103 research outputs found

    On the Adversarial Robustness of Vision Transformers

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    Following the success in advancing natural language processing and understanding, transformers are expected to bring revolutionary changes to computer vision. This work provides the first and comprehensive study on the robustness of vision transformers (ViTs) against adversarial perturbations. Tested on various white-box and transfer attack settings, we find that ViTs possess better adversarial robustness when compared with convolutional neural networks (CNNs). This observation also holds for certified robustness. We summarize the following main observations contributing to the improved robustness of ViTs: 1) Features learned by ViTs contain less low-level information and are more generalizable, which contributes to superior robustness against adversarial perturbations. 2) Introducing convolutional or tokens-to-token blocks for learning low-level features in ViTs can improve classification accuracy but at the cost of adversarial robustness. 3) Increasing the proportion of transformers in the model structure (when the model consists of both transformer and CNN blocks) leads to better robustness. But for a pure transformer model, simply increasing the size or adding layers cannot guarantee a similar effect. 4) Pre-training on larger datasets does not significantly improve adversarial robustness though it is critical for training ViTs. 5) Adversarial training is also applicable to ViT for training robust models. Furthermore, feature visualization and frequency analysis are conducted for explanation. The results show that ViTs are less sensitive to high-frequency perturbations than CNNs and there is a high correlation between how well the model learns low-level features and its robustness against different frequency-based perturbations

    Feasibility and safety of expandable mediastinoscopic and laparoscopic radical esophagectomy

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    BackgroundAt present, minimally invasive radical esophagectomy is the main surgical method for esophageal cancer treatment, but it has inherent limitations. We have developed a novel method of radical esophagectomy without thoracotomy to improve this situation, namely, by using EMLE. We evaluated the feasibility and safety of expandable mediastinoscopic and laparoscopic radical esophagectomy (EMLE) through a retrospective analysis.MethodsFrom January 2019 to June 2022, we successfully performed 106 cases of radical resection of esophageal cancer with this new surgical technique, gradually improved the surgical path, and recorded the perioperative data and postoperative complications of all patients.ResultsThe operation was successfully performed in all patients except for two patients who required a switch to open surgery. The mean operation time was 171.11 ± 33.29 min and the mean intraoperative blood loss was 93.53 ± 56.32 ml. The mean number of removed lymph nodes was 23.59 ± 5.42. The postoperative complications included pneumonia (3.77%), recurrent laryngeal nerve palsy (1.89%), anastomotic leak (14.15%), pleural effusion (5.66%), chylothorax (2.83%), and reoperation (4.72%). All complications were graded I–III per the Clavien–Dindo classification. No perioperative death was recorded.ConclusionExpandable mediastinoscopic and laparoscopic radical esophagectomy is feasible for radical resection of esophageal cancer, with good therapeutic effect and safety. Because of its minimal impact on patients and convenient operation, it is a novel surgical option for patients with esophageal cancer and is expected to become a standard surgical method for radical esophagectomy in the future

    Horizontal animation deformity as unusual complication of neurotoxin modulation of the gummy smile

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    Injections  of  botulinum  toxin  type  A  represent  the  most    common    nonsurgical    cosmetic    treatment    worldwide.  The  authors  report  a  case  of  dynamic  horizontal  wrinkling  in  the  upper  lip  that  appeared  after   botulinum   toxin   type   A   injections   to   treat   gummy    smile    associated    with    nasal    alar    base    reduction,  in  a  28-year-old  woman.  The  anatomic  features and pathogenic mechanism underlying this unusual complication are analyzed and discussed.</p

    Masonry shell structures with discrete equivalence classes

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    This paper proposes a method to model masonry shell structures where the shell elements fall into a set of discrete equivalence classes. Such shell structure can reduce the fabrication cost and simplify the physical construction due to reuse of a few template shell elements. Given a freeform surface, our goal is to generate a small set of template shell elements that can be reused to produce a seamless and buildable structure that closely resembles the surface. The major technical challenge in this process is balancing the desire for high reusability of template elements with the need for a seamless and buildable final structure. To address the challenge, we define three error metrics to measure the seamlessness and buildability of shell structures made from discrete equivalence classes and develop a hierarchical cluster-and-optimize approach to generate a small set of template elements that produce a structure closely approximating the surface with low error metrics. We demonstrate the feasibility of our approach on various freeform surfaces and geometric patterns, and validate buildability of our results with four physical prototypes. Code and data of this paper are at https://github.com/Linsanity81/TileableShell

    Oligodendrocyte-myelin glycoprotein (OMgp) is an inhibitor of neurite outgrowth

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    A protein fraction purified from bovine brain myelin, previously called arretin because of its ability to inhibit neurite outgrowth, has been identified as consisting predominantly of oligodendrocyte-myelin glycoprotein (OMgp). We show that it is a potent inhibitor of neurite outgrowth from rat cerebellar granule and hippocampal cells; from dorsal root ganglion explants in which growth cone collapse was observed; from rat retinal ganglion neurons; and from NG108 and PC12 cells. OMgp purified by a different procedure from both mouse and human myelin behaves identically in all bioassays tested.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66067/1/j.1471-4159.2002.01146.x.pd

    The acute-to-chronic workload ratio:An inaccurate scaling index for an unnecessary normalisation process?

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    BACKGROUND: Problematic use of alcohol and other drugs (AOD) is highly prevalent among people living with the human immunodeficiency virus (PLWH), and untreated AOD use disorders have particularly detrimental effects on human immunodeficiency virus (HIV) outcomes. The Healthcare Effectiveness Data and Information Set (HEDIS) measures of treatment initiation and engagement are important benchmarks for access to AOD use disorder treatment. To inform improved patient care, we compared HEDIS measures of AOD use disorder treatment initiation and engagement and health care utilization among PLWH and patients without an HIV diagnosis. METHODS: Patients with a new AOD use disorder diagnosis documented between October 1, 2014, and August 15, 2015, were identified using electronic health records (EHR) and insurance claims data from 7 health care systems in the United States. Demographic characteristics, clinical diagnoses, and health care utilization data were also obtained. AOD use disorder treatment initiation and engagement rates were calculated using HEDIS measure criteria. Factors associated with treatment initiation and engagement were examined using multivariable logistic regression models. RESULTS: There were 469 PLWH (93% male) and 86,096 patients without an HIV diagnosis (60% male) in the study cohort. AOD use disorder treatment initiation was similar in PLWH and patients without an HIV diagnosis (10% vs. 11%, respectively). Among those who initiated treatment, few engaged in treatment in both groups (9% PLWH vs. 12% patients without an HIV diagnosis). In multivariable analysis, HIV status was not significantly associated with either AOD use disorder treatment initiation or engagement. CONCLUSIONS: AOD use disorder treatment initiation and engagement rates were low in both PLWH and patients without an HIV diagnosis. Future studies need to focus on developing strategies to efficiently integrate AOD use disorder treatment with medical care for HIV
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