1,800 research outputs found
Interpreting time-integrated polarization data of gamma-ray burst prompt emission
Aims. With the accumulation of polarization data in the gamma-ray burst (GRB)
prompt phase, polarization models can be tested. Methods. We predicted the
time-integrated polarizations of 37 GRBs with polarization observation. We used
their observed spectral parameters to do this. In the model, the emission
mechanism is synchrotron radiation, and the magnetic field configuration in the
emission region was assumed to be large-scale ordered. Therefore, the predicted
polarization degrees (PDs) are upper limits. Results. For most GRBs detected by
the Gamma-ray Burst Polarimeter (GAP), POLAR, and AstroSat, the predicted PD
can match the corresponding observed PD. Hence the synchrotron-emission model
in a large-scale ordered magnetic field can interpret both the moderately low
PDs () detected by POLAR and relatively high PDs ()
observed by GAP and AstroSat well. Therefore, the magnetic fields in these GRB
prompt phases or at least during the peak times are dominated by the ordered
component. However, the predicted PDs of GRB 110721A observed by GAP and GRB
180427A observed by AstroSat are both lower than the observed values. Because
the synchrotron emission in an ordered magnetic field predicts the upper-limit
of the PD for the synchrotron-emission models, PD observations of the two
bursts challenge the synchrotron-emission model. Then we predict the PDs of the
High-energy Polarimetry Detector (HPD) and Low-energy Polarimetry Detector
(LPD) on board the upcoming POLAR-2. In the synchrotron-emission models, the
concentrated PD values of the GRBs detected by HPD will be higher than the LPD,
which might be different from the predictions of the dissipative photosphere
model. Therefore, more accurate multiband polarization observations are highly
desired to test models of the GRB prompt phase.Comment: 6 pages, 5 figures, with updated AstroSat data, accepted by A
A method for incremental discovery of financial event types based on anomaly detection
Event datasets in the financial domain are often constructed based on actual
application scenarios, and their event types are weakly reusable due to
scenario constraints; at the same time, the massive and diverse new financial
big data cannot be limited to the event types defined for specific scenarios.
This limitation of a small number of event types does not meet our research
needs for more complex tasks such as the prediction of major financial events
and the analysis of the ripple effects of financial events. In this paper, a
three-stage approach is proposed to accomplish incremental discovery of event
types. For an existing annotated financial event dataset, the three-stage
approach consists of: for a set of financial event data with a mixture of
original and unknown event types, a semi-supervised deep clustering model with
anomaly detection is first applied to classify the data into normal and
abnormal events, where abnormal events are events that do not belong to known
types; then normal events are tagged with appropriate event types and abnormal
events are reasonably clustered. Finally, a cluster keyword extraction method
is used to recommend the type names of events for the new event clusters, thus
incrementally discovering new event types. The proposed method is effective in
the incremental discovery of new event types on real data sets.Comment: 11 pages,4 figure
Hierarchical Metadata Information Constrained Self-Supervised Learning for Anomalous Sound Detection Under Domain Shift
Self-supervised learning methods have achieved promising performance for
anomalous sound detection (ASD) under domain shift, where the type of domain
shift is considered in feature learning by incorporating section IDs. However,
the attributes accompanying audio files under each section, such as machine
operating conditions and noise types, have not been considered, although they
are also crucial for characterizing domain shifts. In this paper, we present a
hierarchical metadata information constrained self-supervised (HMIC) ASD
method, where the hierarchical relation between section IDs and attributes is
constructed, and used as constraints to obtain finer feature representation. In
addition, we propose an attribute-group-center (AGC)-based method for
calculating the anomaly score under the domain shift condition. Experiments are
performed to demonstrate its improved performance over the state-of-the-art
self-supervised methods in DCASE 2022 challenge Task 2
The properties of the high-mass star formation region IRAS22475+5939
IRAS22475+5939 has been well researched by previous astronomers. But we still
get some new characteristics about it, using the first observations in lines of
CO J=2-1,13CO J=2-1,13CO J=3-2 by the KOSMA 3 m telescope. The mapping of the
intensity ratio of 13CO J=3-2 and 13CO J=2-1 shows the distribution of the
temperature with two peaks, which don't coincide with IRAS22475+5939 source and
the center of the HII region, but at the edge of the HII region. The overlays
of the Spitzer IRAC 8um and CO contours indicate that they are associated with
each other and the strongest polycyclic aromatic hydrocarbons (PAHs) emission
is at the position of IRAS22475+5939 source. While the IRAS LRS spectrum at
7-23 um and the PHT-s spectrum at 2-12 um of IRAS22475+5939 source also exhibit
strong PAHs emission characters at the main PAH bands. The diversity of PAH
family should be responsible for the plateaus of PAHs emission in the PHT-s
spectrum and the IRAS-LRS spectrum. An analysis and modeling in infrared bands
suggest that IRAS22475+5939 is more likely to be a Class I YSO. Where this is
the case, the star is likely to have a temperature T_{EFF} \sim 9995.8 K, mass
\sim15.34 M_(sun), luminosity \sim 1.54*10^4 L_(sun) and age \sim 1.54*10^4 yr.
The model shows that the circumstellar disc emission is important for the
wavelength between 1 and 10 um, otherwise, envelope fluxes for lambda >10 um.
The bipolar outflow is confirmed in the molecular cloud. The excited star of
the HII region has the chance to be the driving source of the outflow. The high
resolution is required.Comment: 12 pages, 20 figures and 5 tables, Accepted for publication in RA
High Dose ESAs Are Associated with High iPTH Levels in Hemodialysis Patients with End-Stage Kidney Disease: A Retrospective Analysis
Objective: Anemia and secondary hyperparathyroidism are the two most common complications associated with chronic kidney disease (CKD). Erythropoiesis-stimulating agents (ESAs) are widely used in the management of anemia in hemodialysis patients. A reverse correlation has been established between hyperparathyroidism and hemoglobin levels. The aim of this retrospective study is to evaluate the relationship of high dose ESAs and hyperparathyroidism in hemodialysis patients with anemia. Methods: A total of 240 uremic patients maintained on regular hemodialysis were enrolled into this study. Among them, 142 patients were treated with Epiao® (epoetin-alfa) and 98 patients were treated with Recormon® (epoetin-beta). The target hemoglobin concentration was 110-130 g/L. Laboratory measurements including hemoglobin, calcium, phosphorus, albumin, intact-parathyroid hormone (iPTH), serum ferritin and transferrin saturation were collected. Results: Hemoglobin concentration increased as iPTH level decreased by stratification. However, no significant association between anemia and calcium or phosphorus level was found. Patients with iPTH levels within 150-300 pg/mL had the highest levels of hemoglobin, serum ferritin and transferrin saturation. Patients treated with Recormon and Epiao had similar hemoglobin concentrations. However, the dose of Recormon for anemia treatment was significantly less than that the dose of Epiao (P<0.05). The level of iPTH in the Recormon group was significantly lower than in the Epiao group. In patients with hemoglobin levels between 110-130 g/L (P<0.05), iPTH level was found to be significantly lower in patients treated with lower doses of ESAs than in patients treated with higher doses of ESAs, no matter which ESA was used (Recormon or Epiao, P<0.05). Conclusions: The dose of ESAs might be positively associated with iPTH level, suggesting that a reasonable hemoglobin target can be achieved by using the lowest possible ESA dose
DNA Repair Pathways in Cancer Therapy and Resistance
DNA repair pathways are triggered to maintain genetic stability and integrity when mammalian cells are exposed to endogenous or exogenous DNA-damaging agents. The deregulation of DNA repair pathways is associated with the initiation and progression of cancer. As the primary anti-cancer therapies, ionizing radiation and chemotherapeutic agents induce cell death by directly or indirectly causing DNA damage, dysregulation of the DNA damage response may contribute to hypersensitivity or resistance of cancer cells to genotoxic agents and targeting DNA repair pathway can increase the tumor sensitivity to cancer therapies. Therefore, targeting DNA repair pathways may be a potential therapeutic approach for cancer treatment. A better understanding of the biology and the regulatory mechanisms of DNA repair pathways has the potential to facilitate the development of inhibitors of nuclear and mitochondria DNA repair pathways for enhancing anticancer effect of DNA damage-based therapy
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