637 research outputs found

    Binary Nonlinearization of the Super Akns System Under an Implicit Symmetry Constraint

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    For the super AKNS system, an implicit symmetry constraint between the potentials and the eigenfunctions is proposed. After introducing some new variables to explicitly express potentials, the super AKNS system is decomposed into two compatible finite-dimensional super systems (x-part and tnt_n-part). Furthermore, we show that the obtained super systems are integrable super Hamiltonian systems in supersymmetry manifold R4N+2∣2N+2\mathbb{R}^{4N+2|2N+2}.Comment: 10 pages, 5 figures, to appear in Journal of Physics

    Government Control, Uncertainty, and Investment Decisions in China's Listed Companies

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    AbstractThis paper empirically investigates the relation between uncertainty and investment among China's listed companies, and analyzes the influence of government control on the investment-uncertainty relation. We find that there is a negative relation between total firm uncertainty and investment in China's listed companies. However, this holds only for privately controlled firms. Among privately controlled listed firms, investment is negatively related to firm-specific uncertainty, whereas among government-controlled ones, investment is positively related to market uncertainty. We also find that the risk-taking preference of government-controlled listed companies is greater among those firms with fewer investment opportunities. Finally, among financially distressed firms, the negative relation between investment and uncertainty becomes nonsignificant because of risk shifting, which is more serious among government-controlled listed companies. We conclude that government control leads to state interference and weak corporate governance, which, in turn, distorts investment decision making among listed companies

    Depth classification of underwater targets based on complex acoustic intensity of normal modes

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    In order to solve the problem of depth classification of the underwater target in a very low frequency acoustic field, the active component of cross spectra of particle pressure and horizontal velocity (ACCSPPHV) is adopted to distinguish the surface vessel and the underwater target. According to the effective depth of a Pekeris waveguide, the placing depth forecasting equations of passive vertical double vector hydrophones are proposed. Numerical examples show that when the sum of depths of two hydrophones is the effective depth, the sign distribution of ACCSPPHV has nothing to do with horizontal distance; in addition, the sum of the first critical surface and the second critical surface is equal to the effective depth. By setting the first critical surface less than the difference between the effective water depth and the actual water depth, that is, the second critical surface is greater than the actual depth, the three positive and negative regions of the whole ocean volume are equivalent to two positive and negative regions and therefore the depth classification of the underwater target is obtained. Besides, when the 20 m water depth is taken as the first critical surface in the simulation of underwater targets (40 Hz, 50 Hz, and 60 Hz respectively), the effectiveness of the algorithm and the correctness of relevant conclusions are verified, and the analysis of the corresponding forecasting performance is conducted.National Natural Science Foundation (China) (Grants 1404406, 51179034, 41072176 and 11204109)Public Science and Technology Research Funds Projects of Ocean (Grant 201405036-4)China Postdoctoral Science Foundation (Grant 2013M531015)Defense Technology Research (Grant JSJC2013604C012

    Synthesis of positive plasmas with known chromosomal abnormalities for validation of non-invasive prenatal screening

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    Non-invasive prenatal screening (NIPS) is a DNA sequencing-based screening test for fetal aneuploidies and possibly other pathogenic genomic abnormalities, such as large deletions and duplications. Validation and quality assurance (QA) of this clinical test using plasmas with and without targeted chromosomal abnormalities from pregnant women as negative and positive controls are required. However, the positive plasma controls may not be available for many laboratories that are planning to establish NIPS. Limited synthetic positive plasmas are commercially available, but the types of abnormalities and the number/quantity of synthetic plasmas for each abnormality are insufficient to meet the minimal requirements for the initial validation. We report here a method of making synthetic positive plasmas by adding cell-free DNA (cfDNA) isolated from culture media of prenatal cells with chromosomal abnormalities to the plasmas from non-pregnant women. Thirty-eight positive plasmas with various chromosomal abnormalities, including autosomal and sex chromosomal aneuploidies, large deletions and duplications, were synthesized. The synthetic plasmas were characterized side-by-side with real positive plasmas from pregnant women and commercially available synthetic positive plasmas using the Illumina VeriSeq NIPT v2 system. All chromosomal abnormalities in the synthetic plasmas were correctly identified with the same testing sensitivity and specificity as in the real and commercial synthetic plasmas. The findings demonstrate that the synthetic positive plasmas are excellent alternatives of real positive plasmas for validation and QA of NIPS. The method described here is simple and straightforward, and can be readily used in clinical genetics laboratories with accessibility to prenatal cultures

    Two-Component Super AKNS Equations and Their Finite-Dimensional Integrable Super Hamiltonian System

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    Starting from a matrix Lie superalgebra, two-component super AKNS system is constructed. By making use of monononlinearization technique of Lax pairs, we find that the obtained two-component super AKNS system is a finite-dimensional integrable super Hamiltonian system. And its Lax representation and r-matrix are also given in this paper

    Cerebral Falx Mature Teratoma with Rare Imaging in an Adult

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    Intracranial mature teratoma is a rare lesion in adults. Despite several intracranial mature teratomas had been reported not to be located at the midline region, no one was found to be within cerebral falx. Herein, we reported a 37-year-old female patient with an intracranial mature teratoma confined within frontal cerebral falx. Her main complaint was intermitted headache, which could not be relieved recently by taking painkiller. Excepting for mild papilledema, we did not find positive neurological signs on physical examination. CT scanning showed it was a round homogenously hypodense lesion with hyperdense signal at its rim. MRI revealed the lesion was 3.5cm×3.6cm×4.5cm in volume, with uniformed hypointensity on T1WI, hyperintensity on T2WI and enhancement in the capsule. It was totally removed via inter-hemispheric approach, and we found the lesion was confined within the frontal cerebral falx. Postoperatively, it was proved histologically to be a mature teratoma. At three years of fellow up, neither neurological deficits nor recurrent sings on MRI was found. To our best knowledge, this is the first case of intracranial mature teratoma within cerebral falx

    Wear evolution and stress distribution of single CBN superabrasive grain in high-speed grinding

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    In this study, both finite element analysis (FEA) and experimental observations were used to investigate the single CBN grain wear in high-speed grinding of Inconel 718 superalloy. The wear characteristics for each grinding pass were numerically assessed utilizing the tensile and compressive strength limits of the cutting grain. Additionally, stress distribution within the grain, chip formation and grinding force evolution during multiple passes were investigated. The combined experimental and numerical results show that the CBN grain wear has two major modes: the macro fracture on the grain top surface propagating from the rake surface, and the micro fracture near the cutting edges. The resultant tensile stress is the main factor inducing grain wear. The cutting edges will be under self-sharpening due to the grain wear. With multiple micro cutting edges engaged in grinding process, the limited material removal region was divided into different sliding, ploughing and cutting dominant regions. Overall, the ratio of material elements removed by a cutting process ranges from 80% to 20%, and continue to decrease during the grinding process. With a stronger effect of the cutting process, larger fluctuation of the grinding force will commence, however its average value remains below that with stronger sliding and ploughing process characteristics

    Paced Respiration for Vasomotor and Other Menopausal Symptoms: A Randomized, Controlled Trial

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    poster abstractBackground: Paced respiration has been internationally recommended for vasomotor symptoms (e.g., hot flashes, night sweats) despite limited empirical evidence. Objective: To evaluate efficacy of a paced respiration intervention against breathing control and usual care control for vasomotor and other menopausal symptoms. Design: A 16-week, 3-group, partially blinded, controlled trial with 2:2:1 randomization and stratification by group (breast cancer, no cancer) was conducted in a Midwestern city and surrounding area. Participants: 218 randomized women (96 breast cancer survivors, 122 menopausal women without cancer) were recruited through community mailings and registries (29% minority). Interventions: Training, home practice support, and instructions to use the breathing at the time of each hot flash were delivered via compact disc with printed booklet (paced respiration intervention) or digital videodisc with printed booklet (fast shallow breathing control). Usual care control received a letter regarding group assignment. Main Measures: Outcomes included hot flash frequency, severity, and bother (primary), hot flash interference in daily life, perceived control over hot flashes, and mood and sleep disturbances (secondary). Intervention performance, adherence, and adverse events were assessed. Key Results: There were no significant group differences for primary outcomes at 8- or 16-weeks post-randomization. Most intervention participants did not achieve 50% reduction in vasomotor symptoms despite demonstrated ability to correctly do paced respiration and daily practice. Statistically significant differences in secondary outcomes at 8- and 16-weeks were small, not likely to be clinically relevant, and as likely to favor intervention as breathing control. Conclusions: Paced respiration is unlikely to provide clinical benefit for vasomotor or other menopausal symptoms in breast cancer survivors or menopausal women without cancer
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