Showing papers by "Young Jin Suh published in 2020"

Characterizations of the Lorentzian manifolds admitting a type of semi-symmetric metric connection

Abstract: We set a type of semi-symmetric metric connection on the Lorentzian manifolds. It is proved that a Lorentzian manifold endowed with a semi-symmetric metric $$\rho $$ -connection is a GRW spacetime. We also characterize the Ricci semisymmetric Lorentzian manifold and study the solution of Eisenhart problem of finding the second order parallel (skew-)symmetric tensor on Lorentzian manifolds. Finally, we address physical interpretation of some geometric results of our paper.

A note on almost co-Kähler manifolds

Abstract: We characterize almost co-Kahler manifolds with gradient Yamabe, gradient Einstein and quasi-Yamabe solitons. It is proved that if the metric of a (κ,μ)-almost co-Kahler manifold M2n+1 is a gradien...

Volume replacement with diced acellular dermal matrix in oncoplastic breast-conserving surgery: a prospective single-center experience

Abstract: Several studies have reported the use of acellular dermal matrix in breast reconstruction. However, the primary role of acellular dermal matrix in these studies was to support the implant; there are no reports on the use of acellular dermal matrix exclusively as volume replacement. Thus, we aimed to evaluate the safety and effectiveness of filling of the defect with acellular dermal matrix in oncoplastic breast-conserving surgery. We prospectively recruited 120 adult breast cancer patients who were scheduled to undergo oncoplastic breast-conserving surgery with acellular dermal matrix filling from 2017 to 2018. Intraoperatively, diced human acellular dermal matrix measuring 3–5 mm was used on each side to fill in the excisional defect immediately. After 6 months, satisfaction of the patients and surgeons with overall and cosmetic outcomes was evaluated with a survey using a 10-point scale. Postoperative complications were assessed at 2 weeks and 6 months postoperatively. Of the 117 patients who were evaluated for their satisfaction, 94.0% were strongly satisfied with the cosmetic outcomes and 90.4% were strongly satisfied overall. Patient overall satisfaction scores were higher than surgeon satisfaction scores (p < 0.001). Of the 117 patients who underwent evaluation of complications 6 months postoperatively, six (5.1%) had hematoma and seven (6.0%) had seroma. The overall reoperation rate due to complications was 8.5%. Only two patients needed acellular dermal matrix removal due to hematoma and inflammation. Oncoplastic breast-conserving surgery with acellular dermal matrix filling of defects can be performed safely with high cosmetic satisfaction. ICTRP, KCT0003886; retrospectively registered May 3, 2019, http://apps.who.int/trialsearch/Trial2.aspx?TrialID=KCT0003886

Feasibility of abbreviated magnetic resonance imaging (AB-MRI) screening in women with a personal history (PH) of breast cancer.

Abstract: Purpose To investigate the feasibility of abbreviated magnetic resonance imaging (AB-MRI) in women with a personal history (PH) of breast cancer as a screening tool. Materials and methods We retrospectively reviewed 1880 screening AB-MRIs in 763 women with a PH of breast cancer (median age, 55 years; range, 23–89 years) between October 2015 and October 2016. The total acquisition times of AB-MRI were 8.3 min and 2.8 min with and without T2-weighted imaging, respectively. The tissue diagnosis or one-year follow-up status was used as the reference standard. The characteristics of tumor recurrences detected on AB-MRI screenings were analyzed. The cancer detection rates (CDRs) and additional CDRs for the 1st round and overall rounds of AB-MRI screening were calculated. The recall rate, sensitivity, specificity, positive predictive values for recall (PPV1) and biopsy (PPV3) for the 1st round of AB-MRI screening were calculated. The diagnostic performance of the combination of mammography and ultrasonography was compared with that of AB-MRI by receiver operating characteristic (ROC) curve analysis. Results Fifteen of a total of 21 recurrences were detected on the 1st round of AB-MRI screening: 93.3% were node-negative T1 tumors (median tumor size, 1.02 cm; range, 0.1–2 cm) or Tis; 66.7% were high-grade tumors; 8 of these 15 were mammographically and ultrasonographically occult. The CDR and additional CDR for the 1st round of AB-MRI screening were 0.019 and 0.010 per woman, respectively. The sensitivity, specificity, recall rate, PPV1 and PPV3 for the 1st round of AB-MRI screening were 100%, 96.0%, 14.3%, 13.8% and 58.3%, respectively. For detecting secondary cancer, AB-MRI showed a higher sensitivity and PPV than the combination of mammography and ultrasonography (95.2%, 57.1% vs 47.6%, 38.5%). The area under the ROC curve was higher for AB-MRI (0.966; 95% CI: 0.951–0.978) than the combination of mammography and ultrasonography (0.727; 95% CI: 0.694–0.759) (P<0.0001). Conclusion AB-MRI improved cancer detection with a high specificity, sensitivity and PPV in women with a PH of breast cancer. AB-MRI could be a useful screening tool for detecting secondary cancer considering its high diagnostic performance and short examination time.

Commuting Jacobi Operators on Real Hypersurfaces of Type B in the Complex Quadric

Abstract: In this paper, first, we investigate the commuting property between the normal Jacobi operator ${\bar R}_{N}$ and the structure Jacobi operator Rξ for Hopf real hypersurfaces in the complex quadric Qm = SOm+ 2/SOmSO2 for $m \geqslant 3$ , which is defined by ${\bar R}_{N} R_{\xi } = R_{\xi }{\bar R}_{N}$ . Moreover, a new characterization of Hopf real hypersurfaces with $\mathfrak A$ -principal singular normal vector field in the complex quadric Qm is obtained. By virtue of this result, we can give a remarkable classification of Hopf real hypersurfaces in the complex quadric Qm with commuting Jacobi operators.

Yamabe solitons and gradient Yamabe solitons on three-dimensional N(k)-contact manifolds

Abstract: If a three-dimensional N(k)-contact metric manifold M admits a Yamabe soliton of type (M,g,V ), then the manifold has a constant scalar curvature and the flow vector field V is Killing. Furthermore...

A new classification on parallel Ricci tensor for real hypersurfaces in the complex quadric

Abstract: First we introduce the notion of parallel Ricci tensor ${ abla }\mathrm {Ric}=0$ for real hypersurfaces in the complex quadric Qm = SOm+2/SOmSO2 and show that the unit normal vector field N is singular. Next we give a new classification of real hypersurfaces in the complex quadric Qm = SOm+2/SOmSO2 with parallel Ricci tensor.

Commuting Jacobi operators on Real hypersurfaces of Type B in the complex quadric

Abstract: In this paper, first, we investigate the commuting property between the normal Jacobi operator~${\bar R}_N$ and the structure Jacobi operator~$R_{\xi}$ for Hopf real hypersurfaces in the complex quadric~$Q^m = SO_{m+2}/SO_mSO_2$, $m \geq 3$, which is defined by ${\bar R}_N R_{\xi} = R_{\xi}{\bar R}_N$. Moreover, a new characterization of Hopf real hypersurfaces with $\mathfrak A$-principal singular normal vector field in the complex quadric~$Q^{m}$ is obtained. By virtue of this result, we can give a remarkable classification of Hopf real hypersurfaces in the complex quadric~$Q^{m}$ with commuting Jacobi operators.

The long-term effect of age on cardiovascular disease in patients with breast cancer who received chemotherapy

Abstract: As breast cancer survival has significantly improved and patient life expectancy has increased, greater numbers of elderly breast cancer survivors are at risk for cardiovascular disease (CVD). Therefore, this study investigated the impact of age on the incidence, mortality, and predictors of CVD following adjuvant chemotherapy in the late period of survivorship. 761 Patients who underwent chemotherapy were enrolled and divided into patients aged < 50 years (n = 413, 54.3%) and patients aged ≥ 50 years (n = 348, 45.7%). Among the entire cohort, 445 patients underwent transthoracic echocardiography. During long-term follow-up (median 122 months, range 12–340 months), CVD events developed in 50 (6.57%) patients, including 17 (4.1%) aged < 50 years and 33 (9.5%) aged ≥ 50 years (p = 0.003). 8 (1.1%) of 50 patients with CVD died, including 1 patient aged < 50 years and 7 patients aged ≥ 50 years. CVD-free survival was significantly lower in patients aged ≥ 50 years compared with patients aged < 50 years (p < 0.001). In multivariate analyses, age ≥ 50 years [p < 0.001, hazard ratio (HR) = 3.802, 95% confidence interval (CI) 1.986–7.278], the radio of the peak early and mitral tissue Doppler velocities (p = 0.014, HR = 1.102, 95% CI 1.020–1.190), and global longitudinal strain (p < 0.001, HR = 1.208, 95% CI 1.096–1.332) are significant predictors of CVD. Age, diastolic function, and strain value in patients with breast cancer who underwent chemotherapy has a long-term effect on CVD. Therefore, it is important to consider ethnic and age-specific risks for CVD in breast cancer survivors.

Real hypersurfaces in the complex hyperbolic quadric with Reeb parallel structure Jacobi operator

Abstract: We introduce the notion of Reeb parallel structure Jacobi operator for real hypersurfaces in the complex hyperbolic quadric $Q^{*m}=SO^{0}_{2,m}/SO_{2} SO_{m}$, $m \geqslant 3$, and give a classification theorem for real hypersurfaces in Q∗m, $m \geqslant 3$, with Reeb parallel structure Jacobi operator.

A new classifcation of contact hypersurfaces in the complex hyperbolic two-plane Grassmannian

Abstract: We give a complete classification of contact hypersurfaces in the complex hyperbolic two-plane Grassmannian G2∗(ℂm+2), m≥2. In fact, they are locally congruent to a tube over a totally real totally geodesic ℍHn, m=2n, in the complex hyperbolic two-plane Grassmannian G2∗(ℂm+2), a horosphere whose center at the infinity is singular, or another exceptional case.

Clinical Implications of Serum 25-Hydroxyvitamin D Status after 5-Year Adjuvant Endocrine Therapy for Late Recurrence of Hormone Receptor-positive Breast Cancer.

Abstract: Purpose The prognostic implications of serum vitamin D status after a 5-year adjuvant endocrine therapy on the risk of late recurrence among hormone receptor (HR)-positive breast cancer patients remain unclear. Hence, we investigated this among Korean HR-positive breast cancer patients. Methods A total of 455 patients with HR-positive stage I-III invasive breast cancer who underwent curative surgery at St. Vincent's Hospital between February 2004 and April 2012 were included in this retrospective study. Patients were categorized based on their serum 25-hydroxyvitamin D (25(OH)D) levels after the 5-year adjuvant endocrine therapy. Initial recurrence sites were categorized. The primary clinical outcome was late recurrence-free survival (LRFS). Results Among the 455 patients, 242 and 213 were included in the 25(OH)D-deficient group and 25(OH)D-sufficient group, respectively. Forty-eight patients experienced late recurrence. Across all recurrence sites, the 25(OH)D-deficient group showed significantly worse LRFS rates than the 25(OH)D-sufficient group (hazard ratio [HR], 2.284; 95% confidence interval [CI], 1.155-4.515; p = 0.018). After patient subgrouping based on recurrence site, the 25(OH)D-deficient group also showed significantly worse LRFS rates in terms of regional lymph node (LN) (HR, 17.453; 95% CI, 2.46-128.83; p = 0.005), bone (HR, 2.394; 95% CI, 1.024-5.599; p = 0.044), and visceral (HR, 2.735; 95% CI, 1.182-6.328; p = 0.019) recurrence. However, there was no significant difference between the 2 groups in terms of local recurrence (p = 0.611). Conclusions We found that 25(OH)D deficiency after the 5-year adjuvant endocrine therapy was associated with worse LRFS among HR-positive breast cancer patients, particularly with respect to regional LN, bone, and visceral recurrence.

Cyclic parallel hypersurfaces in complex Grassmannians of rank 2

Abstract: The object of the paper is to study cyclic parallel hypersurfaces in complex (hyperbolic) two-plane Grassmannians which have a remarkable geometric structure as Hermitian symmetric spaces of rank 2...

Derivatives of normal Jacobi operator on real hypersurfaces in the complex quadric

Abstract: In \cite{S 2017}, Suh gave a non-existence theorem for Hopf real hypersurfaces in the complex quadric with parallel normal Jacobi operator. Motivated by this result, in this paper, we introduce some generalized conditions named $\mathcal C$-parallel or Reeb parallel normal Jacobi operators. By using such weaker parallelisms of normal Jacobi operator, first we can assert a non-existence theorem of Hopf real hypersurfaces with $\mathcal C$-parallel normal Jacobi operator in the complex quadric $Q^{m}$, $m \geq 3$. Next, we prove that a Hopf real hypersurface has Reeb parallel normal Jacobi operator if and only if it has an $\mathfrak A$-isotropic singular normal vector field.

⊥-parallel normal Jacobi operators for Hopf hypersurfaces in complex two-plane Grassmannians with generalized Tanaka–Webster connection

Abstract: Abstract We study classifying problems for real hypersurfaces in a complex two-plane Grassmannian G2(ℂm+2). In relation to the generalized Tanaka–Webster connection, we consider a new concept of parallel normal Jacobi operator for real hypersurfaces in G2(ℂm+2) and prove that a real hypersurface in G2(ℂm+2) with generalized Tanaka–Webster 𝔇⊥-parallel normal Jacobi operator is locally congruent to an open part of a tube around a totally geodesic quaternionic projective space ℍPn in G2(ℂm+2), where m = 2n.

Derivatives of normal Jacobi operator on real hypersurfaces in the complex quadric

Abstract: In \cite{S 2017}, Suh gave a non-existence theorem for Hopf real hypersurfaces in the complex quadric with parallel normal Jacobi operator. Motivated by this result, in this paper, we introduce some generalized conditions named $\mathcal C$-parallel or Reeb parallel normal Jacobi operators. By using such weaker parallelisms of normal Jacobi operator, first we can assert a non-existence theorem of Hopf real hypersurfaces with $\mathcal C$-parallel normal Jacobi operator in the complex quadric $Q^{m}$, $m \geq 3$. Next, we prove that a Hopf real hypersurface has Reeb parallel normal Jacobi operator if and only if it has an $\mathfrak A$-isotropic singular normal vector field.

Real Hypersurfaces in the Complex Quadric with Lie Invariant Structure Jacobi Operator

Abstract: We introduce the notion of Lie invariant structure Jacobi operators for real hypersurfaces in the complex quadric with Lie invariant structure Jacobi operators.