Showing papers by "Young Jin Suh published in 2022"

Real Hypersurfaces in Hermitian Symmetric Spaces

Abstract: Hermitian symmetric spaces are an important class of manifolds that can be studied with methods from Kähler geometry and Lie theory. This work gives an introduction to Hermitian symmetric spaces and their submanifolds, and presents classifi cation results for real hypersurfaces in these spaces, focusing on results obtained by Jürgen Berndt and Young Jin Suh in the last 20 years.

Characterizations of Lorentzian manifolds

Abstract: The focus of this paper is to characterize the Lorentzian manifolds equipped with a semi-symmetric non-metric ρ-connection [briefly, [Formula: see text]]. The conditions for a Lorentzian manifold to be a generalized Robertson–Walker spacetime are established and vice versa. We prove that an n-dimensional compact [Formula: see text] is geodesically complete. We also study the properties of almost Ricci solitons and gradient almost Ricci solitons on Lorentzian manifolds and Yang pure space, respectively. Finally, we study the properties of semisymmetric [Formula: see text], and it is proven that [Formula: see text] is semisymmetric if and only if it is a Robertson–Walker spacetime.

COVID-19 Prevention Guidance and the Incidence of Febrile Neutropenia in Patients with Breast Cancer Receiving TAC Chemotherapy with Prophylactic Pegfilgrastim

Abstract: Chemotherapy-induced febrile neutropenia (FN) is a medical emergency that causes severe adverse effects and death. Respiratory infections are one of the main causes of fever in patients with FN. We studied whether infection prevention and control (IPC) guidance for coronavirus 2019 disease reduced the incidence of FN. We reviewed female patients with breast cancer treated with adjuvant docetaxel, doxorubicin, and cyclophosphamide with prophylactic pegfilgrastim between 2019 and 2021. IPC guidance was implemented in April 2020. There was no difference in the incidence of chemotherapy-induced neutropenia between patients with and without IPC. In patients with IPC, the incidence of FN (9.5%) was lower than that of patients without IPC (27.9%). The hospitalization duration (0.7 ± 1.5 days) and total hospital cost (279.6 ± 42.6 USD) of the IPC group were significantly lower than that of the non-IPC group (2.0 ± 3.8 days and 364.7 ± 271.6 USD, respectively). IPC guidance should be implemented to prevent FN in high-risk patients with breast cancer.

Effects of Ruxolitinib and Calcitriol Combination Treatment on Various Molecular Subtypes of Breast Cancer

Abstract: The anticancer effects of ruxolitinib and calcitriol against breast cancer were reported previously. However, the effect of ruxolitinib and calcitriol combination treatment on various molecular subtypes of breast cancer remains unexplored. In this study, we used MCF-7, SKBR3, and MDA-MB-468 cells to investigate the effect of ruxolitinib and calcitriol combination treatment on cell proliferation, apoptosis, cell cycle, and cell signaling markers, in vitro and in vivo. Our results revealed the synergistic anticancer effect of ruxolitinib and calcitriol combination treatment in SKBR3 and MDA-MB-468 cells, but not in MCF-7 cells in vitro, via cell proliferation inhibition, apoptosis induction, cell cycle arrest, and the alteration of cell signaling protein expression, including cell cycle-related (cyclin D1, CDK1, CDK4, p21, and p27), apoptosis-related (c-caspase and c-PARP), and cell proliferation-related (c-Myc, p-p53, and p-JAK2) proteins. Furthermore, in the MDA-MB-468 xenograft mouse model, we demonstrated the synergistic antitumor effect of ruxolitinib and calcitriol combination treatment, including the alteration of c-PARP, cyclin D1, and c-Myc expression, without significant drug toxicity. The combination exhibited a synergistic effect in HER2-enriched and triple-negative breast cancer subtypes. In conclusion, our results suggest different effects of the combination treatment of ruxolitinib and calcitriol depending on the molecular subtype of breast cancer.

Generalized Killing Ricci tensor for real hypersurfaces in the complex quadric

Abstract: First we introduce a new notion of generalized Killing Ricci tensor which is equivalent to the notion of cyclic parallel Ricci tensor for real hypersurfaces in the complex quadric Qm=SOm+2/SOmSO2$Q^m = SO_{m+2}/SO_mSO_2$ . Next, in terms of A$\mathfrak {A}$ ‐principal or A$\mathfrak {A}$ ‐isotropic unit normal vector fields we give a complete classification of real hypersurfaces in Qm=SOm+2/SOmSO2$Q^m = SO_{m+2}/SO_mSO_2$ with cyclic parallel Ricci tensor.

Yamabe and Gradient Yamabe Solitons in the Complex Hyperbolic Two-Plane Grassmannians

Abstract: First, we want to give a complete classification of Yamabe solitons and gradient Yamabe solitons for real hypersurfaces in the complex hyperbolic two-plane Grassmannians [Formula: see text]. Next, as an application we also give a complete classification of quasi-Yamabe and gradient quasi-Yamabe solitons on real hypersurfaces in the complex hyperbolic two-plane Grassmannians [Formula: see text].

Impact of the ACOSOG Z0011 trial on surgical practice in Asian patients: trends in axillary surgery for breast cancer from a Korean Breast Cancer Registry analysis

Abstract: Abstract Background Since the publication of the Z0011 trial, practice-changing clinical guidelines for breast surgery have been developed. Although recent studies confirmed the feasibility of the Z0011 strategy in Asian populations, there has been no study on the trends of axillary surgery in Asian cohort. This study aimed to investigate the time trend of axillary surgery for breast cancer from a Korean Breast Cancer Registry to understand the impact of the Z0011 trial in Asian patients. Methods We collected prospectively constructed data from the nationwide Korean Breast Cancer Registry (KBCR). We identified patients who underwent sentinel node biopsy followed by breast-conserving surgery from 2011 to 2018 and were found to have pathological stage T1-2N1-3M0 disease. Regression analyses were performed to compare the downward trend of axillary lymph node dissection (ALND) in Korean cohort with that previously reported in a Dutch cohort. Results From KBCR data, 7478 patients met the inclusion criteria. The proportion of ALND significantly decreased from 2011 (76.6%) to 2018 (47.5%). Multivariate analysis revealed that earlier years at diagnosis, larger tumor size, and lymphatic invasion were associated with a higher odds ratio of performing ALND. Compared to the Dutch cohort, the downward trend of ALND in Korea was significantly more gradual (annual percent change: 37.2 vs. 5.8%, p < 0.001). Conclusions This study demonstrated a downward trend of ALND in Korean patients with breast cancer. However, the rate of decrease was significantly slower than that in the Dutch cohort.

On the structure Lie operator of a real hypersurface in the complex quadric

Abstract: The almost contact metric structure that we have on a real hypersurface M in the complex quadric Q m = SO m +2 /SO m SO 2 allows us to define, for any nonnull real number k , the k -th generalized Tanaka-Webster connection on M , ˆ ∇ ( k ) . Associated to this connection we have Cho and torsion operators, F ( k ) X and T ( k ) X , respectively, for any vector field X tangent to M . From them and for any symmetric operator B on M we can consider two tensor fields of type (1,2) on M that we will denote by B ( k ) F and B ( k ) T , respectively. We will classify real hypersurfaces M in Q m for which any of those tensors identically vanishes, in the particular case of B being the structure Lie operator L ξ on M . 2010 Mathematics Subject Classification: 53C15, 53B25.

Generalized killing structure jacobi operator for real hypersurfaces in complex hyperbolic two-plane grassmannians

Abstract: . In this paper, first we introduce a new notion of generalized Killing structure Jacobi operator for a real hypersurface M in com- plex hyperbolic two-plane Grassmannians SU 2 ,m /S ( U 2 · U m ). Next we prove that there does not exist a Hopf real hypersurface in complex hy- perbolic two-plane Grassmannians SU 2 ,m /S ( U 2 · U m ) with generalized Killing structure Jacobi operator.