204 research outputs found

    The Role of RSV Infection in Asthma Initiation and Progression: Findings in a Mouse Model

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    Respiratory syncytial virus (RSV) is a common cause of severe lower respiratory tract diseases (bronchiolitis and pneumonia) during infancy and early childhood. There is increasing evidence which indicates that severe pulmonary disease caused by RSV infection in infancy is associated with recurrent wheezing and development of asthma later in childhood. However, the underlying mechanisms linking RSV infection to persistent airway hyperresponsiveness and dysfunction are not fully defined. To study these processes in ways which are not available in humans, animal models have been established and have provided valuable insight into the pathophysiology of RSV-induced disease. In this paper, we discuss experimental models of RSV infection in mice and highlight a new investigative approach in which mice are initially infected as neonates and then reinfected later in life. The findings shed light on the mechanisms underlying the association between early severe RSV infection and development of asthma later in childhood

    EfficientViT: Lightweight Multi-Scale Attention for On-Device Semantic Segmentation

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    Semantic segmentation enables many appealing real-world applications, such as computational photography, autonomous driving, etc. However, the vast computational cost makes deploying state-of-the-art semantic segmentation models on edge devices with limited hardware resources difficult. This work presents EfficientViT, a new family of semantic segmentation models with a novel lightweight multi-scale attention for on-device semantic segmentation. Unlike prior semantic segmentation models that rely on heavy self-attention, hardware-inefficient large-kernel convolution, or complicated topology structure to obtain good performances, our lightweight multi-scale attention achieves a global receptive field and multi-scale learning (two critical features for semantic segmentation models) with only lightweight and hardware-efficient operations. As such, EfficientViT delivers remarkable performance gains over previous state-of-the-art semantic segmentation models across popular benchmark datasets with significant speedup on the mobile platform. Without performance loss on Cityscapes, our EfficientViT provides up to 15x and 9.3x mobile latency reduction over SegFormer and SegNeXt, respectively. Maintaining the same mobile latency, EfficientViT provides +7.4 mIoU gain on ADE20K over SegNeXt. Code: https://github.com/mit-han-lab/efficientvit.Comment: Tech repor

    Design, Syntheses and Biological Applications of Through-bond Energy Transfer Cassettes and Novel Non-covalently Cell Penetrating Peptides

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    A xanthene-BODIPY cassette is used as a ratiometric intracellular pH reporter for imaging protein-dye conjugates in living cells. A model was hypothesized to explain the pH-dependent energy transfer efficiencies from the donor to the acceptor based on the electronic chemistry data. Sulfonation conditions were developed for BODIPY dyes to give water-soluble functionalized monosulfonation and disulfonation donors. A water-soluble TBET cassette, which has good photophysical properties, was synthesized using a bissulfonated BODIPY dye as the donor, and their applications for in vitro protein labeling is achieved. Chemoselective cross-coupling reactions were demonstrated for C-S bonds in the BODIPY dye, and similar reactions were applied to make the acceptor of the watersoluble cassette. Chemiluminescent energy transfer cassettes based on fluorescein and Nile Red were synthesized and their spectral properties were studied. Pep-1 (also known as Chariot), R8 (which is not often used as a non-covalent protein carrier), and a new synthesized compound, Azo-R8, was used for the study of non-covalent delivery of four different proteins into mammalian cells. Data from confocal spectroscopy revealed that all three carriers are effective for translocating protein cargos into live cells. At 37 dgrees C, import into endocytic compartments dominates, but at 4 degrees C weak, diffuse fluorescence is observed in the cytosol indicative of a favorable mode of action

    Leveraging Constraints Plus Dynamic Programming for the Large Dollo Parsimony Problem

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    The last decade of phylogenetics has seen the development of many methods that leverage constraints plus dynamic programming. The goal of this algorithmic technique is to produce a phylogeny that is optimal with respect to some objective function and that lies within a constrained version of tree space. The popular species tree estimation method ASTRAL, for example, returns a tree that (1) maximizes the quartet score computed with respect to the input gene trees and that (2) draws its branches (bipartitions) from the input constraint set. This technique has yet to be used for classic parsimony problems where the input are binary characters, sometimes with missing values. Here, we introduce the clade-constrained character parsimony problem and present an algorithm that solves this problem in polynomial time for the Dollo criterion score. Dollo parsimony, which requires traits/mutations to be gained at most once but allows them to be lost any number of times, is widely used for tumor phylogenetics as well as species phylogenetics, for example analyses of low-homoplasy retroelement insertions across the vertebrate tree of life. Thus, we implement our algorithm in a software package, called Dollo-CDP, and evaluate its utility in the context of species phylogenetics using both simulated and real data sets. Our results show that Dollo-CDP can improve upon heuristic search from a single starting tree, often recovering a better scoring tree. Moreover, Dollo-CDP scales to data sets with much larger numbers of taxa than branch-and-bound while still having an optimality guarantee, albeit a more restricted one. Lastly, we show that our algorithm for Dollo parsimony can easily be adapted to Camin-Sokal parsimony but not Fitch parsimony

    The Effects of Weather on Passenger Flow of Urban Rail Transit

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    Predicting passenger flow on urban rail transit is important for the planning, design and decision-making of rail transit. Weather is an important factor that affects the passenger flow of rail transit by changing the travel mode choice of urban residents. This study aims to explore the influence of weather on urban rail transit ridership, taking four cities in China as examples, Beijing, Shanghai, Guangzhou and Chengdu. To determine the weather effect on daily ridership rate, the three models were proposed with different combinations of the factors of temperature and weather type, using linear regression method.   The large quantities of data were applied to validate the developed models.  The results show that in Guangzhou, the daily ridership rate of rail transit increases with increasing temperature. In Chengdu, the ridership rate increases in rainy days compared to sunny days. While, in Beijing and Shanghai, the ridership rate increases in light rainfall and heavy rainfall (except moderate rainfall) compared to sunny days. The research findings are important to understand the impact of weather on passenger flow of urban rail transit. The findings can provide effective strategies to rail transit operators to deal with the fluctuation in daily passenger flow

    Effects of food restriction on growth, body composition and gene expression related in regulation of lipid metabolism and food intake in grass carp

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    It is well known that most fish would prefer to use body lipid stores for energy expenditure when receiving a long-term food restriction. However, the mechanism of this is still not clear. In the present study, a growth experiment was carried out to investigate the effects of food restriction on growth performance, gene expression related in regulation of lipid metabolism and food ingestion in grass carp (Ctenopharyngodon idellus). Four rations, satiation (S), 80% S, 60% S and 40% S, were adopted in this study. Each treatment was randomly assigned to triplicate net cages of 15 fish (177.3 +/- 3.3 g) per cage. The experiment lasted for 49 days at 30.0 +/- 3.0 degrees C. The experimental results showed that a significant increase in feeding rate and weight gain was found in grass carp with the increased ration level. The body lipid and energy content of the grass carp exhibited a significant decrease when receiving food restriction. The transcriptional levels of the genes involved in lipogenesis (srebp-1c, fas, ppar gamma) were down-regulated at the rations of food restriction. The relative expression of hepatic fas (fatty acid synthetase) and srebp-1c (sterol regulatory element-binding protein 1c) in the fish at satiation were significantly higher than the restricted-fed groups. Similarly, the expressions of hepatic ppar. (peroxisome proliferator-activated receptor-gamma) in the fish at the ration of satiation and 80% S were significantly higher than the group at the low ration of 40% S. However, the expression of hepatic cpt-1a (carnitine palmitoyl transferase I) involved in fatty acid beta-oxidation in fish was significantly up-regulated when receiving food restriction. Other hepatic lipolysis genes of ppar alpha (peroxisome proliferators-activated receptor alpha) and hl (hepatic lipase) didn&#39;t show any significant changes in restricted-fed fish. The transcriptional levels of hepatic leptin and hypothalamus pomc (proopiomelanocortin) were significantly down-regulated in fish fed with restricted rations. But the hypothalamus npy (neuropeptide Y) and lepr (leptin receptor) had no change. The present results indicated that a long-term food restriction could cause less accumulation of lipid and could be through a way of down-regulating lipogenesis genes and up-regulating lipolysis genes. Long-term restriction could also activate the appetite of grass carp by down-regulating some anorexigenic genes. Statement of relevance: Food restriction for some time could lead to a suitable lipid storage, in case of accumulation of fatty acid profile and lipid, in cultured grass carp. (C) 2016 Elsevier B.V. All rights reserved.</p

    Tree-ring stable carbon isotope-based April-June relative humidity reconstruction since AD 1648 in Mt. Tianmu, China

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    Based on accurate dating, we have determined the stable carbon isotope ratios (delta C-13) of five Cryptomeria fortunei specimens from Mt. Tianmu, a subtropical area in southern China. The five delta C-13 time series records are combined into a single representative delta C-13 time series using a &quot;numerical mix method.&quot; These are normalized to remove temporal variations of delta(13) C in atmospheric CO2 to obtain a carbon isotopic discrimination (Delta C-13) time series, in which we observe a distinct correlation between Delta C-13 and local April to June mean relative humidity (RH (AMJ) ) (n = 64, r = 0.858, p &lt; 0.0001). We use this relationship to reconstruct RH (AMJ) variations from ad 1648 to 2014 at Mt. Tianmu. The reconstructed sequence show that over the past 367 years, Mt. Tianmu area was relatively wet, but in the latter part of the twentieth century, under the influence of increasing global warming, it has experienced a sharp reduction in relative humidity. Spatial correlation analysis reveals a significant negative correlation between RH (AMJ) at Mt. Tianmu and Sea Surface Temperature (SSTs) in the western equatorial Pacific and Indian Ocean. In other words, there is a positive correlation between tree-ring delta C-13 in Mt. Tianmu and SSTs. Both observed and reconstructed RH (AMJ) show significant positive correlations with East Asian and South Asian monsoons from 1951 to 2014, which indicate that RH (AMJ) from Mt. Tianmu reflects the variability of the Asian summer monsoon intensity to a great extent. The summer monsoon has weakened since 1960. However, an increase in relative humidity since 2003 implies a recent enhancement in the summer monsoon
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