Estimation of the Survivor Model by Nonparametric Maximum Likelihood, Maximum Penalized Likelihood, and Simulation-Based Estimation

Econometric models ; statistical data

Upper bound of the charge diffusion constant in holography

We investigate the upper bound of charge diffusion constant in holography. For this purpose, we apply the conjectured upper bound proposal related to the equilibration scales ($\omega_{\text{eq}}, k_{\text{eq}}$) to the Einstein-Maxwell-Axion model. ($\omega_{\text{eq}}, k_{\text{eq}}$) is defined as the collision point between the diffusive hydrodynamic mode and the first non-hydrodynamic mode, giving rise to the upper bound of the diffusion constant $D$ at low temperature $T$ as $D = \omega_{\text{eq}}/k_{\text{eq}}^2$. We show that the upper bound proposal also works for the charge diffusion and ($\omega_{\text{eq}}, k_{\text{eq}}$), at low $T$, is determined by $D$ and the scaling dimension $\Delta(0)$ of an infra-red operator as $(\omega_{\text{eq}}, \, k_{\text{eq}}^2) \,=\, (2 \pi T \Delta(0) \,, \omega_{\text{eq}}/D)$, as for other diffusion constants. However, for the charge diffusion, we find that the collision occurs at real $k_{\text{eq}}$, while it is complex for other diffusions. In order to examine the universality of the conjectured upper bound, we also introduce a higher derivative coupling to the Einstein-Maxwell-Axion model. This coupling is particularly interesting since it leads to the violation of the \textit{lower} bound of the charge diffusion constant so the correction may also have effects on the \textit{upper} bound of the charge diffusion. We find that the higher derivative coupling does not affect the upper bound so that the conjectured upper bound would not be easily violated.Comment: v1: 23 pages, 10 figures; v2: minor edits, references adde

Asian real estate investment : data utilization for the decision making process

Thesis (S.M. in Real Estate Development)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (leaf 38).Many investors in developed countries believe the Asian emerging market to be highly risky due to numerous uncertainties including limited market information to make sound investment decisions. However, still successful investment deals were completed by many investors who are already in such markets, and how those investors make sound investment decisions is in need on explanation. Therefore, this thesis explores institutional real estate investors' behavior on entrance to Asian emerging markets, their investment decision making process, and data utilization within each process. Through 14 qualitative in-depth interviews with key institutional investors in the U.S. and Korea, investment decision making processes and data utilization behaviors are examined and summarized in a generalized format. Interview results indicate that an initial entrance to Asian emerging markets occurs rather through a passive introduction of a potential deal by third party than an active search for a target deal by the investor. Also, the general decision-making process for real estate investment starts from sourcing and sorting, followed by review of a potential deal, primary investment committee meeting, due diligence, secondary investment committee meeting, and close of the deal. Each stage of the decision-making process is highly interconnected with simultaneous communication among responsible teams and the investment committee. The Korean real estate market, at least for the office sector, has such abundant market information available that it is rather perceived as "emerged." Investors also have extensive experience in the market and use their market knowledge and third party information as a reference point to verify the deal information. However, they also physically collect market data and use their own internal transaction record when necessary. Furthermore, data utilization in Korea is found to be easy and convenient especially when combined with extensive market experience and a wide professional network in the industry.by Keun Huh.S.M.in Real Estate Developmen

Holography and magnetohydrodynamics with dynamical gauge fields

Within the framework of holography, the Einstein-Maxwell action with Dirichlet boundary conditions corresponds to a dual conformal field theory in presence of an external gauge field. Nevertheless, in many real-world applications, e.g., magnetohydrodynamics, plasma physics, superconductors, etc. dynamical gauge fields and Coulomb interactions are fundamental. In this work, we consider bottom-up holographic models at finite magnetic field and (free) charge density in presence of dynamical boundary gauge fields which are introduced using mixed boundary conditions. We numerically study the spectrum of the lowest quasi-normal modes and successfully compare the obtained results to magnetohydrodynamics theory in $2+1$ dimensions. Surprisingly, as far as the electromagnetic coupling is small enough, we find perfect agreement even in the large magnetic field limit. Our results prove that a holographic description of magnetohydrodynamics does not necessarily need higher-form bulk fields but can be consistently derived using mixed boundary conditions for standard gauge fields.Comment: 54 pages, 22 figure

Enhanced expression of microrna-1273g-3p contributes to alzheimer’s disease pathogenesis by regulating the expression of mitochondrial genes

Alzheimer’s disease (AD) is the most common form of dementia in the elderly population, but its underlying cause has not been fully elucidated. Recent studies have shown that microRNAs (miRNAs) play important roles in regulating the expression levels of genes associated with AD development. In this study, we analyzed miRNAs in plasma and cerebrospinal fluid (CSF) from AD patients and cognitively normal (including amyloid positive) individuals. miR-1273g-3p was identified as an AD-associated miRNA and found to be elevated in the CSF of early-stage AD patients. The overexpression of miR-1273g-3p enhanced amyloid beta (Aβ) production by inducing oxidative stress and mitochondrial impairments in AD model cell lines. A biotin-streptavidin pull-down assay demonstrated that miR-1273g-3p primarily interacts with mitochondrial genes, and that their expression is downregulated by miR-1273g-3p. In particular, the miR-1273g-3p-target gene TIMM13 showed reduced expression in brain tissues from human AD patients. These results suggest that miR1273g-3p expression in an early stage of AD notably contributes to Aβ production and mitochondrial impairments. Thus, miR-1273g-3p might be a biomarker for early diagnosis of AD and a potential therapeutic target to prevent AD progression

Seizure-Like Activities during Head-Up Tilt Test-Induced Syncope

Purpose: Some patients with neurally mediated reflex syncope may be misdiagnosed as epilepsy because myoclonic jerky movements are observed during syncope. The seizure-like activities during the head-up tilt test (HUT) have been rarely reported. The purpose of this study was to assess the characteristics of these seizure-like activities and evaluate whether there are differences in the clinical characteristics and hemodynamic parameters of patients with neurally mediated reflex syncope with and without seizure-like activities during HUT-induced syncope. Materials and Methods: The medical records of 1,383 consecutive patients with a positive HUT were retrospectively reviewed, and 226 patients were included in this study. Results: Of 226 patients, 13 (5.75%) showed seizure-like activities, with 5 of these (2.21%) having multifocal myoclonic jerky movements, 5 (2.21%) having focal seizurelike activity involving one extremity, and 3 (1.33%) having upward deviation of eye ball. Comparison of patients with and without seizure-like activities revealed no significant differences in terms of clinical variables and hemodynamic parameters during HUT. Conclusion: Seizure-like activities occurred occasionally during HUTinduced syncope in patients with neurally mediated reflex syncope. The seizure-like activities during HUT might not be related to the severity of the syncopal episodes or hemodynamic changes during HUT. Key Words: Neurally mediated reflex syncope, seizure-like activities, head-up tilt tes