55 research outputs found
Cosmic Radio Background from Primordial Black Holes at Cosmic Dawn
The presence of an extra radio background besides the cosmic microwave
background has important implications for the observation of the 21-cm signal
during the cosmic Dark Ages, Cosmic Dawn, and epoch of Reionization. The strong
absorption trough found in the 21-cm global spectrum measured by the EDGES
experiment, which has a much greater depth than the standard model prediction,
has drawn great interest to this scenario, but more generally it is still of
great interest to consider such a cosmic radio background (CRB) in the early
Universe. To be effective in affecting the 21-cm signal at early time, such a
radio background must be produced by sources which can emit strong radio
signals but modest amount of X-rays, so that the gas is not heated up too
early. We investigate the scenario that such a radio background is produced by
the primordial black holes (PBHs). For PBH with a single mass, we find that if
the PBHs' abundance (ratio of total PBH mass density to
total matter density) and mass satisfy the relation for , and have jet emission, they can generate
a CRB required for reproducing the 21-cm absorption signal seen by the EDGES.
The accretion rate can be boosted if the PBHs are surrounded by dark matter
halos, which permits lower value to satisfy the EDGES
observation. In the latter scenario, since the accretion rate can evolve
rapidly during the Cosmic Dawn, the frequency (redshift) and depth of the
absorption trough can determine the mass and abundance of the PBHs
simultaneously. For absorption trough redshift 17 and depth
mK, it corresponds to and .Comment: 16 pages, 13 figures, accepted for publication in PR
DeepSolo: Let Transformer Decoder with Explicit Points Solo for Text Spotting
End-to-end text spotting aims to integrate scene text detection and
recognition into a unified framework. Dealing with the relationship between the
two sub-tasks plays a pivotal role in designing effective spotters. Although
transformer-based methods eliminate the heuristic post-processing, they still
suffer from the synergy issue between the sub-tasks and low training
efficiency. In this paper, we present DeepSolo, a simple detection transformer
baseline that lets a single Decoder with Explicit Points Solo for text
detection and recognition simultaneously. Technically, for each text instance,
we represent the character sequence as ordered points and model them with
learnable explicit point queries. After passing a single decoder, the point
queries have encoded requisite text semantics and locations and thus can be
further decoded to the center line, boundary, script, and confidence of text
via very simple prediction heads in parallel, solving the sub-tasks in text
spotting in a unified framework. Besides, we also introduce a text-matching
criterion to deliver more accurate supervisory signals, thus enabling more
efficient training. Quantitative experiments on public benchmarks demonstrate
that DeepSolo outperforms previous state-of-the-art methods and achieves better
training efficiency. In addition, DeepSolo is also compatible with line
annotations, which require much less annotation cost than polygons. The code
will be released.Comment: The code will be available at
https://github.com/ViTAE-Transformer/DeepSol
A New Guide Lifter for the Transceiver of USBL
A new guide lifter has been put forward for the transceiver of Ultra Short Base Line (USBL) with a worm gear reducer applied as self-locking of the lifter and a chain structure applied to drive the sliding shaft moving up and down. The new device is 7500 mm long and connected to the end of the transceiver. Linear motion products are introduced to ensure the shaft unable to rotate and the position measurements are provided by position sensors. A heavy self-sealing sliding bearing, which is 800 mm in length, keeps the shaft running reliably. Then the three-dimensional model is built and the structure parameters of the lifter are calculated. Later, the working process of the lifter is simulated to guarantee the movement parameters meet the request of USBL. Finally, the experiment on the intensity and stiffness of the lifter is carried out via the finite element model of the lifter built in ANSYS with the maximum load conditions and the result has been experimentally verified. This device provides a reliable approach of operating USBL which plays a vitally important role in ocean exploration and the research results are successfully applied to the scientific research vessels of Dayang No. 1 as well as Xiangyanghong No. 9
Visualizing traffic causality for analyzing network anomalies
ABSTRACT Monitoring network traffic and detecting anomalies are essential tasks that are carried out routinely by security analysts. The sheer volume of network requests often makes it difficult to detect attacks and pinpoint their causes. We design and develop a tool to visually represent the causal relations for network requests. The traffic causality information enables one to reason about the legitimacy and normalcy of observed network events. Our tool with a special visual locality property supports different levels of visualbased querying and reasoning required for the sensemaking process on complex network data. Leveraging the domain knowledge, security analysts can use our tool to identify abnormal network activities and patterns due to attacks or stealthy malware. We conduct a user study that confirms our tool can enhance the readability and perceptibility of the dependency for host-based network traffic
Decoupled measurement and modeling of interface reaction kinetics of ion-intercalation battery electrodes
Ultrahigh rate performance of active particles used in lithium-ion battery
electrodes has been revealed by single-particle measurements, which indicates a
huge potential for developing high-power batteries. However, the
charging/discharging behaviors of single particles at ultrahigh C-rates can no
longer be described by the traditional electrochemical kinetics in such
ion-intercalation active materials. In the meantime, regular kinetic measuring
methods meet a challenge due to the coupling of interface reaction and
solid-state diffusion processes of active particles. Here, we decouple the
reaction and diffusion kinetics via time-resolved potential measurements with
an interval of 1 ms, revealing that the classical Butler-Volmer equation
deviates from the actual relation between current density, overpotential, and
Li+ concentration. An interface ion-intercalation model is developed which
considers the excess driving force of Li+ (de)intercalation in the charge
transfer reaction for ion-intercalation materials. Simulations demonstrate that
the proposed model enables accurate prediction of charging/discharging at both
single-particle and electrode scales for various active materials. The kinetic
limitation processes from single particles to composite electrodes are
systematically revealed, promoting rational designs of high-power batteries
Overpotential decomposition enabled decoupling of complex kinetic processes in battery electrodes
Identifying overpotential components of electrochemical systems enables
quantitative analysis of polarization contributions of kinetic processes under
practical operating conditions. However, the inherently coupled kinetic
processes lead to an enormous challenge in measuring individual overpotentials,
particularly in composite electrodes of lithium-ion batteries. Herein, the full
decomposition of electrode overpotential is realized by the collaboration of
single-layer structured particle electrode (SLPE) constructions and
time-resolved potential measurements, explicitly revealing the evolution of
kinetic processes. Perfect prediction of the discharging profiles is achieved
via potential measurements on SLPEs, even in extreme polarization conditions.
By decoupling overpotentials in different electrode/cell structures and
material systems, the dominant limiting processes of battery rate performance
are uncovered, based on which the optimization of electrochemical kinetics can
be conducted. Our study not only shades light on decoupling complex kinetics in
electrochemical systems, but also provides vitally significant guidance for the
rational design of high-performance batteries
High-grade serous papillary ovarian carcinoma combined with nonkeratinizing squamous cell carcinoma of the cervix: a case report
Multiple primary malignant neoplasms are a rare gynecologic malignancy; particularly, cases originating from the heterologous organs, such as the ovary and cervix. Here, we report a case of two primary malignant neoplasms in a patient who had undergone laparoscopic radical hysterectomy + bilateral salpingo-oophorectomy + pelvic lymph node dissection + para-aortic lymphadenectomy + appendectomy + omentectomy + metastasectomy under general anesthesia. The patient experienced complete remission after six courses of postoperative chemotherapy with a standard Taxol and Carboplatin regimen. Genetic testing was performed to detect BRCA2 mutations, and poly (ADP-ribose) polymerase (PARP) inhibitors were used for maintenance therapy
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