Iteratively Coupled Multiple Instance Learning from Instance to Bag Classifier for Whole Slide Image Classification

Whole Slide Image (WSI) classification remains a challenge due to their extremely high resolution and the absence of fine-grained labels. Presently, WSIs are usually classified as a Multiple Instance Learning (MIL) problem when only slide-level labels are available. MIL methods involve a patch embedding process and a bag-level classification process, but they are prohibitively expensive to be trained end-to-end. Therefore, existing methods usually train them separately, or directly skip the training of the embedder. Such schemes hinder the patch embedder's access to slide-level labels, resulting in inconsistencies within the entire MIL pipeline. To overcome this issue, we propose a novel framework called Iteratively Coupled MIL (ICMIL), which bridges the loss back-propagation process from the bag-level classifier to the patch embedder. In ICMIL, we use category information in the bag-level classifier to guide the patch-level fine-tuning of the patch feature extractor. The refined embedder then generates better instance representations for achieving a more accurate bag-level classifier. By coupling the patch embedder and bag classifier at a low cost, our proposed framework enables information exchange between the two processes, benefiting the entire MIL classification model. We tested our framework on two datasets using three different backbones, and our experimental results demonstrate consistent performance improvements over state-of-the-art MIL methods. Code will be made available upon acceptance

Can targeted defense elicitation improve seaweed aquaculture?

Diseases increasingly threaten aquaculture of kelps and other seaweeds. At the same time, protection concepts that are based upon application of biocides are usually not applicable, as such compounds would be rapidly diluted in the sea, causing ecological damage. An alternative concept could be the application of immune stimulants to prevent and control diseases in farmed seaweeds. We here present a pilot study that investigated the effects of oligoalginate elicitation on juvenile and adult sporophytes of Saccharina japonica cultivated in China and on adult sporophytes of Saccharina latissima cultivated in Germany. In two consecutive years, treatment with oligoalginate clearly reduced the detachment of S. japonica juveniles from their substrate curtains during the nursery stage in greenhouse ponds. Oligoalginate elicitation also decreased the density of endobionts and the number of bacterial cells on sporophytes of S. latissima that were cultivated on sea-based rafts. However, the treatment increased the susceptibility of kelp adults to settlement of epibionts (barnacles in Germany and filamentous algal epiphytes in China). In addition, oligoalginate elicitation accelerated the aging of S. japonica adults. Based upon these findings, oligoalginate elicitation could be a feasible way to provide “environmentally friendly” protection of kelp juveniles in nurseries. The same treatment causes not only beneficial, but also unwanted effects in adult kelp sporophytes. Therefore, it is not recommended as a treatment after the juvenile stage is completed. Future tests with other elicitors and other cultivated seaweed species may allow for the development of more feasible applications of targeted defense elicitation in seaweed aquaculture

Heterologous expression of the Haynaldia villosa pattern-recognition receptor CERK1-V in wheat increases resistance to three fungal diseases

Wheat production is under continuous threat by various fungal pathogens. Identification of multiple-disease resistance genes may lead to effective disease control via the development of cultivars with broad-spectrum resistance. Plant Lysin-motif (LysM)-type pattern-recognition receptors, which elicit innate immunity by recognizing fungal pathogen associated molecular patterns such as chitin, are potential candidates for such resistance. In this study, we cloned a LysM receptor-like kinase gene, CERK1-V, from the diploid wheat relative Haynaldia villosa. CERK1-V expression was induced by chitin and Blumeria graminis f. sp. tritici, the causal agent of wheat powdery mildew. Heterologous overexpression of CERK1-V in wheat inhibited the development of three fungal pathogens, thereby increased resistance to powdery mildew, yellow rust, and Fusarium head blight. CERK1-V physically interacted with the wheat LysM protein TaCEBiPs. CERK1-V/TaCEBiPs interaction promoted chitin recognition and activated chitin signal transduction in wheat. Transgenic plants with excessively high CERK1-V expression showed high resistance but abnormal plant growth, whereas plants with moderate expression level showed adequate resistance level with no marked impairment of plant growth. In transgenic lines, RNA-seq showed that gene expression involved in plant innate immunity was activated. Expression of genes involved in photosynthesis, ER stress and multiple phytohormone pathways was also activated. Optimized expression of CERK1-V in wheat can confer disease resistance without compromising growth or defense fitness

Anti-HIV-1 Activity of a New Scorpion Venom Peptide Derivative Kn2-7

For over 30 years, HIV/AIDS has wreaked havoc in the world. In the absence of an effective vaccine for HIV, development of new anti-HIV agents is urgently needed. We previously identified the antiviral activities of the scorpion-venom-peptide-derived mucroporin-M1 for three RNA viruses (measles viruses, SARS-CoV, and H5N1). In this investigation, a panel of scorpion venom peptides and their derivatives were designed and chosen for assessment of their anti-HIV activities. A new scorpion venom peptide derivative Kn2-7 was identified as the most potent anti-HIV-1 peptide by screening assays with an EC50 value of 2.76 µg/ml (1.65 µM) and showed low cytotoxicity to host cells with a selective index (SI) of 13.93. Kn2-7 could inhibit all members of a standard reference panel of HIV-1 subtype B pseudotyped virus (PV) with CCR5-tropic and CXCR4-tropic NL4-3 PV strain. Furthermore, it also inhibited a CXCR4-tropic replication-competent strain of HIV-1 subtype B virus. Binding assay of Kn2-7 to HIV-1 PV by Octet Red system suggested the anti-HIV-1 activity was correlated with a direct interaction between Kn2-7 and HIV-1 envelope. These results demonstrated that peptide Kn2-7 could inhibit HIV-1 by direct interaction with viral particle and may become a promising candidate compound for further development of microbicide against HIV-1

Active Stabilization Control of Multi-Terminal AC/DC Hybrid System Based on Flexible Low-Voltage DC Power Distribution

Multi-terminal AC/DC interconnection will be an important form of future distribution networks. In a multi-terminal AC/DC system, if scheduled power for the AC/DC converter exceeds limits this may result in instability of the DC network. In order to overcome these limitations and avoid an unstable situation during coordinated control, this paper proposes a general active stabilization method for a low-voltage multi-terminal AC/DC hybrid system. First, the typical coordinated control modes for a hybrid system are analyzed. Second, a multi-level active stabilization controller, using the Lyapunov method, is introduced, and a feedback law allowing large signal stability is proposed. Finally, a system simulation model is further established, and the proposed active stabilization method is tested and verified. Study results show that only low stabilizing power with a slight influence on the DC network dynamic can improve the system’s stability and ensure stable system voltage

Analysis of DC voltage oscillation mechanism in AC/DC hybrid distribution system

DC voltage oscillation occurs more and more frequently in voltage source converter (VSC)-based AC/DC hybrid distribution system (AC/DC HDS). However, currently, the explanation of the oscillation mechanism is not clear enough. One reason is the traditional state-space model of the system is too complicated, and the information in the model is too dispersed. This research aims at researching the small-signal stability of AC/DC HDS and revealing the mechanism of DC voltage oscillation. Firstly, a method to reduce the order of the state-space model is proposed. A three-order VSC model with definitude physical meaning is obtained by utilising instantaneous power theory. According to this model, the potential instability factors in VSC are identified. Then, based on this, the interaction behaviour between VSC and DC network is researched by frequency domain analysis. The instability mechanism is ultimately revealed. The analysis result shows that the VSC's phase roll-off characteristic is the root cause of instability, the inherent oscillation characteristics of DC network has negative interactions with VSC and will narrow the system stability boundary. Finally, the correctness of the theory is verified by electromagnetic transient simulation

Recent advances and future challenges of polyamide-based chlorine-resistant membrane

Polyamide (PA) membrane is extensively used in various membrane separation processes due to its easy preparation, high selectivity and good acid-base stability. However, the PA material is vulnerable to the attack of free chlorine which causes PA chlorination degradation and eventually damages the membrane selectivity. As such, developing chlorine-resistant membrane has become a research focus in membrane technology recently. This accelerates the emergence of a large number of novel PA membranes. However, reviews on this aspect are quite rare to date. Thus, providing an updated critical review on the PA-based anti-chlorine membrane is highly needed. This paper aims to critically review the recent development in the PA chlorine-resistant membrane designed specially via the modification of the PA selective layer. The recent advances in the PA anti-chlorine membranes are briefly introduced first. The mechanism and influential factors of the chlorination of PA membrane are subsequently presented. The strengths and limitations of the recently developed PA anti-chlorine membrane are critically evaluated afterward. The challenges and future research directions of the sustainably chlorine-resistant PA membranes are finally discussed. This article can provide insightful guidance for the future development of the PA-based chlorine-resistant membrane

A Fast DC Fault Detection Method for Multi-Terminal AC/DC Hybrid Distribution Network Based on Voltage Change Rate of DC Current-Limiting Inductor

The rapid detection of direct current (DC) faults is one of the key technologies for the development of multi-terminal alternating current (AC)/DC hybrid distribution networks. The DC fault current rises quickly and affects the whole network. Therefore, DC faults must be detected much faster than AC faults. This paper proposes a fast DC fault detection method based on the voltage change rate of the current-limiting inductor (CLI) for the multi-terminal AC/DC hybrid distribution network. Firstly, the characteristics of the fault voltages and currents and of the CLIs are studied in detail, and the feasibility of using the voltage change rate of the CLI to detect DC fault is analyzed. Based on this, a primary fault detection method is proposed to identify the faulty line, determine the fault type and the fault poles using the amplitudes of the single-ended CLI voltage change rates. For high-resistance DC faults, a backup detection method using the directions and amplitudes of the voltage change rates of the double-ended CLIs is proposed. Finally, the proposed method is verified by MATLAB simulations. The simulation results show that the proposed method can detect all DC faults accurately, and the faulty line, fault type and fault poles can be determined quickly. The proposed method is not affected by the fault location, current-limiting inductance, power reversal of the converters, AC fault and communication delay