4,426 research outputs found

    Emergent localized states at the interface of a twofold PT\mathcal{PT}-symmetric lattice

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    We consider the role of non-triviality resulting from a non-Hermitian Hamiltonian that conserves twofold PT-symmetry assembled by interconnections between a PT-symmetric lattice and its time reversal partner. Twofold PT-symmetry in the lattice produces additional surface exceptional points that play the role of new critical points, along with the bulk exceptional point. We show that there are two distinct regimes possessing symmetry-protected localized states, of which localization lengths are robust against external gain and loss. The states are demonstrated by numerical calculation of a quasi-1D ladder lattice and a 2D bilayered square lattice.Comment: 10 pages, 7 figure

    Epidemiological Aspects of Exotic Malaria and Dengue Fever in Travelers in Korea

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    In order to compare the epidemiological aspects of exotic malaria (EM) and dengue fever (DF) imported by travelers in Korea, we have analyzed the current state both of the disease incidence and related risk factors. A total of 345 cases of EM occurred between 2001 and 2008 in Korea, and the average incidence rate per 100,000 population was 0.091. A total of 252 of DF cases occurred during the same period, and its rate was 0.063. While most of the EM and DF prevalence occurred in summer, prevalence in spring and winter was more prominent for EM (P < 0.05 ~ P < 0.01), while outbreaks in summer were more frequent for DF (P < 0.01). In Korea, more males were infected with EM and DF than females (P < 0.01). The remarkable difference between gender distributions in Korea is believed to reflect cultural differences in terms of work and travel. In both diseases, the manhood age bracket (20 - 39 years old) is possible due to increased oversea activities and travel. Moreover, reported EM cases in several prefectures in the regions of Asia and Africa were widely spread by the appropriate vector of mosquitoes, while the vectors of DF in the region of Asia are limited

    Domain Adaptive Transfer Attack (DATA)-based Segmentation Networks for Building Extraction from Aerial Images

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    Semantic segmentation models based on convolutional neural networks (CNNs) have gained much attention in relation to remote sensing and have achieved remarkable performance for the extraction of buildings from high-resolution aerial images. However, the issue of limited generalization for unseen images remains. When there is a domain gap between the training and test datasets, CNN-based segmentation models trained by a training dataset fail to segment buildings for the test dataset. In this paper, we propose segmentation networks based on a domain adaptive transfer attack (DATA) scheme for building extraction from aerial images. The proposed system combines the domain transfer and adversarial attack concepts. Based on the DATA scheme, the distribution of the input images can be shifted to that of the target images while turning images into adversarial examples against a target network. Defending adversarial examples adapted to the target domain can overcome the performance degradation due to the domain gap and increase the robustness of the segmentation model. Cross-dataset experiments and the ablation study are conducted for the three different datasets: the Inria aerial image labeling dataset, the Massachusetts building dataset, and the WHU East Asia dataset. Compared to the performance of the segmentation network without the DATA scheme, the proposed method shows improvements in the overall IoU. Moreover, it is verified that the proposed method outperforms even when compared to feature adaptation (FA) and output space adaptation (OSA).Comment: 11pages, 12 figure

    Online Class Incremental Learning on Stochastic Blurry Task Boundary via Mask and Visual Prompt Tuning

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    Continual learning aims to learn a model from a continuous stream of data, but it mainly assumes a fixed number of data and tasks with clear task boundaries. However, in real-world scenarios, the number of input data and tasks is constantly changing in a statistical way, not a static way. Although recently introduced incremental learning scenarios having blurry task boundaries somewhat address the above issues, they still do not fully reflect the statistical properties of real-world situations because of the fixed ratio of disjoint and blurry samples. In this paper, we propose a new Stochastic incremental Blurry task boundary scenario, called Si-Blurry, which reflects the stochastic properties of the real-world. We find that there are two major challenges in the Si-Blurry scenario: (1) inter- and intra-task forgettings and (2) class imbalance problem. To alleviate them, we introduce Mask and Visual Prompt tuning (MVP). In MVP, to address the inter- and intra-task forgetting issues, we propose a novel instance-wise logit masking and contrastive visual prompt tuning loss. Both of them help our model discern the classes to be learned in the current batch. It results in consolidating the previous knowledge. In addition, to alleviate the class imbalance problem, we introduce a new gradient similarity-based focal loss and adaptive feature scaling to ease overfitting to the major classes and underfitting to the minor classes. Extensive experiments show that our proposed MVP significantly outperforms the existing state-of-the-art methods in our challenging Si-Blurry scenario

    Structural Relationships Among VariablesAffecting Elementary School Students'Career Preparation Behavior: Using a Multi-Group Structural Equation Approach

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    The purpose of this study was to analyze the structural relationships between parent support, career decision self-efficacy, career maturity, and career preparation behaviorfor elementary school students (5th and 6th grade) in Korea and to examine if there are gender differences.A total of 609students of 7 elementary schools in Seoul, Koreawas participated in this research. The collected data were analyzed using a structural equation model. The conclusionsare as follows: First, parent support had significant positive effects on career preparation behavior but affectednegatively career maturity. Second, career decision self-efficacy hada significant effect on career maturity and career preparation behavior for both boys and girls in elementary school.Finally, career decision self-efficacy hada more directand indirect influence on career maturity and career preparation behavior than parent support

    The Mediating Role of Pain Catastrophizing on the Association Between Depression and Pain Severity and Interference Among Elderly Asian Immigrants with Chronic Pain

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    Purpose: The association between depression and chronic pain is well established. However, few studies have examined the pathways from depression to chronic pain. The present cross-cultural study aimed to test the mediating effects of pain catastrophizing on associations between depression and chronic pain (eg, pain severity, pain intensity) among Korean American elderly. Patients and Methods: A total of 132 elderly Korean Americans with chronic pain were recruited from elderly daycare centers and Korean ethnic churches in the community. For mediation analyses, structural equation modeling with full information maximum likelihood estimation method was used. The bias-corrected bootstrap confidence interval (CI) method for inferential tests of the indirect effects was also conducted in mediation analysis. Results: The results indicated that the proportion of comorbid depression and chronic pain was 45.7%. Elderly Korean Americans with depression scored higher in pain severity, pain interference, and pain catastrophizing than those without depression. Pain catastrophizing was found to have a significant mediating effect on the relationship between depression and pain severity (indirect effect = 0.147, Bootstrap 95% CI = [0.079, 0.226]), controlling for demographic covariates, comorbidities and pain area. Pain catastrophizing also mediated the relationship between depression and pain interference (indirect effect =0.164, Bootstrap 95% CI = [0.097, 0.244]), controlling for the covariates. Conclusion: These findings add to the literature by providing evidence that pain catastrophizing plays a role in high levels of pain severity and pain interference comorbid chronic pain and depression in Asian elderly immigrants. Appropriate culturally tailored programs to redirect pain catastrophizing cognitive process should be developed and provided for elderly Asian Americans to reduce chronic pain disparity
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