145 research outputs found
Investigations of supernovae and supernova remnants in the era of SKA
Two main physical mechanisms are used to explain supernova explosions:
thermonuclear explosion of a white dwarf(Type Ia) and core collapse of a
massive star (Type II and Type Ib/Ic). Type Ia supernovae serve as distance
indicators that led to the discovery of the accelerating expansion of the
Universe. The exact nature of their progenitor systems however remain unclear.
Radio emission from the interaction between the explosion shock front and its
surrounding CSM or ISM provides an important probe into the progenitor star's
last evolutionary stage. No radio emission has yet been detected from Type Ia
supernovae by current telescopes. The SKA will hopefully detect radio emission
from Type Ia supernovae due to its much better sensitivity and resolution.
There is a 'supernovae rate problem' for the core collapse supernovae because
the optically dim ones are missed due to being intrinsically faint and/or due
to dust obscuration. A number of dust-enshrouded optically hidden supernovae
should be discovered via SKA1-MID/survey, especially for those located in the
innermost regions of their host galaxies. Meanwhile, the detection of
intrinsically dim SNe will also benefit from SKA1. The detection rate will
provide unique information about the current star formation rate and the
initial mass function. A supernova explosion triggers a shock wave which expels
and heats the surrounding CSM and ISM, and forms a supernova remnant (SNR). It
is expected that more SNRs will be discovered by the SKA. This may decrease the
discrepancy between the expected and observed numbers of SNRs. Several SNRs
have been confirmed to accelerate protons, the main component of cosmic rays,
to very high energy by their shocks. This brings us hope of solving the
Galactic cosmic ray origin's puzzle by combining the low frequency (SKA) and
very high frequency (Cherenkov Telescope Array: CTA) bands' observations of
SNRs.Comment: To be published in: "Advancing Astrophysics with the Square Kilometre
Array", Proceedings of Science, PoS(AASKA14
Integrating Symmetry into Differentiable Planning with Steerable Convolutions
We study how group symmetry helps improve data efficiency and generalization
for end-to-end differentiable planning algorithms when symmetry appears in
decision-making tasks. Motivated by equivariant convolution networks, we treat
the path planning problem as \textit{signals} over grids. We show that value
iteration in this case is a linear equivariant operator, which is a (steerable)
convolution. This extends Value Iteration Networks (VINs) on using
convolutional networks for path planning with additional rotation and
reflection symmetry. Our implementation is based on VINs and uses steerable
convolution networks to incorporate symmetry. The experiments are performed on
four tasks: 2D navigation, visual navigation, and 2 degrees of freedom (2DOFs)
configuration space and workspace manipulation. Our symmetric planning
algorithms improve training efficiency and generalization by large margins
compared to non-equivariant counterparts, VIN and GPPN.Comment: Restructured main text and appendix. Renamed from "Integrating
Symmetry into Differentiable Planning
Lung Adenocarcinoma Identification via Cellular Phenotyping and Neighborhood Analysis with Imaging Mass Cytometry
https://openworks.mdanderson.org/sumexp21/1210/thumbnail.jp
Vertically Oriented and Interpenetrating CuSe Nanosheet Films with Open Channels for Flexible All-Solid-State Supercapacitors
As a p-type multifunctional semiconductor, CuSe nanostructures show great promise in optoelectronic, sensing, and photocatalytic fields. Although great progress has been achieved, controllable synthesis of CuSe nanosheets (NSs) with a desirable spacial orientation and open frameworks remains a challenge, and their use in supercapacitors (SCs) has not been explored. Herein, a highly vertically oriented and interpenetrating CuSe NS film with open channels is deposited on an Au-coated polyethylene terephthalate substrate. Such CuSe NS films exhibit high specific capacitance (209 F g–1) and can be used as a carbon black- and binder-free electrode to construct flexible, symmetric all-solid-state SCs, using polyvinyl alcohol–LiCl gel as the solid electrolyte. A device fabricated with such CuSe NS films exhibits high volumetric specific capacitance (30.17 mF cm–3), good cycling stability, excellent flexibility, and desirable mechanical stability. The excellent performance of such devices results from the vertically oriented and interpenetrating configuration of CuSe NS building blocks, which can increase the available surface and facilitate the diffusion of electrolyte ions. Moreover, as a prototype for application, three such solid devices in series can be used to light up a red light-emitting diode
Benchmarking Large Language Models on CMExam -- A Comprehensive Chinese Medical Exam Dataset
Recent advancements in large language models (LLMs) have transformed the
field of question answering (QA). However, evaluating LLMs in the medical field
is challenging due to the lack of standardized and comprehensive datasets. To
address this gap, we introduce CMExam, sourced from the Chinese National
Medical Licensing Examination. CMExam consists of 60K+ multiple-choice
questions for standardized and objective evaluations, as well as solution
explanations for model reasoning evaluation in an open-ended manner. For
in-depth analyses of LLMs, we invited medical professionals to label five
additional question-wise annotations, including disease groups, clinical
departments, medical disciplines, areas of competency, and question difficulty
levels. Alongside the dataset, we further conducted thorough experiments with
representative LLMs and QA algorithms on CMExam. The results show that GPT-4
had the best accuracy of 61.6% and a weighted F1 score of 0.617. These results
highlight a great disparity when compared to human accuracy, which stood at
71.6%. For explanation tasks, while LLMs could generate relevant reasoning and
demonstrate improved performance after finetuning, they fall short of a desired
standard, indicating ample room for improvement. To the best of our knowledge,
CMExam is the first Chinese medical exam dataset to provide comprehensive
medical annotations. The experiments and findings of LLM evaluation also
provide valuable insights into the challenges and potential solutions in
developing Chinese medical QA systems and LLM evaluation pipelines. The dataset
and relevant code are available at https://github.com/williamliujl/CMExam
Ultra-Strong Long-Chain Polyamide Elastomers With Programmable Supramolecular Interactions and Oriented Crystalline Microstructures
Polyamides are one of the most important polymers. Long-chain aliphatic polyamides could bridge the gap between traditional polyamides and polyethylenes. Here we report an approach to preparing sustainable ultra-strong elastomers from biomass-derived long-chain polyamides by thiol-ene addition copolymerization with diamide diene monomers. The pendant polar hydroxyl and non-polar butyrate groups between amides allow controlled programming of supramolecular hydrogen bonding and facile tuning of crystallization of polymer chains. The presence of thioether groups on the main chain can further induce metal–ligand coordination (cuprous-thioether). Unidirectional step-cycle tensile deformation has been applied to these polyamides and significantly enhances tensile strength to over 210 MPa while maintaining elasticity. Uniaxial deformation leads to a rearrangement and alignment of crystalline microstructures, which is responsible for the mechanical enhancement. These chromophore-free polyamides are observed with strong luminescence ascribed to the effect of aggregation-induced emission (AIE), originating from the formation of amide clusters with restricted molecular motions
Photometry of Variable Stars from Dome A, Antarctica
Dome A on the Antarctic plateau is likely one of the best observing sites on
Earth thanks to the excellent atmospheric conditions present at the site during
the long polar winter night. We present high-cadence time-series aperture
photometry of 10,000 stars with i<14.5 mag located in a 23 square-degree region
centered on the south celestial pole. The photometry was obtained with one of
the CSTAR telescopes during 128 days of the 2008 Antarctic winter.
We used this photometric data set to derive site statistics for Dome A and to
search for variable stars. Thanks to the nearly-uninterrupted synoptic
coverage, we find 6 times as many variables as previous surveys with similar
magnitude limits. We detected 157 variable stars, of which 55% are
unclassified, 27% are likely binaries and 17% are likely pulsating stars. The
latter category includes delta Scuti, gamma Doradus and RR Lyrae variables. One
variable may be a transiting exoplanet.Comment: Accepted for publication in the Astronomical Journal. PDF version
with high-resolution figures available at
http://faculty.physics.tamu.edu/lmacri/papers/wang11.pd
Photometric Variability in the CSTAR Field: Results From the 2008 Data Set
The Chinese Small Telescope ARray (CSTAR) is the first telescope facility
built at Dome A, Antarctica. During the 2008 observing season, the installation
provided long-baseline and high-cadence photometric observations in the i-band
for 18,145 targets within 20 deg2 CSTAR field around the South Celestial Pole
for the purpose of monitoring the astronomical observing quality of Dome A and
detecting various types of photometric variability. Using sensitive and robust
detection methods, we discover 274 potential variables from this data set, 83
of which are new discoveries. We characterize most of them, providing the
periods, amplitudes and classes of variability. The catalog of all these
variables is presented along with the discussion of their statistical
properties.Comment: 38 pages, 11 figures, 4 tables; Accepted for publication in ApJ
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