Search

When solving nonlinear algebraic equations that arise from discretization using the finite element method (FEM), it is often observed that the standard Newton-Raphson (N-R) iteration either fails to converge or necessitates a large number of iterations in the vicinity of critical points. This work proposes an additional numerical strategy, known as the Potra-Pták iterative cycle, to improve the efficiency of solving highly nonlinear structural problems. Therefore, the focus here is on making the nonlinear solver more robust and efficient, allowing the analysis of more complex nonlinear structures. In the Potra-Pták iterative cycle, two corrections of the objective function (energy function) are performed. The introduction of a second correction in the iterative cycle makes the Potra-Pták strategy more efficient than the standard or modified N-R iterations. This numerical strategy was implemented in the homemade Computational System for Advanced Structural Analysis (CS-ASA) program. The program is based on the FEM and is capable of performing static and dynamic nonlinear analysis of steel, concrete, and composite structures, and its efficiency is then verified through the analysis of slender frames and arches. The algorithm details for solving the nonlinear structural problem, characterized by the Potra-Pták scheme, are provided. [ABSTRACT FROM AUTHOR]

STDP is dependent on the timing of pre- and post-synaptic activity. Here, the authors describe a symmetric STDP induction rule at CA3-CA3 synapses, which induces LTP over a broad range of paring intervals. Modelling suggests that this STDP rule may enhance storage capacity and pattern completion in the CA3 cell network.

The whale shark Rhincodon typus was uplisted to ‘Endangered’ in the 2016 IUCN Red List due to >50% population decline, largely caused by continued exploitation in the Indo-Pacific. Though the Philippines protected the whale shark in 1998, concerns remain due to continued take in regional waters. In light of this, understanding the movements of whale sharks in the Philippines, one of the most important hotspots for the species, is vital. We tagged 17 juvenile whale sharks with towed SPOT5 tags from three general areas in the Sulu and Bohol Seas: Panaon Island in Southern Leyte, northern Mindanao, and Tubbataha Reefs Natural Park (TRNP). The sharks all remained in Philippine waters for the duration of tracking (6–126 days, mean 64). Individuals travelled 86–2,580 km (mean 887 km) at a mean horizontal speed of 15.5 ± 13.0 SD km day−1. Whale sharks tagged in Panaon Island and Mindanao remained close to shore but still spent significant time off the shelf (>200 m). Sharks tagged at TRNP spent most of their time offshore in the Sulu Sea. Three of twelve whale sharks tagged in the Bohol Sea moved through to the Sulu Sea, whilst two others moved east through the Surigao Strait to the eastern coast of Leyte. One individual tagged at TRNP moved to northern Palawan, and subsequently to the eastern coast of Mindanao in the Pacific Ocean. Based on inferred relationships with temperature histograms, whale sharks performed most deep dives (>200 m) during the night, in contrast to results from whale sharks elsewhere. While all sharks stayed in national waters, our results highlight the high mobility of juvenile whale sharks and demonstrate their connectivity across the Sulu and Bohol Seas, highlighting the importance of the area for this endangered species.

ATP released from neurons and astrocytes during neuronal activity or under pathophysiological circumstances is able to influence information flow in neuronal circuits by activation of ionotropic P2X and metabotropic P2Y receptors and subsequent modulation of cellular excitability, synaptic strength, and plasticity. In the present paper we review cellular and network effects of P2Y receptors in the brain. We show that P2Y receptors inhibit the release of neurotransmitters, modulate voltage- and ligand-gated ion channels, and differentially influence the induction of synaptic plasticity in the prefrontal cortex, hippocampus, and cerebellum. The findings discussed here may explain how P2Y1 receptor activation during brain injury, hypoxia, inflammation, schizophrenia, or Alzheimer’s disease leads to an impairment of cognitive processes. Hence, it is suggested that the blockade of P2Y1 receptors may have therapeutic potential against cognitive disturbances in these states.

Molecularly imprinted polymers (MIP) are materials capable of recognizing specific molecules, usually through non-covalent bonds. In this work, gallic acid (GA) was selected as the imprinting molecule, and MIP for GA (MIP-GA) was synthesized by bulk polymerization. X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) confirmed the MIP-GA recognition property. Poly(caprolactone) mat containing MIP-GA particles (MIM-GA) was produced by electrospinning, which was morphologically characterized by Scanning electron microscopy (SEM). Functionalized MIM-GA was obtained by washes sequence in methanol for the GA removal from MIM-GA. The GA removal was confirmed by High-performance liquid chromatography (HPLC) with UV-Vis detection at 214 and 268 nm. The functionalized MIM-GA immersed in GA methanolic solution with a concentration of 1.0 mM extracted 96±1.5% of GA at t = 150 minutes. The vibrational modes obtained from FT-IR spectra confirmed the chemical composition of MIM-GA and its functionalization through of band at 770 cm-1. The contact angle measurements were 134.0±1.0° for electrospun MIM-GA and 125.0±1.2° for functionalized MIM-GA. The decrease was due to the absence of GA after the functionalization process. The produced MIM-GA by electrospinning acquired the recognition property of the GA imprinted polymer synthesized, which can be used for the specific detection, extraction, and purification of this important natural polyphenol. [ABSTRACT FROM AUTHOR]

Multilayer (14 layers, 115–122 nm thick each) BiFeO3/CoFe2O4/substrate (BFO/CFO) and CoFe2O4/BiFeO3/substrate (CFO/BFO) nanocomposites were obtained by the method of sol-gel synthesis. It is shown that all samples of the obtained nanocomposites have multiferroic properties at room temperature. At the same time, there is a clearly demonstrated effect of the layering order on the values of remnant polarization and magnetization of these samples. This influence originates from the much smaller size of the crystallites in the BiFeO3 layers for the samples deposited in order (BFO/CFO) at various annealing temperatures (700, 725, and 750 °C). [ABSTRACT FROM AUTHOR]

The whale shark Rhincodon typus was uplisted to 'Endangered' in the 2016 IUCN Red List due to >50% population decline, largely caused by continued exploitation in the Indo-Pacific. Though the Philippines protected the whale shark in 1998, concerns remain due to continued take in regional waters. In light of this, understanding the movements of whale sharks in the Philippines, one of the most important hotspots for the species, is vital. We tagged 17 juvenile whale sharks with towed SPOT5 tags from three general areas in the Sulu and Bohol Seas: Panaon Island in Southern Leyte, northern Mindanao, and Tubbataha Reefs Natural Park (TRNP). The sharks all remained in Philippine waters for the duration of tracking (6-126 days, mean 64). Individuals travelled 86-2,580 km (mean 887 km) at a mean horizontal speed of 15.5 ± 13.0 SD km day-1. Whale sharks tagged in Panaon Island and Mindanao remained close to shore but still spent significant time off the shelf (>200 m). Sharks tagged at TRNP spent most of their time offshore in the Sulu Sea. Three of twelve whale sharks tagged in the Bohol Sea moved through to the Sulu Sea, whilst two others moved east through the Surigao Strait to the eastern coast of Leyte. One individual tagged at TRNP moved to northern Palawan, and subsequently to the eastern coast of Mindanao in the Pacific Ocean. Based on inferred relationships with temperature histograms, whale sharks performed most deep dives (>200 m) during the night, in contrast to results from whale sharks elsewhere. While all sharks stayed in national waters, our results highlight the high mobility of juvenile whale sharks and demonstrate their connectivity across the Sulu and Bohol Seas, highlighting the importance of the area for this endangered species. [ABSTRACT FROM AUTHOR]