Widefield multifrequency fluorescence lifetime imaging using a two-tap complementary metal-oxide semiconductor camera with lateral electric field charge modulators.

Widefield frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) measures the fluorescence lifetime of entire images in a fast and efficient manner. We report a widefield FD-FLIM system based on a complementary metal-oxide semiconductor camera equipped with two-tap true correlated double sampling lock-in pixels and lateral electric field charge modulators. Owing to the fast intrinsic response and modulation of the camera, our system allows parallel multifrequency FLIM in one measurement via fast Fourier transform. We demonstrate that at a fundamental frequency of 20 MHz, 31-harmonics can be measured with 64 phase images per laser repetition period. As a proof of principle, we analyzed cells transfected with Cerulean and with a construct of Cerulean-Venus that shows Förster Resonance Energy Transfer at different modulation frequencies. We also tracked the temperature change of living cells via the fluorescence lifetime of Rhodamine B at different frequencies. These results indicate that our widefield multifrequency FD-FLIM system is a valuable tool in the biomedical field

Negative Magnetoresistance in Dirac Semimetal Cd3As2

A large negative magnetoresistance is anticipated in topological semimetals in the parallel magnetic and electric field configuration as a consequence of the nontrivial topological properties. The negative magnetoresistance is believed to demonstrate the chiral anomaly, a long-sought high-energy physics effect, in solid-state systems. Recent experiments reveal that Cd3As2, a Dirac topological semimetal, has the record-high mobility and exhibits positive linear magnetoresistance in the orthogonal magnetic and electric field configuration. However, the negative magnetoresistance in the parallel magnetic and electric field configuration remains unveiled. Here, we report the observation of the negative magnetoresistance in Cd3As2 microribbons in the parallel magnetic and electric field configuration as large as 66% at 50 K and even visible at room temperatures. The observed negative magnetoresistance is sensitive to the angle between magnetic and electrical field, robust against temperature, and dependent on the carrier density. We have found that carrier densities of our Cd3As2 samples obey an Arrhenius's law, decreasing from 3.0x10^17 cm^-3 at 300 K to 2.2x10^16 cm^-3 below 50 K. The low carrier densities result in the large values of the negative magnetoresistance. We therefore attribute the observed negative magnetoresistance to the chiral anomaly. Furthermore, in the perpendicular magnetic and electric field configuration a positive non-saturating linear magnetoresistance up to 1670% at 14 T and 2 K is also observed. This work demonstrates potential applications of topological semimetals in magnetic devices

Efficient Path Planning in Narrow Passages via Closed-Form Minkowski Operations

Path planning has long been one of the major research areas in robotics, with PRM and RRT being two of the most effective classes of path planners. Though generally very efficient, these sampling-based planners can become computationally expensive in the important case of "narrow passages". This paper develops a path planning paradigm specifically formulated for narrow passage problems. The core is based on planning for rigid-body robots encapsulated by unions of ellipsoids. The environmental features are enclosed geometrically using convex differentiable surfaces (e.g., superquadrics). The main benefit of doing this is that configuration-space obstacles can be parameterized explicitly in closed form, thereby allowing prior knowledge to be used to avoid sampling infeasible configurations. Then, by characterizing a tight volume bound for multiple ellipsoids, robot transitions involving rotations are guaranteed to be collision-free without traditional collision detection. Furthermore, combining the stochastic sampling strategy, the proposed planning framework can be extended to solving higher dimensional problems in which the robot has a moving base and articulated appendages. Benchmark results show that, remarkably, the proposed framework outperforms the popular sampling-based planners in terms of computational time and success rate in finding a path through narrow corridors and in higher dimensional configuration spaces

Inversion of inherent optical properties in optically complex waters using sentinel-3A/OLCI images: A case study using China\u27s three largest freshwater lakes

Inherent optical properties (IOPs) play an important role in underwater light field, and are difficult to estimate accurately using satellite data in optically complex waters. To study water quality in appropriate temporal and spatial scales, it is necessary to develop methods to obtain IOPs form space-based observation with quantified uncertainties. Field-measured IOP data (N = 405) were collected from 17 surveys between 2011 and 2017 in the three major largest freshwater lakes of China (Lake Chaohu, Lake Taihu, and Lake Hongze) in the lower reaches of the Yangtze River and Huai River (LYHR). Here we provide a case-study on how to use in-situ observation of IOPs to devise an improved algorithm for retrieval of IOPs. We then apply this algorithm to observation with Sentinel-3A OLCI (Ocean and Land Colour Instrument, corrected with our improved AC scheme), and use in-situ data to show that the algorithm performs better than the standard OLCI IOP product. We use the satellite derived products to study the spatial and seasonal distributions of IOPs and concentrations of optically active constituents in these three lakes, including chlorophyll-a (Chla) and suspended particulate matter (SPM), using all cloud-free OLCI images (115 scenes) over the lakes in the LYHR basin in 2017. Our study provides a strategy for using local and remote observations to obtain important water quality parameters necessary to manage resources such as reservoirs, lakes and coastal waters

Is the Right to Vote Equal to Democracy? — An Analysis of Substantive and Procedural Democracy in the United States

In modern political society, democracy remains a universal concept. However, different ideologies still have their own views on the concrete realization form of democracy. Nowadays, the understandings of the concept of democracy in the United States and its democratic values have become the mainstream of Western society, and their historical value and role should not be ignored. However, the practice of this democratic system has differed from true democracy and has gradually manifested political confusion. Firstly, this paper introduces the development of democracy and electoral system, and explains that the initial meaning of Western democracy is institutional democracy, namely procedural democracy, which is not the same as what we think of popular sovereignty today, and that the development course of Western democracy is also the expansion process of procedural justice. Then, constructivism theory is used to discuss the proceduralized process of substantive democracy and to explain the relationship between procedural justice and substantive democracy. Finally, through a specific analysis of the evolution and practice of the democratic electoral system in the United States, it concludes that the development of American democracy focuses only on expanding the scope of procedural democracy, but neglects the development of substantive democracy. For this reason, it explores the problems existing in American democracy

PUNR: Pre-training with User Behavior Modeling for News Recommendation

News recommendation aims to predict click behaviors based on user behaviors. How to effectively model the user representations is the key to recommending preferred news. Existing works are mostly focused on improvements in the supervised fine-tuning stage. However, there is still a lack of PLM-based unsupervised pre-training methods optimized for user representations. In this work, we propose an unsupervised pre-training paradigm with two tasks, i.e. user behavior masking and user behavior generation, both towards effective user behavior modeling. Firstly, we introduce the user behavior masking pre-training task to recover the masked user behaviors based on their contextual behaviors. In this way, the model could capture a much stronger and more comprehensive user news reading pattern. Besides, we incorporate a novel auxiliary user behavior generation pre-training task to enhance the user representation vector derived from the user encoder. We use the above pre-trained user modeling encoder to obtain news and user representations in downstream fine-tuning. Evaluations on the real-world news benchmark show significant performance improvements over existing baselines.Comment: Accepted by Findings of EMNLP23. Github Repo: https://github.com/ma787639046/pun

Geometry Aligned Variational Transformer for Image-conditioned Layout Generation

Layout generation is a novel task in computer vision, which combines the challenges in both object localization and aesthetic appraisal, widely used in advertisements, posters, and slides design. An accurate and pleasant layout should consider both the intra-domain relationship within layout elements and the inter-domain relationship between layout elements and the image. However, most previous methods simply focus on image-content-agnostic layout generation, without leveraging the complex visual information from the image. To this end, we explore a novel paradigm entitled image-conditioned layout generation, which aims to add text overlays to an image in a semantically coherent manner. Specifically, we propose an Image-Conditioned Variational Transformer (ICVT) that autoregressively generates various layouts in an image. First, self-attention mechanism is adopted to model the contextual relationship within layout elements, while cross-attention mechanism is used to fuse the visual information of conditional images. Subsequently, we take them as building blocks of conditional variational autoencoder (CVAE), which demonstrates appealing diversity. Second, in order to alleviate the gap between layout elements domain and visual domain, we design a Geometry Alignment module, in which the geometric information of the image is aligned with the layout representation. In addition, we construct a large-scale advertisement poster layout designing dataset with delicate layout and saliency map annotations. Experimental results show that our model can adaptively generate layouts in the non-intrusive area of the image, resulting in a harmonious layout design.Comment: To be published in ACM MM 202

OR-048 Effects and Mechanism of myokines in exercise mediated improving obesity rats skeletal muscle remodeling

Objective Aims From the year 2000, many experimental research data have indicated that skeletal muscle could express, synthesis and secrete multiple cytokines and polypeptides. The cytokines and polypeptides, not only regulate skeletal muscle growth, metabolism and motor function by paracrine/autocrine pathway, but also regulate functions of peripheral tissue and organs by endocrine pathway. Further researches proposed muscle as a secretory organ played a key role in mediating the health-promoting effects of physical activity and proteins expressed and released by skeletal muscle have been termed as myokines. Disorders of skeletal muscle endocrine function have related to the occurrence and development of multiple metabolic diseases, and myokines participate in obesity skeletal muscle remodeling. This study aims to investigate the expression changes of myokines and its effects in exercise mediated improving skeletal muscle remodeling on obesity mice, and explore the underlying mechanism of its functions. Methods Methods Five-week-old male Sprague-Dawley(SD) rats were randomly divided into a control group of 8 and a high-fat diet（HFD）group of 16. The control group was given normal food，while the HFD group were provided with high-fat diet for eight weeks and further divided into a sedentary HFD group and a treadmill running HFD group，each of 8. The exercise mice underwent 60 min treadmill running at 26 m/min each day，5 days/week for 8 weeks. Biochemical analyses, immune-histochemical, ELISA, RT-PCR and Western Blot methods were used to investigate multiple myokines expression changes and its mechanism. Results Results 1) Exercise significantly upregulated the expression of IL-15 in soleus and gastrocnemius muscle of obesity rats, indicating IL-15 could inhibit skeletal muscle endoplasmic reticulum stress and improve insulin sensitivity. 2) Exercise significantly inhibited the expression of myostatin (MSTN) in gastrocnemius muscle and mediated the changes of muscle fiber types. 3) Exercise markedly promoted the expression of apelin/APJ and angiogenesis function in obesity skeletal muscle. 4) Exercise upregulated skeletal muscle vascular endothelial growth factor B receptor expression and improved skeletal muscle ectopic lipid accumulation. Conclusions Conclusion Exercise regulates skeletal muscle myokines expression and secretion and have the effects on skeletal muscle fiber type changes, myofiber capillary density, glucose and lipid metabolism, thus improves the skeletal muscle remodeling and maintain body homeostasis