Narrow-band imaging is an image-enhanced form of endoscopy used to observed microstructures and capillaries of the mucosal epithelium which allows for real-time prediction of histologic features of ...colorectal polyps. However, narrow-band imaging expertise is required to differentiate hyperplastic from neoplastic polyps with high levels of accuracy. We developed and tested a system of computer-aided diagnosis with a deep neural network (DNN-CAD) to analyze narrow-band images of diminutive colorectal polyps.
We collected 1476 images of neoplastic polyps and 681 images of hyperplastic polyps, obtained from the picture archiving and communications system database in a tertiary hospital in Taiwan. Histologic findings from the polyps were also collected and used as the reference standard. The images and data were used to train the DNN. A test set of images (96 hyperplastic and 188 neoplastic polyps, smaller than 5 mm), obtained from patients who underwent colonoscopies from March 2017 through August 2017, was then used to test the diagnostic ability of the DNN-CAD vs endoscopists (2 expert and 4 novice), who were asked to classify the images of the test set as neoplastic or hyperplastic. Their classifications were compared with findings from histologic analysis. The primary outcome measures were diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic time. The accuracy, sensitivity, specificity, PPV, NPV, and diagnostic time were compared among DNN-CAD, the novice endoscopists, and the expert endoscopists. The study was designed to detect a difference of 10% in accuracy by a 2-sided McNemar test.
In the test set, the DNN-CAD identified neoplastic or hyperplastic polyps with 96.3% sensitivity, 78.1% specificity, a PPV of 89.6%, and a NPV of 91.5%. Fewer than half of the novice endoscopists classified polyps with a NPV of 90% (their NPVs ranged from 73.9% to 84.0%). DNN-CAD classified polyps as neoplastic or hyperplastic in 0.45 ± 0.07 seconds—shorter than the time required by experts (1.54 ± 1.30 seconds) and nonexperts (1.77 ± 1.37 seconds) (both P < .001). DNN-CAD classified polyps with perfect intra-observer agreement (kappa score of 1). There was a low level of intra-observer and inter-observer agreement in classification among endoscopists.
We developed a system called DNN-CAD to identify neoplastic or hyperplastic colorectal polyps less than 5 mm. The system classified polyps with a PPV of 89.6%, and a NPV of 91.5%, and in a shorter time than endoscopists. This deep-learning model has potential for not only endoscopic image recognition but for other forms of medical image analysis, including sonography, computed tomography, and magnetic resonance images.
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Abstract
Van der Waals heterobilayers of transition metal dichalcogenides with spin–valley coupling of carriers in different layers have emerged as a new platform for exploring spin/valleytronic ...applications. The interlayer coupling was predicted to exhibit subtle changes with the interlayer atomic registry. Manually stacked heterobilayers, however, are incommensurate with the inevitable interlayer twist and/or lattice mismatch, where the properties associated with atomic registry are difficult to access by optical means. Here, we unveil the distinct polarization properties of valley-specific interlayer excitons using epitaxially grown, commensurate WSe
2
/MoSe
2
heterobilayers with well-defined (AA and AB) atomic registry. We observe circularly polarized photoluminescence from interlayer excitons, but with a helicity opposite to the optical excitation. The negative circular polarization arises from the quantum interference imposed by interlayer atomic registry, giving rise to distinct polarization selection rules for interlayer excitons. Using selective excitation schemes, we demonstrate the optical addressability for interlayer excitons with different valley configurations and polarization helicities.
By means of first-principles calculations, the two-dimensional magnetic metal–organic framework, manganese phthalocyanine (MnPc), is proposed to exhibit nearly zero Poisson’s ratio within the elastic ...regime. Negative Poisson’s ratio can be reached by further increasing the uniaxial tensile strain beyond the yield point. Such an unusual mechanical property is found to rely on the spin-state of Mn atoms. Without strain, the ground state is ferrimagnetic and half-metallic. Interestingly, as the interatomic distance between Mn atoms increases under biaxial tensile strain, the alignment of magnetic moments of neighboring Mn atoms changes from antiparallel to parallel, associated with oscillatory exchange coupling strength. This not only reveals the strain-induced magnetic phase transition, but also indicates the magnetic interaction is mediated by the Ruderman–Kittel–Kasuya–Yosida exchange coupling and thus Kondo effect is likely to exist. Rather than the reported RKKY exchange coupling between supramolecular MnPc adsorbed on substrates, the predicted RKKY exchange coupling here exists in the pristine two-dimensional MnPc lattice. It would be more suitable for device applications because of the reduced size. Besides, it is noted that neighboring Mn atoms with antiparallel magnetic moments are responsible for the conducting behaviors, while those with parallel magnetic moments obstruct the flow of electrons. This property provides possibility of molding the flow of fully spin-polarized electrons through the manipulation of local magnetization by an external magnetic field, which is an attractive magnetoelectric response: the magnetic-field-controlled electron flow.
•Nearly zero Poison’s ratio in a two-dimensional magnetic metal–organic framework.•Ruderman–Kittel–Kasuya–Yosida (RKKY)-mediated exchange coupling in pristine metal–organic framework.•Spin-state controlled magnetoelastic response.•Molding the flow of electron via manipulation of local magnetization.
Plastid engineering provides several advantages for the next generation of transgenic technology, including the convenient use of transgene stacking and the generation of high expression levels of ...foreign proteins. With the goal of generating transplastomic plants with multiresistance against both phytopathogens and insects, a construct containing a monocistronic patterned gene stack was transformed into Nicotiana benthamiana plastids harbouring sweet potato sporamin, taro cystatin and chitinase from Paecilomyces javanicus. Transplastomic lines were screened and characterized by Southern/Northern/Western blot analysis for the confirmation of transgene integration and respective expression level. Immunogold localization analyses confirmed the high level of accumulation proteins that were specifically expressed in leaf and root plastids. Subsequent functional bioassays confirmed that the gene stacks conferred a high level of resistance against both insects and phytopathogens. Specifically, larva of Spodoptera litura and Spodoptera exigua either died or exhibited growth retardation after ingesting transplastomic plant leaves. In addition, the inhibitory effects on both leaf spot diseases caused by Alternaria alternata and soft rot disease caused by Pectobacterium carotovorum subsp. carotovorum were markedly observed. Moreover, tolerance to abiotic stresses such as salt/osmotic stress was highly enhanced. The results confirmed that the simultaneous expression of sporamin, cystatin and chitinase conferred a broad spectrum of resistance. Conversely, the expression of single transgenes was not capable of conferring such resistance. To the best of our knowledge, this is the first study to demonstrate an efficacious stacked combination of plastid‐expressed defence genes which resulted in an engineered tolerance to various abiotic and biotic stresses.
The present study objectively classified the convective cloud objects detected by the space‐borne CloudSat radar over the Asian‐Australian monsoon region using the hierarchical agglomerative ...clustering algorithm. Based on key properties representing the morphological features and convective intensity of the systems, five distinct convective cloud regimes were derived. The unique Coastal‐Intense (CI) regime exhibits the most expansive horizontal scales (>1,000 km), high convective strength, the strongest cloud radiative effects, the highest probability of extreme rainfall, and a significant coupling with the sharp onset of the Asian summer monsoon circulation. Second, the Coastal regime illustrates smaller but also highly organized coastal convections, with the strongest convective strength. Less than 10% of the systems in the CI and Coastal regimes overlap with the tropical cyclones. The rest three regimes mark the less organized convection at various life cycle stages mainly over the land areas, with small seasonal variation in their occurrence.
Plain Language Summary
One of the key features of the Asian‐Australian monsoon is the occurrence of intense rainfall and organized convective systems coupled with the change of large‐scale circulation in the summer hemisphere. In this study, the convective systems from the multi‐year satellite observations over the Asian‐Australian monsoon region were classified objectively into five distinct regimes by a data‐driven approach based on systems' physical properties. The most organized Coastal Intense regime, mainly occurring over the coastal area, exhibits the highest probability of extreme rainfall among all regimes, and tightly follows the sharp seasonal switch of the monsoon circulation. The Coastal regime illustrates smaller organized coastal convections with the strongest convective strength. Three of the less organized regimes represent convection at various life stages over the land areas.
Key Points
Five convective cloud regimes are derived from CloudSat observations based on object‐based cluster analysis of five physical properties
Two regimes are highly organized systems over coastal areas and three regimes are the less organized systems mainly over land
The coastal‐intense regime exhibits strong cloud radiative effects and extreme rainfall, clearly coupled with the large‐scale circulation
We present an analysis to extract kaon parton distribution functions (PDFs) using meson-induced Drell-Yan and quarkonium production data. Starting from the statistical model first developed for ...determining the partonic structure of spin-1/2 nucleon and later applied to the spin-0 pion, we have extended this approach to perform a global fit to existing kaon-induced Drell-Yan and J/ψ production data. These data are well described by the statistical model, allowing an extraction of the kaon PDFs. We find that both the Drell-Yan and the J/ψ data favor a harder valence distribution for strange quark than for up quark in kaon. The kaon gluon distribution is further constrained by the J/ψ production data. In particular, the momentum fraction carried by gluons is found to be similar for pion and kaon.
High superconducting critical temperature ( T c ) of 73.6 K at ambient pressure is predicted in BSiC2 by means of the first-principles electron-phonon calculations. Without the need for doping or ...pressurization, the stoichiometric BSiC2 exhibits strong electron-phonon coupling (EPC) and highest T c among BCS-superconductors at ambient pressure. Also, it is hydrogen-free that makes easier the sample growth. The dramatic softening of the E 2 g mode is the main account for the strong EPC. In addition, we find that BC3, derived from the replacement of Si in BSiC2 by another C, is also superconducting with a high T c ∼ 40 K. Our work indicates that these materials form a new family of high- T c BCS-superconductors at ambient pressure.
Flavor structure of the nucleon sea Chang, Wen-Chen; Peng, Jen-Chieh
Progress in particle and nuclear physics,
11/2014, Letnik:
79
Journal Article
Recenzirano
Odprti dostop
We review the current status and future prospects on the subject of flavor structure of the nucleon sea. The flavor structure of the nucleon sea provides unique information on the non-perturbative ...aspects of strong interactions allowing stringent tests of various models on the partonic structures of the nucleons as well as lattice QCD calculations. The scope of this review covers the unpolarized, polarized, and the transverse-momentum dependent sea–quark distributions of the nucleons. While the main focus of this review is on the physics motivation and recent progress on the subject of the nucleon sea, we also discuss future prospects of addressing some outstanding issues on the flavor structure of the nucleon sea.
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