130 research outputs found

    Neural Dependencies Emerging from Learning Massive Categories

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    This work presents two astonishing findings on neural networks learned for large-scale image classification. 1) Given a well-trained model, the logits predicted for some category can be directly obtained by linearly combining the predictions of a few other categories, which we call \textbf{neural dependency}. 2) Neural dependencies exist not only within a single model, but even between two independently learned models, regardless of their architectures. Towards a theoretical analysis of such phenomena, we demonstrate that identifying neural dependencies is equivalent to solving the Covariance Lasso (CovLasso) regression problem proposed in this paper. Through investigating the properties of the problem solution, we confirm that neural dependency is guaranteed by a redundant logit covariance matrix, which condition is easily met given massive categories, and that neural dependency is highly sparse, implying that one category correlates to only a few others. We further empirically show the potential of neural dependencies in understanding internal data correlations, generalizing models to unseen categories, and improving model robustness with a dependency-derived regularizer. Code for this work will be made publicly available

    Linear Positional Isomer Sorting in Nonporous Adaptive Crystals of a Pillar[5]arene

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    Here we show a new adsorptive separation approach using nonporous adaptive crystals of a pillar[5]­arene. Desolvated perethylated pillar[5]­arene crystals (<b>EtP5</b>α) with a nonporous character selectively adsorb 1-pentene (<b>1-Pe</b>) over its positional isomer 2-pentene (<b>2-Pe</b>), leading to a structural change from <b>EtP5</b>α to <b>1-Pe</b> loaded structure (<b>1-Pe</b>@<b>EtP5</b>). The purity of <b>1-Pe</b> reaches 98.7% in just one cycle and <b>EtP5</b>α can be reused without losing separation performance

    Upregulated expression of MNX1-AS1 long noncoding RNA predicts poor prognosis in gastric cancer

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    As important regulators of gene expression long noncoding RNAs (lncRNAs) are implicated in various physiological and pathological processes, including cancer. An oncogenic role of MNX1 antisense RNA 1 (MNX1-AS1) lncRNA has been suggested in cervical cancer and glioblastoma. In this study, we investigated the clinicopathological significance and biological function of MNX1-AS1 in gastric cancer (GC). The expression of MNX1-AS1 was analyzed by qRT-PCR in 96 GC and adjacent non-tumor tissues in relation to clinicopathological features and overall survival (OS) of patients, and in five human GC cell lines compared to a normal gastric epithelial cell line. Loss-of-function experiments using small interfering RNA (siRNA) targeting MNX1-AS1 (si-MNX1-AS1) were carried out in AGS and MGC-803 GC cell lines. Cell proliferation (CCK-8 assay), migration (Transwell) and invasion (Transwell Matrigel), and protein expression of proliferating cell nuclear antigen (PCNA), E-cadherin, N-cadherin, vimentin and matrix metallopeptidase 9 (MMP-9) were analyzed in transfected GC cells. Expression of MNX1-AS1 was significantly higher in GC vs. adjacent non-tumor tissues. Higher MNX1-AS1 expression was significantly associated with tumor size, TNM stage and lymph node metastasis. Kaplan–Meier analysis showed that GC patients with higher MNX1-AS1 expression had worse OS compared to patients with lower MNX1-AS1 expression. Multivariate analysis showed that MNX1-AS1 is an independent poor prognostic factor in GC. Knockdown of MNX1-AS1 significantly inhibited proliferation, migration and invasion of AGS and MGC-803 cells, and resulted in increased E-cadherin and decreased PCNA, N-cadherin, vimentin and MMP-9 expression. Taken together, these results suggest that MNX1-AS1 has an oncogenic function in GC and potential as a molecular target in GC therapy

    Solar-Driven H_2O_2 Generation From H_2O and O_2 Using Earth-Abundant Mixed-Metal Oxide@Carbon Nitride Photocatalysts

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    Light-driven generation of H_2O_2 only from water and molecular oxygen could be an ideal pathway for clean production of solar fuels. In this work, a mixed metal oxide/graphitic-C_3N_4 (MMO@C_3N_4) composite was synthesized as a dual-functional photocatalyst for both water oxidation and oxygen reduction to generate H_2O_2. The MMO was derived from a NiFe-layered double hydroxide (LDH) precursor for obtaining a high dispersion of metal oxides on the surface of the C_3N_4 matrix. The C_3N_4 is in the graphitic phase and the main crystalline phase in MMO is cubic NiO. The XPS analyses revealed the doping of Fe^(3+) in the dominant NiO phase and the existence of surface defects in the C3N4 matrix. The formation and decomposition kinetics of H_2O_2 on the MMO@C_3N_4 and the control samples, including bare MMO, C_3N_4 matrix, Ni- or Fe-loaded C_3N_4 and a simple mixture of MMO and C_3N_4, were investigated. The MMO@C_3N_4 composite produced 63 μmol L^(−1) of H_2O_2 in 90 min in acidic solution (pH 3) and exhibited a significantly higher rate of production for H_2O_2 relative to the control samples. The positive shift of the valence band in the composite and the enhanced water oxidation catalysis by incorporating the MMO improved the light-induced hole collection relative to the bare C_3N_4 and resulted in the enhanced H_2O_2 formation. The positively shifted conduction band in the composite also improved the selectivity of the two-electron reduction of molecular oxygen to H_2O_2

    Integrated Sensing and Communications: Recent Advances and Ten Open Challenges

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    It is anticipated that integrated sensing and communications (ISAC) would be one of the key enablers of next-generation wireless networks (such as beyond 5G (B5G) and 6G) for supporting a variety of emerging applications. In this paper, we provide a comprehensive review of the recent advances in ISAC systems, with a particular focus on their foundations, system design, networking aspects and ISAC applications. Furthermore, we discuss the corresponding open questions of the above that emerged in each issue. Hence, we commence with the information theory of sensing and communications (S&\&C), followed by the information-theoretic limits of ISAC systems by shedding light on the fundamental performance metrics. Next, we discuss their clock synchronization and phase offset problems, the associated Pareto-optimal signaling strategies, as well as the associated super-resolution ISAC system design. Moreover, we envision that ISAC ushers in a paradigm shift for the future cellular networks relying on network sensing, transforming the classic cellular architecture, cross-layer resource management methods, and transmission protocols. In ISAC applications, we further highlight the security and privacy issues of wireless sensing. Finally, we close by studying the recent advances in a representative ISAC use case, namely the multi-object multi-task (MOMT) recognition problem using wireless signals.Comment: 26 pages, 22 figures, resubmitted to IEEE Journal. Appreciation for the outstanding contributions of coauthors in the paper

    Styrene Purification by Guest-Induced Restructuring of Pillar[6]arene

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    The separation of styrene (St) and ethylbenzene (EB) mixtures is important in the chemical industry. Traditionally, this is done using energy-intensive vacuum distillation columns. Adsorptive separation is an alternative approach. Here, we explore the St and EB adsorption selectivity of two pillar-shaped macrocyclic pillar[n]arenes (EtP5 and EtP6; n 5 and 6). Both crystalline and amorphous EtP6 can capture St from a St-EB mixture with remarkably high selectivity. We show that EtP6 can be used to separate St from a 50:50 v/v St:EB mixture, yielding in a single adsorption cycle St with a purity of > 99 %. Single crystal structures, powder X-ray diffraction patterns and molecular simulations all suggest that this selectivity is due to a guest-induced structural change in EtP6 rather than a simple cavity/pore size effect. This restructuring means that the material ‘self-heals’ upon each recrystallization, and St separation can be carried out over multiple cycles with no loss of performance
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