1,014 research outputs found

    Sensitive frequency-dependence of the carrier-envelope phase effect on bound-bound transition: an interference perspective

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    We investigate numerically with Hylleraas coordinates the frequency dependence of the carrier-envelope phase (CEP) effect on bound-bound transitions of helium induced by an ultrashort laser pulse of few cycles. We find that the CEP effect is very sensitive to the carrier frequency of the laser pulse, occurring regularly even at far-off resonance frequencies. By analyzing a two-level model, we find that the CEP effect can be attributed to the quantum interference between neighboring multi-photon transition pathways, which is made possible by the broadened spectrum of the ultrashort laser pulse. A general picture is developed along this line to understand the sensitivity of the CEP effect to laser's carrier frequency. Multi-level influence on the CEP effect is also discussed

    Nonlinear Inertia Weighted Teaching-Learning-Based Optimization for Solving Global Optimization Problem

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    Teaching-learning-based optimization (TLBO) algorithm is proposed in recent years that simulates the teaching-learning phenomenon of a classroom to effectively solve global optimization of multidimensional, linear, and nonlinear problems over continuous spaces. In this paper, an improved teaching-learning-based optimization algorithm is presented, which is called nonlinear inertia weighted teaching-learning-based optimization (NIWTLBO) algorithm. This algorithm introduces a nonlinear inertia weighted factor into the basic TLBO to control the memory rate of learners and uses a dynamic inertia weighted factor to replace the original random number in teacher phase and learner phase. The proposed algorithm is tested on a number of benchmark functions, and its performance comparisons are provided against the basic TLBO and some other well-known optimization algorithms. The experiment results show that the proposed algorithm has a faster convergence rate and better performance than the basic TLBO and some other algorithms as well

    Clinical radiomics-based machine learning versus three-dimension convolutional neural network analysis for differentiation of thymic epithelial tumors from other prevascular mediastinal tumors on chest computed tomography scan

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    PurposeTo compare the diagnostic performance of radiomic analysis with machine learning (ML) model with a convolutional neural network (CNN) in differentiating thymic epithelial tumors (TETs) from other prevascular mediastinal tumors (PMTs).MethodsA retrospective study was performed in patients with PMTs and undergoing surgical resection or biopsy in National Cheng Kung University Hospital, Tainan, Taiwan, E-Da Hospital, Kaohsiung, Taiwan, and Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan between January 2010 and December 2019. Clinical data including age, sex, myasthenia gravis (MG) symptoms and pathologic diagnosis were collected. The datasets were divided into UECT (unenhanced computed tomography) and CECT (enhanced computed tomography) for analysis and modelling. Radiomics model and 3D CNN model were used to differentiate TETs from non-TET PMTs (including cyst, malignant germ cell tumor, lymphoma and teratoma). The macro F1-score and receiver operating characteristic (ROC) analysis were performed to evaluate the prediction models.ResultIn the UECT dataset, there were 297 patients with TETs and 79 patients with other PMTs. The performance of radiomic analysis with machine learning model using LightGBM with Extra Tree (macro F1-Score = 83.95%, ROC-AUC = 0.9117) had better performance than the 3D CNN model (macro F1-score = 75.54%, ROC-AUC = 0.9015). In the CECT dataset, there were 296 patients with TETs and 77 patients with other PMTs. The performance of radiomic analysis with machine learning model using LightGBM with Extra Tree (macro F1-Score = 85.65%, ROC-AUC = 0.9464) had better performance than the 3D CNN model (macro F1-score = 81.01%, ROC-AUC = 0.9275).ConclusionOur study revealed that the individualized prediction model integrating clinical information and radiomic features using machine learning demonstrated better predictive performance in the differentiation of TETs from other PMTs at chest CT scan than 3D CNN model

    Complications after radical gastrectomy following FOLFOX7 neoadjuvant chemotherapy for gastric cancer

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    <p>Abstract</p> <p>Background</p> <p>This study assessed the postoperative morbidity and mortality occurring in the first 30 days after radical gastrectomy by comparing gastric cancer patients who did or did not receive the FOLFOX7 regimen of neoadjuvant chemotherapy.</p> <p>Methods</p> <p>We completed a retrospective analysis of 377 patients after their radical gastrectomies were performed in our department between 2005 and 2009. Two groups of patients were studied: the SURG group received surgical treatment immediately after diagnosis; the NACT underwent surgery after 2-6 cycles of neoadjuvant chemotherapy.</p> <p>Results</p> <p>There were 267 patients in the SURG group and 110 patients in the NACT group. The NACT group had more proximal tumours (P = 0.000), more total/proximal gastrectomies (P = 0.000) and longer operative time (P = 0.005) than the SURG group. Morbidity was 10.0% in the NACT patients and 17.2% in the SURG patients (P = 0.075). There were two cases of postoperative death, both in the SURG group (P = 1.000). No changes in complications or mortality rate were observed between the SURG and NACT groups.</p> <p>Conclusion</p> <p>The FOLFOX7 neoadjuvant chemotherapy is not associated with increased postoperative morbidity, indicating that the FOLFOX7 neoadjuvant chemotherapy is a safe choice for the treatment of local advanced gastric cancer.</p

    A Consistent Test of the Distance-Duality Relation with Galaxy Clusters and Type Ia Supernave

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    We propose a new consistent method to test of the distance-duality (DD) relation which related angular diameter distances (DA) to the luminosity distances (DL) in a cosmology-independent way. In order to avoid any bias brought by redshift incoincidence between galaxy clusters and Type Ia Supernave (SNe Ia), as well as to ensure the integrity of the galaxy clusters samples, we obtain the luminosity distance of a certain SN Ia point at the same redshift of the corresponding galaxy cluster by interpolating from the nearby SNe Ia. With the observational data at the same redshifts of the angular diameter distances from the complete 38 galaxy cluster sample for the spherical model and the corrected luminosity distances interpolated from the Union2 set, we find that ηDL(1+z)2/DA=1\eta \equiv {D_L}{(1+z)}^{-2}/{D_A}=1 is satisfied within 2σ2\sigma confidence level for various parameterizations of η(z)\eta(z), which are more stringent than previous testing results without considering redshift bias.Comment: 7 pages, 5 figures, 1 table; accepted for publication in MNRA

    Oxygen Ion Butterfly Distributions Observed in a Magnetotail Dipolarizing Flux Bundle

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    Cluster observed two intermittent oxygen ion (O+) flux enhancements with energy dispersions in a dipolarizing flux bundle, which is known as a region of enhanced northward magnetic field (Bz) embedded in the earthward high‐speed flow. The flux enhancements of O+ show clear pitch angle dependences, which are termed as butterfly distributions. Two corresponding flux enhancements of field‐aligned protons (H+) are also shown in its spectrum, but they are weaker and emerge later (~10 s) than those of O+. Simulation shows that both enhanced ion species are the counterstreaming populations. They originated from the lobe region and were driven into the center plasma sheet by the dawn‐dusk electric field (Ey). Backward tracing test‐particle simulations reproduce the butterfly O+ and the counterstreaming H+ distribution. The differences between O+ and H+ are because of their different gyroradii. The lobe O+ can arrive at the magnetic equatorial plane in less than one gyromotion due to its large gyroradius, and O+ with a larger field‐aligned velocity can arrive at the equatorial plane earlier, leading to the energy and pitch angle dependence. While H+ with similar energy can drift into dipolarizing flux bundle through electric field drift (E × B motion) and arrive at the equatorial plane through adiabatic motion, which consequently forms the field‐aligned flux enhancements in dipolarizing flux bundle, that is, the Bz‐dominant region. The simulation further confirms that intermittent increases of Ey component can produce the two intermittent flux enhancements, as indicated in the in situ observation.Key PointsTwo intermittent butterfly O+ and counterstreaming H+ flux enhancements are observed in a dipolarizing flux bundleO+ enhancements are more intense and emerge earlier than those of H+Convection electric field plays a key role in the formation of butterfly O+ and counterstreaming H+Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153633/1/jgra55404_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153633/2/jgra55404.pd

    Caspase-8 inactivation drives autophagy-dependent inflammasome activation in myeloid cells.

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    Caspase-8 activity controls the switch from cell death to pyroptosis when apoptosis and necroptosis are blocked, yet how caspase-8 inactivation induces inflammasome assembly remains unclear. We show that caspase-8 inhibition via IETD treatment in Toll-like receptor (TLR)-primed Fadd-/-Ripk3-/- myeloid cells promoted interleukin-1β (IL-1β) and IL-18 production through inflammasome activation. Caspase-8, caspase-1/11, and functional GSDMD, but not NLRP3 or RIPK1 activity, proved essential for IETD-triggered inflammasome activation. Autophagy became prominent in IETD-treated Fadd-/-Ripk3-/- macrophages, and inhibiting it attenuated IETD-induced cell death and IL-1β/IL-18 production. In contrast, inhibiting GSDMD or autophagy did not prevent IETD-induced septic shock in Fadd-/-Ripk3-/- mice, implying distinct death processes in other cell types. Cathepsin-B contributes to IETD-mediated inflammasome activation, as its inhibition or down-regulation limited IETD-elicited IL-1β production. Therefore, the autophagy and cathepsin-B axis represents one of the pathways leading to atypical inflammasome activation when apoptosis and necroptosis are suppressed and capase-8 is inhibited in myeloid cells
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