125 research outputs found

    Typical Scales in the Spatial Distribution of QSOs

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    We present results of searching for the possible typical scales in the spatial distribution of QSOs. Our method is based on the second derivative of the two-point correlation function. This statistic is sensitive to the scale of the maximum in the spectrum P(k)P(k) of the density perturbation in the universe. This maximum or bend scale can be detected as the wavelengths of the periodic component in the second derivative of the integral correlation function. For various QSO samples compiled from surveys of pencil-beam and bright QSOs, a typical scale of about 93 ±\pm 10 h1^{-1}Mpc for q0=0.5q_0=0.5 has been detected. This typical scale is in good agreement with that found in the spatial distributions of galaxies, clusters of galaxies, and CIV absorption systems of QSOs if q0q_0 is taken to be 0.2\sim 0.2. Therefore, it is likely a common or universal scale in the large scale structure traced by these objects. This result is consistent with the assumption that the typical scale comes from a characteristic scale in the spectrum of the density perturbation in the universe.Comment: 16 pages, 13 figures (available upon request), Latex, AZPH-TH/94-02, to appear in Ap.

    Enhanced thermopower in an intergrowth cobalt oxide Li0.48_{0.48}Na0.35_{0.35}CoO2_{2}

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    We report the measurements of thermopower, electrical resistivity and thermal conductivity in a complex cobalt oxide Li0.48_{0.48}Na0.35_{0.35}CoO2_{2}, whose crystal structure can be viewed as an intergrowth of the O3 phase of Lix_{x}CoO2_{2} and the P2 phase of Nay_{y}CoO2_{2} along the c axis. The compound shows large room-temperature thermopower of \sim180 μ\muV/K, which is substantially higher than those of Lix_{x}CoO2_{2} and Nay_{y}CoO2_{2}. The figure of merit for the polycrystalline sample increases rapidly with increasing temperature, and it achieves nearly 104^{-4} K1^{-1} at 300 K, suggesting that Lix_{x}Nay_{y}CoO2_{2} system is a promising candidate for thermoelectric applications.Comment: Submitted to AP

    Fully Automated Bone Age Assessment On Large-Scale Hand X-Ray Dataset

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    Bone age assessment (BAA) is an essential topic in the clinical practice of evaluating the biological maturity of children. Because the manual method is time-consuming and prone to observer variability, it is attractive to develop computer-aided and automated methods for BAA. In this paper, we present a fully automatic BAA method. To eliminate noise in a raw X-ray image, we start with using U-Net to precisely segment hand mask image from a raw X-ray image. Even though U-Net can perform the segmentation with high precision, it needs a bigger annotated dataset. To alleviate the annotation burden, we propose to use deep active learning (AL) to select unlabeled data samples with sufficient information intentionally. These samples are given to Oracle for annotation. After that, they are then used for subsequential training. In the beginning, only 300 data are manually annotated and then the improved U-Net within the AL framework can robustly segment all the 12611 images in RSNA dataset. The AL segmentation model achieved a Dice score at 0.95 in the annotated testing set. To optimize the learning process, we employ six off-the-shell deep Convolutional Neural Networks (CNNs) with pretrained weights on ImageNet. We use them to extract features of preprocessed hand images with a transfer learning technique. In the end, a variety of ensemble regression algorithms are applied to perform BAA. Besides, we choose a specific CNN to extract features and explain why we select that CNN. Experimental results show that the proposed approach achieved discrepancy between manual and predicted bone age of about 6.96 and 7.35 months for male and female cohorts, respectively, on the RSNA dataset. These accuracies are comparable to state-of-the-art performance

    Functional examination of novel kisspeptin phosphinic peptides

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    Kisspeptins acting on their cognate G protein-coupled receptor, kisspeptin receptor, play important roles in the suppression of cancer cell metastasis and regulation of the reproductive system, and therefore are important for therapeutic intervention. All native functional human kisspeptins (kisspeptin-54, kisspsptin-14 and kisspeptin-13) share the 10 amino acids of kisspeptin-10 at their C-terminus (45–54). However, they are inactivated rapidly by matrix metalloproteinases (MMPs) through the cleavage of the peptide bond between glycine51 and leucine52, which limits their clinical applications. Development of MMP-resistant analogues of kisspeptins may provide better therapeutic outputs. In the present study, two kisspeptin phosphinic peptides were designed and synthesized, and their ability to induce phosphorylation of ERK1/2 through kisspeptin receptor and their inhibition on MMP-2 and MMP-9 whose activity correlates with cancer metastasis were assessed. The results showed that one analogue, phosphinic kisspeptin R isomer (PKPR), exhibited kisspeptin receptor-agonistic activity and also inhibitory activity on MMP-2, indicating that PKPR may serve as a lead for the further development of kisspeptin analogues for therapeutic purpose

    Sub-percentage measure of distances to redshift of 0.1 by a new cosmic ruler

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    Distance-redshift diagrams probe expansion history of the Universe. We show that the stellar mass-binding energy (massE) relation of galaxies proposed in our previous study offers a new distance ruler at cosmic scales. By using elliptical galaxies in the main galaxy sample of the Sloan Digital Sky Survey Data Release 7, we construct a distance-redshift diagram over the redshift range from 0.05 to 0.2 with the massE ruler. The best-fit dark energy density is 0.675+-0.079 for flat Lambda-CDM, consistent with those by other probes. At the median redshift of 0.11, the median distance is estimated to have a fractional error of 0.34%, much lower than those by supernova (SN) Ia and baryonic acoustic oscillation (BAO) and even exceeding their future capability at this redshift. The above low-z measurement is useful for probing dark energy that dominates at the late Universe. For a flat dark energy equation of state model (flat wCDM), the massE alone constrains w to an error that is only a factor of 2.2, 1.7 and 1.3 times larger than those by BAO, SN Ia, and cosmic microwave background (CMB), respectively.Comment: 8 pages, 5 figures, MNRAS in press. The cosmoSIS modules for the massE ruler is at https://astronomy.nju.edu.cn/DFS//file/2022/07/02/20220702161632756vbde28.zi

    Experimental demonstration of picometer level signal extraction with time-delay interferometry technique

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    In this work, we have built an experimental setup to simulate the clock noise transmission with two spacecrafts and two optical links, and further demonstrated the extraction of picometer level signal drowned by the large laser frequency noise and clock noise with the data post-processing method. Laser frequency noise is almost eliminated by using the idea of time-delay interferometry (TDI) to construct an equal arm interferometer. Clock asynchronism and clock jitter noise are significantly suppressed by laser sideband transmitting the clock noise using an electro-optic modulator (EOM). Experimental results show a reduction in laser frequency noise by approximately 10^5 and clock noise by 10^2, recovering a weak displacement signal with an average amplitude about 60 picometer and period 1 second. This work has achieved the principle verification of the noise reduction function of TDI technique to some extent, serving the data processing research of space-borne gravitational wave detection

    Face Recognition Under Occlusions and Variant Expressions With Partial Similarity

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    Functional Ecological Gene Networks to Reveal the Changes Among Microbial Interactions Under Elevated Carbon Dioxide Conditions

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    Biodiversity and its responses to environmental changes is a central issue in ecology, and for society. Almost all microbial biodiversity researches focus on species richness and abundance but ignore the interactions among different microbial species/populations. However, determining the interactions and their relationships to environmental changes in microbial communities is a grand challenge, primarily due to the lack of information on the network structure among different microbial species/populations. Here, a novel random matrix theory (RMT)-based conceptual framework for identifying functional ecological gene networks (fEGNs) is developed with the high throughput functional gene array hybridization data from the grassland microbial communities in a long-term FACE (Free Air CO2 Enrichment) experiment. Both fEGNs under elevated CO2 (eCO2) and ambient CO2 (aCO2) possessed general characteristics of many complex systems such as scale-free, small-world, modular and hierarchical. However, the topological structure of the fEGNs is distinctly different between eCO2 and aCO2, suggesting that eCO2 dramatically altered the interactions among different microbial functional groups/populations. In addition, the changes in network structure were significantly correlated with soil carbon and nitrogen dynamics, and plant productivity, indicating the potential importance of network interactions in ecosystem functioning. Elucidating network interactions in microbial communities and their responses to environmental changes are fundamentally important for research in microbial ecology, systems microbiology, and global change

    Black holes regulate cold gas accretion in massive galaxies

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    Nearly every massive galaxy contains a supermassive black hole (BH) at its center. For decades, both theory and numerical simulations have indicated that BHs play a central role in regulating the growth and quenching of galaxies. Specifically, BH feedback by heating or blowing out the interstellar medium (ISM) serves as the groundwork for current models of massive galaxy formation. However, direct evidence for such an impact on the galaxy-wide ISM from BHs has only been found in some extreme objects. For general galaxy populations, it remains unclear whether and how BHs impact the ISM. Here based on a large sample of nearby galaxies with measurements of masses of both black holes and atomic hydrogen, the major component of cold ISM, we reveal that the atomic hydrogen content (fHI=MHI/Mf_{\rm HI} = M_{\rm HI}/M_{\star}) is tightly and anti-correlated with black hole mass (MBHM_{\rm BH}) with fHIMBHαf_{\rm HI} \propto M^{-\alpha}_{\rm BH} (α0.50.6\alpha \sim 0.5-0.6). This correlation is valid across five orders of magnitude in MBHM_{\rm BH}. Once this correlation is taken into account, fHIf_{\rm HI} loses dependence on other galactic parameters, demonstrating that MBHM_{\rm BH} serves as the primary driver of fHIf_{\rm HI}. These findings provide critical evidence for how the accumulated energy from BH accretion impacts galaxy-wide ISM, representing a crucial step forward in our understanding on the role of BHs in regulating the growth and quenching of massive galaxies.Comment: 24 pages, 7 figures. Submitted to Natur

    WordArt Designer: User-Driven Artistic Typography Synthesis using Large Language Models

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    This paper introduces WordArt Designer, a user-driven framework for artistic typography synthesis, relying on the Large Language Model (LLM). The system incorporates four key modules: the LLM Engine, SemTypo, StyTypo, and TexTypo modules. 1) The LLM Engine, empowered by the LLM (e.g., GPT-3.5), interprets user inputs and generates actionable prompts for the other modules, thereby transforming abstract concepts into tangible designs. 2) The SemTypo module optimizes font designs using semantic concepts, striking a balance between artistic transformation and readability. 3) Building on the semantic layout provided by the SemTypo module, the StyTypo module creates smooth, refined images. 4) The TexTypo module further enhances the design's aesthetics through texture rendering, enabling the generation of inventive textured fonts. Notably, WordArt Designer highlights the fusion of generative AI with artistic typography. Experience its capabilities on ModelScope: https://www.modelscope.cn/studios/WordArt/WordArt.Comment: Accepted by EMNLP 2023, 10 pages, 11 figures, 1 table, the system is at https://www.modelscope.cn/studios/WordArt/WordAr
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