233 research outputs found

    Hybrid Genetic-cuckoo Search Algorithm for Solving Runway Dependent Aircraft Landing Problem

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    Abstract: As the demand for air transportation continues to grow, some flights cannot land at their preferred landing times because the airport is near its runway capacity. Therefore, devising a method for tackling the Aircraft Landing Problem (ALP) in order to optimize the usage of existing runways at airports is the focus of this study. This study, a hybrid Genetic-Cuckoo Search (GCS) algorithm for optimization the ALP with runway is proposed. The numerical results showed that the proposed GCS algorithm can effectively and efficiently determine the runway allocation, sequence and landing time for arriving aircraft for the three test cases by minimizing total delays under the separation constraints in comparison with the outcomes yielded by previous studies

    Dissipative elastic metamaterial with a lowfrequency passband

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    We design and experimentally demonstrate a dissipative elastic metamaterial structure that functions as a bandpass filter with a low-frequency passband. The mechanism of dissipation in this structure is well described by a mass-spring-damper model that reveals that the imaginary part of the wavenumber is non-zero, even in the passband of dissipative metamaterials. This indicates that transmittance in this range can be low. A prototype for this viscoelastic metamaterial model is fabricated by 3D printing techniques using soft and hard acrylics as constituent materials. The transmittance of the printed metamaterial is measured and shows good agreement with theoretical predictions, demonstrating its potential in the design of compact waveguides, filters and other advanced devices for controlling mechanical waves

    Dissipative elastic metamaterial with a lowfrequency passband

    Get PDF
    We design and experimentally demonstrate a dissipative elastic metamaterial structure that functions as a bandpass filter with a low-frequency passband. The mechanism of dissipation in this structure is well described by a mass-spring-damper model that reveals that the imaginary part of the wavenumber is non-zero, even in the passband of dissipative metamaterials. This indicates that transmittance in this range can be low. A prototype for this viscoelastic metamaterial model is fabricated by 3D printing techniques using soft and hard acrylics as constituent materials. The transmittance of the printed metamaterial is measured and shows good agreement with theoretical predictions, demonstrating its potential in the design of compact waveguides, filters and other advanced devices for controlling mechanical waves

    Cross talk between heat shock protein 10 and a heat shock factor identified from Marsupenaeus japonicus

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    Abstract(#br)Heat shock factors (HSFs) and heat shock proteins (HSPs) are crucial regulators and effectors of the heat shock response (HSR). In this study, the full-length cDNA sequences of MjHSP10 and MjHSF1 were cloned by rapid amplification of cDNA ends (RACE). The deduced MjHSP10 and MjHSF1 amino acid (aa) sequences exhibited conserved structures and the functional features of HSP10 and HSF1, respectively. The tissue distributions and mRNA expression profiles of the two genes in response to heat stress were analyzed by quantitative real-time PCR (qRT-PCR). MjHSP10 and MjHSF1 were ubiquitously expressed in various tissues. Heat stress induced a significant increase in MjHSP10 expression that tend to positively correlate with temperature. Additionally, MjHSF1 transcription was up-regulated less than MjHSP10 transcription under heat stress. MjHSF1 expression in the hepatopancreas was up-regulated under only long-term (48 h) heat stress, and MjHSF1 transcription in the gill increased under only acute (34 °C) heat stress. MjHSF1 knockdown by RNA interference (RNAi) down-regulated MjHSP10 expression. Glutathione-S-transferase (GST) pull-down assays showed an interaction between MjHSP10 and the DNA-binding domain (DBD) of MjHSF1. This study provided new insights into cross talk between HSP10 and HSF1 in Marsupenaeus japonicus

    Identification of two novel C-type lectins involved in immune defense against white spot syndrome virus and Vibrio parahaemolyticus from Marsupenaeus japonicus

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    Abstract(#br)C-type lectins (CTLs) are vital molecules in crustacean innate immunity with the capacity to recognize and eliminate invaders, such as viruses and bacteria. Here, two novel CTLs were identified from the kuruma shrimp Marsupenaeus japonicus , and their molecular characteristics and immune function were investigated. Sequence analysis revealed that the two CTLs possessed the typical CTL structure and function features. Tissue distribution analysis showed that the two CTLs were most abundantly expressed in the hepatopancreas and weakly expressed in other examined tissues. The transcription of the two CTLs significantly increased in the hepatopancreas of shrimp challenged with both white spot syndrome virus (WSSV) and Vibrio parahaemolyticus , and MjCTL4 was found to be more sensitive to the two pathogens than MjCTL3, being induced at relatively faster and higher increments. GST pull-down assays showed that the two CTLs could directly interact with several WSSV envelope proteins (VP19, VP24, VP26 and VP28). Moreover, the two CTLs displayed obvious binding and antibacterial ability to V. parahaemolyticus , and MjCTL3 exhibited stronger anti- V. parahaemolyticus activity than MjCTL4. These results suggest that the two novel CTLs might function as pattern recognition receptors (PRRs) and antibacterial molecules in M. japonicus innate immunity, and the two CTLs may be alternative agents for the prevention and treatment of diseases caused by WSSV and V. parahaemolyticus

    Cross talk between heat shock protein 10 and a heat shock factor identified from Marsupenaeus japonicus.

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    Heat shock factors (HSFs) and heat shock proteins (HSPs) are crucial regulators and effectors of the heat shock response (HSR). In this study, the full-length cDNA sequences of MjHSP10 and MjHSF1 were cloned by rapid amplification of cDNA ends (RACE). The deduced MjHSP10 and MjHSF1 amino acid (aa) sequences exhibited conserved structures and the functional features of HSP10 and HSF1, respectively. The tissue distributions and mRNA expression profiles of the two genes in response to heat stress were analyzed by quantitative real-time PCR (qRT-PCR). MjHSP10 and MjHSF1 were ubiquitously expressed in various tissues. Heat stress induced a significant increase in MjHSP10 expression that tend to positively correlate with temperature. Additionally, MjHSF1 transcription was up-regulated less than MjHSP10 transcription under heat stress. MjHSF1 expression in the hepatopancreas was up-regulated under only long-term (48 h) heat stress, and MjHSF1 transcription in the gill increased under only acute (34 °C) heat stress. MjHSF1 knockdown by RNA interference (RNAi) down-regulated MjHSP10 expression. Glutathione-S-transferase (GST) pull-down assays showed an interaction between MjHSP10 and the DNA-binding domain (DBD) of MjHSF1. This study provided new insights into cross talk between HSP10 and HSF1 in Marsupenaeus japonicus

    Piercing Through Highly Obscured and Compton-thick AGNs in the Chandra Deep Fields: I. X-ray Spectral and Long-term Variability Analyses

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    We present a detailed X-ray spectral analysis of 1152 AGNs selected in the Chandra Deep Fields (CDFs), in order to identify highly obscured AGNs (NH>1023 cm2N_{\rm H} > 10^{23}\ \rm cm^{-2}). By fitting spectra with physical models, 436 (38%) sources with LX>1042 erg s1L_{\rm X} > 10^{42}\ \rm erg\ s^{-1} are confirmed to be highly obscured, including 102 Compton-thick (CT) candidates. We propose a new hardness-ratio measure of the obscuration level which can be used to select highly obscured AGN candidates. The completeness and accuracy of applying this method to our AGNs are 88% and 80%, respectively. The observed logN-logS relation favors cosmic X-ray background models that predict moderate (i.e., between optimistic and pessimistic) CT number counts. 19% (6/31) of our highly obscured AGNs that have optical classifications are labeled as broad-line AGNs, suggesting that, at least for part of the AGN population, the heavy X-ray obscuration is largely a line-of-sight effect, i.e., some high-column-density clouds on various scales (but not necessarily a dust-enshrouded torus) along our sightline may obscure the compact X-ray emitter. After correcting for several observational biases, we obtain the intrinsic NH distribution and its evolution. The CT-to-highly-obscured fraction is roughly 52% and is consistent with no evident redshift evolution. We also perform long-term (~17 years in the observed frame) variability analyses for 31 sources with the largest number of counts available. Among them, 17 sources show flux variabilities: 31% (5/17) are caused by the change of NH, 53% (9/17) are caused by the intrinsic luminosity variability, 6% (1/17) are driven by both effects, and 2 are not classified due to large spectral fitting errors.Comment: 32 pages, 21 figures, 9 tables, accepted for publication in Ap

    Characteristic Metabolic Alterations Identified in Primary Neurons Under High Glucose Exposure

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    Cognitive dysfunction is a central nervous system (CNS) complication of diabetes mellitus (DM) that is characterized by impaired memory and cognitive ability. An in-depth understanding of metabolic alterations in the brain associated with DM will facilitate our understanding of the pathogenesis of cognitive dysfunction. The present study used an in vitro culture of primary neurons in a high-glucose (HG) environment to investigate characteristic alterations in neuron metabolism using nuclear magnetic resonance (NMR)-based metabonomics. High performance liquid chromatography (HPLC) was also used to measure changes in the adenosine phosphate levels in the hippocampal regions of streptozotocin (STZ)-induced diabetic rats. Our results revealed significant elevations in phosphocholine and ATP production in neurons and decreased formate, nicotinamide adenine dinucleotide (NAD+), tyrosine, methionine, acetate and phenylalanine levels after HG treatment. However, the significant changes in lactate, glutamate, taurine and myo-inositol levels in astrocytes we defined previously in astrocytes, were not found in neurons, suggested cell-specific metabolic alterations. We also confirmed an astrocyte-neuron lactate shuttle between different compartments in the brain under HG conditions, which was accompanied by abnormal acetate transport. These alterations reveal specific information on the metabolite levels and transport processes related to neurons under diabetic conditions. Our findings contribute to the understanding of the metabolic alterations and underlying pathogenesis of cognitive decline in diabetic patients

    A Structure Design Method for Reduction of MRI Acoustic Noise

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    The acoustic problem of the split gradient coil is one challenge in a Magnetic Resonance Imaging and Linear Accelerator (MRI-LINAC) system. In this paper, we aimed to develop a scheme to reduce the acoustic noise of the split gradient coil. First, a split gradient assembly with an asymmetric configuration was designed to avoid vibration in same resonant modes for the two assembly cylinders. Next, the outer ends of the split main magnet were constructed using horn structures, which can distribute the acoustic field away from patient region. Finally, a finite element method (FEM) was used to quantitatively evaluate the effectiveness of the above acoustic noise reduction scheme. Simulation results found that the noise could be maximally reduced by 6.9 dB and 5.6 dB inside and outside the central gap of the split MRI system, respectively, by increasing the length of one gradient assembly cylinder by 20 cm. The optimized horn length was observed to be 55 cm, which could reduce noise by up to 7.4 dB and 5.4 dB inside and outside the central gap, respectively. The proposed design could effectively reduce the acoustic noise without any influence on the application of other noise reduction methods

    Characterization of Montmorillonite–Biochar Composite and Its Application in the Removal of Atrazine in Aqueous Solution and Soil

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    Atrazine is a widely used triazine herbicide, which poses a serious threat to human health and aquatic ecosystem. A montmorillonite–biochar composite (MMT/BC) was prepared for atrazine remediation. Biochar samples were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectrometer (XPS). Structural and morphological analysis of raw biochar (BC) and MMT/BC showed that MMT particles have been successfully coated on the surface of biochar. Sorption experiments in aqueous solution indicated that the MMT/BC has higher removal capacity of atrazine compared to BC (about 3.2 times). The sorption of atrazine on the MMT/BC was primarily controlled by both physisorption and chemisorption mechanisms. The amendment of MMT/BC increased the sorption capacity of soils and delayed the degradation of atrazine. Findings from this work indicate that the MMT/BC composite can effectively improve the sorption capacity of atrazine in aquatic environment and farmland soil and reduce the environmental risk.Characterization of Montmorillonite–Biochar Composite and Its Application in the Removal of Atrazine in Aqueous Solution and SoilpublishedVersio
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