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Department of Mathematical SciencesIn modern society, financial industry and human-being establish a truly inseparable relationship. Moreover, financial industry becomes inter-correlated market following the advance of globalization. Thus, they interact both directly and indirectly with each other. Therefore, if an outbreak of financial crisis occurs in one sector, one can anticipate that the crisis effect will diffuse to other financial sectors similar with contagious disease. This research analyzes and does modeling of diffusion of financial crisis from one financial sector to other sectors by using epidemic models. This work mainly focuses on the impact and contagious phenomenon of US financial shock developed in 2008 on Korean corporations enlisted in KOSPI & KOSDAQ index. And then, more precisely, by classifying industries as several groups, it analyzes how financial crisis influences on each group. The SIR model (Susceptible-Infected-Removed model) is set and the aspect of the model is compared with the result obtained from a quantitative indicator, EDF model (Expected Default Frequency model). Throughout this research, the validity of using epidemic models is discussed how proper it is, to estimate the diffusion of financial crisis to another financial sector or country, and furthermore, to each industry group within one financial sector. In this research, the fundamental data from KRX and FSS is used for EDF model. It includes stock price, total market value, and current liabilities of each corporation from Jan. 2007 to Dec. 2010. From this data, the contagious features started from US financial crisis are observed ??? within infected corporations, EDF value is increase or maintains sustained level right after US crisis. With respect to the average EDF value and DD value of each group, parameters for deterministic epidemic model, including contact rate and recovery rate, are presumed.clos

How donor's regulatory focus changes the effectiveness of a sadness-evoking charity appeal

Past research offers conflicting findings on whether sadness-evoking charity appeals help solicit a donation. To reconcile these findings, we introduce prospective donors' regulatory focus as a moderator for understanding when and why sadness appeals motivate or demotivate giving. Specifically, we propose that the sense of helplessness or loss of control associated with sadness appeals increases donors' sensitivity to advertiser's manipulative persuasion tactics, as those tactics can threaten donors' control over their donation decision. As a result, sadness appeals are more likely to activate persuasion knowledge among prevention- (vs. promotion-) oriented donors who tend to be vigilant against manipulative persuasion attempts. Across six main studies and two supplementary studies, we find that a prevention (vs. promotion) focus discourages charitable giving when it is solicited using a sadness appeal, whereas regulatory focus does not affect the giving when other emotion appeals (e.g., happiness appeal or guilt appeal) are used. We find that a prevention (vs. promotion) focus demotivates donation solicited by a sadness appeal because it activates persuasion knowledge that evaluates solicitor's motive behind the sadness appeal, resulting in increased skepticism, dampened feelings of sympathy, and consequently, reduced charitable giving. However, when persuasion knowledge is deactivated (e.g., when donors' cognitive capacity is constrained or the soliciting charity has a reliable reputation), regulatory focus no longer affects donor skepticism, sympathy, and charitable giving, even when a sadness appeal is used to call for donation

Anti-inflammatory effects of spermidine in lipopolysaccharide-stimulated BV2 microglial cells

<p>Abstract</p> <p>Background</p> <p>Spermidine, a naturally occurring polyamine, displays a wide variety of internal biological activities including cell growth and proliferation. However, the molecular mechanisms responsible for its anti-inflammatory activity have not yet been elucidated.</p> <p>Methods</p> <p>The anti-inflammatory properties of spermidine were studied using lipopolysaccharide (LPS)-stimulated murine BV2 microglia model. As inflammatory parameters, the production of nitric oxide (NO), prostaglandin E₂(PGE₂), interleukin (IL)-6 and tumor necrosis factor (TNF)-α were evaluated. We also examined the spermidine's effect on the activity of nuclear factor-kappaB (NF-κB), and the phosphoinositide 3-kinase (PI3K)/Akt and mitogen-activated protein kinases (MAPKs) pathways.</p> <p>Results</p> <p>Pretreatment with spermidine prior to LPS treatment significantly inhibited excessive production of NO and PGE₂in a dose-dependent manner, and was associated with down-regulation of expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Spermidine treatment also attenuated the production of pro-inflammatory cytokines, including IL-6 and TNF-α, by suppressing their mRNA expressions. The mechanism underlying spermidine-mediated attenuation of inflammation in BV2 cells appeared to involve the suppression of translocation of NF-κB p65 subunit into the nucleus, and the phosphorylation of Akt and MAPKs.</p> <p>Conclusions</p> <p>The results indicate that spermidine appears to inhibit inflammation stimulated by LPS by blocking the NF-κB, PI3K/Akt and MAPKs signaling pathways in microglia.</p

Angle Dependence of Landau Level Spectrum in Twisted Bilayer Graphene

In the context of the low energy effective theory, the exact Landau level spectrum of quasiparticles in twisted bilayer graphene with small twist angle is analytically obtained by spheroidal eigenvalues. We analyze the dependence of the Landau levels on the twist angle to find the points, where the two-fold degeneracy for twist angles is lifted in the nonzero modes and below/above which massive/massless fermion pictures become valid. In the perpendicular magnetic field of 10\,T, the degeneracy is removed at $\theta_{{\rm deg}}\sim 3^\circ$ %angles around 3 degrees for a few low levels, specifically, $\theta_{\rm deg}\simeq 2.56^\circ$ for the first pair of nonzero levels and $\theta_{\rm deg}\simeq 3.50^\circ$ for the next pair. Massive quasiparticle appears at $\theta<\theta_{{\rm c}}\simeq 1.17^\circ$ in 10\,T, %angles less than 1.17 degrees. which match perfectly with the recent experimental results. Since our analysis is applicable to the cases of arbitrary constant magnetic fields, we make predictions for the same experiment performed in arbitrary constant magnetic fields, e.g., for B=40\,T we get $\theta_{\rm c}\simeq 2.34^\circ$ and the sequence of angles $\theta_{\rm deg} = 5.11, 7.01, 8.42,...$ for the pairs of nonzero energy levels. The symmetry restoration mechanism behind the massive/massless transition is conjectured to be a tunneling (instanton) in momentum space.Comment: 8 pages, 7 figures, version to appear in PR

Some Identities on the High-Order -Euler Numbers and Polynomials with Weight 0

We construct the th order nonlinear ordinary differential equation related to the generating function of -Euler numbers with weight 0. From this, we derive some identities on -Euler numbers and polynomials of higher order with weight 0