1,357 research outputs found
The relation of H2CO, 12CO, and 13CO in molecular clouds
Aims. We seek to understand how the 4.8 GHz formaldehyde absorption line is
distributed in the MON R2, S156, DR17/L906, and M17/M18 regions. More
specifically, we look for the relationship among the H2CO, 12CO, and 13CO
spectral lines. Methods. The four regions of MON R2 (60'x90'), S156 (5'0x70'),
DR17/L906 (40'x60'), and M17 /M18 (70'x80')were observed for H2CO (beam 10'),
H110a recombination (beam 10'), 6 cm continuum (beam 10'), 12CO (beam 1'), and
13CO (beam 1'). We compared the H2CO,12CO,13CO, and continuum distributions,
and also the spectra line parameters of H2CO,12CO, and 13CO. Column densities
of H2CO,13CO, and H2 were also estimated. Results. We found out that the H2CO
distribution is similar to the 12CO and the 13CO distributions on a large
scale. The correlation between the 13 CO and the H2CO distributions is better
than between the 12CO and H2CO distributions. The H2CO and the 13CO tracers
systematically provide consistent views of the dense regions. T heir maps have
similar shapes, sizes, peak positions, and molecular spectra and present
similar centr al velocities and line widths. Such good agreement indicates that
the H2CO and the 13CO arise from similar regions.Comment: 21 pages, 12 figures published, 201
MVP: Multi-task Supervised Pre-training for Natural Language Generation
Pre-trained language models (PLMs) have achieved remarkable success in
natural language generation (NLG) tasks. Up to now, most NLG-oriented PLMs are
pre-trained in an unsupervised manner using the large-scale general corpus. In
the meanwhile, an increasing number of models pre-trained with labeled data
(i.e. "supervised pre-training") showcase superior performance compared to
unsupervised pre-trained models. Motivated by the success of supervised
pre-training, we propose Multi-task superVised Pre-training (MVP) for natural
language generation. We collect a large-scale natural language generation
corpus, MVPCorpus, from datasets over diverse NLG tasks. Then we
unify these examples into a general text-to-text format to pre-train the text
generation model MVP in a supervised manner. For each task, we further
pre-train specific soft prompts to stimulate the model's capacity to perform a
specific task. Our MVP model can be seen as a practice that utilizes recent
instruction tuning on relatively small PLMs. Extensive experiments have
demonstrated the effectiveness and generality of our MVP model in a number of
NLG tasks, which achieves state-of-the-art performance on out of
datasets, outperforming BART by and Flan-T5 by .Comment: Accepted by ACL 202
Far-field Super-resolution Chemical Microscopy
Far-field chemical microscopy providing molecular electronic or vibrational
fingerprint information opens a new window for the study of three-dimensional
biological, material, and chemical systems. Chemical microscopy provides a
nondestructive way of chemical identification without exterior labels. However,
the diffraction limit of optics hindered it from discovering more details under
the resolution limit. Recent development of super-resolution techniques gives
enlightenment to open this door behind far-field chemical microscopy. Here, we
review recent advances that have pushed the boundary of far-field chemical
microscopy in terms of spatial resolution. We further highlight applications in
biomedical research, material characterization, environmental study, cultural
heritage conservation, and integrated chip inspection.Comment: 34 pages, 8 figures,1 tabl
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