Jie Li

An applications-oriented review of optical parametric amplifiers in fiber communications is presented. The emphasis is on parametric amplifiers in general and single pumped parametric amplifiers in particular. While a theoretical framework based on highly efficient four-photon mixing is provided, the focus is on the intriguing applications enabled by the parametric gain, such as all-optical signal sampling, time-demultiplexing, pulse generation, and wavelength conversion. As these amplifiers offer high gain and low noise at arbitrary wavelengths with proper fiber design and pump wavelength allocation, they are also candidate enablers to increase overall wavelength-division-multiplexing system capacities similar to the more well-known Raman amplifiers. Similarities and distinctions between Raman and parametric amplifiers are also addressed. Since the first fiber-based parametric amplifier experiments providing net continuous-wave gain in the for the optical fiber communication applications interesting 1.5-/spl mu/m region were only conducted about two years ago, there is reason to believe that substantial progress may be made in the future, perhaps involving "holey fibers" to further enhance the nonlinearity and thus the gain. This together with the emergence of practical and inexpensive high-power pump lasers may in many cases prove fiber-based parametric amplifiers to be a desired implementation in optical communication systems.

Abstract Ion migration as well as electron transfer and coupling in resistive switching materials endow memristors with a physically tunable conductance to resemble synapses, neurons, and their networks. Four different types of volatile memristors and another four types of nonvolatile memristors are systemically surveyed in terms of the switching mechanisms and electrical properties that are the basis of different computing applications. The volatile memristor features spontaneous conductance decay after the cease of electrical/optical stimulations, which are closely related to the surface atom diffusion, metal–insulator–transition (including charge–density–wave), thermal spontaneous emission, and charge polarization. Such unique dynamic state evolution at the edge of chaos has enabled them to emulate certain synaptic and neural dynamics, leading to various applications ranging from spiking neural networks to combinatorial optimizations. Nonvolatile resistive switching behavior originated from the electron spins, ferroelectric polarization, crystalline‐amorphous transitions or interplay between ions and electrons enables the memristor array to implement the vector–matrix multiplication, which is the key convolutional operation in artificial neural networks. The progress, challenges, and opportunities for both volatile and nonvolatile memristor in the level of materials, integration technology, algorithm, and system are highlighted in this review.

Aberrant lysine lactylation (Kla) is associated with various diseases which are caused by excessive glycolysis metabolism. However, the regulatory molecules and downstream protein targets of Kla remain largely unclear. Here, we observed a global Kla abundance profile in colorectal cancer (CRC) that negatively correlates with prognosis. Among lactylated proteins detected in CRC, lactylation of eEF1A2K408 resulted in boosted translation elongation and enhanced protein synthesis which contributed to tumorigenesis. By screening eEF1A2 interacting proteins, we identified that KAT8, a lysine acetyltransferase that acted as a pan-Kla writer, was responsible for installing Kla on many protein substrates involving in diverse biological processes. Deletion of KAT8 inhibited CRC tumor growth, especially in a high-lactic tumor microenvironment. Therefore, the KAT8-eEF1A2 Kla axis is utilized to meet increased translational requirements for oncogenic adaptation. As a lactyltransferase, KAT8 may represent a potential therapeutic target for CRC.