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Although topographic mapping missions and geological surveys carried out by Autonomous Underwater Vehicles (AUVs) are becoming increasingly prevalent, the lack of precise navigation in these scenarios still limits their application. This paper deals with the problems of long-term underwater navigation for AUVs and provides new mapping techniques by developing a Bathymetric Simultaneous Localisation And Mapping (BSLAM) method based on graph SLAM technology. To considerably reduce the calculation cost, the trajectory of the AUV is divided into various submaps based on Differences of Normals (DoN). Loop closures between submaps are obtained by terrain matching; meanwhile, maximum likelihood terrain estimation is also introduced to build weak data association within the submap. Assisted by one weight voting method for loop closures, the global and local trajectory corrections work together to provide an accurate navigation solution for AUVs with weak data association and inaccurate loop closures. The viability, accuracy and real-time performance of the proposed algorithm are verified with data collected onboard, including an 8 km planned track recorded at a speed of 4 knots in Qingdao, China.
Conventional underwater navigation and positioning methods for Autonomous Underwater Vehicles (AUVs) either require the installation of acoustic arrays, which make AUVs less independent, or result in cumulative errors. This paper proposes an Underwater Terrain Positioning Method (UTPM) using Maximum a Posteriori (MAP) estimation and a Pulse Coupled Neural Network (PCNN) model for highly accurate navigation by AUVs. The PCNN model is used as a secondary discriminant to effectively identify pseudo-anchor points in flat terrain feature areas and to find the true positioning point, which significantly improves the matching positioning accuracy in these areas. Simulation results show that the proposed method effectively corrects Inertial Navigation System (INS) cumulative errors and has high matching positioning accuracy, which satisfy the requirements of AUV underwater navigation and positioning.
In inertial confinement fusion experiments that involve short-laser pulses such as fast ignition (FI), diagnosis of neutrons is usually very challenging because high-intensity γ rays generated by short-laser pulses would mask the much weaker neutron signal. In this paper, fast-response scintillators with low afterglow and gated microchannel plate photomultiplier tubes are combined to build neutron time-of-flight (nTOF) spectrometers for such experiments. Direct-drive implosion experiments of deuterium-gas-filled capsules were performed at the Shenguang-II Upgrade (SG-II-UP) laser facility to study the compressed fuel areal density (〈ρR〉) and evaluate the performance of such nTOF diagnostics. Two newly developed quenched liquid scintillator detectors and a gated ultrafast plastic scintillator detector were used to measure the secondary DT neutrons and primary DD neutrons, respectively. The secondary neutron signals were clearly discriminated from the γ rays from (n, γ) reactions, and the compressed fuel areal density obtained with the yield-ratio method agrees well with the simulations. Additionally, a small scintillator decay tail and a clear DD neutron signal were observed in an integrated FI experiment as a result of the low afterglow of the oxygen-quenched liquid scintillator.
As important epigenetic regulators, microRNA regulate protein expression by triggering the degradation of target mRNA and/or by inhibiting their translation. Dysregulation of microRNA expression has been reported in several cancers, including colorectal cancer. In this study, microRNA-array differential analysis revealed strongly enhanced expression of miR-24-1-5p in the colon tissue of azoxymethane/dextran sulphate sodium-induced mice that were fed with black raspberry anthocyanins for 9 weeks. Overexpression of miR-24-1-5p in human colorectal cancer cells significantly repressed β-catenin expression, and simultaneously decreased cell proliferation, migration and survival. Furthermore, miR-24-1-5p could target β-catenin and trigger a negative regulatory loop for β-catenin and its downstream target genes. β-Catenin signalling is vital to the formation and progression of human colorectal cancer. The current findings therefore identified miR-24-1-5p as a potent regulator of β-catenin, and this may provide a novel chemopreventive and therapeutic strategy for β-catenin signalling-driven colorectal cancer.
A method for extracting the substrate-independent stress–strain curves of thin films was developed using spherical nanoindentation to investigate the yield behavior of diamond-like carbon (DLC) thin films with Young’s moduli of ∼73 GPa and ∼76 GPa. The resulting stress–strain curves showed that these films commence yielding at ∼13 GPa and ∼14 GPa, respectively. These yield strength values agree with the critical pressure necessary to initiate the transformation of sp2-bonded carbon into significantly harder sp3-bonded carbon, indicating that the yielding of the materials is associated with the sp2-to-sp3 phase transition. The ability of a DLC film to accommodate a progressively increasing contact stress with strain beyond the yield point while dissipating part of the accumulated strain energy, as evidenced in this work, implies a unique mechanism of the brittle material for passively mitigating contact deformation and fracture in tribological applications.
Seed shape (SS) affects the yield and appearance of soybean seeds significantly. However, little detailed information has been reported about the quantitative trait loci (QTL) affecting SS, especially SS components such as seed length (SL), seed width (SW) and seed thickness (ST), and their mutual ratios of length-to-weight (SLW), length-to-thickness (SLT) and weight-to-thickness (SWT). The aim of the present study was to identify QTL underlying SS components using 129 recombinant inbred lines derived from a cross between Dongnong46 and L-100. Phenotypic data were collected from this population after it was grown across nine environments. A total of 213 simple sequence repeat markers were used to construct the genetic linkage map, which covered approximately 3623·39 cM, with an average distance of 17·01 cM between markers. Five QTL were identified as being associated with SL, five with SW, three with ST, four with SLW, two with SLT and three with SWT. These QTL could explain 1·46–22·16% of the phenotypic variation in SS component traits. Three QTL were identified in more than six tested environments three for SL, two for SW, one for ST, two for SLW and one for SLT. These QTL have great potential value for marker-assistant selection of SS in soybean seeds.
Lutein benefits human health significantly, including that of the eyes, skin and heart. Therefore, increasing lutein content in soybean seeds is an important objective for breeding programmes. However, no information about soybean lutein-related quantitative trait loci (QTL) has been reported, as of 2016. The aim of the present study was to identify QTLs underlying the lutein content in soybean seeds. A population including 129 recombinant inbred lines was developed from the cross between ‘Dongnong46’ (lutein 13·10 µg/g) and ‘L-100’ (lutein 23·96 µg/g), which significantly differed in seed lutein contents. This population was grown in ten environments including Harbin in 2012, 2013, 2014 and 2015; Hulan in 2013, 2014 and 2015; and Acheng in 2013, 2014 and 2015. A total of 213 simple sequence repeat markers were used to construct the genetic linkage map, which covered approximately 3623·39 cM, with an average distance of 17·01 cM between markers. In the present study, eight QTLs associated with lutein content were found initially, which could explain 1·01–19·66% of the observed phenotypic variation in ten different tested environments. The phenotypic contribution of qLU-1 (located near BARC-Satt588 on chromosome 9 (Chr 9; linkage group (LG) K)) was >10% across seven tested environments, while qLU-2 (located near Satt192 of Chr 12 (LG H)) and qLU-3 (located near Satt353 of Chr12 (LGH)) could explain 5–10% of the observed phenotypic variation in more than seven environments, respectively. qLU-5, qLU-6, qLU-7 and qLU-8 could be detected in more than four environments. These eight QTLs were novel, and have considerable potential value for marker-assistant selection of higher lutein content in soybean lines.
The North China Craton (NCC) is one of the classic examples of decratonization through extensive lithospheric destruction during Mesozoic time. Among the various pulses of magmatism associated with cratonic erosion are the rare mafic intrusions in the Yanshan Belt. Here we investigate the Shangzhuang layered intrusion belonging to this suite, which is characterized by compositional layering with troctolite, noritic gabbro and gabbro/gabbroic anorthosite/gabbrodiorite from the bottom to top. The different lithologies of this intrusion exhibit close field relationships, similar chemical patterns and overall identical Lu–Hf isotopes indicating a co-magmatic nature. The fine-grained gabbros occurring near the margin of the intrusion display U–Pb ages similar to those of the other rocks and are considered to represent the composition of the parent magma, characterized by Fe, Mg and Ti enrichment. The magma was sourced from low-degree partial melting of spinel lherzolite sub-continental lithospheric mantle, which had been enriched by crust–mantle interaction and metasomatic fluids derived from the Mongolian oceanic slab subduction beneath the NCC during Late Palaeozoic time. In addition, limited asthenospheric or deeper-mantle materials were also locally mixed with the enriched mantle as the final source component. Our zircon U–Pb data constrain the emplacement age of this intrusion as c. 128–123 Ma in Early Cretaceous time, and correlates with the regional extensional tectonics between c. 135 and 115 Ma in the eastern and central NCC. Mantle upwelling associated with this event resulted in the thermal and chemical erosion of the lithospheric mantle, and emplacement of the parent magma of this layered intrusion.
A method is proposed for improving the accuracy and self-consistency of bathymetric maps built using an Autonomous Underwater Vehicle (AUV) to create precise prior maps for Terrain-Aided Navigation (TAN), when the Global Positioning System (GPS) or another precise location method is unavailable. This method consists of front-end and back-end. For the front-end, the AUV predicts the measurement of the bathymetry system through Terrain Elevation Measurement Extrapolation Estimation (TEMEE) and calculates the likelihood function using real measurements. After the final Inertial Navigation System (INS) error is obtained by communicating with sensor nodes, the process enters the back-end. A Terrain Correlation Correction Method (TCCM) and an Improved Terrain Correlation Correction Method (ITCCM) are proposed to solve the gradual distribution of the final INS error to each point on a path, and the accuracy of ITCCM was confirmed experimentally. Finally, a TAN simulation experiment was conducted to prove the importance and necessity of map correction using ITCCM. ITCCM was proven to be an effective and important method for correcting maps built using an AUV.
By using high purity aluminum powders and multi-walled carbon nanotubes (MWCNTs) as raw materials, MWCNTs/Al composites were fabricated with ball milling, followed by cold pressing, vacuum sintering, and hot extrusion. It was found that when the sintering temperature was 863 K, MWCNTs/Al composite sintered for 4 h showed good comprehensive properties, and its tensile strength and elongation reached to 156 MPa and 21%, respectively. The comprehensive mechanical properties of the composites became better with raising sintering temperature when the sintering time was 4 h. When the sintering temperature raised to 923 K, the tensile strength of the composite reached to 167 MPa which is three times more than that of annealed high purity aluminum, mainly due to the higher density and better interface bonding resulted from higher sintering temperature. CNTs' pulling out were observed obviously in the fractured surfaces, and load transfer may be the main strengthening mechanism.
In this paper, a novel wideband right-angle transition between thin substrate integrated waveguide (SIW) and rectangular waveguide (RWG) based on multi-section structure operating at center frequency 31.5 GHz is presented. A multi-section SIW with a rectangular aperture etched on the broad wall and two stepped ridges embedded in the RWG flange are introduced to obtain a wide impedance matching. The simulations show that the bandwidth with return loss better than 20 dB is about 17 GHz. In order to verify our designs, two back-to-back transitions with different lengths are fabricated and measured. The experimental results agree well with simulations. The proposed component shows an insertion loss less than 0.44 dB and a return loss better than 14.5 dB over 12.15 GH, which corresponds to 38.57% bandwidth.
The present study examined sequence variability in two mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1), and internal transcribed spacer (ITS) of nuclear ribosomal DNA (rDNA) among Oesophagostomum asperum isolates from goats in Hunan Province, China. A portion of the cox1 (pcox1), nad1 (pnad1) genes and the ITS (ITS1+5.8S rDNA+ITS2) rDNA were amplified by polymerase chain reaction (PCR) separately from adult O. asperum individuals and the representative amplicons were subjected to sequencing from both directions. The lengths of pcox1, pnad1 and ITS rDNA were 366 bp, 681 bp and 785 bp, respectively. The A+T contents of gene sequences were 71.5–72% for pcox1, 73.7–74.2% for pnad1 and 58–58.8% for ITS rDNA. Intra-specific sequence variations within O. asperum were 0–1.6% for pcox1, 0–1.9% for pnad1 and 0–1.7% for ITS rDNA, while inter-specific sequence differences among members of the genus Oesophagostomum were significantly higher, being 11.1–12.5%, 13.3–17.7% and 8.5–18.6% for pcox1, pnad1 and ITS rDNA, respectively. Phylogenetic analyses using combined sequences of pcox1 and pnad1, with three different computational algorithms (Bayesian inference, maximum likelihood and maximum parsimony), revealed distinct groups with high statistical support. These findings demonstrated the existence of intra-specific variation in mtDNA and rDNA sequences among O. asperum isolates from goats in Hunan Province, China, and have implications for studying molecular epidemiology and population genetics of O. asperum.
Outbreak of Mycobacterium tuberculosis infections associated with acupuncture has not been reported. Thirteen patients with a painful swollen lump were referred to our hospital. The index patient received acupuncture and paraspinal muscular injection at a local acupuncture clinic in April 2011 and was diagnosed with M. tuberculosis 1 month later. From May 2011 to August 2011, 12 more patients with a swollen lump on the nuchal region or in the lower back or the buttocks region were referred to our hospital. Tuberculin skin test (TST), T-SPOT.TB, acid-fast stain, M. tuberculosis culture, chest radiograph, and lump magnetic resonance imaging (MRI) were performed and the patients were diagnosed with tuberculous abscess of the lump. All 13 patients received intramuscular injection at the paraspinal muscle by two acupuncturists at a local clinic and reported a swollen lump at the injection site. The needles and syringes were reused after autoclave sterilization. The TST was positive in all patients. Twelve patients had positive acid-fast stains. Mycobacterial cultures of abscess specimens were positive in all 13 patients. T-SPOT.TB tests were positive in all patients who underwent the test. The lesions and biopsies were subjected to polymerase chain reaction (PCR) and gene sequencing by the Disease Control Center of Zhejiang Province, China and the causative agent was identified as M. tuberculosis, Beijing type. In conclusion, physicians should consider the possibility of mycobacterial infections, apart from other bacterial agents, in patients with a swollen paraspinal lump following intramuscular injection.
Toxoplasma gondii is a major cause of congenital brain disease; however, the underlying mechanism of neuropathogenesis in brain toxoplasmosis remains elusive. To explore the role of T. gondii in the development of neural stem cells (NSCs), NSCs were isolated from GD14 embryos of ICR mice and were co-cultured with tachyzoites of T. gondii RH strain. We found that apoptosis levels of the NSCs co-cultured with 1×106 RH tachyzoites for 24 and 48 h significantly increased in a dose-dependent manner, as compared with the control. Western blotting analysis displayed that the protein level of C/EBP homologous protein (CHOP) was up-regulated, and caspase-12 and c-Jun N-terminal kinase (JNK) were activated in the NSCs co-cultured with the parasites. Pretreatment with endoplasmic reticulum stress (ERS) inhibitor (TUDCA) and caspase-12 inhibitor (Z-ATAD-FMK) inhibited the expression or activation of the key molecules involved in the ERS-mediated apoptotic pathway, and subsequently decreased the apoptosis levels of the NSCs induced by the T. gondii. The findings here highlight that T. gondii induced apoptosis of the NSCs through the ERS signal pathway via activation of CHOP, caspase-12 and JNK, which may constitute a potential molecular mechanism responsible for the cognitive disturbance in neurological disorders of T. gondii.
Recent experimental evidence on nano-particle and nano-wire silicon anodes showed an initial rapid velocity of reaction front at the initial stage of lithiation, followed by an apparent slowing or even halting of the reaction front propagation. This intriguing phenomenon is attributed to the lithiation-induced mechanical stresses across the reaction front which is believed to play an important role in the kinetics of reaction at the front. Here, through theoretical formulation, we presented a comprehensive study on lithiation-induced stress field and its contribution to the driving force of lithiation in hollow spherical anodes with different boundary conditions at the inner surface of the particle. Our results reveal that hollow spherical silicon anodes can be lithiated more easily than solid spherical silicon particles and thus may serve as an optimal design of high performance anodes of lithium-ion battery.
Somatic cell nuclear transfer can be used to produce embryonic stem (ES) cells, cloned animals, and can even increase the population size of endangered animals. However, the application of this technique is limited by the low developmental rate of cloned embryos, a situation that may result from abnormal expression of some zygotic genes. In this study, sheep–sheep intra-species cloned embryos, goat–sheep inter-species cloned embryos, or sheep in vitro fertilized embryos were constructed and cultured in vitro and the developmental ability and expression of three pluripotency genes, SSEA-1, Nanog and Oct4, were examined. The results showed firstly that the developmental ability of in vitro fertilized embryos was significantly higher than that of cloned embryos. In addition, the percentage of intra-species cloned embryos that developed to morula or blastocyst stages was also significantly higher than that of the inter-species cloned embryos. Secondly, all three types of embryos expressed SSEA-1 at the 8-cell and morula stages. At the 8-cell stage, a higher percentage of in vitro fertilized embryos expressed SSEA-1 than occurred for cloned embryos. However, at the morula stage, all detected embryos could express SSEA-1. Thirdly, the three types of embryos expressed Oct4 mRNA at the morula and blastocyst stages, and embryos at the blastocyst stage expressed Nanog mRNA. The rate of expression of Oct4 and Nanog mRNA at these developmental stages was higher in in vitro fertilized embryos than in cloned embryos. These results indicated that, during early development, the failure to reactivate some pluripotency genes maybe is a reason for the low cloning efficiency found with cloned embryos.
Using molecular dynamics simulations, we demonstrate a transportation mechanism of hydrogen molecules enabled by the torsional buckling instability of carbon nanoscrolls. The transportation mechanism is shown to be of high efficacy and robust over a range of loading rates. The findings shed light on potential application of carbon nanoscroll based hydrogen storage.
Seed filling rate of soybean has been shown to be a dynamic process in different developmental stages affected by both genotype and environment. The objective of the present study was to determine additive, epistatic and quantitative trait loci (QTLs)×environment interaction (QE) effects of the QTL underlying a seed filling rate of soybean. One hundred and forty-three recombinant inbred lines (RILs) derived from the cross of Charleston and Dongnong 594 were used with 2 years of field data (2004 and 2005). Eleven QTLs with significantly unconditional and conditional additive (a) effect and/or additive×environment interaction (ae) effect at different filling stages were identified. Of them six QTLs showed positive a effects and four QTLs had negative a effects on the seed filling rate during seed development. aa and aae effects of 12 pairs of QTLs were identified by unconditional mapping from the initial stage to the final stage. Thirteen pairs of QTLs underlying the seed filling rate with aa and aae effects were identified by conditional mapping. QTLs with aa and aae (additive×additive×environment) effects appeared to vary at different filling stages. Our results demonstrated that the mass filling rate in soybean seed were under genetic and environmental control.
Our previous epidemiological study indicated that excessive intake of iodine could potentially lead to hypothyroidism. In the present study, we aimed to investigate the time and dose effect of iodine intake on serum thyrotropin (thyroid-stimulating hormone, TSH) levels and to explore the non-autoimmune regulation of serum TSH by pituitary type 2 deiodinase (D2). A total of 360 Wistar rats were randomly divided into five groups depending on administered iodine dosages (folds of physiological dose): normal iodine (NI), 3-fold iodine (3HI), 6-fold iodine (6HI), 10-fold iodine (10HI) and 50-fold iodine (50HI). At 4, 8, 12 and 24 weeks after administration of sodium iodide, blood was collected for serum TSH measurement by chemiluminescent immunoassay. Pituitaries were also excised for measurement of TSHβ subunit expression, D2 expression and activity, monocarboxylate transporter 8 (MCT8) and thyroid hormone receptor β2 isoform (TRβ2) levels. The results showed that iodine intake of 10HI and 50HI significantly increased pituitary and serum TSH levels from 8 to 24 weeks (P < 0·05 v. NI). Excess iodine had no effect on D2 mRNA or protein expression; however, 10HI and 50HI administration significantly inhibited pituitary D2 activities from 8 to 24 weeks (P < 0·05 v. NI). Iodine had no effect on MCT8 or TRβ2 protein levels. We conclude that prolonged high iodine intake inhibits pituitary D2 activity and induces elevation of serum TSH levels. These findings may provide a potential mechanism of iodine excess-induced overt and subclinical hypothyroidism.