2,538 research outputs found

    Heterogeneous Trajectory Forecasting via Risk and Scene Graph Learning

    Full text link
    Heterogeneous trajectory forecasting is critical for intelligent transportation systems, while it is challenging because of the difficulty for modeling the complex interaction relations among the heterogeneous road agents as well as their agent-environment constraint. In this work, we propose a risk and scene graph learning method for trajectory forecasting of heterogeneous road agents, which consists of a Heterogeneous Risk Graph (HRG) and a Hierarchical Scene Graph (HSG) from the aspects of agent category and their movable semantic regions. HRG groups each kind of road agents and calculates their interaction adjacency matrix based on an effective collision risk metric. HSG of driving scene is modeled by inferring the relationship between road agents and road semantic layout aligned by the road scene grammar. Based on this formulation, we can obtain an effective trajectory forecasting in driving situations, and superior performance to other state-of-the-art approaches is demonstrated by exhaustive experiments on the nuScenes, ApolloScape, and Argoverse datasets.Comment: Submitted to IEEE Transactions on Intelligent Transportation Systems, 202

    Dense GeV electron–positron pairs generated by lasers in near-critical-density plasmas

    Get PDF
    Pair production can be triggered by high intensity lasers via the Breit-Wheeler process. However, the straightforward laser-laser colliding for copious numbers of pair creation requires light intensities several orders of magnitude higher than possible with the ongoing laser facilities. Despite the numerous proposed approaches, creating high-energy-density pair plasmas in laboratories is still challenging. Here we present an all-optical scheme for overdense pair production by two counter-propagating lasers irradiating near-critical-density plasmas at only ~1022W cm-2. In this scheme, bright γ-rays are generated by radiation-trapped electrons oscillating in the laser fields. The dense γ-photons then collide with the focused counter-propagating lasers to initiate the multi-photon Breit-Wheeler process. Particle-in-cell simulations indicate that one may generate a high-yield (1.05×1011) overdense (4×1022 cm-3 ) GeV positron beam using 10 PW scale lasers. Such a bright pair source has many practical applications and could be basis for future compact high luminosity electron-positron colliders

    Do Dose-Dependent Microbial Changes Occur during Spine Surgery as a Result of Applying Intrawound Vancomycin Powder?: A Systematic Literature Review

    Get PDF
    We analyzed dose-dependent effects of vancomycin on wound infection bacteria and investigated the relationship between dose and microbial imbalances in patients treated with intrawound vancomycin powder during spine surgery. Numerous trials have confirmed that using intrawound vancomycin powder during spine surgery may decrease postoperative wound infection rates. However, potential risks include changes in wound infection bacteria, inhibition of bone fusion, and systemic toxicity. We searched PubMed for articles published since October 2016 with the following terms: “local vancomycin” or “intrawound vancomycin” or “intraoperative vancomycin” or “intrawound vancomycin” or “topical vancomycin” and “spinal surgery” or “spine surgery.” We also screened the reference lists of included articles for additional studies and extracted data related to dose, infecting bacteria, sample size, infection rate and types, location of spine surgery, and perioperative antibiotics used. Our review includes one prospective and nine retrospective studies. Overall, 1 or 2 g local vancomycin powder was used in 2,394 patients. Gram-negative bacteria were dominant in patients in whom 1 g vancomycin powder was used, whereas gram-positive bacteria were dominant in those in whom 2 g powder was used. The exact mechanism underlying this dose-dependent trend remains unclear, although it may be attributed to the pharmacological characteristics of vancomycin. The included studies showed that trends in infection bacteria may change after the use of topical vancomycin powder. In addition, the observed increase in gram-negative bacteria when intrawound vancomycin powder is used has generated considerable attention. The present results differ from previous results but do not provide additional information regarding vancomycin dose and microbial changes in infected wounds. Additional large randomized controlled trials are needed to determine the relationship between vancomycin dose and the types of wound infection bacteria in patients treated with intrawound vancomycin powder during spine surgery

    Latest Cosmological Constraints on Cardassian expansion models including the updated Gamma-ray bursts

    Full text link
    In this paper, we constrain the Cardassian expansion models from the latest observations including the updated Gamma-ray bursts (GRBs), which calibrated cosmology-independently from the Union2 compilation of type Ia supernovae (SNe Ia). By combining the GRB data to the joint observations with the Union2 SNe Ia set, along with the Cosmic Microwave Background radiation observation from the seven-year Wilkinson Microwave Anisotropy Probe result, the baryonic acoustic oscillation observation from the spectroscopic Sloan Digital Sky Survey Data Release galaxy sample, we find significant constraints on model parameters of the original Cardassian model ΩM0=0.2820.014+0.015\Omega_{{\rm M0}}=0.282_{-0.014}^{+0.015}, n=0.030.05+0.05n= 0.03_{-0.05}^{+0.05}; and n=0.163.26+0.25n= -0.16_{-3.26}^{+0.25}, β=0.760.58+0.34\beta=0.76_{-0.58}^{+0.34} of the modified polytropic Cardassian model, which are consistent with the Λ\LambdaCDM model in 1-σ\sigma confidence region. From the reconstruction of the deceleration parameter q(z)q(z) in Cardassian models, we obtain the transition redshift zT=0.73±0.04z_{\rm T}=0.73\pm{0.04} for the original Cardassian model, and zT=0.68±0.04z_{\rm\rm T}=0.68\pm{0.04} for the modified polytropic Cardassian model.Comment: 11 pages, 5 figures, 1 table; accepted for publication in Res. Astron. Astrophy

    HAb18G/CD147 cell-cell contacts confer resistance of a HEK293 subpopulation to anoikis in an E-cadherin-dependent manner

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Acquisition of resistance to "anoikis" facilitates the survival of cells under independent matrix-deficient conditions, such as cells in tumor progression and the production of suspension culture cells for biomedical engineering. There is evidence suggesting that CD147, an adhesion molecule associated with survival of cells in tumor metastasis and cell-cell contacts, plays an important role in resistance to anoikis. However, information regarding the functions of CD147 in mediating cell-cell contacts and anoikis-resistance remains limited and even self-contradictory.</p> <p>Results</p> <p>An anoikis-resistant clone (HEK293ar), derived from anoikis-sensitive parental Human Embryonic Kidney 293 cells, survived anoikis by the formation of cell-cell contacts. The expression of HAb18G/CD147 (a member of the CD147 family) was upregulated and the protein was located at cell-cell junctions. Upregulation of HAb18G/CD147 in suspended HEK293ar cells suppressed anoikis by mediating the formation of cell-cell adhesions. Anoikis resistance in HEK293ar cells also required E-cadherin-mediated cell-cell contacts. Knock-down of HAb18G/CD147 and E-cadherin inhibited cell-cell contacts formation and increased anoikis sensitivity respectively. When HAb18G/CD147 was downregulated, E-cadherin expression in HEK293ar cells was significantly suppressed; however, knockdown of E-cadherin by E-cadherin siRNA or blocking of E-cadherin binding activity with a specific antibody and EDTA had no significant effect on HAb18G/CD147 expression. Finally, pretreatment with LY294002, a phosphoinositide 3-kinase (PI3K/AKT) inhibitor, disrupted cell-cell contacts and decreased cell number, but this was not the case in cells treated with the extracellular signal-regulated kinase (ERK) inhibitor PD98059.</p> <p>Conclusions</p> <p>Our results provide new evidence that HAb18G/CD147-mediated cell-cell contact confers anoikis resistance in an E-cadherin-dependent manner; and cell-cell contact mediated resistance to anoikis implicates PI3K pathway in a highly relevant cell model (HEK293ar). Understanding of the role of HAb18G/CD147 cell-cell contacts in anoikis resistance may help in understanding the survival of cells in anchorage-independent growth, such as cells in tumor metastasis and suspension culture produced for biomedical engineering. Our results also contribute to a better understanding of the biology of HEK293 cell spheroids, a major workhorse for producing human therapeutic agents and viral vaccines.</p

    Molecular Etiology of Hearing Impairment in Inner Mongolia: mutations in SLC26A4 gene and relevant phenotype analysis

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>The molecular etiology of hearing impairment in Chinese has not been thoroughly investigated. Study of <it>GJB2 </it>gene revealed that 30.4% of the patients with hearing loss in Inner Mongolia carried <it>GJB2 </it>mutations. The <it>SLC26A4 </it>gene mutations and relevant phenotype are analyzed in this study.</p> <p>Methods</p> <p>One hundred and thirty-five deaf patients were included. The coding exons of <it>SLC26A4 </it>gene were sequence analyzed in 111 patients, not including 22 patients carrying bi-allelic <it>GJB2 </it>mutations or one patient carrying a known <it>GJB2 </it>dominant mutation as well as one patient with <it>mtDNA </it>1555A>G mutation. All patients with <it>SLC26A4 </it>mutations or variants were subjected to high resolution temporal bone CT scan and those with confirmed enlarged vestibular aqueduct and/or other inner ear malformation were then given further ultrasound scan of thyroid and thyroid hormone assays.</p> <p>Results</p> <p>Twenty-six patients (19.26%, 26/135) were found carrying <it>SLC26A4 </it>mutation. Among them, 17 patients with bi-allelic <it>SLC26A4 </it>mutations were all confirmed to have EVA or other inner ear malformation by CT scan. Nine patients were heterozygous for one <it>SLC26A4 </it>mutation, including 3 confirmed to be EVA or EVA and Mondini dysplasia by CT scan. The most common mutation, IVS7-2A>G, accounted for 58.14% (25/43) of all <it>SLC26A4 </it>mutant alleles. The shape and function of thyroid were confirmed to be normal by thyroid ultrasound scan and thyroid hormone assays in 19 of the 20 patients with EVA or other inner ear malformation except one who had cystoid change in the right side of thyroid. No Pendred syndrome was diagnosed.</p> <p>Conclusion</p> <p>In Inner Mongolia, China, mutations in <it>SLC26A4 </it>gene account for about 12.6% (17/135) of the patients with hearing loss. Together with <it>GJB2 </it>(23/135), <it>SLC26A4 </it>are the two most commonly mutated genes causing deafness in this region. Pendred syndrome is not detected in this deaf population. We established a new strategy that detects <it>SLC26A4 </it>mutations prior to the temporal bone CT scan to find EVA and inner ear malformation patients. This model has a unique advantage in epidemiologic study of large deaf population.</p

    Generation of GeV positron and γ-photon beams with controllable angular momentum by intense lasers

    Get PDF
    Although several laser–plasma-based methods have been proposed for generating energetic electrons, positrons and γ-photons, manipulation of their microstructures is still challenging, and their angular momentum control has not yet been achieved. Here, we present and numerically demonstrate an all-optical scheme to generate bright GeV γ-photon and positron beams with controllable angular momentum by use of two counter-propagating circularly-polarized lasers in a near-critical-density plasma. The plasma acts as a 'switching medium', where the trapped electrons first obtain angular momentum from the drive laser pulse and then transfer it to the γ-photons via nonlinear Compton scattering. Further through the multiphoton Breit–Wheeler process, dense energetic positron beams are efficiently generated, whose angular momentum can be well controlled by laser–plasma interactions. This opens up a promising and feasible way to produce ultra-bright GeV γ-photons and positron beams with desirable angular momentum for a wide range of scientific research and applications
    corecore