631 research outputs found

    Robust Outdoor Vehicle Visual Tracking Based on k-Sparse Stacked Denoising Auto-Encoder

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    Robust visual tracking for outdoor vehicle is still a challenging problem due to large object appearance variations caused by illumination variation, occlusion, and fast motion. In this chapter, k-sparse constraint is added to the encoder part of stacked auto-encoder network to learn more invariant feature of object appearance, and a stacked k-sparse-auto-encoder–based robust outdoor vehicle tracking method under particle filter inference is further proposed to solve the problem of appearance variance during the tracking. Firstly, a stacked denoising auto-encoder is pre-trained to learn the generic feature representation. Then, a k-sparse constraint is added to the stacked denoising auto-encoder, and the encoder of k-sparse stacked denoising auto-encoder is connected with a classification layer to construct a classification neural network. Finally, confidence of each particle is computed by the classification neural network and is used for online tracking under particle filter framework. Comprehensive tracking experiments are conducted on a challenging single-object tracking benchmark. Experimental results show that our tracker outperforms most state-of-the-art trackers

    Landau level crossing in a spin-orbit coupled two-dimensional electron gas

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    We have studied experimentally theᅠLandau levelᅠ(LL) spectrum of a two-dimensionalᅠelectron gasᅠ(2DEG)ᅠin an In0.53Ga0.47As/InPᅠquantum wellᅠstructure by means of low-temperature magneto-transport coincidence measurement in vectorᅠmagnetic fields.ᅠIt is well known that LL crossing occurs in tiltedᅠmagnetic fieldsᅠdue to a competition between cyclotron energy andᅠZeeman effect.ᅠRemarkably, here we observe an additional type of level-crossing resulting from a competition between Rashba andᅠZeeman splittingᅠin a smallᅠmagnetic field,ᅠconsistent with theᅠtheoreticalᅠprediction for strongly spin-orbit coupledᅠ2DEG

    W-exchange and W-annihilation processes of B mesons

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    Using the PQCD method we calculate the W-exchange and the W-annihilation processes of B mesons, which in general involve a charm quark or anti-quark in the final state. The nonvanishing amplitudes of these processes are found to be suppressed by a factor of mc/mbm_c/m_b compared to the tree or the time-like penguin processes, but some of them are within the reach of observation at the future B-factories, and Bˉd0Ds+K\bar B_d^0 \to D^+_s K^- whose branching ratio is found to be 6.6×1066.6 \times 10^{-6} can be found even before the B-factory era. Comparisons with the results based on the BSW model are also given.Comment: 11 Pages including figures, accepted in Phys. Lett.

    Site-specific selection reveals selective constraints and functionality of tumor somatic mtDNA mutations.

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    BACKGROUND: Previous studies have indicated that tumor mitochondrial DNA (mtDNA) mutations are primarily shaped by relaxed negative selection, which is contradictory to the critical roles of mtDNA mutations in tumorigenesis. Therefore, we hypothesized that site-specific selection may influence tumor mtDNA mutations. METHODS: To test our hypothesis, we developed the largest collection of tumor mtDNA mutations to date and evaluated how natural selection shaped mtDNA mutation patterns. RESULTS: Our data demonstrated that both positive and negative selections acted on specific positions or functional units of tumor mtDNAs, although the landscape of these mutations was consistent with the relaxation of negative selection. In particular, mutation rate (mutation number in a region/region bp length) in complex V and tRNA coding regions, especially in ATP8 within complex V and in loop and variable regions within tRNA, were significantly lower than those in other regions. While the mutation rate of most codons and amino acids were consistent with the expectation under neutrality, several codons and amino acids had significantly different rates. Moreover, the mutations under selection were enriched for changes that are predicted to be deleterious, further supporting the evolutionary constraints on these regions. CONCLUSION: These results indicate the existence of site-specific selection and imply the important role of the mtDNA mutations at some specific sites in tumor development

    Quantifying and Attributing the Hallucination of Large Language Models via Association Analysis

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    Although demonstrating superb performance on various NLP tasks, large language models (LLMs) still suffer from the hallucination problem, which threatens the reliability of LLMs. To measure the level of hallucination of LLMs, previous works first categorize the hallucination according to the phenomenon similarity, then quantify the proportion that model outputs contain hallucinatory contents. However, such hallucination rates could easily be distorted by confounders. Moreover, such hallucination rates could not reflect the reasons for the hallucination, as similar hallucinatory phenomena may originate from different sources. To address these issues, we propose to combine the hallucination level quantification and hallucination reason investigation through an association analysis, which builds the relationship between the hallucination rate of LLMs with a set of risk factors. In this way, we are able to observe the hallucination level under each value of each risk factor, examining the contribution and statistical significance of each risk factor, meanwhile excluding the confounding effect of other factors. Additionally, by recognizing the risk factors according to a taxonomy of model capability, we reveal a set of potential deficiencies in commonsense memorization, relational reasoning, and instruction following, which may further provide guidance for the pretraining and supervised fine-tuning process of LLMs to mitigate the hallucination

    A quantitative approach to shortening the levator palpebrae superioris to correct congenital ptosis in children

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    AIM:To develop a feasible method to correct congenital ptosis in children.METHODS: Sixty-four patients(102 eyelids)were divided into three groups based on the degree of ptosis: mild(4 mm). All patients underwent the same levator resection surgery in which the suspensory system of the LPS is retained. After capturing a standard photograph of primary position, the height of the superior palpebral margin was measured preoperatively by using Image J software to calculate its ideal height required during surgery. Postoperative outcome measures included upper eyelid margin height, degree of scleral exposure and exposure keratitis. The patients were followed-up at 1wk, 1mo and 6mo postoperatively.RESULTS: In the early postoperative period, except two cases with overcorrection, the positions of the eyelid upper margins were normal in all cases in the mild and moderate groups. Six months postoperatively, the eye with overcorrection in the moderate group showed improvement, while the eye in the mild group did not. Seven eyes in the severe group exhibited residual ptosis to varying degrees. The eyelids exhibited appropriate closing functionality; exposure keratitis was absent.CONCLUSION:Using this preoperative quantification technique to guide surgery not only provided a gauge for LPS shortening under general anesthesia, but also increased the success rate of surgery

    A protocol specialized for microbial DNA extraction from living poplar wood

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    Microbial DNA extraction is a critical step in metagenomic research. High contents of chemical substances in wood tissues always cause low microbial DNA yield and quality. Up to date, almost no specialized methods involved in microbial DNA extraction from living wood were reported. In this study, an improved protocol (M1) concerning microbial DNA extraction from living poplar wood was developed. We compared microbial DNA yield and quality by M1 with those by other seven methods, including PowerSoil DNA isolation kit (M2), two soil microbial DNA extraction methods (M3 and M4), poplar genomic DNA extraction method from wood (M5), and microbial DNA extraction method from herb stems (M6), isolating bacteria (M7) and isolating fungus (M8). Results showed that M1 yielded much better quality and concentration of microbial DNA than the other methods (M2-M8) from both poplar wetwood and sapwood tissues. Following M1 protocol, 1 g of wetwood sample could yield 272.27 ng/ul (vol=50 ul) pure microbial DNA with the absorption ratios of 1.87 (A260/A230) and 1.66 (A260/A280). For 1 g of sapwood sample, these values were 361.83 ng/ul, 1.85 and 2.24, respectively. These DNA could be stably visualized by agarose gel electrophoresis and amplified by primer sets of bacteria (16S V3-V4, 16S-V4, 16S V4-V5) and fungus (ITS1, ITS2). While, the other seven methods only obtained less or contaminated microbial DNA, which could not be amplified stably by aforementioned primer sets. Our protocol provided an approach for microbial community study in living poplar wood in a more accurate way by molecular biology techniques

    Deep Spatio-Temporal Neural Networks for Click-Through Rate Prediction

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    Click-through rate (CTR) prediction is a critical task in online advertising systems. A large body of research considers each ad independently, but ignores its relationship to other ads that may impact the CTR. In this paper, we investigate various types of auxiliary ads for improving the CTR prediction of the target ad. In particular, we explore auxiliary ads from two viewpoints: one is from the spatial domain, where we consider the contextual ads shown above the target ad on the same page; the other is from the temporal domain, where we consider historically clicked and unclicked ads of the user. The intuitions are that ads shown together may influence each other, clicked ads reflect a user's preferences, and unclicked ads may indicate what a user dislikes to certain extent. In order to effectively utilize these auxiliary data, we propose the Deep Spatio-Temporal neural Networks (DSTNs) for CTR prediction. Our model is able to learn the interactions between each type of auxiliary data and the target ad, to emphasize more important hidden information, and to fuse heterogeneous data in a unified framework. Offline experiments on one public dataset and two industrial datasets show that DSTNs outperform several state-of-the-art methods for CTR prediction. We have deployed the best-performing DSTN in Shenma Search, which is the second largest search engine in China. The A/B test results show that the online CTR is also significantly improved compared to our last serving model.Comment: Accepted by KDD 201

    Experimental test of the Jarzynski equality in a single spin-1 system using high-fidelity single-shot readouts

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    The Jarzynski equality (JE), which connects the equilibrium free energy with non-equilibrium work statistics, plays a crucial role in quantum thermodynamics. Although practical quantum systems are usually multi-level systems, most tests of the JE were executed in two-level systems. A rigorous test of the JE by directly measuring the work distribution of a physical process in a high-dimensional quantum system remains elusive. Here, we report an experimental test of the JE in a single spin-1 system. We realized nondemolition projective measurement of this three-level system via cascading high-fidelity single-shot readouts and directly measured the work distribution utilizing the two-point measurement protocol. The validity of the JE was verified from the non-adiabatic to adiabatic zone and under different effective temperatures. Our work puts the JE on a solid experimental foundation and makes the NV center system a mature toolbox to perform advanced experiments of stochastic quantum thermodynamics

    The prognostic value of Foxp3+ tumor-infiltrating lymphocytes in patients with glioblastoma

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    Forkhead box protein 3 (Foxp3) is known as a specific marker for regulatory T cells which contribute to immunosuppression in tumor microenvironment. However, existing studies regarding clinical significance of Foxp3+ tumor-infiltrating lymphocytes (TILs) in glioblastoma (GBM) remained discrepant. In this study, we aimed to explore whether this subtype of TILs correlated with prognosis in patients with GBM. Foxp3+ TILs as well as CD8+ ones were detected by immunohistochemistry on paraffin-embedded tumor samples from 62 patients. Staining for p53, MGMT and Ki-67 were also performed. The correlation of TIL subtypes with clinicopathologic features were analyzed. Progression-free survival (PFS) and overall survival (OS) were estimated by Kaplan–Meier method and compared using log-rank test. Independent prognostic factors for PFS and OS were determined through univariate and multivariate analysis. Significant correlation was found between Foxp3 and CD8 expression (P = 0.003), but not between TIL subtypes and clinicopathologic characteristics. Patients with higher density of Foxp3+ TILs showed relatively shorter PFS (P < 0.001) and OS (P = 0.003) whereas patients with higher density of CD8+ TILs obtained no significant differences in survival. Survival analysis based on molecular classifications further clarified these predictive values. Univariate and multivariate analysis revealed that frequency of Foxp3+ TILs was probably associated with both PFS (P = 0.002) and OS (P = 0.003). In conclusion, the results suggest that Foxp3 positive infiltrates could provide an independent predictive factor in GBM. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11060-013-1314-0) contains supplementary material, which is available to authorized users
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