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  • Sun, Wei  (8)
  • Wu, Xin  (8)
  • 2020-2024  (8)
  • 1
    Online Resource
    Online Resource
    American Astronomical Society ; 2021
    In:  The Astrophysical Journal Supplement Series Vol. 254, No. 1 ( 2021-05-01), p. 8-
    In: The Astrophysical Journal Supplement Series, American Astronomical Society, Vol. 254, No. 1 ( 2021-05-01), p. 8-
    Abstract: We give a possible splitting method to a Hamiltonian for the description of charged particles moving around the Reissner–Nordström-(anti)-de Sitter black hole with an external magnetic field. This Hamiltonian can be separated into six analytical solvable pieces, whose solutions are explicit functions of proper time. In this case, second- and fourth-order explicit symplectic integrators are easily available. They exhibit excellent long-term behavior in maintaining the boundness of Hamiltonian errors regardless of ordered or chaotic orbits if appropriate step sizes are chosen. Under some circumstances, an increase of the positive cosmological constant gives rise to strengthening the extent of chaos from the global phase space; namely, chaos of charged particles occurs easily for the accelerated expansion of the universe. However, an increase of the magnitude of the negative cosmological constant does not. The different contributions to chaos are because the cosmological constant acts as a repulsive force in the Reissner–Nordström-de Sitter black hole, but an attractive force in the Reissner–Nordström-anti-de Sitter black hole.
    Type of Medium: Online Resource
    ISSN: 0067-0049 , 1538-4365
    RVK:
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2961-0
    detail.hit.zdb_id: 2006860-8
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    American Astronomical Society ; 2021
    In:  The Astrophysical Journal Vol. 914, No. 1 ( 2021-06-01), p. 63-
    In: The Astrophysical Journal, American Astronomical Society, Vol. 914, No. 1 ( 2021-06-01), p. 63-
    Abstract: In previous papers, explicit symplectic integrators were designed for nonrotating black holes, such as a Schwarzschild black hole. However, they fail to work in the Kerr spacetime because not all variables can be separable, or not all splitting parts have analytical solutions as explicit functions of proper time. To cope with this difficulty, we introduce a time transformation function to the Hamiltonian of Kerr geometry so as to obtain a time-transformed Hamiltonian consisting of five splitting parts, whose analytical solutions are explicit functions of the new coordinate time. The chosen time transformation function can cause time steps to be adaptive, but it is mainly used to implement the desired splitting of the time-transformed Hamiltonian. In this manner, new explicit symplectic algorithms are easily available. Unlike Runge–Kutta integrators, the newly proposed algorithms exhibit good long-term behavior in the conservation of Hamiltonian quantities when appropriate fixed coordinate time steps are considered. They are better than same-order implicit and explicit mixed symplectic algorithms and extended phase-space explicit symplectic-like methods in computational efficiency. The proposed idea on the construction of explicit symplectic integrators is suitable for not only the Kerr metric but also many other relativistic problems, such as a Kerr black hole immersed in a magnetic field, a Kerr–Newman black hole with an external magnetic field, axially symmetric core–shell systems, and five-dimensional black ring metrics.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    RVK:
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 3
    In: Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 41, No. 16_suppl ( 2023-06-01), p. 5551-5551
    Abstract: 5551 Background: Niraparib has significantly extended PFS as 1st-L MT OC in PRIMA/PRIME. Due to the more complex in treatment and status of the patients (pts) in clinal practice, more real-world data is needed to verify the efficacy and safety of Niraparib. Meanwhile, exploring the link between clinical characters and PFS, may to establish a clinical model to predict Niraparib benefits. Methods: This is a retrospective multicentric study recruiting OC pts received Niraparib as 1st-L MT from fourteen hospitals throughout China from Jan. 2019 to Dec. 2021. The database lock-time was on Dec. 31st, 2022. The pts’ basic characters, especially biomarkers, KELIM scores, etc. were recorded. Survival analyses were conducted using the Kaplan-Meier method and log-rank test, and 95% CI were calculated. The primary endpoint was PFS, and secondary endpoints included time to treatment discontinuation (TTD), time to first subsequent therapy (TFST) and safety. The exploratory endpoint was to establish a clinical prediction model of Niraparib benefits. Results: 199 pts’ data were analyzed. The median(m) follow-up at the time of the data cutoff was 14.93 months (mos) (12.17, 39.47). Baseline characteristics were shown in Table. MPFS was not reached (NR) (29.80 to not be estimated, NE), with maturity 29.64%, and PFS rate at 6, 12, 18, 24mos was 89.4%, 79.5%, 68.3%, 64.5% respectively, showing the efficacy of Niraparib. MPFS (95% CI) in subgroups were as follows: BRCAwt 23.83mos (23.83 to NE); HRD negative 15.63mos (12.6 to NE); KELIM<1 NR (15.33 to NE); BRCA1/2m, HRD positive and KEILM≥1 subgroups were all NR yet, due to the no longer enough follow-up time and low data maturity. Multivariate analysis found that pts with 〈 65 years, BRCA1/2m, HRD positive, KELIM>1, and R0 after primary cytoreductive surgery were likely to have longer PFS. The rate of grade ≥3 thrombocytopenia was 19.1%. Treatment discontinuation occurred in 11 (5.5%) pts due to TEAEs. The clinical prediction model for probability of progression was established from 149 pts (training dataset): Score = 0.612 Age >65 + 0.3889 BMI ≤23.90 + 0.097 FIGO IV + 0.191Chronic N +1.398 Surgery result R1/R2 +2.552 BRCA wt . The probability of disease progression received Niraparib in 6, 12 and 18m can be obtained by mapping the score to the nomogram. Conclusions: The efficacy and safety of Niraparib in this study are consistent with the results in PRIME. The clinical predictive model established in this database needs more data to be matured and verified. [Table: see text]
    Type of Medium: Online Resource
    ISSN: 0732-183X , 1527-7755
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Clinical Oncology (ASCO)
    Publication Date: 2023
    detail.hit.zdb_id: 2005181-5
    detail.hit.zdb_id: 604914-X
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  • 4
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2021
    In:  The European Physical Journal C Vol. 81, No. 9 ( 2021-09)
    In: The European Physical Journal C, Springer Science and Business Media LLC, Vol. 81, No. 9 ( 2021-09)
    Abstract: In a recent work of Wu, Wang, Sun and Liu, a second-order explicit symplectic integrator was proposed for the integrable Kerr spacetime geometry. It is still suited for simulating the nonintegrable dynamics of charged particles moving around the Kerr black hole embedded in an external magnetic field. Its successful construction is due to the contribution of a time transformation. The algorithm exhibits a good long-term numerical performance in stable Hamiltonian errors and computational efficiency. As its application, the dynamics of order and chaos of charged particles is surveyed. In some circumstances, an increase of the dragging effects of the spacetime seems to weaken the extent of chaos from the global phase-space structure on Poincaré sections. However, an increase of the magnetic parameter strengthens the chaotic properties. On the other hand, fast Lyapunov indicators show that there is no universal rule for the dependence of the transition between different dynamical regimes on the black hole spin. The dragging effects of the spacetime do not always weaken the extent of chaos from a local point of view.
    Type of Medium: Online Resource
    ISSN: 1434-6044 , 1434-6052
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 1397769-6
    detail.hit.zdb_id: 1459069-4
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  • 5
    Online Resource
    Online Resource
    American Astronomical Society ; 2021
    In:  The Astrophysical Journal Vol. 909, No. 1 ( 2021-03-01), p. 22-
    In: The Astrophysical Journal, American Astronomical Society, Vol. 909, No. 1 ( 2021-03-01), p. 22-
    Abstract: In a previous paper, second- and fourth-order explicit symplectic integrators were designed for a Hamiltonian of the Schwarzschild black hole. Following this work, we continue to trace the possibility of construction of explicit symplectic integrators for a Hamiltonian of charged particles moving around a Reissner–Nordström black hole with an external magnetic field. Such explicit symplectic methods are still available when the Hamiltonian is separated into five independently integrable parts with analytical solutions as explicit functions of proper time. Numerical tests show that the proposed algorithms share desirable properties in their long-term stability, precision, and efficiency for appropriate choices of step size. For the applicability of one of the new algorithms, the effects of black hole’s charge, the Coulomb part of the electromagnetic potential and the magnetic parameter on the dynamical behavior are surveyed. Under some circumstances, the extent of chaos becomes strong with an increase of the magnetic parameter from a global phase-space structure. No variation of the black hole’s charge other than the Coulomb part affects the regular and chaotic dynamics of the particles’ orbits. A positive Coulomb part more easily induces chaos than a negative one.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    RVK:
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 6
    Online Resource
    Online Resource
    American Astronomical Society ; 2022
    In:  The Astrophysical Journal Vol. 940, No. 2 ( 2022-12-01), p. 166-
    In: The Astrophysical Journal, American Astronomical Society, Vol. 940, No. 2 ( 2022-12-01), p. 166-
    Abstract: Many Hamiltonian problems in the solar system are separable into two analytically solvable parts, and thus serve as a great chance to develop and apply explicit symplectic integrators based on operator splitting and composing. However, such constructions are not in general available for curved spacetimes in general relativity and modified theories of gravity because these curved spacetimes correspond to nonseparable Hamiltonians without the two-part splits. Recently, several black hole spacetimes such as the Schwarzschild black hole were found to allow for the construction of explicit symplectic integrators, since their corresponding Hamiltonians are separable into more than two explicitly integrable pieces. Although some other curved spacetimes including the Kerr black hole do not have such multipart splits, their corresponding appropriate time-transformation Hamiltonians do. In fact, the key problem in obtaining symplectic analytically integrable decomposition algorithms is how to split these Hamiltonians or time-transformation Hamiltonians. Considering this idea, we develop explicit symplectic schemes in curved spacetimes. We introduce a class of spacetimes whose Hamiltonians are directly split into several explicitly integrable terms. For example, the Hamiltonian of a rotating black ring has a 13-part split. We also present two sets of spacetimes whose appropriate time-transformation Hamiltonians have the desirable splits. For instance, an eight-part split exists in a time-transformed Hamiltonian of a Kerr–Newman solution with a disformal parameter. In this way, the proposed symplectic splitting methods can be used widely for long-term integrations of orbits in most curved spacetimes we know of.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    RVK:
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2022
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 7
    Online Resource
    Online Resource
    American Astronomical Society ; 2021
    In:  The Astrophysical Journal Vol. 907, No. 2 ( 2021-02-01), p. 66-
    In: The Astrophysical Journal, American Astronomical Society, Vol. 907, No. 2 ( 2021-02-01), p. 66-
    Abstract: Symplectic integrators that preserve the geometric structure of Hamiltonian flows and do not exhibit secular growth in energy errors are suitable for the long-term integration of N -body Hamiltonian systems in the solar system. However, the construction of explicit symplectic integrators is frequently difficult in general relativity because all variables are inseparable. Moreover, even if two analytically integrable splitting parts exist in a relativistic Hamiltonian, all analytical solutions are not explicit functions of proper time. Naturally, implicit symplectic integrators, such as the midpoint rule, are applicable to this case. In general, these integrators are numerically more expensive to solve than same-order explicit symplectic algorithms. To address this issue, we split the Hamiltonian of Schwarzschild spacetime geometry into four integrable parts with analytical solutions as explicit functions of proper time. In this manner, second- and fourth-order explicit symplectic integrators can be easily made available. The new algorithms are also useful for modeling the chaotic motion of charged particles around a black hole with an external magnetic field. They demonstrate excellent long-term performance in maintaining bounded Hamiltonian errors and saving computational cost when appropriate proper time steps are adopted.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    RVK:
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2960-9
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 8
    In: Targeted Oncology, Springer Science and Business Media LLC, Vol. 18, No. 6 ( 2023-11), p. 869-883
    Type of Medium: Online Resource
    ISSN: 1776-2596 , 1776-260X
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2222136-0
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