An Analysis of Social Participation Structure of Middle School Mathematics Classroom in Korea

2007The research aims to set the foundation for the understanding of the mathematics instruction in the institutional setting of a Korean middle school classroom. To fulfill this purpose, we focused on understanding the types and characteristics of participation structure created by class participants' interaction. One second grade middle school mathematics class was adopted for participant observation and long-term data was collected and analyzed. We have discovered several distinct types of social participation structure based on literature review and the criteria drawn from the comprehensive analysis of the characteristics of the teacher's and students' interaction and behavior

Clinical outcomes in patients with persistent atrial fibrillation after technologic advances including contact force-guided and ablation index-guided ablation

We aimed to evaluate the influence of technological advances on ablation outcomes in patients with persistent atrial fibrillation (AF) (PeAF). Radiofrequency ablation for patients with AF has advanced, including contact force (CF)-sensing catheters and the ablation index (AI). Between 2009 and 2018, we analyzed 173 patients with PeAF who underwent catheter ablation. We categorized them into three groups: AF ablation without CF and AI information (no-CF group, n = 63), with CF without AI (CF-only group, n = 49), and with optimal AI-guided ablation (AI group, n = 61). Early (within 3months, ER) and late (from 3months to 1year, LR) AF recurrence after ablation was assessed. Procedure-related complications were also evaluated. The baseline characteristics were similar among the 3 groups, excluding the baseline antiarrhythmic drug history. Additional substrate modification after pulmonary vein isolation was significantly low in frequency in the AI group (71.4%, no-CF; 69.4%, CF-only; 41.0%, AI, p = 0.001). The AI group had a shorter mean procedure-related time than the other groups. Both ER and LR of PeAF showed a trend of reduction with technological advances. With a short experience (less than 1year), the CF-only group showed more ER and LR than that shown by the AI group. However, with a long experience (more than 1year), ER and LR occurred similarly in the two groups. Procedure-related complications improved with technological advances. As ablation technology advanced, favorable clinical outcomes with short procedural times were observed. However, prospective, large multicenter studies are needed to verify these results.This work was supported by the Korea Medical Device Development Fund grant funded by the Korean Government (the Ministry of Science and ICT, the Ministry of Trade, Industry and Energy, the Ministry of Health & Welfare, Republic of Korea, the Ministry of Food and Drug Safety) (Project Number: 202013B14) and by the Korea National Research Foundation funded by the Ministry of Education, Science and Technology (Grant 2020R1F1A106740)

Impedance drop determines ablation lesion volume at the same level of ablation index

New parameters such as ablation index (AI) have been developed to create reliable ablation lesions. This study was performed to evaluate whether RF energy delivery with the same ablation index creates the similar ablation lesion volume. Ablation lesions were created in 5 pig hearts at ex-vivo state. Ablation was performed using an external-irrigation contact-force sensing catheter on the epicardial side of the left ventricle with 90-degree of angle. RF ablation time was adjusted for targeting AI 600 at 8 different conditions. Lesion volume created with 0–5g of contact force at 20 W was significantly lower than that of 11–20g at 40W despite of the same AI (125 ± 76.2 vs. 272 ± 49.5 mm3, P < 0.05). Quality of ablation lesion was variable in the condition of poor contact at low power for the ablation of ex-vivo swine left ventricle, and high-quality lesions could be expected when the impedance drop is satisfactory even though the same level of AI is applied during ablation

A High-Yield Fabrication Process for Silicon Neural Probes

There is a great need for silicon microelectrodes that can simultaneously monitor the activity of many neurons in the brain. However, one of the existing processes for fabricating silicon microelectrodes—reactive- ion etching in combination with anisotropic KOH etching—breaks down at the wet-etching step for device release. Here we describe amodified wet-etching sidewall-protection technique for the high-yield fabrication of well-defined silicon probe structures, using a Teflon® shield and low-pressure chemical vapor deposition (LPCVD) silicon nitride. In the proposed method, a micro-tab holds each individual probe to the central scaffold, allowing uniform anisotropicKOHetching. Using this approach, we obtained a well-defined probe structure without device loss during the wet-etching process. This simple method yielded more accurate fabrication and an improved mechanical profile.This work was supported in part by the Korean Science and Foundation (KOSEF) through the Nano-Bioelectronics and Systems Research Center, Seoul National Universit

Young age: an independent risk factor for disease-free survival in women with operable breast cancer

BACKGROUND: The incidence of breast cancer in young women (age < 35) is low. The biology of the disease in this age group is poorly understood, and there are conflicting data regarding the prognosis for these women compared to older patients. METHODS: We retrospectively analyzed 2040 consecutive primary invasive breast cancer patients who underwent surgical procedures at our institution between 1990 and 1999. The younger age group was defined as patients aged <35 years at the time of diagnosis. The clinicopathological characteristics and treatment outcomes were compared between younger and older age groups. RESULTS: A total of 256 (12.5%) patients were aged <35. There was a significantly higher incidence of nuclear grade 3 and medullary histological-type tumors in younger patients compared to older patients. Axillary lymph node status, T stage, histological grade, c-erbB2 expression and estrogen receptor status did not differ significantly between the two age groups. Younger patients had a greater probability of recurrence and death at all time periods. Although there was no significant difference in disease-free survival between the two age groups in lymph node-negative patients, the younger group showed worse prognosis among lymph node-positive patients (p < 0.001). In multivariate analysis, young age remained a significant predictor of recurrence (p = 0.010). CONCLUSION: Young age (<35) is an independent risk factor for relapse in operable breast cancer patients

Adjuvant Chemotherapy in Microsatellite Instability-High Gastric Cancer

Purpose Microsatellite instability (MSI) status may affect the efficacy of adjuvant chemotherapy in gastric cancer. In this study, the clinical characteristics of MSI-high (MSI-H) gastric cancer and the predictive value of MSI-H for adjuvant chemotherapy in large cohorts of gastric cancer patients were evaluated. Materials and Methods This study consisted of two cohorts. Cohort 1 included gastric cancer patients who received curative resection with pathologic stage IB-IIIC. Cohort 2 included patients with MSI-H gastric cancer who received curative resection with pathologic stage II/III. MSI was examined using two mononucleotide markers and three dinucleotide markers. Results Of 359 patients (cohort 1), 41 patients (11.4%) had MSI-H. MSI-H tumors were more frequently identified in older patients (p < 0.001), other histology than poorly cohesive, signet ring cell type (p=0.005), intestinal type (p=0.028), lower third tumor location (p=0.005), and absent perineural invasion (p=0.027). MSI-H status has a tendency of better disease-free survival (DFS) and overall survival (OS) in multivariable analyses (hazard ratio [HR], 0.4; p=0.059 and HR, 0.4; p=0.063, respectively). In the analysis of 162 MSI-H patients (cohort 2), adjuvant chemotherapy showed a significant benefit with respect to longer DFS and OS (p=0.047 and p=0.043, respectively). In multivariable analysis, adjuvant chemotherapy improved DFS (HR, 0.4; p=0.040). Conclusion MSI-H gastric cancer had distinct clinicopathologic findings. Even in MSI-H gastric cancer of retrospective cohort, adjuvant chemotherapy could show a survival benefit, which was in contrast to previous prospective studies and should be investigated in a further prospective trial.