70 research outputs found

    Counting hypergraph matchings up to uniqueness threshold

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    We study the problem of approximately counting matchings in hypergraphs of bounded maximum degree and maximum size of hyperedges. With an activity parameter λ\lambda, each matching MM is assigned a weight λ∣M∣\lambda^{|M|}. The counting problem is formulated as computing a partition function that gives the sum of the weights of all matchings in a hypergraph. This problem unifies two extensively studied statistical physics models in approximate counting: the hardcore model (graph independent sets) and the monomer-dimer model (graph matchings). For this model, the critical activity λc=ddk(d−1)d+1\lambda_c= \frac{d^d}{k (d-1)^{d+1}} is the threshold for the uniqueness of Gibbs measures on the infinite (d+1)(d+1)-uniform (k+1)(k+1)-regular hypertree. Consider hypergraphs of maximum degree at most k+1k+1 and maximum size of hyperedges at most d+1d+1. We show that when λ<λc\lambda < \lambda_c, there is an FPTAS for computing the partition function; and when λ=λc\lambda = \lambda_c, there is a PTAS for computing the log-partition function. These algorithms are based on the decay of correlation (strong spatial mixing) property of Gibbs distributions. When λ>2λc\lambda > 2\lambda_c, there is no PRAS for the partition function or the log-partition function unless NP==RP. Towards obtaining a sharp transition of computational complexity of approximate counting, we study the local convergence from a sequence of finite hypergraphs to the infinite lattice with specified symmetry. We show a surprising connection between the local convergence and the reversibility of a natural random walk. This leads us to a barrier for the hardness result: The non-uniqueness of infinite Gibbs measure is not realizable by any finite gadgets

    On the Importance of Accurate Geometry Data for Dense 3D Vision Tasks

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    Learning-based methods to solve dense 3D vision problems typically train on 3D sensor data. The respectively used principle of measuring distances provides advantages and drawbacks. These are typically not compared nor discussed in the literature due to a lack of multi-modal datasets. Texture-less regions are problematic for structure from motion and stereo, reflective material poses issues for active sensing, and distances for translucent objects are intricate to measure with existing hardware. Training on inaccurate or corrupt data induces model bias and hampers generalisation capabilities. These effects remain unnoticed if the sensor measurement is considered as ground truth during the evaluation. This paper investigates the effect of sensor errors for the dense 3D vision tasks of depth estimation and reconstruction. We rigorously show the significant impact of sensor characteristics on the learned predictions and notice generalisation issues arising from various technologies in everyday household environments. For evaluation, we introduce a carefully designed dataset\footnote{dataset available at https://github.com/Junggy/HAMMER-dataset} comprising measurements from commodity sensors, namely D-ToF, I-ToF, passive/active stereo, and monocular RGB+P. Our study quantifies the considerable sensor noise impact and paves the way to improved dense vision estimates and targeted data fusion.Comment: Accepted at CVPR 2023, Main Paper + Supp. Mat. arXiv admin note: substantial text overlap with arXiv:2205.0456

    Updating systematic reviews can improve the precision of outcomes: a comparative study

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    Objectives: The objective of this study was to investigate the main characteristics and the precision of outcomes between updated and original systematic reviews (SRs). Study Design and Setting: We searched PubMed and Embase.com on 31 March 2019 and included 30 pairs of updated and original SRs. We calculated changes in outcomes and the precision of effect size estimates in updated SRs, compared with original SRs. Review Manager 5.3 software was adopted to create forest plots showing comparable outcomes. Results: The average update time was 56.0 months, and incorporating new trials (23 SRs, 76.7%) was the main reason for the update. Compared with original SRs, 24 (80.0%) updated SRs included more randomized controlled trials and 22 (73.3%) updated SRs involved a larger number of patients. Of the 130 comparable outcomes, only three (2.3%) outcomes were observed with a significant change in three SR updates. No new data from randomized controlled trials were added to 36 (27.7%) outcomes during the update process. Of the 94 outcomes including new evidence, 83 (88.3%) showed an improvement in precision, 5 (5.3%) showed a decrease in precision, and 6 (6.4%) did not exhibit changes in precision. Conclusion: Updating SRs could increase the precision of most comparable outcomes, although the conclusions of almost all updated SRs were similar to original SRs

    Methodological and reporting quality in non-Cochrane systematic review updates could be improved: a comparative study

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    Objectives: To compare the methodological and reporting quality of updated systematic reviews (SRs) and original SRs. Study Design and Setting: We included 30 pairs of non-Cochrane updated and original SRs, identified from a search of PubMed and Embase.com. We used AMSTAR 2 to assess methodological quality and PRISMA for reporting quality. Stratified analyses were conducted to compare the differences between updated SRs and original SRs and explore factors that might affect the degree of quality change. Results: Of the 60 non-Cochrane SRs, only 2 (3.3%) were of low quality, the remaining 58 (96.7%) were of critical low quality. There were no statistically significant differences in methodological quality between the updated SRs and original SRs, although the compliance rates of 8 items of updated SRs were higher than that of original SRs. Updated SRs showed an improvement on 15 PRISMA items, but no items with statistically significant differences. The differences in fully reported AMSTAR 2 and PRISMA items between original SRs and updated SRs were also not statistically significant after adjusting for multiple review characteristics. Conclusions: The methodological and reporting quality of updated SRs were not improved compared with original SRs, although the quality could be further improved for both updated SRs and original SRs

    Biological and genomic analysis of a symbiotic nitrogen fixation defective mutant in Medicago truncatula

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    Medicago truncatula has been selected as one of the model legume species for gene functional studies. To elucidate the functions of the very large number of genes present in plant genomes, genetic mutant resources are very useful and necessary tools. Fast Neutron (FN) mutagenesis is effective in inducing deletion mutations in genomes of diverse species. Through this method, we have generated a large mutant resource in M. truncatula. This mutant resources have been used to screen for different mutant using a forward genetics methods. We have isolated and identified a large amount of symbiotic nitrogen fixation (SNF) deficiency mutants. Here, we describe the detail procedures that are being used to characterize symbiotic mutants in M. truncatula. In recent years, whole genome sequencing has been used to speed up and scale up the deletion identification in the mutant. Using this method, we have successfully isolated a SNF defective mutant FN007 and identified that it has a large segment deletion on chromosome 3. The causal deletion in the mutant was confirmed by tail PCR amplication and sequencing. Our results illustrate the utility of whole genome sequencing analysis in the characterization of FN induced deletion mutants for gene discovery and functional studies in the M. truncatula. It is expected to improve our understanding of molecular mechanisms underlying symbiotic nitrogen fixation in legume plants to a great extent

    The Chinese pine genome and methylome unveil key features of conifer evolution

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    Conifers dominate the world's forest ecosystems and are the most widely planted tree species. Their giant and complex genomes present great challenges for assembling a complete reference genome for evolutionary and genomic studies. We present a 25.4-Gb chromosome-level assembly of Chinese pine (Pinus tabuliformis) and revealed that its genome size is mostly attributable to huge intergenic regions and long introns with high transposable element (TE) content. Large genes with long introns exhibited higher expressions levels. Despite a lack of recent whole-genome duplication, 91.2% of genes were duplicated through dispersed duplication, and expanded gene families are mainly related to stress responses, which may underpin conifers' adaptation, particularly in cold and/or arid conditions. The reproductive regulation network is distinct compared with angiosperms. Slow removal of TEs with high-level methylation may have contributed to genomic expansion. This study provides insights into conifer evolution and resources for advancing research on conifer adaptation and development

    1st Workshop on Maritime Computer Vision (MaCVi) 2023: Challenge Results

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    The 1st^{\text{st}} Workshop on Maritime Computer Vision (MaCVi) 2023 focused on maritime computer vision for Unmanned Aerial Vehicles (UAV) and Unmanned Surface Vehicle (USV), and organized several subchallenges in this domain: (i) UAV-based Maritime Object Detection, (ii) UAV-based Maritime Object Tracking, (iii) USV-based Maritime Obstacle Segmentation and (iv) USV-based Maritime Obstacle Detection. The subchallenges were based on the SeaDronesSee and MODS benchmarks. This report summarizes the main findings of the individual subchallenges and introduces a new benchmark, called SeaDronesSee Object Detection v2, which extends the previous benchmark by including more classes and footage. We provide statistical and qualitative analyses, and assess trends in the best-performing methodologies of over 130 submissions. The methods are summarized in the appendix. The datasets, evaluation code and the leaderboard are publicly available at https://seadronessee.cs.uni-tuebingen.de/macvi.Comment: MaCVi 2023 was part of WACV 2023. This report (38 pages) discusses the competition as part of MaCV

    31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

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    Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

    Leaf Functional Traits and Relationships with Soil Properties of Zanthoxylum planispinum &lsquo;dintanensis&rsquo; in Plantations of Different Ages

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    To explore the changes of leaf functional traits of Zanthoxylum planispinum &lsquo;dintanensis&rsquo; with growth and development and its relationship with soil properties, which can clarify the response of the plantation to soil properties and suitable strategy. The research results can provide a scientific basis for plantations management. We explored the response of leaf functional traits to soil by using redundancy analysis in 5&ndash;7-, 10&ndash;12-, 20&ndash;22-, and 28&ndash;32-year Z. planispinum &lsquo;dintanensis&rsquo; plantations. The results showed that: (1) The coefficients of variation of leaf traits ranged from 0.41% to 39.51%, with mostly medium and low variation, with the lowest variability in leaf water content (0.51&ndash;0.85%); The 5&ndash;7, 10&ndash;12, 20&ndash;22-year-old plantations were laid at the &ldquo;slow investment-return&rdquo; end of the economic spectrum while 28&ndash;32-year plantations were close to &ldquo;fast investment-return&rdquo; end. (2) The Z. planispinum &lsquo;dintanensis&rsquo; tended to suit the environment via making trade-off and coordination of leaf functional traits. Leaf dry matter content decreased with an increase in leaf carbon/leaf nitrogen ratio, which is the trade-off between nitrogen usage efficiency and nutrient fixation capacity in Z. planispinum &lsquo;dintanensis&rsquo;. (3) Redundancy analysis suggested that soil carbon/nitrogen ratio, soil total calcium, soil water content, soil available phosphorus, soil carbon/calcium ratio were highly correlated with leaf functional traits, while soil elemental stoichiometry had a greater reflection on leaf functional traits than their own content

    Ultra-Wideband Imaging via Frequency Diverse Array with Low Sampling Rate

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    Imaging systems based on millimeter waves (mm-waves) are advancing to achieve higher resolution and wider bandwidth. However, a large bandwidth requires high sample rates, which may limit the development of ultra-wideband imaging systems. In this letter, we introduce the concept of frequency diverse array (FDA) into mm-wave imaging systems. In particular, we propose an ultra-wideband imaging method based on the FDA configuration to reduce sampling rates. In the proposed method, the required sampling rate of an imaging system with N transmit elements is only one-Nth of the conventional systems. Hence, the proposed method can significantly reduce the sampling rate. Unlike compressed-sensing-based sampling methods, the proposed method does not require repeated observations, and is easier to implement. Thanks to the FDA concept, the proposed method can scan the space without phase-shifters or rotation of antennas. We perform matched filtering process in the frequency domain to obtain frequency-delay-dependent vectors. By discretizing the scene, we establish a dictionary covering the imaging scene. Accordingly, a convex optimization problem with measured results and the dictionary based on sparse reconstruction are formulated to realize super-resolution imaging. Compared to conventional methods, the proposed method can distinguish smaller target intervals with low sampling rate in an easy-to-implement way. The proposed method provides a different perspective for the development of ultra-wideband imaging systems
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