Range ambiguity suppression is a significant problem in traditional pulse‐Doppler radar systems, especially when the pulse repetition frequency is set high to avoid Doppler ambiguity. One possible ...way to deal with such problem is to apply the noise radar system, by transmitting pulse‐agile waveforms and using a group of matched filters as the receiver to accumulate the power of unambiguous echoes while dispersing the range‐ambiguous ones. However, when strong targets or heavy clutters exist, the dispersed ambiguous power is still high, which leads to high range‐Doppler sidelobes and overwhelms the weak targets. This paper explores a new way to deal with the range‐ambiguity suppression problem in noise radar. The range‐ambiguity suppression as a sparse recovery problem is formulated, and then both the unambiguous and ambiguous targets (and/or clutters) can be simultaneously reconstructed. The proposed method can enhance the range‐ambiguity suppression performance and synthetic an ambiguity‐free range‐Doppler map with a low sidelobe level, which ensures the weak target recovery performance even in a cluttered environment.
Buried pipelines are the main means of long distance transportation of natural gas. These pipelines are in high risk crossing liquefaction areas due to large deformations and stresses that may exist ...in pipe induced by the buoyancy load. In this study, a systematic analytical and numerical analysis were performed to investigate the mechanical behavior of a buried gas pipeline subjected to buoyancy in liquefaction areas. Soil constraints on pipe were considered accurately in the proposed models through soil spring assumptions. Effects of axial forces on pipe’s bending deformation were also considered via the governing equations for beam under bending and tension. Deformation compatibility condition was utilized to derive the axial forces in pipe. The accuracy of the proposed analytical model was validated by comparing its results with those derived by an established rigorous finite element model. In addition, parametric analysis was finally performed using the analytical model to study the influences of pipe diameter, pipe wall thickness, soil spring stiffness and width of liquefaction zone on pipe’s mechanical responses. This study can be referenced in the strength analysis and performance based safety evaluation of buried gas pipelines crossing liquefaction areas.
Vaccines are urgently needed to combat the global coronavirus disease 2019 (COVID-19) pandemic, and testing of candidate vaccines in an appropriate non-human primate (NHP) model is a critical step in ...the process. Infection of African green monkeys (AGM) with a low passage human isolate of SARS-CoV-2 by aerosol or mucosal exposure resulted in mild clinical infection with a transient decrease in lung tidal volume. Imaging with human clinical-grade 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) co-registered with computed tomography (CT) revealed pulmonary lesions at 4 days post-infection (dpi) that resolved over time. Infectious virus was shed from both respiratory and gastrointestinal (GI) tracts in all animals in a biphasic manner, first between 2-7 dpi followed by a recrudescence at 14-21 dpi. Viral RNA (vRNA) was found throughout both respiratory and gastrointestinal systems at necropsy with higher levels of vRNA found within the GI tract tissues. All animals seroconverted simultaneously for IgM and IgG, which has also been documented in human COVID-19 cases. Young AGM represent an species to study mild/subclinical COVID-19 disease and with possible insights into live virus shedding. Future vaccine evaluation can be performed in AGM with correlates of efficacy being lung lesions by PET/CT, virus shedding, and tissue viral load.
Abstract
Background
Enterococcus faecalis
(
E. faecalis
) plays an important role in the failure of root canal treatment and refractory periapical periodontitis. As an important virulence factor of
...E. faecalis
, extracellular polysaccharide (EPS) serves as a matrix to wrap bacteria and form biofilms. The homologous
rnc
gene, encoding Ribonuclease III, has been reported as a regulator of EPS synthesis. In order to develop novel anti-biofilm targets, we investigated the effects of the
rnc
gene on the biological characteristics of
E. faecalis
, and compared the biofilm tolerance towards the typical root canal irrigation agents and traditional Chinese medicine fluid Pudilan.
Methods
E. faecalis rnc
gene overexpression (
rnc
+) and low-expression (
rnc
−) strains were constructed. The growth curves of
E. faecalis
ATCC29212,
rnc
+, and
rnc
− strains were obtained to study the regulatory effect of the
rnc
gene on
E. faecalis
. Scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and crystal violet staining assays were performed to evaluate the morphology and composition of
E. faecalis
biofilms. Furthermore, the wild-type and mutant biofilms were treated with 5% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), and Pudilan. The residual viabilities of
E. faecalis
biofilms were evaluated using crystal violet staining and colony counting assays.
Results
The results demonstrated that the
rnc
gene could promote bacterial growth and EPS synthesis, causing the EPS-barren biofilm morphology and low EPS/bacteria ratio. Both the
rnc
+ and
rnc
− biofilms showed increased susceptibility to the root canal irrigation agents. The 5% NaOCl group showed the highest biofilm removing effect followed by Pudilan and 2% CHX. The colony counting results showed almost complete removal of bacteria in the 5% NaOCl, 2% CHX, and Chinese medicine agents’ groups.
Conclusions
This study concluded that the
rnc
gene could positively regulate bacterial proliferation, EPS synthesis, and biofilm formation in
E. faecalis
. The
rnc
mutation caused an increase in the disinfectant sensitivity of biofilm, indicating a potential anti-biofilm target. In addition, Pudilan exhibited an excellent ability to remove
E. faecalis
biofilm.
Streptococcus mutans
constantly coexists with
Candida albicans
in plaque biofilms of early childhood caries (ECC). The progression of ECC can be influenced by the interactions between
S. mutans
and
...C. albicans
through exopolysaccharides (EPS). Our previous studies have shown that
rnc
, the gene encoding ribonuclease III (RNase III), is implicated in the cariogenicity of
S. mutans
by regulating EPS metabolism. The
DCR1
gene in
C. albicans
encodes the sole functional RNase III and is capable of producing non-coding RNAs. However, whether
rnc
or
DCR1
can regulate the structure or cariogenic virulence of the cross-kingdom biofilm of
S. mutans
and
C. albicans
is not yet well understood. By using gene disruption or overexpression assays, this study aims to investigate the roles of
rnc
and
DCR1
in modulating the biological characteristics of dual-species biofilms of
S. mutans
and
C. albicans
and to reveal the molecular mechanism of regulation. The morphology, biomass, EPS content, and lactic acid production of the dual-species biofilm were assessed. Quantitative real-time polymerase chain reaction (qRT-PCR) and transcriptomic profiling were performed to unravel the alteration of
C. albicans
virulence. We found that both
rnc
and
DCR1
could regulate the biological traits of cross-kingdom biofilms. The
rnc
gene prominently contributed to the formation of dual-species biofilms by positively modulating the extracellular polysaccharide synthesis, leading to increased biomass, biofilm roughness, and acid production. Changes in the microecological system probably impacted the virulence as well as polysaccharide or pyruvate metabolism pathways of
C. albicans
, which facilitated the assembly of a cariogenic cross-kingdom biofilm and the generation of an augmented acidic milieu. These results may provide an avenue for exploring new targets for the effective prevention and treatment of ECC.
Histone deacetylases (HDACs), known as histone acetylation erasers, function crucially in plant growth and development. Although there are abundant reports focusing on
of Arabidopsis and illustrating ...their important roles, the knowledge of
genes in Tartary buckwheat (Polygonales Polygonaceae
(L.) Gaertn) is still scarce. In the study, a total of 14
genes were identified and divided into three main groups: Reduced Potassium Dependency-3/His-52 tone Deacetylase 1 (RPD3/HDA1), Silent Information Regulator 2 (SIR2), and the plant-53 specific HD2. Domain and motif composition analysis showed there were conserved domains and motifs in members from the same subfamilies. The 14
were distributed asymmetrically on 7 chromosomes, with three segmental events and one tandem duplication event identified. The prediction of the
-element in promoters suggested that
probably acted in numerous biological processes including plant growth, development, and response to environmental signals. Furthermore, expression analysis based on RNA-seq data displayed that all
genes were universally and distinctly expressed in diverse tissues and fruit development stages. In addition, we found divergent alterations in
transcript abundance in response to different light conditions according to RNA-seq and RT-qPCR data, indicating that five
might be involved in light response. Our findings could provide fundamental information for the HDAC gene family and supply several targets for future function analysis of
related with light response of Tartary buckwheat.
Since SARS-CoV-2 emerged in late 2019, it spread from China to the rest of the world. An initial concern was the potential for vaccine- or antibody-dependent enhancement (ADE) of disease as had been ...reported with other coronaviruses. To evaluate this, we first developed a ferret model by exposing ferrets to SARS-CoV-2 by either mucosal inoculation (intranasal/oral/ocular) or inhalation using a small particle aerosol. Mucosal inoculation caused a mild fever and weight loss that resolved quickly; inoculation via either route resulted in virus shedding detected in the nares, throat, and rectum for 7–10 days post-infection. To evaluate the potential for ADE, we then inoculated groups of ferrets intravenously with 0.1, 0.5, or 1 mg/kg doses of a human polyclonal anti-SARS-CoV-2 IgG from hyper-immunized transchromosomic bovines (SAB-185). Twelve hours later, ferrets were challenged by mucosal inoculation with SARS-CoV-2. We found no significant differences in fever, weight loss, or viral shedding after infection between the three antibody groups or the controls. Signs of pathology in the lungs were noted in infected ferrets but no differences were found between control and antibody groups. The results of this study indicate that healthy, young adult ferrets of both sexes are a suitable model of mild COVID-19 and that low doses of specific IgG in SAB-185 are unlikely to enhance the disease caused by SARS-CoV-2.
With continued increasing construction of both electrified facilities and buried high‐strength pipelines in China, stray current corrosion defects have become an nonignorable threat for these ...pipelines. A comprehensive investigation on a new failure pressure prediction model for high‐strength pipes with stray current corrosion defects was conducted in this study. The mechanism of stray current corrosion in steel pipes was firstly elaborated in brief. After that, a parameterized finite element model for stress analysis of pipes with external corrosion defects was programmed by APDL code developed by general software ANSYS. By comparing numerical results with full‐scale experimental results, both the numerical model and the failure criteria for pipe burst were proven to be reasonable. Based on the finite element model, parametric analysis was performed using a calculation matrix set by orthogonal testing method to investigate the effects of three main dimensionless factors, that is, ratio of pipe diameter to wall thickness, nondimensional corrosion defect length, and nondimensional corrosion defect depth on pipe's failure pressure. Utilizing the parametric analysis results as database, a multilayer feed‐forward artificial neural network (ANN) was developed for failure pressure prediction. By comparison with experimental burst test results and results of previous failure pressure estimation model, the ANN model results were proven to have both high accuracy and efficiency, which could be referenced in residual strength or safety assessment of high‐strength pipes with corrosion defects.
A three‐dimensional nonlinear finite element model for burst failure simulation of corroded pipes has been established and validated by experimental data. A novel failure pressure prediction method for high‐strength line pipes has been proposed via multilayer artificial neural network technique and FEM results derived by orthogonal experimental design.
Two-dimensional (2D) gold multiple signal classification (gold-MUSIC) is proposed in order to reduce the complexity of MUSIC and make real-time processing possible for joint range and angle ...estimation by multi-carrier frequency multiple-input multiple-output radar. 2D gold-MUSIC evaluates the MUSIC spectrum at coarse intervals, then determines peaks by narrowing the 2D search area iteratively based on a simultaneous gold-section of range and angle to find accurate localisation of the peaks. The proposed method eliminates huge computation burden caused by a grid-by-grid spectral search of classical MUSIC and obtains remarkable resolution in range and angle with no dependence on array configurations. Numerical studies demonstrate the effectiveness and efficiency of the proposed method.
The gastric microbial community plays a fundamental role in gastric cancer (GC), and the two main anatomical subtypes of GC, non-cardia and cardia GC, are associated with different risk factors ...(Helicobacter pylori for non-cardia GC). To decipher the different microbial spatial communities of GC, we performed a multicenter retrospective analysis to characterize the gastric microbiota in 223 GC patients, including H. pylori-positive or -negative patients, with tumors and paired adjacent normal tissues, using third-generation sequencing. In the independent validation cohort, both dental plaque and GC tumoral tissue samples were collected and sequenced. The prevalence of H. pylori and oral-associated bacteria was verified using fluorescence in situ hybridization (FISH) assays in GC tumoral tissues and matched nontumoral tissues. We found that the vertical distribution of the gastric microbiota, at the upper, middle, and lower third sites of GC, was likely an important factor causing microbial diversity in GC tumor tissues. The oral-associated microbiota cluster, which included Veillonella parvula, Streptococcus oralis, and Prevotella intermedia, was more abundant in the upper third of the GC. However, H. pylori was more abundant in the lower third of the GC and exhibited a significantly high degree of microbial correlation. The oral-associated microbiota module was co-exclusive with H. pylori in the lower third site of the GC tumoral tissue. Importantly, H. pylori-negative GC patients with oral-associated gastric microbiota showed worse overall survival, while the increase in microbial abundance in H. pylori-positive GC patients showed no difference in overall survival. The prevalence of V. parvula in both the dental plaque and GC tissue samples was concordant in the independent validation phase. We showed that the oral-associated species V. parvula and S. oralis were correlated with overall survival. Our study highlights the roles of the oral-associated microbiota in the upper third of the GC. In addition, oral-associated species may serve as noninvasive screening tools for the management of GC and an independent prognostic factor for H. pylori-negative GCs.IMPORTANCEOur study highlights the roles of the oral-associated microbiota in the upper third of gastric cancer (GC).We showed that the oral-associated species Veillonella parvula and Streptococcus oralis were correlated with overall survival. In addition, oral-associated species may serve as noninvasive screening tools for the management of GC and an independent prognostic factor for Helicobacter pylori-negative GCs.
PDF
