Concept for a Future Super Proton-Proton Collider

Following the discovery of the Higgs boson at LHC, new large colliders are being studied by the international high-energy community to explore Higgs physics in detail and new physics beyond the Standard Model. In China, a two-stage circular collider project CEPC-SPPC is proposed, with the first stage CEPC (Circular Electron Positron Collier, a so-called Higgs factory) focused on Higgs physics, and the second stage SPPC (Super Proton-Proton Collider) focused on new physics beyond the Standard Model. This paper discusses this second stage.Comment: 34 pages, 8 figures, 5 table

Artemisia pollen allergy in China : Component-resolved diagnosis reveals allergic asthma patients have significant multiple allergen sensitization

Background: Artemisia pollen allergy is a major cause of asthma in Northern China. Possible associations between IgE responses to Artemisia allergen components and clinical phenotypes have not yet been evaluated. This study was to establish sensitization patterns of four Artemisia allergens and possible associations with demographic characteristics and clinical phenotypes in three areas of China. Methods: Two hundred and forty patients allergic to Artemisia pollen were examined, 178 from Shanxi and 30 from Shandong Provinces in Northern China, and 32 from Yunnan Province in Southwestern China. Allergic asthma, rhinitis, conjunctivitis, and eczema symptoms were diagnosed. All patients sera were tested by ImmunoCAP with mugwort pollen extract and the natural components nArt v 1, nArt ar 2, nArt v 3, and nArt an 7. Results: The frequency of sensitization and the IgE levels of the four components in Artemisia allergic patients from Southwestern China were significantly lower than in those from the North. Art v 1 and Art an 7 were the most frequently recognized allergens (84% and 87%, respectively), followed by Art v 3 (66%) and Art ar 2 (48%). Patients from Northern China were more likely to have allergic asthma (50%) than patients from Southwestern China (3%), and being sensitized to more than two allergens increased the risk of allergic asthma, in which cosensitization to three major allergens Art v 1, Art v 3, and Art an 7 is prominent. Conclusions: Componentresolved diagnosis of Chinese Artemisia pollenallergic patients helps assess the potential risk of mugwortassociated allergic asthma.(VLID)329956

Cellular-resolution endoscopic optical coherence tomography and image analytics

Coronary artery disease (CAD) and gastrointestinal (GI) cancers are among the top killers worldwide and in Singapore. Acute myocardial infarction (AMI, = heart attack), the clinical manifestation of CAD, is one of the leading causes of global morbidity and mortality. Due to the high prevalence and high risk of AMI, identification of vulnerable plaque associated with AMI is critical for early detection and subsequently interventional treatment. Esophageal, gastric and colorectal cancers are among the commonly diagnosed GI cancers worldwide and early diagnosis of these cancers is vital for the effective therapeutics. Intraepithelial neoplasia (IEN) may develop rapidly into invasive cancers without noticeable symptoms. Therefore, early detection of IEN when they are confined in epithelium is the key to achieving a good prognosis. However, we are limited in methods to obtain histology images of coronary arteries because it is hardly practical to take biopsy from coronary arteries. Even though biopsies can be routinely taken from GI tissues, sampling error may also lead to diagnostic errors. Therefore, a nondestructive imaging tool that can provide cellular-resolution images is critical for improving diagnostic accuracy. We have developed a desktop micro-optical coherence tomography (µOCT) imaging system and a novel endoscopic µOCT fiber-optic probe towards cellular-resolution imaging in coronary arteries and GI tracts. The desktop µOCT imaging system is an improved version of previously reported µOCT system in that it has a fiber-optic flexible handheld probe, which enables in vivo imaging of living animals. The first main technical contribution of this thesis is the development of the endoscopic µOCT fiber-optic probe. The µOCT fiber-optic probe achieves an axial resolution of 2.48 µm in air and transverse resolution of 4.8 µm, which are 4 times and 4.17 times better than the current endoscopic OCT devices, respectively. In particular, we used a novel beamsplitter design at the distal end of the fiber-optic probe so that we can realize the common-path design, annular focusing, and an all-glass optical path. The common-path design eliminates the dispersion difference between the sample and reference arms so that optimal axial resolution of 2.48 µm in air can be achieved, as well as eliminates the polarization mismatch between the two arms during the probe rotation for circumferential scanning. The annular focusing enables a 1.3 times extended depth-of-focus (DOF) which mitigates the problem of DOF limitation. The all-glass optical path makes it easier to fabricate the probe. Besides, we also employed a rigid outer sheath surrounding the probe so that areas of interest were properly maintained around the relatively small focal region to alleviate the issue of limited DOF. In order to investigate the capability of µOCT for visualizing cellular structures, we firstly imaged rat colon in vivo using the desktop µOCT imaging system. Imaging results show that the detailed microstructures, such as the crypt lumens and the goblet cells, could be clearly identified which was supported by corresponding histology images. Secondly, we conducted ex vivo imaging of fresh intact swine colon, swine coronary arteries, and human atherosclerotic coronary arteries by the endoscopic µOCT fiber probe. In normal swine colon we were able to visualize cellular-level microstructures such as goblet cells; we also clearly visualized smooth muscle cells and foam cells in atherosclerotic plaques. These results demonstrate that this endoscopic µOCT fiber-optic probe is capable of visualizing cellular-level morphological features of both GI tracts and coronary arteries. The second main technical contribution of this thesis is the design and simulation of the second fiber probe, which may improve the DOF by 2 times. The rationale for this effort is that the DOF of the above-mentioned first probe is still not enough for in vivo use. This second probe design follows the principle of multiple aperture synthesis (MAS) and digital refocusing. It uses a novel calcite-based polarization beamsplitter to create two apertures at the pupil plane of the objective lens and to form three apertures in the detection path. The phases of interferometric signals collected through these three sub-apertures can be digitally manipulated so that the three beams can be "refocused" at an out-of-focus point. I have completed the optical design and simulation of the optical performances, and fabricated the second fiber probe. In addition to the above-mentioned two technical contributions, I have conducted mechanical simulations to model the plaque stability in coronary atherosclerosis. As firstly pointed out, rupture of vulnerable plaque is critically associated with cardiovascular thrombosis and even AMI, whereas its detailed mechanisms are not fully understood. Recent studies have found abundant cholesterol crystals in ruptured plaques, and it has been proposed that the rapid expansion of cholesterol crystals in a limited space during crystallization may contribute to plaque rupture. However, the potential effect of cholesterol crystals on plaque rupture remains elusive due to the lack of the geometry of cholesterol crystals for analysis. In previous studies, µOCT can clearly visualize cholesterol crystals within arterial tissues ex vivo, and opens the possibility for evaluating the relationship between cholesterol crystallization and plaque rupture. Based on the measured geometric information of cholesterol crystals in human atherosclerotic aorta tissues, we developed a two-dimensional finite element method model of atherosclerotic plaques containing expanding cholesterol crystals and investigated the effect of the magnitude and distribution of crystallization on the peak circumferential stress.Doctor of Philosophy (EEE

The Employment Effect of Inward FDI in China: What Do We Learn from the History?

This study investigates the long-term influence of colonial legacy on the nexus between inward foreign direct investment (FDI) and labor market. We construct a panel dataset containing 285 Chinese cities 2011 to 2017 along with detailed information about Chinese modern history during 1842-1955). Our results show that the inward FDI has a positive effect on employment and such an effect is more pronounced in the regions with colonial influence than their counterparts. Further, we find that the experience of Western colonization strengthens the positive effect of inward FDI on employment whereas the experience of Japanese colonization weakens or even overturns this positive effect. These findings are robust to controlling for the endogeneity between inward FDI and employment as well as employing alternative measures for the colonization

Cross-platform privacy-preserving CT image COVID-19 diagnosis based on source-free domain adaptation

In the wake of the Coronavirus disease (COVID-19) pandemic, chest computed tomography (CT) has become an invaluable component in the rapid and accurate detection of COVID-19. CT scans traditionally require manual inspections from medical professionals, which is expensive and tedious. With advancements in machine learning, deep neural networks have been applied to classify CT scans for efficient diagnosis. However, three challenges hinder this application of deep learning: (1) Domain shift across CT platforms and human subjects impedes the performance of neural networks in different hospitals. (2) Unsupervised Domain Adaptation (UDA), the traditional method to overcome domain shift, typically requires access to both source and target data. This is not realistic in COVID-19 diagnosis due to the sensitivity of medical data. The privacy of patients must be protected. (3) Data imbalance may exist between easy/hard samples and between data classes which can overwhelm the training of deep networks, causing degenerate models. To overcome these challenges, we propose a Cross-Platform Privacy-Preserving COVID-19 diagnosis network (CP 3 Net) that integrates domain adaptation, self-supervised learning, imbalanced label learning, and rotation classifier training into one synergistic framework. We also create a new CT benchmark by combining real-world datasets from multiple medical platforms to facilitate the cross-domain evaluation of our method. Through extensive experiments, we demonstrate that CP 3 Net outperforms many popular UDA methods and achieves state-of-the-art results in diagnosing COVID-19 using CT scans.Nanyang Technological UniversityThis work is supported by NTU Presidential Postdoctoral Fellowship, ‘‘Adaptive Multimodal Learning for Robust Sensing and Recognition in Smart Cities’’ project fund, at Nanyang Technological University, Singapore

Diagnostic Value of Structural and Functional Neuroimaging in Autoimmune Epilepsy

Epilepsy is a common nervous system disease, which affects about 70 million people all over the world. In 2017, the International League Against Epilepsy (ILAE) considered immune factors as its independent cause, and the concept of autoimmune epilepsy (AE) was widely accepted. Early diagnosis and timely treatment can effectively improve the prognosis of the disease. However, due to the diversity of clinical manifestations, the expensive cost of autoantibody detection, and the increased prevalence in Western China, the difficulty for clinicians in early diagnosis and treatment has increased. Fortunately, convenient and fast imaging examinations are expected to help even more. The imaging manifestations of AE patients were characteristic, especially the combined application of structural and functional neuroimaging, which improved the diagnostic value of imaging. In this paper, several common autoantibodies associated with AE and their structure and function changes in neuroimaging were reviewed to provide help for neurologists to achieve the goal of precision medicine

Cross-domain retinopathy classification with optical coherence tomography images via a novel deep domain adaptation method

Deep learning based retinopathy classification with optical coherence tomography (OCT) images has recently attracted great attention. However, existing deep learning methods fail to work well when training and testing datasets are different due to the general issue of domain shift between datasets caused by different collection devices, subjects, imaging parameters, etc. To address this practical and challenging issue, we propose a novel deep domain adaptation (DDA) method to train a model on a labeled dataset and adapt it to an unlabelled dataset (collected under different conditions). It consists of two modules for domain alignment, that is, adversarial learning and entropy minimization. We conduct extensive experiments on three public datasets to evaluate the performance of the proposed method. The results indicate that there are large domain shifts between datasets, resulting a poor performance for conventional deep learning methods. The proposed DDA method can significantly outperform existing methods for retinopathy classification with OCT images. It achieves retinopathy classification accuracies of 0.915, 0.959 and 0.990 under three cross-domain (cross-dataset) scenarios. Moreover, it obtains a comparable performance with human experts on a dataset where no labeled data in this dataset have been used to train the proposed DDA method. We have also visualized the learnt features by using the t-distributed stochastic neighbor embedding (t-SNE) technique. The results demonstrate that the proposed method can learn discriminative features for retinopathy classification.Ministry of Education (MOE)Ministry of Health (MOH)National Medical Research Council (NMRC)Submitted/Accepted versionWe sincerely appreciate funding support from Singapore Ministry of Health's National Medical Research Council under its Open Fund Individual Research Grant (MOH-OFIRG19may-0009), and Ministry of Education Singapore under its Academic Research Fund Tier1 (2018-T1-001-144) and its Academic Research Funding Tier 2 (MOE-T2EP30120-0001)

High-resolution extended source optical coherence tomography

High resolution optical coherence tomography (OCT) is capable of providing detailed tissue microstructures that are critical for disease diagnosis, yet its sensitivity is usually degraded since the system key components are typically not working at their respective center wavelengths. We developed a novel imaging system that achieves enhanced sensitivity without axial resolution degradation by the use of a spectrally encoded extended source (SEES) technique; it allows larger sample power without exceeding the maximum permissible exposure (MPE). In this study, we demonstrate a high-resolution extended source (HRES) OCT system, which is capable of providing a transverse resolution of 4.4 µm and an axial resolution of 2.1 µm in air with the SEES technique. We first theoretically show a sensitivity advantage of 6-dB of the HRES-OCT over that of its point source counterpart using numerical simulations, and then experimentally validate the applicability of the SEES technique to high-resolution OCT (HR-OCT) by comparing the HRES-OCT with an equivalent point-source system. In the HRES-OCT system, a dispersive prism was placed in the infinity space of the sample arm optics to spectrally extend the visual angle (angular subtense) of the light source to 10.3 mrad. This extended source allowed ~4 times larger MPE than its point source counterpart, which results in an enhancement of ~6 dB in sensitivity. Specifically, to solve the unbalanced dispersion between the sample and the reference arm optics, we proposed easy and efficient methods for system calibration and dispersion correction, respectively. With a maximum scanning speed reaching up to 60K A-lines/s, we further conducted imaging experiments with HRES-OCT using the human fingertip in vivo and the swine eye tissues ex vivo. Results demonstrate that the HRES-OCT is able to achieve significantly larger penetration depth than its conventional point source OCT counterpart.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)NMRC (Natl Medical Research Council, S’pore)Accepted versio

Toward High-Speed Imaging of Cellular Structures in Rat Colon Using Micro-optical Coherence Tomography

The mucosal microanatomy of the large intestine is characterized by the presence of crypts of Lieberkühn, which is associated predominantly with goblet cells. Such cellular-level intestinal microstructures undergo morphological changes during the progression of bowel diseases, such as colon cancer or ulcerative colitis. As an indicator of gastric cancers, intestinal metaplasia in the large intestine is characterized by the appearance of goblet cells in gastric epithelium, and therefore, visualization of intestinal microstructure changes in cross-sectional view, particularly in vivo, in a high-speed fashion would assist early disease diagnosis and its treatment. In this paper, we investigated the capability of micro-optical coherence tomography (μOCT) for high-speed cellular-level crypt and goblet cell structures imaging ex vivo and in vivo . The adopted μOCT system achieved a resolution of 2.0 μm in both the lateral and axial directions in air. Ex vivo and video-rate in vivo images acquired in 3-D at respective imaging rates of 20 and 60 frames/s are presented and compared with the histology images. Imaging results show that the detailed microstructures, such as the crypt lumen and the goblet cells, could be clearly identified and are also comparable with those in histology images. Such comparisons also indicate that high-resolution μOCT could be a powerful tool to perform “optical biopsy” in colorectal tissue. This is the first work, to the best of our knowledge, on cellular-level structure imaging in intestinal mucosa using spectral-domain OCT.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)NMRC (Natl Medical Research Council, S’pore)Published versio