888 research outputs found
Multiple positive solutions for second order impulsive boundary value problems in Banach spaces
By means of the fixed point index theory of strict set contraction operators, we establish new existence theorems on multiple positive solutions to a boundary value problem for second-order impulsive integro-differential equations with integral boundary conditions in a Banach space. Moreover, an application is given to illustrate the main result
Dynamic Low-Rank Instance Adaptation for Universal Neural Image Compression
The latest advancements in neural image compression show great potential in
surpassing the rate-distortion performance of conventional standard codecs.
Nevertheless, there exists an indelible domain gap between the datasets
utilized for training (i.e., natural images) and those utilized for inference
(e.g., artistic images). Our proposal involves a low-rank adaptation approach
aimed at addressing the rate-distortion drop observed in out-of-domain
datasets. Specifically, we perform low-rank matrix decomposition to update
certain adaptation parameters of the client's decoder. These updated
parameters, along with image latents, are encoded into a bitstream and
transmitted to the decoder in practical scenarios. Due to the low-rank
constraint imposed on the adaptation parameters, the resulting bit rate
overhead is small. Furthermore, the bit rate allocation of low-rank adaptation
is \emph{non-trivial}, considering the diverse inputs require varying
adaptation bitstreams. We thus introduce a dynamic gating network on top of the
low-rank adaptation method, in order to decide which decoder layer should
employ adaptation. The dynamic adaptation network is optimized end-to-end using
rate-distortion loss. Our proposed method exhibits universality across diverse
image datasets. Extensive results demonstrate that this paradigm significantly
mitigates the domain gap, surpassing non-adaptive methods with an average
BD-rate improvement of approximately across out-of-domain images.
Furthermore, it outperforms the most advanced instance adaptive methods by
roughly BD-rate. Ablation studies confirm our method's ability to
universally enhance various image compression architectures.Comment: Accepted by ACM MM 2023, 13 pages, 12 figure
Cryopreservation in Ophthalmology
Amniotic membranes (AMs) and corneas are critical materials in ocular surface reconstruction. AM has specific structures (e.g., basement and two types of cells with stemness characteristics: amniotic epithelial cells and amniotic mesenchymal cells), which contribute to its attractive physical and biological properties that make it fundamental to clinical application. The corneal endothelial cell is a vital part of the cornea, which can influence postoperative vision directly. However, widespread use of fresh AM and cornea has been limited due to their short use span and safety concerns. To overcome these concerns, different preservation methods have been introduced. Cryopreservation is distinguished from many preservation methods for its attractive advantages of prolonged use span, optimally retained tissue structure, and minimized infection risk. This review will focus on recent advances of cryopreserved AM and cornea, including different cryopreservation methods and their indications in ophthalmology
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Estimation of monthly pan evaporation using support vector machine in Three Gorges Reservoir Area, China
Pan evaporation plays a critical role in estimating water budget and modeling crop water requirements. However, it has been measured at a very limited number of meteorological stations. Estimation of pan evaporation from measured meteorological variables offers an important alternative and drawn increasing attention in the recent years. This paper investigated the performance of support vector machine (SVM) in the estimation of monthly pan evaporation using commonly measured meteorological variables in Three Gorges Reservoir Area in China. Evaluation suggested that SVM models showed remarkable performances and significantly outperformed the empirical model. The SVM model with polynomial as kernel function outperformed that with radial basis function. In the case of unavailable measurements of pan evaporation and meteorological variables to construct the SVM model, pan evaporation can be well-estimated by SVM model developed using data at other sites. The results indicated that the SVM method would be a promising alternative over the traditional approaches for estimating pan evaporation from measured meteorological variables
Reexamine the dark matter scenario accounting for the positron excess in a new cosmic ray propagation model
The positron excess in cosmic rays has stimulated a lot of interests in the
last decade. The dark matter origin of the extra positrons has attracted great
attention. However, the -ray search set very stringent constraints on
the dark matter annihilation/decay rate, which leads to great disfavor of the
dark matter scenario. In the work, we incorporate the recent progress in cosmic
rays propagation and reexamine the dark matter scenario accounting for the
positron excess. Recent observations indicate that cosmic rays propagation in
the Milky Way may be not uniform and diffusion in the Galactic disk should be
slower than that in the halo. In the spatial-dependent propagation model, the
positrons/electrons are more concentrated in the disk and lead to smaller dark
matter annihilation/decay rate to account for the positron excess and also a
smaller deficit in the background positron flux. Especially for the
channel the positron spectrum fit the AMS-02 latest data perfectly
and the annihilation rate satisfies all the present constraints from
-ray and CMB observations.Comment: 11 pages, 4 figure
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