Synchronization in a network of model neurons

We study the spatiotemporal dynamics of a network of coupled chaotic maps modelling neuronal activity, under variation of coupling strength ε and degree of randomness in coupling p. We find that at high coupling strengths (ε > εfixed) the unstable saddle point solution of the local chaotic maps gets stabilized. The range of coupling where this spatiotemporal fixed point gains stability is unchanged in the presence of randomness in the connections, namely εfixed is invariant under changes in p. As coupling gets weaker (ε < εfixed), the spatiotemporal fixed point loses stability, and one obtains chaos. In this regime, when the coupling connections are completely regular (p=0), the network becomes spatiotemporally chaotic. Interestingly however, in the presence of random links (p > 0) one obtains spatial synchronization in the network. We find that this range of synchronized chaos increases exponentially with the fraction of random links in the network. Further, in the space of fixed coupling strengths, the synchronization transition occurs at a finite value of p, a scenario quite distinct from the many examples of synchronization transitions at p→0. Further we show that the synchronization here is robust in the presence of parametric noise, namely in a network of nonidentical neuronal maps. Finally we check the generality of our observations in networks of neurons displaying both spiking and bursting dynamics

A Novel Method for Classification and Modelling of Underwater Acoustic Communication through Machine Learning and Image Processing Technique

The increasing prevalence of underwater activities has highlighted the urgent need for reliable underwater acoustic communication systems. However, the challenging nature of the underwater environment poses significant obstacles to the implementation of conventional voice communication methods. To better understand and improve upon these systems, simulations of the underwater audio channel have been developed using mathematical models and assumptions. In this study, we utilize real-world information gathered from both a measured water reservoir and Lake to evaluate the ability of machine learning and machine learning methods, specifically Long Short-Term Memory (LSTM) and Deep Neural Network (DNN), to accurately reconstruct the underwater audio channel. The outcomes validate the efficiency of machine learning methods, particularly LSTM, in accurately simulating the underwater acoustic communication channel with low mean absolute percentage error. Additionally, this research also includes an image processing to identify the objects present the in the acoustic environmen

Optimizing enzymatic dyeing of wool and leather

This work reports on the environmental friendly enzymatic dyeing of wool and leather performed at low temperature and mild pH conditions without any dyeing auxiliaries. The substrates have been dyed with “in situ” generated pigment by means of laccase-catalyzed oxidative coupling of dye modifier 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and dye precursor 1,3-benzenediol in a batchwise process. The process reaction variables (laccase, precursor and modifier concentrations, temperature and dyeing time) were optimized by response surface methodology using an appropriate experimental design. The temperature, precursor concentration, interaction between precursor and modifier and time are the most important factors in the dyeing process. The best-optimized wool dyeing conditions (2 h reaction time, 50 μl laccase (0.1 U), 500 mM precursor, 10 mM modifier at 40 °C) were then successfully applied onto leather material. The enzymatic-dyeing optimized process can be successfully performed on wool and leather at low temperature and mild pH obtaining different hues and depths of shades by varying the modifier concentration and time. The colouring enzymatic system has a good reusability (which has a huge advantage in terms of cost reduction) and washing durability and is comparable in terms of fastness properties to the traditional dyeing process for both wool and leather.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for funding the project UID/CTM/00264/2019 and A. Zille contract IF/00071/2015

Suitability of selected vegetable tannins traditionally used in leather making in Tanzania

This research article published by Elsevier Ltd., 2020The use of chromium salt has dominated in tanning industry worldwide due to its high versatility in quality leather production. However, Environmental concerns of chromium have shifted the interest of current research to chrome-free and greener chemical processing options. Vegetable tannins, especially when used in combination with some benign metals, have been proven to be environmentally safe and manageable, while producing good quality leather with similar shrinkage temperature as that of chromium tanned. As such, shortage of vegetable tannin supply necessitates characterization of non-commercialized sources locally available to feed cottage tanneries. In the present work, extracts from Acacia mearnsii, Acacia xanthophloea, Euclea divinorum and Euclea racemosa, leached by simple technique at 30–80 °C temperature range were characterized for extract yield, tannin, total flavonoid and phenolic contents, crosslinking ability as well as properties of tanned leather. Results indicate that at 50 °C extraction temperature, A. xanthophloea bark gave extract with properties similar to that of A. mearnsii (commercialized source of tannin). Extract from E. divinorum bark contain fairly less extract yield, tannin, total flavonoid and phenolic contents than that of A. mearnsii, but had good crosslinking ability and tanning performance similar to that of A. mearnsii when used in combination with Aluminium Sulphate [Al2(SO4)3]. The 2% Aluminium Oxide (Al2O3) equivalent was established to be optimal dose of Al2(SO4)3 for extract pre-treatment. E. racemosa barks have high extract yield, but very low crosslinking ability, making it not suitable as a tannin source. This work provides useful information on the potential source of tannins for cottage leather industries in Tanzanian and beyond

Trends in Compulsory Licensing of Pharmaceuticals Since the Doha Declaration: A Database Analysis

Reed Beall and Randall Kuhn describe their findings from an analysis of use of compulsory licenses for pharmaceutical products by World Trade Organization members since 1995

Control of intestinal stem cell function and proliferation by mitochondrial pyruvate metabolism.

Most differentiated cells convert glucose to pyruvate in the cytosol through glycolysis, followed by pyruvate oxidation in the mitochondria. These processes are linked by the mitochondrial pyruvate carrier (MPC), which is required for efficient mitochondrial pyruvate uptake. In contrast, proliferative cells, including many cancer and stem cells, perform glycolysis robustly but limit fractional mitochondrial pyruvate oxidation. We sought to understand the role this transition from glycolysis to pyruvate oxidation plays in stem cell maintenance and differentiation. Loss of the MPC in Lgr5-EGFP-positive stem cells, or treatment of intestinal organoids with an MPC inhibitor, increases proliferation and expands the stem cell compartment. Similarly, genetic deletion of the MPC in Drosophila intestinal stem cells also increases proliferation, whereas MPC overexpression suppresses stem cell proliferation. These data demonstrate that limiting mitochondrial pyruvate metabolism is necessary and sufficient to maintain the proliferation of intestinal stem cells

Interactive decision support in hepatic surgery

BACKGROUND: Hepatic surgery is characterized by complicated operations with a significant peri- and postoperative risk for the patient. We developed a web-based, high-granular research database for comprehensive documentation of all relevant variables to evaluate new surgical techniques. METHODS: To integrate this research system into the clinical setting, we designed an interactive decision support component. The objective is to provide relevant information for the surgeon and the patient to assess preoperatively the risk of a specific surgical procedure. Based on five established predictors of patient outcomes, the risk assessment tool searches for similar cases in the database and aggregates the information to estimate the risk for an individual patient. RESULTS: The physician can verify the analysis and exclude manually non-matching cases according to his expertise. The analysis is visualized by means of a Kaplan-Meier plot. To evaluate the decision support component we analyzed data on 165 patients diagnosed with hepatocellular carcinoma (period 1996–2000). The similarity search provides a two-peak distribution indicating there are groups of similar patients and singular cases which are quite different to the average. The results of the risk estimation are consistent with the observed survival data, but must be interpreted with caution because of the limited number of matching reference cases. CONCLUSION: Critical issues for the decision support system are clinical integration, a transparent and reliable knowledge base and user feedback