Decentralized Douglas-Rachford splitting methods for smooth optimization over compact submanifolds

We study decentralized smooth optimization problems over compact submanifolds. Recasting it as a composite optimization problem, we propose a decentralized Douglas-Rachford splitting algorithm, DDRS. When the proximal operator of the local loss function does not have a closed-form solution, an inexact version of DDRS, iDDRS, is also presented. Both algorithms rely on an ingenious integration of the nonconvex Douglas-Rachford splitting algorithm with gradient tracking and manifold optimization. We show that our DDRS and iDDRS achieve the best-known convergence rate of $\mathcal{O}(1/K)$. The main challenge in the proof is how to handle the nonconvexity of the manifold constraint. To address this issue, we utilize the concept of proximal smoothness for compact submanifolds. This ensures that the projection onto the submanifold exhibits convexity-like properties, which allows us to control the consensus error across agents. Numerical experiments on the principal component analysis are conducted to demonstrate the effectiveness of our decentralized DRS compared with the state-of-the-art ones

Extinction Pattern of Reef Ecosystems in Latest Permian

Studies of two Permian-Triassic boundary (PTB) sections on top of a Changhsingian reef in Ziyun, Guizhou Province, southwestern China indicate that the end-Permian mass extinction of reef ecosystems occurred in two steps. The first step is the extinction of all stenotropic organisms such as calcisponges and fusulinids in the latest Permian (in the Clarkina yini conodont zone). The biota after the first extinction is simple, comprising eurytropic organisms including microgastropods, ostracods, and some small burrowing organisms, or only algal mats. At the beginning of the Early Triassic (i.e. the beginning of the Hindeodus parvus zone), the environments became anoxic, and the microgastropod dominated biota or algal mats disappeared, which constituted the second episode of the mass extinction. The biota after the second extinction comprises small spherical microproblematica, some kinds of specialized organisms tolerant of anoxic or oxygen-poor conditions. As the environments became oxygenated, the specialized biota was replaced by a microgastropod-dominated simple biota. When the environmental conditions improved further, the simple biota was replaced by a diverse biota with normal-sized ammonoids, bivalves, and gastropods, representing restoration of normal oceanic conditions. Comparison with PTB sections in Dolomites, Italy and Meishan, Zhejiang Province shows that non-reef ecosystems had a similar first episode of mass extinction in the latest Permian. In the case that oceanic anoxia happened, non-reef ecosystems had a second extinction episode similar to that of reef ecosystems

Subspecies in Przewalski's gazelle Procapra przewalskii and its conservation implication

Przewalski's gazelle Procapra przewalskii is an endangered species endemic to China. A question remains about subspecific variation in this species. Skulls of Przewalski's gazelle collected from its current remnant ranges around the Qinghai Lake in combi

China is on the track tackling Enteromorpha spp forming green tide

Green tide management is supposed to be a long term fight rather than an episode during the 29th Olympic Games for China, since it has been gaining in scale and frequency during the past 3 decades in both marine and estuary environment all over the world. A number of rapid-responding studies including oceanographic comprehensive surveys along the coastline have been conducted during the bloom and post-bloom periods in 2008 by Chinese marine scientists. The preliminary results are as below: (1) phylogenetic analysis indicates that the bloom forming alga forms a clade with representatives of the green seaweed Enteromorpha linza, though, the alga has been identified as E. proliera by means of morphological; (2) the present data suggest that the bloom was originated from south of Yellow Sea, but not the severely affected area near Qingdao City; (3) pathways of reproduction for E. prolifera have approved to be multifarious, including sexual, asexual and vegetative propagation; (4) somatic cells may act as a propagule bank, which is supposed to be a very dangerous transmitting way for its marked movability, adaptability and viability; (5) pyrolysis of the alga showed that three stages appeared during the process, which are dehydration (18–20^o^C), main devolatilization (200–450^o^C) and residual decomposition (450–750^o^C), and activation energy of the alga was determined at 237.23 KJ•mol^-1^. Although the scarce knowlegde on E. prolifera not yet allow a fully understanding of the green tide, some of the results suggests possible directions in further green tide research and management

Purification, composition analysis and antioxidant activity of different polysaccharides from the fruiting bodies of Pholiota adiposa

Three water-soluble polysaccharide fractions (PAP1-1, PAP1-2 and PAP2-1) were isolated and purified from the fruiting bodies of Pholiota adiposa by diethylaminoethanol (DEAE) Sepharose fast flow column and superdexTM 200 column chromatography on an AKTA Purifier system. Results of high-performance size-exclusion  chromatography (HPSEC) indicated that the average molecular weights of PAP1-1, PAP1-2 and PAP2-1 were 2.3 x 106 Da, 8.8 x 103 Da and 2.1 x 106 Da, respectively. Monosaccharide compositions analysis revealed that PAP1-1 and PAP2-1 were both mainly composed of glucose, and PAP1-2 was composed of rhamnose and  glucose with a mole ratio of 1:3.61. The evaluation of antioxidant activity suggested that PAP1-1 with  β-configuration glycosidic bond exhibited stronger scavenging activity of superoxide radical and hydroxyl  radical than PAP1-2 and PAP2-1 contained both α- and β-configuration glycosidic bond, and should be  explored as a novel potential antioxidant. Available data obtained with in vitro models suggested that  antioxidant activity of polysaccharide may be related to the configuration of glycosidic bond.Key words: Pholiota adipose, polysaccharide, purification, antioxidant activity

Cross-View Hierarchy Network for Stereo Image Super-Resolution

Stereo image super-resolution aims to improve the quality of high-resolution stereo image pairs by exploiting complementary information across views. To attain superior performance, many methods have prioritized designing complex modules to fuse similar information across views, yet overlooking the importance of intra-view information for high-resolution reconstruction. It also leads to problems of wrong texture in recovered images. To address this issue, we explore the interdependencies between various hierarchies from intra-view and propose a novel method, named Cross-View-Hierarchy Network for Stereo Image Super-Resolution (CVHSSR). Specifically, we design a cross-hierarchy information mining block (CHIMB) that leverages channel attention and large kernel convolution attention to extract both global and local features from the intra-view, enabling the efficient restoration of accurate texture details. Additionally, a cross-view interaction module (CVIM) is proposed to fuse similar features from different views by utilizing cross-view attention mechanisms, effectively adapting to the binocular scene. Extensive experiments demonstrate the effectiveness of our method. CVHSSR achieves the best stereo image super-resolution performance than other state-of-the-art methods while using fewer parameters. The source code and pre-trained models are available at https://github.com/AlexZou14/CVHSSR.Comment: 10 pages, 7 figures, CVPRW, NTIRE202

Tunable nonlinear optical bistability based on Dirac semimetal in photonic crystal Fabry-Perot cavity

In this paper, we study the nonlinear optical bistability (OB) in a symmetrical multilayer structure. This structure is constructed by embedding a nonlinear three-dimensional Dirac semimetal (3D DSM) into a solution filled one-dimensional photonic crystal Fabry-Perot cavity. OB stems from the third order nonlinear conductivity of 3D DSM and the local field of resonance mode could enhance the nonlinearity and reduce the thresholds of OB. This structure achieves the tunability of OB due to that the transmittance could be modulated by the Fermi energy. OB threshold and threshold width could be remarkably reduced by increasing the Fermi energy. Besides, it is found that the OB curve depends heavily on the angle of incidence of the incoming light, the structural parameters of the Fabry-Perot cavity, and the position of 3D DSM inside the cavity. After parameter optimization, we obtained OB with a threshold of 106 V/m. We believe this simple structure provides a reference idea for realizing low threshold and tunable all optical switching devices. Keywords: Optical bistability, Dirac semimetal, Fabry-Perot cavity

Isolation and Functional Determination of SKOR Potassium Channel in Purple Osier Willow, Salix purpurea.

Potassium (K+) plays key roles in plant growth and development. However, molecular mechanism studies of K+ nutrition in forest plants are largely rare. In plants, SKOR gene encodes for the outward rectifying Shaker-type K+ channel that is responsible for the long-distance transportation of K+ through xylem in roots. In this study, we determined a Shaker-type K+ channel gene in purple osier (Salix purpurea), designated as SpuSKOR, and determined its function using a patch clamp electrophysiological system. SpuSKOR was closely clustered with poplar PtrSKOR in the phylogenetic tree. Quantitative real-time PCR (qRT-PCR) analyses demonstrated that SpuSKOR was predominantly expressed in roots, and expression decreased under K+ depletion conditions. Patch clamp analysis via HEK293-T cells demonstrated that the activity of the SpuSKOR channel was activated when the cell membrane voltage reached at -10 mV, and the channel activity was enhanced along with the increase of membrane voltage. Outward currents were recorded and induced in response to the decrease of external K+ concentration. Our results indicate that SpuSKOR is a typical voltage dependent outwardly rectifying K+ channel in purple osier. This study provides theoretical basis for revealing the mechanism of K+ transport and distribution in woody plants.Peer Reviewe