136 research outputs found
Solving the Strongly Coupled 2D Gravity: 2. Fractional-Spin Operators, and Topological Three-Point Functions
Progress along the line of a previous article are reported. One main point is
to include chiral operators with fractional quantum group spins (fourth or
sixth of integers) which are needed to achieve modular invariance. We extend
the study of the chiral bootstrap (recently completed by E. Cremmer, and the
present authors) to the case of semi-infinite quantum-group representations
which correspond to positive integral screening numbers. In particular, we
prove the Bidenharn-Elliot and Racah identities for q-deformed 6-j symbols
generalized to continuous spins. The decoupling of the family of physical
chiral operators (with real conformal weights) at the special values
C_{Liouville}= =7, 13, and 19, is shown to provide a full solution of Moore and
Seiberg's equations, only involving operators with real conformal weights.
Moreover, our study confirms the existence of the strongly coupled topological
models. The three-point functions are shown to be given by a product of leg
factors similar to the ones of the weakly coupled models. However, contrary to
this latter case, the equality between the quantum group spins of the
holomorphic and antiholomorphic components is not preserved by the local vertex
operator. Thus the ``c=1'' barrier appears as connected with a deconfinement of
chirality.Comment: 45 pages Latex file, 14 figures (uuencoded
Methods and Models for Metabolic Assessment in Mice
The development of new therapies for the treatment of type 2 diabetes requires robust, reproducible and well validated in vivo experimental systems. Mice provide the most ideal animal model for studies of potential therapies. Unlike larger animals, mice have a short gestational period, are genetically similar, often give birth to many offspring at once and can be housed as multiple groups in a single cage. The mouse model has been extensively metabolically characterized using different tests. This report summarizes how these tests can be executed and how arising data are analyzed to confidently determine changes in insulin resistance and insulin secretion with high reproducibility. The main tests for metabolic assessment in the mouse reviewed here are the glucose clamp, the intravenous and the oral glucose tolerance tests. For all these experiments, including some commonly adopted variants, we describe: (i) their performance; (ii) their advantages and limitations; (iii) the empirical formulas and mathematical models implemented for the analysis of the data arising from the experimental procedures to obtain reliable measurements of peripheral insulin sensitivity and beta cell function. Finally, a list of previous applications of these methods and analytical techniques is provided to better comprehend their use and the evidences that these studies yielded
Impact of glucose dosing regimens on modeling of glucose tolerance and ÎČ-cell function by intravenous glucose tolerance test in diet-induced obese mice.
Insulin sensitivity declines in overweight and obese individuals and, under normal conditions, insulin secretion adaptively increases which in healthy non-diabetic subjects maintains normal glycemia. This adaptation is best described by the disposition index derived from modeling of insulin and glucose data from an intravenous glucose tolerance testing (IVGTT). One caveat of the IVGTT is that basing the glucose dose on the individual total body weight can result in large differences in the amount of glucose given to lean and obese individuals. The effect this has on determination of insulin sensitivity and ÎČ-cell function is unknown. In this study, we therefore evaluated alternative glucose dosing regimens for determination of the impact of glucose dosing on measures of ÎČ-cell function in normal and diet-induced obese (DIO) mice. The glucose dosing regimens used for the IVGTT were 0.35 mg per kg total body weight (BW) or per kg lean BW or a fixed glucose dose based on the average BW for all experimental mice. Each regimen detected a similar decrease in insulin sensitivity in DIO mice. The different glucose dosing regimens gave, however, diverging results in regard to glucose elimination and the acute insulin response. Thus, the fixed-dose regimen was the only that revealed impairment of glucose elimination, whereas dosing according to total BW was the only regimen which showed significant increases in acute insulin response in DIO mice. The fixed-dose glucose dosing regimen was the only that revealed a significant decline in the disposition index value in DIO mice, which is characteristic of type 2 diabetes in humans. Our results therefore show that using different glucose dosing regimens during IVGTT in DIO mice one can model different aspects of physiology which are similar to prediabetes and type 2 diabetes in humans, with the fixed-dose regimen producing a phenotype that most closely resembles human type 2 diabetes
Differential Development of Glucose Intolerance and Pancreatic Islet Adaptation in Multiple Diet Induced Obesity Models
Background: The C57BL/6 mouse fed a high fat diet is a common and valuable model in experimental studies of obesity and type 2 diabetes (T2D). Different high fat diets are used and in order to determine which diet produces a model most accurately resembling human T2D, they need to be compared head-to-head. Methods: Four different diets, the 60% high fat diet (HFD) and the 58% high fat-high sucrose Surwit diet (HFHS) and their respective controls, were compared in C57BL/6J mice using glucose tolerance tests (IVGTT) and the euglycemic clamp. Results: Mice fed a HFD gained more weight than HFHS fed mice despite having similar energy intake. Both high fat diet models were glucose intolerant after eight weeks. Mice fed the HFD had elevated basal insulin, which was not seen in the HFHS group. The acute insulin response (AIR) was unchanged in the HFD group, but slightly increased in the HFHS diet group. The HFHS diet group had a threefold greater total insulin secretion during the IVGTT compared to its control, while no differences were seen in the HFD group. Insulin sensitivity was decreased fourfold in the HFD group, but not in the HFHS diet group. Conclusion: The HFD and HFHS diet models show differential effects on the development of insulin resistance and beta cell adaptation. These discrepancies are important to acknowledge in order to select the appropriate diet for specific studies
Template-based Abstractive Microblog Opinion Summarisation
We introduce the task of microblog opinion summarisation (MOS) and share a
dataset of 3100 gold-standard opinion summaries to facilitate research in this
domain. The dataset contains summaries of tweets spanning a 2-year period and
covers more topics than any other public Twitter summarisation dataset.
Summaries are abstractive in nature and have been created by journalists
skilled in summarising news articles following a template separating factual
information (main story) from author opinions. Our method differs from previous
work on generating gold-standard summaries from social media, which usually
involves selecting representative posts and thus favours extractive
summarisation models. To showcase the dataset's utility and challenges, we
benchmark a range of abstractive and extractive state-of-the-art summarisation
models and achieve good performance, with the former outperforming the latter.
We also show that fine-tuning is necessary to improve performance and
investigate the benefits of using different sample sizes.Comment: Accepted for publication in Transactions of the Association for
Computational Linguistics (TACL), 2022. Pre-MIT Press publication versio
Spatio-temporal characteristics of PM\u3csub\u3e2.5\u3c/sub\u3e, PM\u3csub\u3e10\u3c/sub\u3e, and AOD over the central line project of Chinaâs South-NorthWater diversion in Henan Province (China)
© 2021 by the authors. Licensee MDPI, Basel, Switzerland. The spatio-temporal characteristics of particulate matter with a particle size less than or equal to 2.5 ”m (PM2.5), particulate matter with a particle size less than or equal to 10 ”m (PM10), meteorological parameters from September 2018 to September 2019, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) aerosol optical depth (AOD) from 2007 to 2019 were investigated over the Central Line Project of Chinaâs South-North Water Diversion (CSNWD) in Henan Province. To better understand the characteristics of the atmospheric environment over the CSNWD, air quality monitoring stations were installed in Nanyang (in the upper reaches), Zhengzhou (in the middle reaches), and Anyang (in the lower reaches). In this study, daily, monthly, and seasonal statistical analyses of PM2.5 and PM10 concentrations were performed and their relationship with meteorological parameters was investigated. The results show extremely poor air quality conditions over the Zhengzhou Station compared with the Nanyang and Anyang Stations. The annual average PM2.5 concentration did not meet Chinaâs ambient air secondary standard (35 ”g/m3 annual mean) over all the stations, while the annual average PM10 concentration satisfied Chinaâs ambient air secondary standard (100 ”g/m3 annual mean) over the Anyang and Nanyang Stations, except for the Zhengzhou Station. The highest PM2.5 and PM10 concentrations were observed during winter compared with the other seasons. The results show that PM2.5 and PM10 concentrations were negatively correlated with wind speed and temperature at the Nanyang and Zhengzhou Stations, but positively correlated with relative humidity. However, no significant negative or positive correlation was observed at Anyang Station. There is a strong linear positive correlation between PM2.5 and PM10 (R = 0.99), which indicates that the particulate matter at the three stations was mainly caused by local emissions. Additionally, the AOD values at the three stations were the highest in summer, which may be related to the residues of crops burned in Henan Province in summer
Comparison and Analysis of Network Construction Methods for Seismicity Based on Complex Networks
The approach of the complex network has well described seismic complex systems. In this paper, this is the first time three classical network construction methods for seismicity are compared. By using the same dataset from the Southern California Seismic Network, three networks are constructed. They all present the scale-free, small-world properties, a strength-degree correlation, and an assortative mixing feature. However, they show some differences in the hierarchical clustering feature. On observing the evolution results, three measures show a similar correlation with seismicity dynamics, but one measure shows a different result. These results show that different network construction methods will present some similarities and differences in network properties. This situation needs to be considered, especially when discussing a predictive indicator of seismicity
Template-based Abstractive Microblog Opinion Summarization
We introduce the task of microblog opinion summarization (MOS) and share a dataset of 3100 gold-standard opinion summaries to facilitate research in this domain. The dataset contains summaries of tweets spanning a 2-year period and covers more topics than any other public Twitter summarization dataset. Summaries are abstractive in nature and have been created by journalists skilled in summarizing news articles following a template separating factual information (main story) from author opinions. Our method differs from previous work on generating gold-standard summaries from social media, which usually involves selecting representative posts and thus favors extractive summarization models. To showcase the datasetâs utility and challenges, we benchmark a range of abstractive and extractive state-of-the-art summarization models and achieve good performance, with the former outperforming the latter. We also show that fine-tuning is necessary to improve performance and investigate the benefits of using different sample sizes
Macrophageâderived MMPâ9 enhances the progression of atherosclerotic lesions and vascular calcification in transgenic rabbits
Matrix metalloproteinaseâ9 (MMPâ9), or gelatinase B, has been hypothesized to be involved in the progression of atherosclerosis. In the arterial wall, accumulated macrophages secrete considerable amounts of MMPâ9 but its pathophysiological functions in atherosclerosis have not been fully elucidated. To examine the hypothesis that macrophageâderived MMPâ9 may affect atherosclerosis, we created MMPâ9 transgenic (Tg) rabbits to overexpress the rabbit MMPâ9 gene under the control of the scavenger receptor A enhancer/promoter and examined their susceptibility to cholesterol dietâinduced atherosclerosis. Tg rabbits along with nonâTg rabbits were fed a cholesterol diet for 16 and 28Â weeks, and their aortic and coronary atherosclerosis was compared. Gross aortic lesion areas were significantly increased in female Tg rabbits at 28Â weeks; however, pathological examination revealed that all the lesions of Tg rabbits fed a cholesterol diet for either 16 or 28Â weeks were characterized by increased monocyte/macrophage accumulation and prominent lipid core formation compared with those of nonâTg rabbits. Macrophages isolated from Tg rabbits exhibited higher infiltrative activity towards a chemoattractant, MCPâ1 in vitro and augmented capability of hydrolysing extracellular matrix in granulomatous tissue. Surprisingly, the lesions of Tg rabbits showed more advanced lesions with remarkable calcification in both aortas and coronary arteries. In conclusion, macrophageâderived MMPâ9 facilitates the infiltration of monocyte/macrophages into the lesions thereby enhancing the progression of atherosclerosis. Increased accumulation of lesional macrophages may promote vascular calcification.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154927/1/jcmm15087-sup-0001-FigS1-S13.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154927/2/jcmm15087.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154927/3/jcmm15087_am.pd
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