908 research outputs found

    The catalogues and mid-infrared environment of Interstellar OH Masers

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    Data for a number of OH maser lines have been collected from surveys. The posi- tions are compared to recent mid-infrared (MIR) surveys such as Spitzer-GLIMPSE and WISE, restricting the comparison to point sources. The colors and intensities of the IR sources are compared. There are many 18 cm OH masers, but far fewer in lines arising from higher energy levels. We also make a comparison with the 5 cm Class II methanol masers. We have divided the results into 3 subsamples: those associated with OH masers only, those associated with OH masers and Class II methanol masers, and those only associated with Class II methanol masers. There are no obvious dif- ferences in the color-color or color-magnitude results for the GLIMPSE point sources. However, according to the results from the WISE 22 {\mu}m survey, the sources associ- ated with OH masers are brighter than those associated with methanol masers. We interpret the presence of OH and methanol masers mark the locations of regions where stars are forming. The OH masers are located on the borders of sharp features found in the IR. These are referred to as bubbles. If the OH masers mark the positions of protostars, the result provides indirect evidence for triggered star formation caused by the expansion of the bubbles.Comment: 23 pages (11 pages online only), 12 figures, Accepted. Monthly Notices of the Royal Astronomical Society,201

    Transformer-based models and hardware acceleration analysis in autonomous driving: A survey

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    Transformer architectures have exhibited promising performance in various autonomous driving applications in recent years. On the other hand, its dedicated hardware acceleration on portable computational platforms has become the next critical step for practical deployment in real autonomous vehicles. This survey paper provides a comprehensive overview, benchmark, and analysis of Transformer-based models specifically tailored for autonomous driving tasks such as lane detection, segmentation, tracking, planning, and decision-making. We review different architectures for organizing Transformer inputs and outputs, such as encoder-decoder and encoder-only structures, and explore their respective advantages and disadvantages. Furthermore, we discuss Transformer-related operators and their hardware acceleration schemes in depth, taking into account key factors such as quantization and runtime. We specifically illustrate the operator level comparison between layers from convolutional neural network, Swin-Transformer, and Transformer with 4D encoder. The paper also highlights the challenges, trends, and current insights in Transformer-based models, addressing their hardware deployment and acceleration issues within the context of long-term autonomous driving applications

    A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz

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    A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz is carried out using the Shanghai Tian Ma 65 m Radio Telescope (TMRT-65m) with a sensitivity of < 7 mK. Thirty-five spectral lines of 12 different molecules and radicals are detected in total. Except for SiS, the detected molecules are all carbon-chain molecules, including HC3N, HC5N, HC7N, HC9N, C6H, C6H-, C8H, SiC2, SiC4, c-C3H2 and l-C5H. The presence of rich carbon-bearing molecules is consistent with the identity of IRC +10216 as a carbon-rich AGB star. The excitation temperatures and column densities of the observed species are derived by assuming a local thermodynamic equilibrium and homogeneous conditions.Comment: This is the authors' version of the manuscript; 16 pages, 5 figures, 6 tables; Accepted for publication in A&A 8/17/201

    Detection of a methanol megamaser in a major-merger galaxy

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    We have detected emission from both the 4_{-1}-3_{0} E (36.2~GHz) class I and 7_{-2}-8_{-1} E (37.7~GHz) class II methanol transitions towards the centre of the closest ultra-luminous infrared galaxy Arp 220. The emission in both the methanol transitions show narrow spectral features and have luminosities approximately 8 orders of magnitude stronger than that observed from typical class I methanol masers observed in Galactic star formation regions. The emission is also orders of magnitude stronger than the expected intensity of thermal emission from these transitions and based on these findings we suggest that the emission from the two transitions are masers. These observations provides the first detection of a methanol megamaser in the 36.2 and 37.7 GHz transitions and represents only the second detection of a methanol megamaser, following the recent report of an 84 GHz methanol megamaser in NGC1068. We find the methanol megamasers are significantly offset from the nuclear region and arise towards regions where there is Ha emission, suggesting that it is associated with starburst activity. The high degree of correlation between the spatial distribution of the 36.2 GHz methanol and X-ray plume emission suggests that the production of strong extragalactic class I methanol masers is related to galactic outflow driven shocks and perhaps cosmic rays. In contrast to OH and H2O megamasers which originate close to the nucleus, methanol megamasers provide a new probe of feedback (e.g. outflows) processes on larger-scales and of star formation beyond the circumnuclear starburst regions of active galaxies.Comment: Accepted for publication in ApJ

    The Effect of Operating in Many Realities on Memory: An Experiment on Memory Recognition in Extended Realities

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    Extended reality (XR) such as VR and AR have been increasingly adopted across domains in cognitively challenging activities such as learning, shopping, and gaming among others. There are a few concerns about the inferior cognitive affordance of XR-mediated functioning, e.g., with respect to memory retention. For better understanding how different XR technologies influence memory performance (e.g., recognition), we examine the effects of VR and AR -mediation on the ability to remember (i.e., recognize afterward) text and image-based information based on a 2 × 2 between-subject experiment (n = 155). The results indicate that VR had a negative main effect on text-based information recognition but no effect on image-based information recognition. AR had no significant main effect on the recognition of either information types. Overall, the findings as further supported by the interaction effects analysis, suggest that for memory recognition, it is always best to have a fully physical (no-AR & no-VR) or fully digital environment (AR & VR) compared to having either VR or AR alone

    Institutional Environment and Overinvestment in Emerging Markets-Empirical Evidence from Chinese Listed Companies

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    We use China’s unique institutional environment as a basis to study the country’s enterprise overinvestment behavior. In recent years, China has seen a surge in enterprise investment due to the huge availability of investment funds leading to difficulties in governing listed firms in the country. We separately analyze the impact of government intervention, rule of law and financial development of various regions on the overinvestment behavior of the listed companies. The results show that government intervention is positively related to overinvestment of listed companies. However, rule of law and financial development are negatively related to overinvestment of listed companies. In addition, the results further show that improved institutional environment can restrict overinvestment in listed companies. Further research indicates that, compared to the rule of law and financial development, government intervention is a fundamental factor which influences overinvestment the most. The study’s results have implications, particularly for the regulators, as they provide useful and detailed information which can be used in the design of more appropriate and functional systems to govern listed companies and help in curbing the overinvestment problem. Keywords: Government intervention; rule of law; financial development; overinvestment, Emerging Market

    Quality Difference Study of Six Varieties of Ganoderma lucidum with Different Origins

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    The quality difference of six varieties Ganoderma lucidum with different origins was investigated in this study by comparing the contents of ganoderic acid A and B, polysaccharide, and triterpenoids. The contents of ganoderic acid A and B in G. lucidum were analyzed by ultra performance liquid chromatography (UPLC). There was higher content of ganoderic acid A in G. lucidum of Dabie Mountain and Longquan. The G. lucidum from Longquan has the highest content of ganoderic acid B. The content of polysaccharide was determined by Anthrone–sulfuric acid method. The highest of polysaccharide content is G. lucidum from Liaocheng. The content of triterpenoid in G. lucidum was quantified by ultraviolet spectrophotometer at 548.1 nm using Ursolic acid as standard. The G. lucidum from Dabie Mountain has the highest content of triterpenoids. In summary, the content of ganoderic acid A and B, polysaccharide, and triterpenoids in G. lucidum with different origins are remarkably different, which may be caused by the conditions of cultivation and geographic environment
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