Magnetorheological fluids (MRFs) are one of the categories of smart materials, whose viscosity increases considerably in the presence of a magnetic field. These fluids are prepared by dispersing ...magnetizable micro-size particles into a carrier fluid with stabilizer additives. The main feature of these fluids is their ability to change from liquid to semi-solid state with controllable yield stress just a few milliseconds after applying a magnetic field. Low magnetorheological effect and instability of MRFs are the most important problems against the extensive application of MRFs technology in modern industries. Various methods have been proposed and used by researchers to improve the magnetorheological effect and also the stability of these fluids. The main focus of this study is to present a comprehensive review on different methods of preparation and stabilization of MR fluids. Furthermore, rheological models and application of MR fluids are discussed briefly in this study.
•MRF synthesis was studied with respect to their stability and the MR effect.•Stabilization of magnetic suspensions as the main challenge still need to investigate.•Carbonyl iron particles are the most appropriate candidates for MRF synthesis.
•We used dendrochronology for simulating groundwater level fluctuations.•Tree-rings extent changes with groundwater fluctuations in alluvial aquifer.•Integration of dendrochronology and ANN has high ...efficiency in groundwater simulation.•We will find more exact results in the site with more groundwater fluctuations.•The simulated groundwater level can be applied to evaluate droughts.
Groundwater is the most important water resource in semi-arid and arid regions such as Iran. It is necessary to study groundwater level fluctuations to manage disasters (such as droughts) and water resources. Dendrochronology, which uses tree-rings to reconstruct past events such as hydrologic and climatologic events, can be used to evaluate groundwater level fluctuations. In this study, groundwater level fluctuations are simulated using dendrochronology (tree-rings) and an artificial neural network (ANN) for the period from 1912 to 2013. The present study was undertaken using the Quercus Castaneifolia species, which is present in an alluvial aquifer of the Caspian southern coasts, Iran. A multilayer percepetron (MLP) network was adopted for the ANN. Tree-ring diameter and precipitation were the input parameters for the study, and groundwater levels were the outputs. After the training process, the model was validated. The validated network and tree-rings were used to simulate groundwater level fluctuations during the past century. The results showed that an integration of dendrochronology and an ANN renders a high degree of accuracy and efficiency in the simulation of groundwater levels. The simulated groundwater levels by dendrochronology can be used for drought evaluation, drought period prediction and water resources management.
The Hippo pathway is a central regulator of tissue development and homeostasis, and has been reported to have a role during vascular development. Here we develop a bioluminescence-based biosensor ...that monitors the activity of the Hippo core component LATS kinase. Using this biosensor and a library of small molecule kinase inhibitors, we perform a screen for kinases modulating LATS activity and identify VEGFR as an upstream regulator of the Hippo pathway. We find that VEGFR activation by VEGF triggers PI3K/MAPK signaling, which subsequently inhibits LATS and activates the Hippo effectors YAP and TAZ. We further show that the Hippo pathway is a critical mediator of VEGF-induced angiogenesis and tumor vasculogenic mimicry. Thus, our work offers a biosensor tool for the study of the Hippo pathway and suggests a role for Hippo signaling in regulating blood vessel formation in physiological and pathological settings.
A differential single-port switched-RC N-path filter with band-pass characteristic is proposed. The switching frequency defines the center frequency, while the RC-time and duty cycle of the clock ...define the bandwidth. This allows for high-Q highly tunable filters which can for instance be useful for cognitive radio. Using a linear periodically time-variant (LPTV) model, exact expressions for the filter transfer function are derived. The behavior of the circuit including non-idealities such as maximum rejection, spectral aliasing, noise and effects due to mismatch in the paths is modeled and verified via measurements. A simple RLC equivalent circuit is provided, modeling bandwidth, quality factor and insertion loss of the filter. A 4-path architecture is realized in 65 nm CMOS. An off-chip transformer acts as a balun, improves filter-Q and realizes impedance matching. The differential architecture reduces clock-leakage and suppresses selectivity around even harmonics of the clock. The filter has a constant -3 dB bandwidth of 35 MHz and can be tuned from 100 MHz up to 1 GHz. Over the whole band, IIP3 is better than 14 dBm, P 1dB =2 dBm and the noise figure is 3-5 dB, while the power dissipation increases from 2 mW to 16 mW (only clocking power).
N-path switched-RC circuits can realize filters with very high linearity and compression point while they are tunable by a clock frequency. In this paper, both differential and single-ended N-path ...notch filters are modeled and analyzed. Closed-form equations provide design equations for the main filtering characteristics and nonidealities such as: harmonic mixing, switch resistance, mismatch and phase imbalance, clock rise and fall times, noise, and insertion loss. Both an eight-path single-ended and differential notch filter are implemented in 65-nm CMOS technology. The notch center frequency, which is determined by the switching frequency, is tunable from 0.1 to 1.2 GHz. In a 50-Ω environment, the N-path filters provide power matching in the passband with an insertion loss of 1.4-2.8 dB. The rejection at the notch frequency is 21-24 dB, P 1 dB > +2 dBm, and IIP3 > +17 dBm.
In this paper, we demonstrate a new type of two-dimensional photonic crystal wavelength division demultiplexers based on ring resonators that can be applicable to photonic integrated circuits. The ...proposed structure mechanism is performed based on coupling between a waveguide and a ring resonator. Based on the calculated position, this structure is designed and verified by finite-difference time-domain computation; our simulation by using this method results over 82% output efficiency. We use a heterostructure which is constructed of three different values of dielectric constant to obtain our wavelength division demultiplexer.
Detection of viral genomes by the innate immune system elicits an antiviral gene program mediated by type I interferons (IFNs). While viral RNA and DNA species induce IFN via separate pathways, the ...mechanisms by which these pathways are differentially modulated are unknown. Here we show that the positive regulator of IFN in the RNA pathway, TRAF3, has an inhibitory function in the DNA pathway. Loss of TRAF3 coincides with increased expression of the alternative NF-κB-inducing molecule, NIK, which interacts with the DNA pathway adaptor, STING, to enhance IFN induction. Cells lacking NIK display defective IFN activation in the DNA pathway due to impaired STING signaling, and NIK-deficient mice are more susceptible to DNA virus infection. Mechanistically, NIK operates independently from alternative NF-κB signaling components and instead requires autophosphorylation and oligomerization to activate STING. Thus a previously undescribed pathway for NIK exists in activating IFN in the DNA pathway.
Electrowetting is one of the most feasible methods for manipulating low-volume droplets on lab-on-a-chip systems. Finding the applied electrowetting force on a droplet and its comparison with ...movement resistive forces could be very useful in predicting the efficiency of an electrowetting actuator. In this study, the electrowetting force was calculated as a function of droplet position with the aid of analytical way and finite element method (FEM) at different applied voltages. In order to evaluate the results, a coplanar electrowetting actuator with SU-8 dielectric layer was fabricated. Then, an accurate droplet positioning system was utilized and one droplet (10 µl) was positioned on a specific point of the actuator to assess the ability of electrowetting force to overcome the resistive forces. This process was repeated for various points along the workspace of the actuator at different voltages. The experimental results indicated that the errors of FEM and analytical solution in predicting the least moveable voltage was 14%.
► In this study, a new supervised noise-artifact-robust heart arrhythmia fusion classification solution, is introduced. ► Proposed method consists of structurally diverse classifiers with a new QRS ...complex geometrical feature extraction technique. ► Discrimination power of proposed classifier in isolation of different Gold standard beats was assessed with accuracy 98.20%. ► Proposed learning machine was applied to 7 arrhythmias belonging to 15 different records and accuracy 98.06% was achieved. ► Comparisons with peer-reviewed studies prove a marginal progress in computerized heart arrhythmia recognition technologies.
In this study, a new supervised noise-artifact-robust heart arrhythmia fusion classification solution, is introduced. Proposed method consists of structurally diverse classifiers with a new QRS complex geometrical feature extraction technique.
Toward this objective, first, the events of the electrocardiogram (ECG) signal are detected and delineated using a robust wavelet-based algorithm. Then, each QRS region and also its corresponding discrete wavelet transform (DWT) are supposed as virtual images and each of them is divided into eight polar sectors. Next, the curve length of each excerpted segment is calculated and is used as the element of the feature space. Discrimination power of proposed classifier in isolation of different Gold standard beats was assessed with accuracy 98.20%. Also, proposed learning machine was applied to 7 arrhythmias belonging to 15 different records and accuracy 98.06% was achieved. Comparisons with peer-reviewed studies prove a marginal progress in computerized heart arrhythmia recognition technologies.
In this paper, a new viewpoint in ECG detection is presented using continuous wavelet transform (CWT). In order to magnify QRS complex and reduce the effects of other peaks, the concept of dominant ...rescaled wavelet coefficients (DRWC) is defined. Using this concept, the relations between the time duration of components of a QRS complex and their wavelet transforms are derived analytically. The proposed relations are used to define local search interval at the vicinity of each QRS complex components. Using DRWC concept, the proposed detection algorithm enables us to detect the
R peaks even at the presence of long
P and
T peaks. Then, each detected complex is classified based on its morphology. The classification is carried out regarding possible QRS patterns and their wavelet transform. We evaluate the algorithm on the MIT-BIH Arrhythmia database. The QRS detector has an average sensitivity of
Se
=
99.91% and a positive predictivity
P
+=
99.72% over the first lead of the database.
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