19,425 research outputs found

    The effect of bioenergetic impairment of cytosolic processes in spatio-temporal Ca²⁺ dynamics in a three-dimensional cardiomyocyte model

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    The heart consumes large amounts of energy with each beat. Mitochondria are the source of over 95% of this energy in the form of ATP and rely on increased Ca²⁺ uptake to stimulate production in times of increased work. Ca²⁺ uptake into the mitochondria primarily occurs within microdomains. Structural remodeling associated with heart failure may disrupt these microdomains leading to impaired mitochondrial Ca²⁺ uptake and energetic impairment. To investigate the effect of structural changes on single cell behavior, a model describing mitochondrial dynamics and energetics production is modified and incorporated into a recently developed three-dimensional model of spatio-temporal calcium handling, which preserves microdomain structure and incorporates stochastic processes in Ca²⁺ handling protein kinetics. Modifications to the mitochondria model included a reformulation of mitochondrial Ca²⁺ uniporter uptake, making it suitable for concentrations in microdomains. With this model we demonstrate the importance of an ordered structure within the cell for normal function. Changes in the arrangement of mitochondria can have a pronounced effect on intracellular Ca²⁺ dynamics through their energetic regulation of SERCA, leading to spatially heterogeneous sarcoplasmic reticulum uptake and loading

    Shear enhanced heterogeneous nucleation in some Mg- and Al- alloys

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    Intensive shearing was applied to alloy melts at temperatures above their liquidus by using a twinscrew mechanism. The sheared melt was then cast into a TP1 mould for microstructural examination. Alloy melts with or without shearing were also filtered using the Prefil technique developed by N-Tech Ltd in order to analyse oxides and other second phase particles. The experimental results showed a significant grain refinement through enhancement of heterogeneous nucleation. The intensive melt shearing converted oxide films and agglomerates into well dispersed fine particles with a narrow size distribution. It was confirmed that the fine oxide particles can act as potent sites for nucleation during the solidification of the sheared melt. This paper presents the experimental results and theoretical analysis of shear enhanced heterogeneous nucleation during solidification of Mg- and Al-alloys. A multi-step heterogeneous nucleation mechanism has been proposed and discussed

    Melt conditioning by advanced shear technology (MCAST) for refining solidification microstructures

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    MCAST (melt conditioning by advanced shear technology) is a novel processing technology developed recently by BCAST at Brunel University for conditioning liquid metal prior to solidification processing. The MCAST process uses a twin screw mechanism to impose a high shear rate and a high intensity of turbulence to the liquid metal, so that the conditioned liquid metal has uniform temperature, uniform chemical composition and well-dispersed and completely wetted oxide particles with a fine size and a narrow size distribution. The microstructural refinement is achieved through an enhanced heterogeneous nucleation rate and an increased nuclei survival rate during the subsequent solidification processing. In this paper we present the MCAST process and its applications for microstructural refinement in both shape casting and continuous casting of light alloys

    Analysis of cybersecurity threats in Industry 4.0: the case of intrusion detection

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    Nowadays, industrial control systems are experiencing a new revolution with the interconnection of the operational equipment with the Internet, and the introduction of cutting-edge technologies such as Cloud Computing or Big data within the organization. These and other technologies are paving the way to the Industry 4.0. However, the advent of these technologies, and the innovative services that are enabled by them, will also bring novel threats whose impact needs to be understood. As a result, this paper provides an analysis of the evolution of these cyber-security issues and the requirements that must be satis ed by intrusion detection defense mechanisms in this context.Springer ; Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Dynamic analysis of sugar metabolism in different harvest seasons of pineapple (Ananas comosus L. (Merr.))

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    In pineapple fruits, sugar accumulation plays an important role in flavor characteristics, which varies according to the stage of fruit development. Metabolic changes in the contents of fructose, sucrose and glucose and reducing sugar related to the activities of soluble acid invertase (AI), neutral invertase (NI), sucrose synathase (SS) and sucrose-phosphate synthase (SPS) were studied in winter and summer pineapple fruits in this paper. Sucrose was significantly increased in most of the harvesting winter fruits which reached the peak of 64.87 mg·g-1 FW at 130 days after anthesis, while hexose was mainly accumulated at the 90 day of the summer fruits in July. The ratio of hexose to sucrose was 5.92:0.73 from the winter fruit in February. Interestingly, the activities of SPS and SS synthetic direction of the harvested fruits in February were significantly higher than those in July, whereas the invertase activities were exactly opposite. NI activity showed a similar trend to AI, but the amount of NI activity was higher than AI in both months. Therefore, NI appears to be one of the vital enzymes in pineapple fruit development. Conclusively, the enzyme activities related to sugar play key roles in the eating of quality pineapple, which could be improved by cultivation in different seasons. So we can arbitrate different temperature to improve the quality of pineapple fruits according to market demand.Keywords: Pineapple (Ananas comosus), different harvest seasons, sucrose, sucrose phosphate synthase, sucrose synthas

    Parental death during childhood and adult cardiovascular risk in a developing country: The Guangzhou Biobank Cohort study

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    Background: In observational studies from western countries childhood emotional adversity is usually associated with adult cardiovascular disease. These findings are open to contextual biases making evidence from other settings valuable. We examined the association of a potential marker of childhood emotional adversity with cardiovascular disease risk factors in a developing country. Methods: We used multivariable regression in cross-sectional analysis of older (≥50 years) men (n = 7,885) and women (n = 20,886) from the Guangzhou Biobank Cohort Study (2003-8) to examine the adjusted association of early life (<18 years) parental death (none, one or two deaths) with blood pressure, fasting glucose, LDL-cholesterol, HDL-cholesterol, triglycerides, body mass index (BMI), waist-hip ratio (WHR) and white blood cell count (WBC). We used seated height and delayed 10-word recall to assess content validity of parental death as a measure of childhood emotional adversity. We also examined whether associations varied by sex. Results: Early life parental death was associated with shorter age- and sex-adjusted seated height. It was also associated with lower 10-word recall score adjusted for age, sex, socio-economic position, leg length and lifestyle. Similarly, adjusted early life parental death was not associated with blood pressure, fasting glucose, LDL-cholesterol or HDL-cholesterol but was associated with lower BMI (-0.40, 95% confidence interval (CI) -0.62 to -0.19 for 2 compared with no early life parental deaths) and triglycerides. Associations varied by sex for WHR and WBC. Among men only, early life parental death was associated with lower WHR (-0.008, 95% CI -0.015 to -0.001) and WBC (-0.35 10 9/L, 95% CI -0.56 to -0.13). Conclusions: In a non-western population from a developing country, childhood emotional adversity was negatively associated with some cardiovascular risk factors, particularly among men. Our study suggests that some of the observed associations in western populations may be socially rather than biologically based or may be population specific. © 2011 Schooling et al.published_or_final_versio

    Successful Endoscopic Removal of a Lighter Swallowed 17 Months Before

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    The majority of ingested foreign bodies will pass safely through the gastrointestinal tract, but long and rigid foreign bodies are associated with an increased risk of gastrointestinal impaction, perforation and bleeding. However, large foreign bodies which have been swallowed can remain trapped in the stomach over a longer period of time without any significant symptoms. This case report describes the case of a 36-year-old man addicted to heroin who purposefully swallowed a lighter (double wrapped in cellophane) and presented with hematemesis and melena 17 months after the ingestion of the foreign body. The lighter was successfully removed via flexible endoscopy using a polypectomy snare. Swallowed long and rigid foreign bodies trapped in the stomach over a long period of time always represent a special clinical and endoscopic challenge. In cases where endoscopic removal fails, a laparoscopic surgical approach may be an alternative

    Fruit and vegetable consumption and cardiovascular risk factors in older Chinese: The Guangzhou Biobank Cohort Study

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    When Traffic Flow Prediction and Wireless Big Data Analytics Meet

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    In this article, we verify whether or not prediction performance can be improved by fitting the actual data to optimize the parameter values of a prediction model. The traffic flow prediction is an important research issue for solving the traffic congestion problem in an Intelligent Transportation System (ITS). The traffic congestion is one of the most serious problems in a city, which can be predicted in advance by analyzing traffic flow patterns. Such prediction is possible by analyzing the realtime transportation data from correlative roads and vehicles. The verification in this article is conducted by comparing the optimized and the normal time series prediction models. With the verification, we can learn that the era of big data is here and will become an important aspect for the study of traffic flow prediction to solve the congestion problem. Experimental results of a case study are provided to verify the existence of the performance improvement in the prediction, while the research challenges of this data-analytics-based prediction are presented and discussed

    A Study of Archiving Strategies in Multi-Objective PSO for Molecular Docking

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    Molecular docking is a complex optimization problem aimed at predicting the position of a ligand molecule in the active site of a receptor with the lowest binding energy. This problem can be formulated as a bi-objective optimization problem by minimizing the binding energy and the Root Mean Square Deviation (RMSD) difference in the coordinates of ligands. In this context, the SMPSO multi-objective swarm-intelligence algorithm has shown a remarkable performance. SMPSO is characterized by having an external archive used to store the non-dominated solutions and also as the basis of the leader selection strategy. In this paper, we analyze several SMPSO variants based on different archiving strategies in the scope of a benchmark of molecular docking instances. Our study reveals that the SMPSOhv, which uses an hypervolume contribution based archive, shows the overall best performance.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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