11,843 research outputs found

    The ungulates of northern China

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    Presently, thirty five species of ungulates occur in northern China. Some species are threatened or endangered. There are three species of Equidae (E. przewalskii, E. hemionus, E. kiang), one of Suidae (Sus scrofa), one of Camelidae (Camelus bactrianus), 14 species of Cervidae (with the genera Moschus, Elaphus, Cervus, Elaphurus, Alces, Rangifer, Capreolus) and 16 species of Bovidae (within the genera Bos, Gazella, Procapra, Pantholops, Saiga, Nemorhaedus, Capricornis, Budorcas, Capra, Pseudois, Ovis). They inhabit different biotopes, i.e. temperate mountain forest and steppe, temperate desert and semi-desert, and vast alpine ranges. Ungulate fossils are widespread in China evidencing that Asia was an evolutionary centre for some ungulates. Although new data have been gathered through research efforts in China since 1949 it is a fact that some ungulate species have suffered serious population set-backs and some have become endangered or even extinct. Detailed studies of ungulate populations and protection of habitats are now most important future research needs

    Diagnostic Accuracy of CEUS LI-RADS for the Characterization of Liver Nodules 20 mm or Smaller in Patients at Risk for Hepatocellular Carcinoma.

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    Background: American College of Radiology contrast agent–enhanced US Liver Imaging Reporting and Data System (CEUS LI-RADS) was developed to improve the accuracy of hepatocellular carcinoma (HCC) diagnosis at contrast agent2enhanced US. However, to the knowledge of the authors, the diagnostic accuracy of the system in characterization of liver nodules 20 mm or smaller has not been fully evaluated. Purpose: To evaluate the diagnostic accuracy of CEUS LI-RADS in diagnosing HCC in liver nodules 20 mm or smaller in patients at risk for HCC. Materials and Methods: Between January 2015 and February 2018, consecutive patients at risk for HCC presenting with untreated liver nodules 20 mm or less were enrolled in this retrospective double-reader study. Each nodule was categorized according to the CEUS LI-RADS and World Federation for Ultrasound in Medicine and Biology (WFUMB)–European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) criteria. Diagnostic performance of CEUS LI-RADS and WFUMB-EFSUMB characterization was evaluated by using tissue histologic analysis, multiphase contrast-enhanced CT and MRI, and imaging follow-up as reference standard and compared by using McNemar test. Results: The study included 175 nodules (mean diameter, 16.1 mm 6 3.4) in 172 patients (mean age, 51.8 years 6 10.6; 136 men). The sensitivity of CEUS LR-5 versus WFUMB-EFSUMB criteria in diagnosing HCC was 73.3% (95% confidence inter-val [CI]: 63.8%, 81.5%) versus 88.6% (95% CI: 80.9%, 94%), respectively (P, .001). The specificity of CEUS LR-5 versus WFUMB-EFSUMB criteria was 97.1% (95% CI: 90.1%, 99.7%) versus 87.1% (95% CI: 77%, 94%), respectively (P = .02). No malignant lesions were found in CEUS LR-1 and LR-2 categories. Only two nodules (of 41; 5%, both HCC) were malignant in CEUS LR-3 category. The incidences of HCC in CEUS LR-4, LR-5, and LR-M were 48% (11 of 23), 98% (77 of 79), and 75% (15 of 20), respectively. Two of 175 (1.1%) histologic analysis2confirmed intrahepatic cholangiocarcinomas were categorized as CEUS LR-M by CEUS LI-RADS and misdiagnosed as HCC by WFUMB-EFSUMB criteria. Conclusion: The contrast-enhanced US Liver Imaging Reporting and Data System (CEUS LI-RADS) algorithm was an effective tool for characterization of small (≤20 mm) liver nodules in patients at risk for hepatocellular carcinoma (HCC). Compared with World Federation for Ultrasound in Medicine and Biology2European Federation of Societies for Ultrasound in Medicine and Biology criteria, CEUS LR-5 demonstrated higher specificity for diagnosing small HCCs with lower sensitivity

    A Process for Preparing High Graphene Sheet Content Carbon Materials from Biochar Materials

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    Graphene is monolayer graphite and has higher electron mobility than silicon, high heat conduction, and special optical properties. In this study, we have attempted to use a two-step process (an acid pretreatment followed by a heat treatment) for producing high graphene sheet content (>80%) carbon materials (GSCCMs) from monocotyledonous and dicotyledonous biochar materials prepared at 350°C. The highest graphene sheet content of 83.86% is found with the CH3COOH pretreatment followed by a 1500°C heat treatment of monocotyledonous biochar materials, and its conductivity was measured at 84.69 S/cm. Therefore, preparing GSCCMs from biochar materials could highly reduce the cost

    On q-deformed infinite-dimensional n-algebra

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    The qq-deformation of the infinite-dimensional nn-algebra is investigated. Based on the structure of the qq-deformed Virasoro-Witt algebra, we derive a nontrivial qq-deformed Virasoro-Witt nn-algebra which is nothing but a sh-nn-Lie algebra. Furthermore in terms of the pseud-differential operators on the quantum plane, we construct the (co)sine nn-algebra and the qq-deformed SDiff(T2)SDiff(T^2) nn-algebra. We prove that they are the sh-nn-Lie algebras for the case of even nn. An explicit physical realization of the (co)sine nn-algebra is given.Comment: 22 page

    Electrocardiogram Baseline Wander Suppression Based on the Combination of Morphological and Wavelet Transformation Based Filtering

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    One of the major noise components in electrocardiogram (ECG) is the baseline wander (BW). Effective methods for suppressing BW include the wavelet-based (WT) and the mathematical morphological filtering-based (MMF)algorithms. However, the T waveform distortions introduced by the WTand the rectangular/trapezoidal distortions introduced by MMF degrade the quality of the output signal. Hence, in this study, we introduce a method by combining the MMF and WTto overcome the shortcomings of both existing methods. To demonstrate the effectiveness of the proposed method, artificial ECG signals containing a clinicalBW are used for numerical simulation, and we also create a realistic model of baseline wander to compare the proposed method with other state-of-the-art methods commonly used in the literature. /e results show that the BW suppression effect of the proposed method is better than that of the others. Also, the new method is capable of preserving the outline of the BW and avoiding waveform distortions caused by the morphology filter, thereby obtaining an enhanced quality of ECG

    Absence of a transport signature of spin-orbit coupling in graphene with indium adatoms

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    Enhancement of the spin-orbit coupling in graphene may lead to various topological phenomena and also find applications in spintronics. Adatom absorption has been proposed as an effective way to achieve the goal. In particular, great hope has been held for indium in strengthening the spin-orbit coupling and realizing the quantum spin Hall effect. To search for evidence of the spin-orbit coupling in graphene absorbed with indium adatoms, we carry out extensive transport measurements, i.e., weak localization magnetoresistance, quantum Hall effect and non-local spin Hall effect. No signature of the spin-orbit coupling is found. Possible explanations are discussed.Comment: 5 pages, 4 figures, with supplementary material

    Study on the control algorithm for lower limb exoskeleton based on ADAMS/Simulink co-simulation

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    A sliding mode control algorithm based on proportional switching function was developed to make the lower limb exoskeleton more fit the human walking gait trajectory. It could improve the comfort of the exoskeleton wearer and enhance the reliability of the system. The three-dimensional mechanical model of the exoskeleton built using software SolidWorks was introduced to ADAMS and then the model parameters were set. The model was combined with the software MATLAB so that the human-machine cooperation control algorithm for lower limb exoskeleton based on ADAMS and Simulink co-simulation was developed. The simulation result was compared with the desired trajectory and the trajectory under PID control. The research discovered that the ability of trajectory tracking under the sliding mode control was much better than that under PID control. It provided an important theoretical basis for the research on human-machine cooperation control algorithm
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