Phoebe's orbit from ground-based and space-based observations

The ephemeris of Phoebe, the ninth satellite of Saturn, is not very accurate. Previous dynamical models were usually too simplified, the astrometry is heterogeneous and, the Saturn's ephemeris itself is an additionnal source of error. The aim is to improve Phoebe's ephemeris by using a large set of observations, correcting some systematic errors and updating the dynamical model. The dynamical model makes use of the most recent ephemeris of planets and Saturnian satellites. The astrometry of Phoebe is improved by using a compilation of ground-based and space-based observations and by correcting the bias in stellar catalogues used for the reduction. We present an accurate ephemeris of Phoebe with residuals of 0.45 arcsec and with an estimated accuracy of Phoebe's position of less that 100 km on 1990-2020 period.Comment: 10 pages, 9 figures, accepted by A&

Bis[1-(2,6-dichloro­benz­yl)-3-methyl­pyrazin-1-ium] bis­(maleonitrile­dithiol­ato)nickelate(II)

In the crystal structure of the title compound, (C12H11Cl2N2)2[Ni(C4N2S2)2], the NiII complex dianion is located on an inversion centre. The NiII atom is coordinated by four S atoms in a square-planar geometry. In the cation, the dihedral angle between the benzene and pyrazine rings is 85.2 (2)°

Knockdown of Rab5a expression decreases cancer cell motility and invasion through integrin-mediated signaling pathway

<p>Abstract</p> <p>Background</p> <p>Rab GTPases function as modulators in intracellular transport. Rab5a, a member of the Rab subfamily of small GTPases, is an important regulator of vesicle traffic from the plasma membrane to early endosomes. Recent findings have reported that Rab5a gene was involved in the progression of cancer. In the present study, we investigated the effect of Rab5a on cervical cancer invasion and metastasis and the molecular mechanism underlying the involvement of Rab5a.</p> <p>Methods</p> <p>Rab5a expression was assessed by immunohistochemical analysis on a cervical cancer tissue microarray. RNA interference (RNAi) was performed to knock down the endogenous expression of Rab5a gene in HeLa and SiHa cells. Cell motility was evaluated using invasion assay and wound migration assay <it>in vitro</it>. The expression levels of integrin-associated molecules were detected by Western blot and immunofluorescence.</p> <p>Results</p> <p>We found that Rab5a was expressed at a high level in cervical cancer tissues. Silencing of Rab5a expression significantly decreased cancer cell motility and invasiveness. The down-regulation of integrin-associated focal adhesion signaling molecules was further detected in Rab5a knockdown cells. Meanwhile, active GTP-bound Rac1, Cdc42, and RhoA were also down-regulated, accompanied with the reduction in the number and size of filopodia and lamellipodia.</p> <p>Conclusions</p> <p>Taken together, these data suggest that Rab5a functions in regulating the invasion phenotype, and we propose that this regulation may be via integrin-mediated signaling pathway in cervical cancer cells.</p

Straight-line path following for asymmetric unmanned platform with disturbance estimation

The problem of straight-line path following for asymmetric unmanned platform exposed to unknown disturbances was addressed in this paper. The mathematical model of asymmetric unmanned platform was established and the inputs in sway and yaw directions were decoupled, which facilitated the establishment of control strategy of path following. The guidance law and the cross-track error were derived from the classical line-of-sight (LOS) guidance principle. And the equilibrium point of the cross-track error was proven to be uniformly semiglobally exponentially stable (USGES), which guaranteed the exponential convergence to zero. A new disturbance estimation law was developed by adding a linear item of the estimation error into the classical one, which improved the principle’s precision and sensitivity dramatically. The control strategy was developed based on the integrator backstepping technique and the new disturbance estimation law, which made the equilibrium system to be uniformly globally asymptotically stable (UGAS). Computer simulations were conducted to verify the effectiveness of the estimation and control laws during straight-line path following for asymmetric unmanned platform in the presence of unknown disturbances

Deep Learning for Video Object Segmentation:A Review

As one of the fundamental problems in the field of video understanding, video object segmentation aims at segmenting objects of interest throughout the given video sequence. Recently, with the advancements of deep learning techniques, deep neural networks have shown outstanding performance improvements in many computer vision applications, with video object segmentation being one of the most advocated and intensively investigated. In this paper, we present a systematic review of the deep learning-based video segmentation literature, highlighting the pros and cons of each category of approaches. Concretely, we start by introducing the definition, background concepts and basic ideas of algorithms in this field. Subsequently, we summarise the datasets for training and testing a video object segmentation algorithm, as well as common challenges and evaluation metrics. Next, previous works are grouped and reviewed based on how they extract and use spatial and temporal features, where their architectures, contributions and the differences among each other are elaborated. At last, the quantitative and qualitative results of several representative methods on a dataset with many remaining challenges are provided and analysed, followed by further discussions on future research directions. This article is expected to serve as a tutorial and source of reference for learners intended to quickly grasp the current progress in this research area and practitioners interested in applying the video object segmentation methods to their problems. A public website is built to collect and track the related works in this field: https://github.com/gaomingqi/VOS-Review

Effect of early vitrectomy combined with silicone oil tamponade for severe infectious traumatized endophthalmitis

AIM: To explore the relations of clinical efficacy and surgical timing of vitrectomy combined with silicone oil tamponade for severe infectious traumatized endophthalmitis.<p>METHODS: Totally 59 patients(59 eyes)with severe infectious traumatized endophthalmitis accepted vitrectomy combined with silicone oil tamponade. Patients were divided into two groups by different surgical timing. Group A accepted operation in 24 hours. Group B accepted operation 24 hours after injury. Retina status during operation, clinical efficacy and best-corrected visual acuity were observed and recorded. <p>RESULTS: The cases of early operation group got lesser retina injury and higher efficacy and better best-corrected visual acuity. <p>CONCLUSION:Vitrectomy combined with silicone oil tamponade is an effective way to cure severe infected traumatized endophthalmitis. Early surgical treatment is the key to achieve better effect

Disrupting the Interaction between Retinoblastoma Protein and Raf-1 Leads to Defects in Progenitor Cell Proliferation and Survival during Early Inner Ear Development

The retinoblastoma protein (pRb) is required for cell-cycle exit of embryonic mammalian hair cells but is not required for hair cell fate determination and early differentiation, and this provides a strategy for hair cell regeneration by manipulating the pRb pathway. To reveal the mechanism of pRb functional modification in the inner ear, we compared the effects of attenuated pRb phosphorylation by an inhibitor of the Mitogen-Activated Protein (MAP) kinase pathway and an inhibitor of the Rb–Raf-1 interaction on cultured chicken otocysts. We demonstrated that the activity of pRb is correlated with its phosphorylation state, which is regulated by a newly established cell cycle-independent pathway mediated by the physical interaction between Raf-1 and pRb. The phosphorylation of pRb plays an important role during the early stage of inner ear development, and attenuated phosphorylation in progenitor cells leads to cell cycle arrest and increased apoptosis along with a global down-regulation of the genes involved in cell cycle progression. Our study provides novel routes to modulate pRb function for hair cell regeneration