Abstract
deepCR
is a deep-learning-based cosmic-ray (CR) rejection framework originally presented by Zhang & Bloom. The original approach requires a dedicated training set that consists of multiple ...frames of the same fields, enabling automatic CR labeling through comparison with their median coadds. Here, we present a novel training approach that circumvents the need for a dedicated training set, but instead utilizes dark frames and the science images requiring CR removal themselves. During training, CRs present in dark frames are added to the science images, which the network is then trained to identify. In turn, the trained deepCR model can then be applied to identify CRs originally present in the science images. Using this approach, we present a new
deepCR
model trained on a diverse set of Hubble Space Telescope images taken from resolved galaxies in the Local Group, which is universally applicable across all WFC3/UVIS filters. We introduce a robust approach to determining the threshold for generating binary cosmic-ray masks from predictions from
deepCR
probability maps. When applied to the Panchromatic Hubble Andromeda Southern Treasury survey, our new
deepCR
model added ∼7% of good-quality stars that exhibit distinct features in their color–magnitude diagrams.
Abstract
The offset microlensing degeneracy, recently proposed by Zhang et al., has been shown to generalize the close–wide and inner–outer
caustic
degeneracies into a unified regime of
magnification
...degeneracy in the interpretation of two-body planetary microlensing observations. While the inner–outer degeneracy expects the source trajectory to pass equidistant to the planetary caustics of the degenerate lens configurations, the offset degeneracy states that the same mathematical expression applies to any combination of the close, wide, and resonant caustic topologies, where the projected star–planet separations differ by an offset (
s
A
≠
s
B
) that depends on where the source trajectory crosses the lens axis. An important implication is that the
s
A
= 1/
s
B
solution of the close–wide degeneracy never strictly manifests in observations except when the source crosses a singular point near the primary. Nevertheless, the offset degeneracy was proposed upon numerical calculations, and no theoretical justification was given. Here, we provide a theoretical treatment of the offset degeneracy, which demonstrates its nature as a mathematical degeneracy. From first principles, we show that the offset degeneracy formalism is exact to zeroth order in the mass ratio (
q
) for two cases: when the source crosses the lens axis inside of caustics, and for
(
s
A
−
s
B
)
6
≪
1
when crossing outside of caustics. The extent to which the offset degeneracy persists in oblique source trajectories is explored numerically. Finally, it is shown that the superposition principle allows for a straightforward generalization to
N
-body microlenses with
N
− 1 planetary lens components (
q
≪ 1), which results in a 2
N
−1
-fold degeneracy.
Background
Gastric schwannoma is a rarely seen gastric tumor accounting for only 0.2% of all gastric tumors. It is difficult to distinguish a gastric schwannoma from other gastric tumors ...preoperatively.
Case presentation: A 30-year-old man with no significant medical history or physical examination findings presented with a 1-month history of right upper abdominal discomfort. The preoperative diagnosis was a gastrointestinal stromal tumor, but the postoperative pathologic and immunohistochemical examinations confirmed a gastric schwannoma. The patient underwent laparoscopic wedge resection of the stomach without additional postoperative treatment, and his postoperative recovery was uneventful. No recurrence or metastasis was found at the 2-year follow-up examination.
Conclusion
Although gastric schwannomas are usually not malignant, they are difficult to distinguish from other malignant stromal tumors preoperatively. Surgical resection should be recommended when a schwannoma is malignant or considered to be at risk of becoming malignant.
COVID-19 is now a global public health crisis with unprecedented political, economic, and social consequences affecting nations across the world. It also has a profound impact on the mobility of ...international students. When the COVID-19 was under control in China, and it was spreading dramatically in the United Kingdom, Chinese international students studying in the United Kingdom have been caught in a double bind over whether to return home or not.
This study aims to explore the factors that influenced Chinese international students' choices of return during the COVID-19 pandemic when the COVID-19 was under control in China, while it was spreading dramatically in the United Kingdom.
Taking Chinese international students studying in the United Kingdom as an empirical case, this study used qualitative and quantitative research methods to explore the factors that influenced their choices of return. Based on the Rational Choice Theory and qualitative analysis of text data, this paper constructed the influencing factors model of returning to China. On this basis, we developed a questionnaire and collected data from 1,333 students in late April and early May 2020. Binary Logistic Regression with 95% CI for odds ratio (OR) was used to identify significant factors.
The reserve of epidemic prevention supplies (OR = 0.712), transportation expenses (OR = 0.618), and quarantine expenses (OR = 0.702) negatively affected the return choice of overseas students. The supply of daily necessities (OR = 1.495), the anti-epidemic policy of the United Kingdom (OR = 1.684), and the demand for job hunting after graduation (OR = 1.661) had positive effects.
The institutional rationality had the biggest promoting effect, replaced development rationality, and became the most important factor for overseas students to return to China during the COVID-19 pandemic. Economic rationality, which has a significant negative effect, is the biggest obstacle to returning home. These conclusions have policy implications for governments' response to the COVID-19 epidemic and improvement of the quality of services for overseas students.
On 2019 August 14, the Advanced LIGO and Virgo interferometers detected the high-significance gravitational wave (GW) signal S190814bv. The GW data indicated that the event resulted from a neutron ...star-black hole (NSBH) merger, or potentially a low-mass binary BH merger. Due to the low false-alarm rate and the precise localization (23 deg2 at 90%), S190814bv presented the community with the best opportunity yet to directly observe an optical/near-infrared counterpart to an NSBH merger. To search for potential counterparts, the GROWTH Collaboration performed real-time image subtraction on six nights of public Dark Energy Camera images acquired in the 3 weeks following the merger, covering >98% of the localization probability. Using a worldwide network of follow-up facilities, we systematically undertook spectroscopy and imaging of optical counterpart candidates. Combining these data with a photometric redshift catalog, we ruled out each candidate as the counterpart to S190814bv and placed deep, uniform limits on the optical emission associated with S190814bv. For the nearest consistent GW distance, radiative transfer simulations of NSBH mergers constrain the ejecta mass of S190814bv to be Mej < 0.04 M at polar viewing angles, or Mej < 0.03 M if the opacity is κ < 2 cm2g−1. Assuming a tidal deformability for the NS at the high end of the range compatible with GW170817 results, our limits would constrain the BH spin component aligned with the orbital momentum to be χ < 0.7 for mass ratios Q < 6, with weaker constraints for more compact NSs.
Brain computer interfaces (BCIs) have been demonstrated to have the potential to enhance motor recovery after stroke. However, some stroke patients with severe paralysis have difficulty achieving the ...BCI performance required for participating in BCI-based rehabilitative interventions, limiting their clinical benefits. To address this issue, we presented a BCI intervention approach that can adapt to patients' BCI performance and reported that adaptive BCI-based functional electrical stimulation (FES) treatment induced clinically significant, long-term improvements in upper extremity motor function after stroke more effectively than FES treatment without BCI intervention. These improvements were accompanied by a more optimized brain functional reorganization. Further comparative analysis revealed that stroke patients with low BCI performance (LBP) had no significant difference from patients with high BCI performance in rehabilitation efficacy improvement. Our findings suggested that the current intervention may be an effective way for LBP patients to engage in BCI-based rehabilitation treatment and may promote lasting motor recovery, thus contributing to expanding the applicability of BCI-based rehabilitation treatments to pave the way for more effective rehabilitation treatments.
The importance of SPX-domain-containing proteins to phosphate (Pi) homeostasis and signalling transduction has been established in plants. In this study, phylogenetic analysis revealed that OsSPX3 ...and OsSPX5 (SPX3/5) are paralogous SPX genes ( SYG1/Pho81/XPR1) in cereal crops. SPX3/5 are specifically responsive to Pi starvation at both the transcriptional and post-transcriptional levels. Similar tissue expression patterns of the two genes and proteins were identified by in situ hybridization and the transgenic plants harbouring SPX3pro-SPX3-GUS or SPX5pro-SPX5-GUS fusions, respectively. Both SPX3/5 are localized in the nucleus and cytoplasm in rice protoplasts and plants. SPX3/5 negatively regulate root-to-shoot Pi translocation with redundant function. The data showed that the Pi-starvation-accumulated SPX3/5 proteins are players in restoring phosphate balance following phosphate starvation. In vitro and in vivo protein–protein interaction analyses indicated that these two proteins can form homodimers and heterodimers, also implying their functional redundancy. Genetic interaction analysis indicated that SPX3/5 are functional repressors of OsPHR2 (PHR2), the rice orthologue of the central regulator AtPHR1 for Pi homeostasis and Pi signalling. These results suggest that the evolution of the additional redundant paralogous SPX genes is beneficial to plants recovering Pi homeostasis after Pi starvation by PHR2 pathway.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
ABSTRACT
Under the perturbative picture of planetary microlensing, the planet is considered to act as a uniform-shear Chang–Refsdal lens on one of the two images produced by the host star that comes ...close to the angular Einstein radius of the planet, leaving the other image unaffected. However, this uniform-shear approximation is only valid for isolated planetary caustics and breaks down in the resonant regime. Recently, the planetary-caustic degeneracy arising from the above formalism is found to generalize to the regime of central and resonant caustics, indicating that the perturbative picture and Chang–Refsdal lens approximation may have been underexplored in the past. Here, I introduce a new variable-shear Chang–Refsdal lens approximation, which not only supports central and resonant caustics, but also enables full magnification maps to be calculated analytically. Moreover, I introduce the generalized perturbative picture, which relaxes the required proximity between the planet and the image being perturbed in the previous work. Specifically, the planet always perturbs the image in the same half of the lens plane as the planet itself, leaving the other image largely unaffected. It is demonstrated how this new framework results in the offset degeneracy as a consequence of physical symmetry. The generalized perturbative picture also points to an approach to solve the two-body lens equation semi-analytically. The analytic and semi-analytic microlensing solutions associated with this work may allow for substantially faster light-curve calculations and modelling of observed events. A Python implementation is provided.
The discovery of a transient kilonova following the gravitational-wave (GW) event GW170817 highlighted the critical need for coordinated rapid and wide-field observations, inference, and follow-up ...across the electromagnetic spectrum. In the southern hemisphere, the Dark Energy Camera (DECam) on the Blanco 4 m telescope is well suited to this task, as it is able to cover wide fields quickly while still achieving the depths required to find kilonovae like the one accompanying GW170817 to ∼500 Mpc, the binary neutron star (NS) horizon distance for current generation of LIGO/Virgo collaboration (LVC) interferometers. Here, as part of the multi-facility follow-up by the Global Relay of Observatories Watching Transients Happen collaboration, we describe the observations and automated data movement, data reduction, candidate discovery, and vetting pipeline of our target-of-opportunity DECam observations of S190426c, the first possible NS-black hole merger detected in GWs. Starting 7.5 hr after S190426c, over 11.28 hr of observations, we imaged an area of 525 deg2 (r band) and 437 deg2 (z band); this was 16.3% of the total original localization probability, and nearly all of the probability visible from the southern hemisphere. The machine-learning-based pipeline was optimized for fast turnaround, delivering transients for human vetting within 17 minutes, on average, of shutter closure. We reported nine promising counterpart candidates 2.5 hr before the end of our observations. One hour after our data-taking ended (roughly 20 hr after the announcement of S190426c), LVC released a refined skymap that reduced the probability coverage of our observations to 8.0%, demonstrating a critical need for localization updates on shorter (∼hour) timescales. Our observations yielded no detection of a bona fide counterpart to mz = 21.7 and mr = 22.2 at the 5 level of significance, consistent with the refined LVC positioning. We view these observations and rapid inferencing as an important real-world test for this novel end-to-end wide-field pipeline.
Risk management is very important for individual investors or companies. There are several ways to measure the risk of investment. Prices of risky assets vary rapidly and randomly due to the ...complexity of finance market. Random interval is a good tool to describe uncertainty including both randomness and imprecision. Considering the uncertainty of financial market, we employ random intervals to describe returns of a risk asset and define an interval-valued risk measurement, which considers the tail risk. It is called the interval-valued conditional value-at-risk (ICVaR, for short). Similar to the classical conditional value-at-risk, ICVaR satisfies the sub-additivity. Under the new risk measure ICVaR, as a manner similar to the classical Mean-CVaR portfolio model, two optimal interval-valued portfolio selection models are built. The sub-additivity of ICVaR guarantees the global optimal solution to the Mean-ICVaR portfolio model. Based on the real data from mainland Chinese stock markets and international stock markets, the case study shows that our models are interpretable and consistent with the practical scenarios.
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