. In this paper, we propose orthogonal low-rank adaptation (O-LoRA), a simple and efficient approach for continual learning in language models, effectively mitigating catastrophic forgetting while learning new tasks. Specifically, O-LoRA learns tasks in different (low-rank) vector subspaces that are kept orthogonal to each other in order to minimize interference. Our method induces only marginal additional parameter costs and requires no user data storage for replay. Experimental results on continual learning benchmarks show that our method outperforms state-of-the-art methods. Furthermore, compared to previous approaches, our method excels in preserving the generalization ability of LLMs on unseen tasks.Comment: EMNLP 2023 finding

Soliton Molecules and Multisoliton States in Ultrafast Fibre Lasers: Intrinsic Complexes in Dissipative Systems

Benefiting from ultrafast temporal resolution, broadband spectral bandwidth, as well as high peak power, passively mode-locked fibre lasers have attracted growing interest and exhibited great potential from fundamental sciences to industrial and military applications. As a nonlinear system containing complex interactions from gain, loss, nonlinearity, dispersion, etc., ultrafast fibre lasers deliver not only conventional single soliton but also soliton bunching with different types. In analogy to molecules consisting of several atoms in chemistry, soliton molecules (in other words, bound solitons) in fibre lasers are of vital importance for in-depth understanding of the nonlinear interaction mechanism and further exploration for high-capacity fibre-optic communications. In this Review, we summarize the state-of-the-art advances on soliton molecules in ultrafast fibre lasers. A variety of soliton molecules with different numbers of soliton, phase-differences and pulse separations were experimentally observed owing to the flexibility of parameters such as mode-locking techniques and dispersion control. Numerical simulations clearly unravel how different nonlinear interactions contribute to formation of soliton molecules. Analysis of the stability and the underlying physical mechanisms of bound solitons bring important insights to this field. For a complete view of nonlinear optical phenomena in fibre lasers, other dissipative states such as vibrating soliton pairs, soliton rains, rogue waves and coexisting dissipative solitons are also discussed. With development of advanced real-time detection techniques, the internal motion of different pulsing states is anticipated to be characterized, rendering fibre lasers a versatile platform for nonlinear complex dynamics and various practical applications