Source signatures from combined isotopic analyses of PM2.5 carbonaceous and nitrogen aerosols at the peri-urban Taehwa Research Forest, South Korea in summer and fall.

Isotopes are essential tools to apportion major sources of aerosols. We measured the radiocarbon, stable carbon, and stable nitrogen isotopic composition of PM2.5 at Taehwa Research Forest (TRF) near Seoul Metropolitan Area (SMA) during August-October 2014. PM2.5, TC, and TN concentrations were 19.4 ± 10.1 μg m-3, 2.6 ± 0.8 μg C m-3, and 1.4 ± 1.4 μg N m-3, respectively. The δ13C of TC and the δ15N of TN were - 25.4 ± 0.7‰ and 14.6 ± 3.8‰, respectively. EC was dominated by fossil-fuel sources with Fff (EC) of 78 ± 7%. In contrast, contemporary sources were dominant for TC with Fc (TC) of 76 ± 7%, revealing the significant contribution of contemporary sources to OC during the growing season. The isotopic signature carries more detailed information on sources depending on air mass trajectories. The urban influence was dominant under stagnant condition, which was in reasonable agreement with the estimated δ15N of NH4+. The low δ15N (7.0 ± 0.2‰) with high TN concentration was apparent in air masses from Shandong province, indicating fossil fuel combustion as major emission source. In contrast, the high δ15N (16.1 ± 3.2‰) with enhanced TC/TN ratio reveals the impact of biomass burning in the air transported from the far eastern border region of China and Russia. Our findings highlight that the multi-isotopic composition is a useful tool to identify emission sources and to trace regional sources of carbonaceous and nitrogen aerosols

Vector Quantized Bayesian Neural Network Inference for Data Streams

Bayesian neural networks (BNN) can estimate the uncertainty in predictions, as opposed to non-Bayesian neural networks (NNs). However, BNNs have been far less widely used than non-Bayesian NNs in practice since they need iterative NN executions to predict a result for one data, and it gives rise to prohibitive computational cost. This computational burden is a critical problem when processing data streams with low-latency. To address this problem, we propose a novel model VQ-BNN, which approximates BNN inference for data streams. In order to reduce the computational burden, VQ-BNN inference predicts NN only once and compensates the result with previously memorized predictions. To be specific, VQ-BNN inference for data streams is given by temporal exponential smoothing of recent predictions. The computational cost of this model is almost the same as that of non-Bayesian NNs. Experiments including semantic segmentation on real-world data show that this model performs significantly faster than BNNs while estimating predictive results comparable to or superior to the results of BNNs.Comment: AAAI 202

Methylsulfonylmethane Suppresses Breast Cancer Growth by Down-Regulating STAT3 and STAT5b Pathways

Breast cancer is the most aggressive form of all cancers, with high incidence and mortality rates. The purpose of the present study was to investigate the molecular mechanism by which methylsulfonylmethane (MSM) inhibits breast cancer growth in mice xenografts. MSM is an organic sulfur-containing natural compound without any toxicity. In this study, we demonstrated that MSM substantially decreased the viability of human breast cancer cells in a dose-dependent manner. MSM also suppressed the phosphorylation of STAT3, STAT5b, expression of IGF-1R, HIF-1α, VEGF, BrK, and p-IGF-1R and inhibited triple-negative receptor expression in receptor-positive cell lines. Moreover, MSM decreased the DNA-binding activities of STAT5b and STAT3, to the target gene promoters in MDA-MB 231 or co-transfected COS-7 cells. We confirmed that MSM significantly decreased the relative luciferase activities indicating crosstalk between STAT5b/IGF-1R, STAT5b/HSP90α, and STAT3/VEGF. To confirm these findings in vivo, xenografts were established in Balb/c athymic nude mice with MDA-MB 231 cells and MSM was administered for 30 days. Concurring to our in vitro analysis, these xenografts showed decreased expression of STAT3, STAT5b, IGF-1R and VEGF. Through in vitro and in vivo analysis, we confirmed that MSM can effectively regulate multiple targets including STAT3/VEGF and STAT5b/IGF-1R. These are the major molecules involved in tumor development, progression, and metastasis. Thus, we strongly recommend the use of MSM as a trial drug for treating all types of breast cancers including triple-negative cancers

Bank risk-taking, regulations and market discipline : three essays

textIn the first chapter, I analyze how early corrective actions affect bank risk taking and welfare of agents in an economy. Early corrective actions considered in this paper are classified into two categories: early closure and (early) recapitalization. It is shown that early closure might be preferable to save government expenses (explicit costs), but it causes inefficient bank risk-taking (implicit costs). It is not obvious whether the resolution costs and inefficiency in bank risk taking are smaller under recapitalization. However, there is a type of recapitalization in which not only does the government incur no resolution costs, but also recapitalization might reduce inefficiency. This type of recapitalization gives better ex ante expected returns so that there is Pareto improvement. The second chapter examines market discipline in the Korean banking system. Evidence of strong market discipline is essential to justify the cession of government regulatory control to the market. Two types of markets are tested: (i) the market for uninsured liabilities, and (ii) the market for bank equity. I find week evidence of market discipline in the market for uninsured liabilities in Korea. In the case of the market for bank equity, no evidence of market discipline is found. Overall, the estimation results in the two markets do not provide strong evidence of market discipline in the Korean banking system during the sample periods. In the third chapter, I examine the relationship between bank size, diversification and risk in Korean banks. Recent mergers in the Korean banking industry show that the government encourages and supports banking consolidation in various ways as a part of restructuring the financial sector. This policy trend is based on the presumptions that bigger banks are better diversified than smaller banks, and that diversification can potentially reduce the probability of failure. I test this conventional wisdom. The estimation results provide strong evidence of the positive relationship between bank size and diversification; bigger banks are better diversified than small banks. However, the results show that bigger banks’ diversification, at least in bank loans, does not generate enhanced safety in Korean banks. This suggests the possibility of the “too-big-to-fail” (TBTF) moral hazard incentives that could drive large banks to hold diversified but riskier asset portfolios.Economic