For the past decades, the density of DRAM has been remarkably increased by making access transistors and capacitors smaller in size per unit area. However, shrinking devices far beyond the 10 nm process node increasingly poses process and reliability challenges. As Flash technology made a pivotal and successful innovation via 3D NAND, DRAM technology may also adopt vertical stacking memory cells. Vertically stacked DRAM (VS-DRAM) continues to increase bit density on a die by increasing the number of layers along with reducing the size of the transistor. In this paper, the opportunities and challenges of VS-DRAM are discussed.

Background We investigated the association between geographic proximity to hospitals and the administration rate of reperfusion therapy for acute ischemic stroke. Methods We identified patients with acute ischemic stroke who visited the hospital within 12 hours of symptom onset from a prospective nationwide multicenter stroke registry. Reperfusion therapy was classified as intravenous thrombolysis (IVT), endovascular therapy (EVT), or combined therapy. The association between the proportion of patients who were treated with reperfusion therapy and the ground transport time was evaluated using a spline regression analysis adjusted for patient-level characteristics. We also estimated the proportion of Korean population that lived within each 30-minute incremental service area from 67 stroke centers accredited by the Korean Stroke Society. Results Of 12,172 patients (mean age, 68 ± 13 years; men, 59.7%) who met the eligibility criteria, 96.5% lived within 90 minutes of ground transport time from the admitting hospital. The proportion of patients treated with IVT decreased significantly when stroke patients lived beyond 90 minutes of the transport time (P = 0.006). The proportion treated with EVT also showed a similar trend with the transport time. Based on the residential area, 98.4% of Korean population was accessible to 67 stroke centers within 90 minutes. Conclusion The use of reperfusion therapy for acute stroke decreased when patients lived beyond 90 minutes of the ground transport time from the hospital. More than 95% of the South Korean population was accessible to 67 stroke centers within 90 minutes of the ground transport time.

PurposeThe poor response of breast cancer to immune checkpoint blockade might result from low immunogenicity and the immune-suppressive tumor microenvironment. We hypothesized that in situ tumor vaccination via radiation therapy (RT) and suppression of immune tolerance via phosphoinositide 3-kinase δ (PI3Kδ) inhibition would enhance the efficacy of immune checkpoint blockade.Methods and Materials4T1 murine breast cancer cells were grown in both immune-competent and -deficient BALB/c mice, and tumors were irradiated with 24 Gy in 3 fractions. A PD-1 blockade and a PI3Kαδ inhibitor were then administered every other day for 2 weeks. Fluorescence-activated cell sorting and immunohistochemistry served to monitor subsequent changes in immune cell repertoire.ResultsThe triple combination of RT, PD-1 blockade, and PI3Kαδ inhibitor significantly delayed tumor growth. The immune-deficient syngeneic 4T1 murine tumor model failed to show this tumor growth delay. Use of RT and PI3Kαδ inhibitor increased the proportions of CD8+ T cells; PI3Kαδ inhibitor led to a decrease in regulatory T cells and polymorphonuclear myeloid-derived suppressor cells. The triple combination resulted in a remarkable increase in cytotoxic CD8+ T cells, suggesting a prominent immune-modulatory effect. The abscopal effect was most prominent in the triple-combination therapy group, and it correlated with splenic CD8+ T cell accumulation.ConclusionsThese findings collectively indicate that combining RT, PI3Kαδ inhibitor, and PD-1 blockade could be a viable approach, helping to overcome the therapeutic resistance of immunologically cold tumors, such as breast cancer, with an immunosuppressive tumor microenvironment.

In this phantom study, attachment of a 0.4 mm tin filter with HQH protocols could effectively reduce streak artifacts without degradation of other image quality indices. In addition, the accompanied imaging doses did not increase.

BACKGROUND: As there had been no reduction in the TB burden in South Korea since 2000, a public-private mix (PPM) strategy was launched in 2011. The purpose of this study was to investigate the reasons for lost to follow-up (LTFU) among TB patients and their clinical characteristics.METHOD: A multicentre, cross-sectional study based on in-depth interviews with patients and their families by TB specialist nurses was conducted. Patients who were reported with a final outcome of LTFU in 2015-2017 at all PPM hospitals across the country were enrolled. Enrolled patients were classified into six subgroups by age and three major reasons for LTFU (adverse effects, refusal of treatment, marginalisation) and their clinical features were compared.RESULTS: Among 780 patients, those who were lost to follow-up due to adverse effects accounted for the largest proportion (n = 387). LTFU in those aged <65 years who refused treatment (n = 189) and those aged <65 years who were marginalised (n = 108) were related to having smear-positive TB and a previous history of unfavourable outcomes.CONCLUSION: To reduce LTFU in South Korea, comprehensive strategies, including management of adverse effects, systematic counselling and education, should be implemented.

Background: This study aims to investigate the effect of reference dose calculation grid size (RDCGS) on gamma passing rate (GPR) for patient-specific quality assurance of intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Materials and Methods: A total of 20 patients were retrospectively selected. Both IMRT and VMAT plans were generated for each patient. Reference dose distributions for gamma analysis were calculated with RDCGS of 1-5 mm at intervals of 1 mm. Dose distributions were measured using MapCHECK2 and ArcCHECK dosimeters. Both global and local gamma analyses with gamma criteria of 3%/3 mm, 2%/3 mm, 2%/2 mm, and 2%/1 mm were performed with various RDCGS. Results: As the RDCGS increased from 1 mm to 5 mm, the average global GPRs with 2%/2 mm for VMAT with MapCHECK2 and ArcCHECK decreased by 9.3% and 5.9%, respectively. The average local GPRs decreased by 14% and 11.7%, respectively. For IMRT, the global GPRs decreased by 4.8% and 6%, respectively, whereas the local GPRs decreased by 10.5% and 8.6%, respectively. The effect of the RDCGS on the GPRs became larger when performing local gamma analysis as well as when applying small distance-to-agreement (DTA). As the RDCGS increased, the average changes in the GPR per mm of DTA change increased regardless of the type of radiotherapy, detector, or gamma analysis. Conclusion: For an accurate verification of the IMRT and VMAT plans, it is recommended that the reference dose distribution must be calculated with the smallest possible RDCGS.