Research on Maritime Radio Wave Multipath Propagation Based on Stochastic Ray Method

Multipath effect in vessel communication is caused by a combination of reflections from the sea surface and vessels. This paper proposes employing stochastic ray method to analyze maritime multipath propagation properties. The paper begins by modeling maritime propagation environment of radio waves as random lattice grid, by utilizing maximum entropy principle to calculate the probability of stochastic ray undergoing k time(s) reflection(s), and by using stochastic process to produce the basic random variables. Then, the paper constructs the multipath channel characteristic parameters, including amplitude gain, time delay, and impulse response, based on the basic random variables. Finally, the paper carries out a digital simulation in two-dimensional specific fishery fleet model environment. The statistical properties of parameters, including amplitude response, probability delay distribution, and power delay profiles, are obtained. Using these parameters, the paper calculates the root-mean-squared (rms) delay spread value with the amount of 9.64 μs. It is a good reference for the research of maritime wireless transmission rate of the vessels. It contributes to a better understanding of the causes and effects of multipath effect in vessel communication

Surface and molecular modification of polyimides via graft copolymerization and functionalization

Ph.DDOCTOR OF PHILOSOPH

Comparative Transcriptome Analysis of Resistant and Susceptible Tomato Lines in Response to Infection by Xanthomonas perforans Race T3

Bacterial spot, incited by several Xanthomonas sp., is a serious disease in tomato (Solanum lycopersicum L.). Although genetics of resistance has been widely investigated, the interactions between the pathogen and tomato plants remain unclear. In this study, tanscriptomes of X. perforans race T3 infected tomato lines were compared to those of controls. An average of 7 million reads were generated with approximately 21,526 genes mapped in each sample post-inoculation at 6h (6 HPI) and 6d (6 DPI) using RNA-sequencing technology. Overall, the numbers of differentially expressed genes (DEGs) were higher in the resistant tomato line PI 114490 than in the susceptible line OH 88119, and the numbers of DEGs were higher at 6 DPI than at 6 HPI. Fewer genes (78 in PI 114490 and 15 in OH 88119) were up-regulated and most DEGs were down-regulated, suggesting that the inducible defense response might not be fully activated at 6 HPI. Accumulation expression levels of 326 co-up regulated genes in both tomato lines at 6 DPI might be involved in basal defense, while the specific and strongly induced genes at 6 DPI might be correlated with the resistance in PI114490. Most DEGs were involved in plant hormone signal transduction, plant-pathogen interaction and phenylalanine metabolism, and the genes significantly up-regulated in PI114490 at 6 DPI were associated with defense response pathways. DEGs containing NBS-LRR domain or defense-related WRKY transcription factors were also identified. The results will provide a valuable resource for understanding the interactions between X. perforans and tomato plants

Relationship of Seam Smoldering Velocity and Oxygen Volume Fraction Gradient in Roadway

AbstractSmoldering is an oxygen control reaction and its velocity is determined by oxygen supplying rate. Oxygen volume fraction gradient was used to characterize oxygen supplying rate in roadway according to situation that the velocity of wind flowing is very low during smoldering in roadway. Relationship of smoldering velocity and oxygen volume fraction gradient in roadway during lignite smoldering was researched in experiment drawing support of seam smoldering simulating experiment device in roadway and one-variable linear regression technology was used to establish the relation equation of smoldering velocity and oxygen volume fraction gradient in roadway when lignite was smoldering. This relation equation showed that smoldering velocity and oxygen volume fraction gradient took on linear increasing relationship in roadway during lignite smoldering

Analysis of failure mode and deformation evolution characteristics of slopes under the influence of highwall mining

The slope has the typical deformation failure and instability characteristics under the interaction of natural and human factors which has been given a lot of attention in geotechnical and mining engineering. During highwall mining, in particular, deformation evolution characteristics and failure mode are more complex under dual influence of open pit mine and underground mine. Physical modelling is an important means to study the characteristics and behavior of deformation and evolution of various types of rock and soil mass, and it is also an important supplement to the field study of large-scale rock and soil mass. It is widely used in mines and geotechnical engineering. The determination of the material used for physical modeling is the foundation and key links of research. Therefore, the article firstly selected river sand/aggregate, lime and gypsum/cemented material as the experimental materials through the relevant literature review and based on the principle of economic and convenience, and adopted two proportioning schemes to make standard specimens. The uniaxial compression test was carried out to compare and analyze the strength of the original rock, and it was determined that the scheme 2 could be used as the research scaling number of the physical modelling; Secondly, on the basis of determining the material proportion, the physical and structural model of highwall mining is established, and the analysis shows that the evolution characteristics of slope deformation and failure in the process of highwall mining can be divided into superficial transformation stage, structural transformation stage and aging deformation stage, the deformed and damaged rock mass can be divided into “vertical three zones”, namely caved zone, fractured zone and continuous bending zone. According to the length of the panel, the coal seam can be divided into three stages: initial stage, middle stage and final stage. The lower coal seam can be divided into two stages: the initial stage and the final stage. The evolution of the slope rock mass due to the extraction of the upper coal seam to the stopping line is characterized by the formation of subsidence faded areas along the center of the goaf to both sides, and finally a symmetrical distribution of semi-“pyramid” shape is formed. The rock mass that is deformed and damaged due to the extraction of the lower seam to the mining stop line is in a semi-curve-like shape; Finally, based on the analysis of physical modelling and field monitoring, it is concluded that when the upper coal seam of the highwall coal seam is mined to about 120 m, the slope shows a slight instability. When the lower coal seam is mined to about 120 m, the goaf between the upper and lower coal seams is connected, and the instability is intensified until the mining reaches the stopping line. In the upper part of the slope, 1400 step forms a local collapse instability zone pointing to the open-pit, while the rest of the step are anti-dip instability pointing to the goaf

Antiviral biflavonoids from Radix Wikstroemiae (Liaogewanggen)

<p>Abstract</p> <p>Background</p> <p><it>Radix Wikstroemiae </it>is a common Chinese herbal medicine. The ethyl acetate fraction of the ethanolic extract of <it>W. indica </it>possesses potent <it>in vitro </it>antiviral activity against respiratory syncytial virus (RSV). This study aims to identify the antiviral components of the active fraction.</p> <p>Methods</p> <p>The active fraction of the <it>Radix Wikstroemiae </it>extract was isolated with chromatographic methods such as silica gel, Sephadex LH-20 and semi-preparative high performance liquid chromatography (HPLC) columns. The structures of the isolated compounds were determined based on spectroscopic analyses. The <it>in vitro </it>antiviral activity of the compounds against RSV was tested with the cytopathic effect (CPE) reduction assay and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method.</p> <p>Results</p> <p>Four biflavonoids, namely neochamaejasmin B, genkwanol B, genkwanol C and stelleranol, were isolated and characterized. Genkwanol B, genkwanol C and stelleranol, which are stereo isomers of spirobiflavonoids, showed potent anti-RSV activity whereas neochamaejasmin B did not.</p> <p>Conclusion</p> <p>Neochamaejasmin B, genkwanol B, genkwanol C and stelleranol were isolated from <it>Radix Wikstroemiae </it>and the complete absolute configurations of five chiral carbons in stelleranol were substantiated for the first time. Furthermore, the anti-RSV activity of genkwanol B, genkwanol C and stelleranol was reported for the first time.</p

Altered Gray Matter Volume and Its Correlation With PTSD Severity in Chinese Earthquake Survivors

Objective: To detect the changes of gray matter volume (GMV) and their correlation with severity of symptom in patients with post-traumatic stress disorder (PTSD) who were defined with updated DSM-5 diagnostic criteria.Method: 71 participants were assigned into PTSD group (n = 35) or trauma-exposed control (TEC) group (n = 36) with the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Voxel-based morphometry analysis was used to detect alterations in GMV in the PTSD group.Results: We found that the PTSD group had larger GMV in the left middle temporal gyrus (MTG) and in the right dorsal medial prefrontal cortex (dmPFC), and smaller GMV in the region of the right temporal pole (TP) than the TEC group. We also found that PTSD Checklist for DSM-5 (PCL-5) scores correlated positively with the left MTG and right dmPFC GMV, and negatively with left TP GMV. These correlations were consistent with the findings of the between-group comparisons.Conclusions: GMV alterations in the MTG, dmPFC, and TP are detected in the group comparisons and correlated with symptom severity when classifying PTSD individuals according to DSM-5 diagnostic criteria within an earthquake-exposed population

Epigenetic Enzyme Mutations: Role in Tumorigenesis and Molecular Inhibitors

Epigenetic modifications, such as DNA methylation and histone modification, result in heritable changes in gene expression without changing the DNA sequence. Epigenetic regulatory enzymes such as DNA methyltransferases, histone methyltransferases, and histone deacetylases are involved in epigenetic modification. Studies have shown that the dysregulation caused by changes in the amino acid sequence of these enzymes is closely correlated with tumor onset and progression. In addition, certain amino acid changes in the metabolic enzyme isocitrate dehydrogenase (IDH) are linked to altered epigenetic modifications in tumors. Some small molecule inhibitors targeting these aberrant enzymes have shown promising anti-cancer efficacy in preclinical and clinical trials. For example, the small molecule inhibitor ivosidenib, which targets IDH1 with a mutation at R132, has been approved by the FDA for the clinical treatment of acute myeloid leukemia. In this review, we summarize the recurrent “hotspot” mutations in these enzymes in various tumors and their role in tumorigenesis. We also describe candidate inhibitors of the mutant enzymes which show potential therapeutic value. In addition, we introduce some previously unreported mutation sites in these enzymes, which may be related to tumor development and provide opportunities for future study