17 research outputs found
Modeling the Light Curves of the Luminous Type Ic Supernova 2007D
SN 2007D is a nearby (redshift z = 0.023146), luminous Type Ic supernova (SN) having a narrow light curve (LC) and high peak luminosity. Previous research based on the assumption that it was powered by the 56Ni cascade decay suggested that the inferred 56Ni mass and the ejecta mass are ~1.5 M ⊙ and ~3.5 M ⊙, respectively. In this paper, we employ some multiband LC models to model the R-band LC and the color (V − R) evolution of SN 2007D to investigate the possible energy sources powering them. We find that the pure 56Ni model is disfavored; the multiband LCs of SN 2007D can be reproduced by a magnetar whose initial rotational period P 0 and magnetic field strength B p are (or ) ms and (or ) G, respectively. By comparing the spectrum of SN 2007D with that of some superluminous SNe (SLSNe), we find that it might be a luminous SN like several luminous gap-filler optical transients that bridge ordinary and SLSNe, rather than a genuine SLSN
Modeling the Light Curves of the Luminous Type Ic Supernova 2007D
SN~2007D is a nearby (redshift ), luminous Type Ic supernova
(SN) having a narrow light curve (LC) and high peak luminosity. Previous
research based on the assumption that it was powered by the Ni cascade
decay suggested that the inferred Ni mass and the ejecta mass are M and M, respectively. In this paper, we
employ some multiband LC models to model the -band LC and the color ()
evolution of SN~2007D to investigate the possible energy sources powering them.
We find that the pure Ni model is disfavored; the multiband LCs of
SN~2007D can be reproduced by a magnetar whose initial rotational period
and magnetic field strength are (or
) ms and (or
) G, respectively. By comparing the
spectrum of SN~2007D with that of some superluminous SNe (SLSNe), we find that
it might be a luminous SN like several luminous ``gap-filler" optical
transients that bridge ordinary and SLSNe, rather than a genuine SLSN.Comment: 11 pages, 5 figures, 1 table, accepted for publication in Ap
UniDexGrasp: Universal Robotic Dexterous Grasping via Learning Diverse Proposal Generation and Goal-Conditioned Policy
In this work, we tackle the problem of learning universal robotic dexterous
grasping from a point cloud observation under a table-top setting. The goal is
to grasp and lift up objects in high-quality and diverse ways and generalize
across hundreds of categories and even the unseen. Inspired by successful
pipelines used in parallel gripper grasping, we split the task into two stages:
1) grasp proposal (pose) generation and 2) goal-conditioned grasp execution.
For the first stage, we propose a novel probabilistic model of grasp pose
conditioned on the point cloud observation that factorizes rotation from
translation and articulation. Trained on our synthesized large-scale dexterous
grasp dataset, this model enables us to sample diverse and high-quality
dexterous grasp poses for the object point cloud.For the second stage, we
propose to replace the motion planning used in parallel gripper grasping with a
goal-conditioned grasp policy, due to the complexity involved in dexterous
grasping execution. Note that it is very challenging to learn this highly
generalizable grasp policy that only takes realistic inputs without oracle
states. We thus propose several important innovations, including state
canonicalization, object curriculum, and teacher-student distillation.
Integrating the two stages, our final pipeline becomes the first to achieve
universal generalization for dexterous grasping, demonstrating an average
success rate of more than 60\% on thousands of object instances, which
significantly outperforms all baselines, meanwhile showing only a minimal
generalization gap.Comment: Accepted to CVPR 202
De novo design of a pH-triggered self-assembled β-hairpin nanopeptide with the dual biological functions for antibacterial and entrapment
Abstract Background Acid-tolerant enteric pathogens can evade small intestinal acid barriers, colonize and infect the intestinal tract. However, broad-spectrum antibiotics are not the best therapeutic strategy because of the disruption of intestinal flora caused by its indiscriminate antimicrobial activity against beneficial and harmful bacteria. So that is what inspired us to combine pH regulation with nanotechnology to develop a pH-triggered site-targeted antimicrobial peptide with entrapping function. Results A pH-triggered dual biological functional self-assembled peptide (SAP) was designed according to the features of amino-acid building blocks and the diagonal cation–π interaction principle. The results of characterization experiments showed that changes in pH conditions could trigger microstructural transformation of the nanopeptide from nanospheres to nanofibers. The subsequent antibacterial and toxicity experiments determined that SAP had great antimicrobial activity against Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, and Bacillus cereus above 15.6 μg/mL under acidic conditions by disrupting bacterial membrane integrity, excellent biocompatibility in vitro even at 250 μg/mL and high tolerance in physical environment. Moreover, at peptide concentrations greater than 62.5 μg/mL, SAP showed the entrapment property, which played an important role in phagocytic clearance in infection forces. Meanwhile, the in vivo results revealed that SAP possessed excellent therapeutic effect and good biosafety. Conclusions Our study revealed the antibacterial activity of a short β-hairpin forming self-assembled peptide, and established an innovative design strategy for peptide-based nanomaterials and a new treatment strategy for gastrointestinal bacterial infections. Graphic Abstrac