156 research outputs found
Stabilization via delay feedback for highly nonlinear stochastic time-varying delay systems with Markovian switching and Poisson jump
Little work seems to be known about stabilization results of highly nonlinear stochastic time-varying delay systems (STVDSs) with Markovian switching and Poisson jump. This paper is concerned with the stabilization problem for a class of STVDSs with Markovian switching and Poisson jump. The coefficients of such systems do not satisfy the conventional linear growth conditions, but are subject to high nonlinearity. The aim of this paper is to design a delay feedback controller to make an unstable highly nonlinear STVDSs with Markovian switching and Poisson jump H∞-stable and asymptotically stable. Besides, an illustrative example is provided to support the theoretical results
Coded Modulation and Impairment Compensation Techniques in Optical Fiber Communication
This chapter deals with coded modulation and impairment compensation techniques in optical fiber communication. Probabilistic shaping is a new coded modulation technology, which can reduce transmission power by precoding, reduce bit error rate and improve communication rate. We proposed a probabilistic shaping 16QAM modulation scheme based on trellis coded modulation. Experimental results show that this scheme can achieve better optical SNR gain and BER performance. On the other hand, in order to meet the demand of transmission rate of next generation high speed optical communication systems, multi-dimensional modulation and coherent detection are sufficiently applied. The imperfect characteristics of optoelectronic devices and fiber link bring serious impairments to the high baud-rate and high order modulation format signal, causes of performance impairment are analyzed, pre-compensation and receiver side’s DSP techniques designed for coherent systems are introduced
UCP2 Inhibits ROS-Mediated Apoptosis in A549 under Hypoxic Conditions
The Crosstalk between a tumor and its hypoxic microenvironment has become increasingly important. However, the exact role of UCP2 function in cancer cells under hypoxia remains unknown. In this study, UCP2 showed anti-apoptotic properties in A549 cells under hypoxic conditions. Over-expression of UCP2 in A549 cells inhibited reactive oxygen species (ROS) accumulation (P<0.001) and apoptosis (P<0.001) compared to the controls when the cells were exposed to hypoxia. Moreover, over-expression of UCP2 inhibited the release of cytochrome C and reduced the activation of caspase-9. Conversely, suppression of UCP2 resulted in the ROS generation (P = 0.006), the induction of apoptosis (P<0.001), and the release of cytochrome C from mitochondria to the cytosolic fraction, thus activating caspase-9. These data suggest that over-expression of UCP2 has anti-apoptotic properties by inhibiting ROS-mediated apoptosis in A549 cells under hypoxic conditions
Stabilization via delay feedback for highly nonlinear stochastic time-varying delay systems with Markovian switching and Poisson jump
The correlation between the enzymatic saccharification and the multidimensional structure of cellulose changed by different pretreatments
Ultrafast field-driven monochromatic photoemission from carbon nanotubes
Ultrafast electron pulses, combined with laser-pump and electron-probe
technologies, allow for various forms of ultrafast microscopy and spectroscopy
to elucidate otherwise challenging to observe physical and chemical
transitions. However, the pursuit of simultaneous ultimate spatial and temporal
resolution has been largely subdued by the low monochromaticity of the electron
pulses and their poor phase synchronization to the optical excitation pulses.
State-of-the-art photon-driven sources have good monochromaticity but poor
phase synchronization. In contrast, field-driven photoemission has much higher
light phase synchronization, due to the intrinsic sub-cycle emission dynamics,
but poor monochromaticity. Such sources suffer from larger electron energy
spreads (3 - 100 eV) attributed to the relatively low field enhancement of the
conventional metal tips which necessitates long pump wavelengths (> 800 nm) in
order to gain sufficient ponderomotive potential to access the field-driven
regime. In this work, field-driven photoemission from ~1 nm radius carbon
nanotubes excited by a femtosecond laser at a short wavelength of 410 nm has
been realized. The energy spread of field-driven electrons is effectively
compressed to 0.25 eV outperforming all conventional ultrafast electron
sources. Our new nanotube-based ultrafast electron source opens exciting
prospects for attosecond imaging and emerging light-wave electronics
Robust Super-Resolution Imaging Based on a Ring Core Fiber with Orbital Angular Momentum
Single fiber imaging technology offers unique insights for research and
inspection in difficult to reach and narrow spaces. In particular,
ultra-compact multimode fiber (MMF) imaging, has received increasing interest
over the past decade. However, MMF imaging will be seriously distorted when
subjected to dynamic perturbations due to time-varying mode coupling, and the
imaging of space objects via Gaussian beam will be relatively degraded at the
edge due to insufficient contrast. Here, a robust super-resolution imaging
method based on a ring core fiber (RCF) with orbital angular momentum (OAM) has
been proposed and experimentally demonstrated. The OAM modes propagating in the
RCF form a series of weakly-coupled mode groups, making our imaging system
robust to external perturbations. In addition, a spiral phase plate is used as
a vortex filter to produce OAM for edge enhancement, thus improving the image
resolution. Furthermore, a few-shot U-Transformer neural network is proposed to
enhance the resilience of the developed RCF-OAM imaging system against
environmental perturbations. Finally, the developed RCF-OAM imaging system
achieves biological image transmission, demonstrating the practicality of our
scheme. This pioneering RCF OAM imaging system may have broad applications,
potentially revolutionising fields such as biological imaging and industrial
non-destructive testing
BianQue: Balancing the Questioning and Suggestion Ability of Health LLMs with Multi-turn Health Conversations Polished by ChatGPT
Large language models (LLMs) have performed well in providing general and
extensive health suggestions in single-turn conversations, exemplified by
systems such as ChatGPT, ChatGLM, ChatDoctor, DoctorGLM, and etc. However, the
limited information provided by users during single turn results in inadequate
personalization and targeting of the generated suggestions, which requires
users to independently select the useful part. It is mainly caused by the
missing ability to engage in multi-turn questioning. In real-world medical
consultations, doctors usually employ a series of iterative inquiries to
comprehend the patient's condition thoroughly, enabling them to provide
effective and personalized suggestions subsequently, which can be defined as
chain of questioning (CoQ) for LLMs. To improve the CoQ of LLMs, we propose
BianQue, a ChatGLM-based LLM finetuned with the self-constructed health
conversation dataset BianQueCorpus that is consist of multiple turns of
questioning and health suggestions polished by ChatGPT. Experimental results
demonstrate that the proposed BianQue can simultaneously balance the
capabilities of both questioning and health suggestions, which will help
promote the research and application of LLMs in the field of proactive health
Wavelength and pulse duration tunable ultrafast fiber laser mode-locked with carbon nanotubes.
Ultrafast lasers with tunable parameters in wavelength and time domains are the choice of light source for various applications such as spectroscopy and communication. Here, we report a wavelength and pulse-duration tunable mode-locked Erbium doped fiber laser with single wall carbon nanotube-based saturable absorber. An intra-cavity tunable filter is employed to continuously tune the output wavelength for 34 nm (from 1525 nm to 1559 nm) and pulse duration from 545 fs to 6.1 ps, respectively. Our results provide a novel light source for various applications requiring variable wavelength or pulse duration
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