5,15-Bis(3,5-di-tert-butyl­phen­yl)-10,20-bis­(phenyl­ethyn­yl)porphyrin

In the centrosymmetric title compound, C64H62N4, the two phenyl­ethynyl groups lie at diagonal meso positions. The 24-membered porphyrin has in-plane distortion with respect to the mean plane of the macrocycle and two intra-ring bifurcated N—H⋯(N,N) hydrogen bonds occur. The dihedral angles between the phenyl rings in the phenyl­ethynyl group and the 3,5-bis­(tert-but­yl)phenyl group with respect to the mean plane of the porphyrin are 17.2 (2) and 59.2 (3)°. The tert-butyl groups are disordered over two sets of sites in a 0.661 (13):0.339 (13) ratio

Financial crisis : through various perspectives

Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, 2010.Cataloged from PDF version of thesis.Includes bibliographical references.The 2007 financial crisis can be viewed from various perspectives. First, it can be explained in a wider macroeconomic context, for example by looking at the housing bubble. Monetary policy can be explained according to the BB-NN and IS-LM models. Another way to view the crisis is from a banking perspective by analyzing the changes in the financial market and the deregulation of the banking industry. As the financial sector has grown enormously over the past years, the principle of "Too Big to Fail" should also be scrutinized. Wall Street's economic power was closely related to politics, and therefore it is very helpful to study the financial crisis from a political perspective. After looking at these perspectives, the regulation system should be considered in more detail, paying special attention to systemic risk. Apart from these perspectives, there is still another way to look at the financial crisis: as a Black Swan event. I will point out how the Black Swan event can provide a framework and meaning to interpret the financial crisis. Lastly, the problem of credit rating agencies will be addressed, as this is one of the main causes of the financial crisis. The goal of this thesis is to analyze the financial crisis from various perspectives, and find an appropriate solution to prevent the next financial crisis.by Joon Hee Kim.S.M

A Comparison of Online Trust Building Factors between Potential Customers and Repeat Customers

While vendors on the Internet may have enjoyed an increase in the number of clicks on their Web sites, they have also faced disappointments in converting these clicks into purchases. Lack of trust is identified as one of the greatest barriers inhibiting Internet transactions. Thus, it is essential to understand how trust is created and how it evolves in the Electronic Commerce (EC) context throughout a customer\u27s purchase experience with an Internet store. As the first step in studying the dynamics of online trust building, this research aims to compare online trust-building factors between potential customers and repeat customers. For this purpose, we classify trust in an Internet store into potential customer trust and repeat customer trust, depending on the customer\u27s purchase experience with the store. We find that trust building differs between potential customers and repeat customers in terms of antecedents. We also compare the effects of shared antecedents on trust between potential customers and repeat customers. We find that customer satisfaction has a stronger effect on trust building for repeat customers than other antecedents. We discuss the theoretical reasons for the differences and the implications of our research

INVESTGATING THE INTENTION OF PURCHASING DIGITAL ITEMS IN VIRTUAL COMMUNITIES

Most virtual community (VC) providers lack profitable business models. The challenge for VC providers is to generate and increase revenue from sources other than advertising. The sale of digital items (e.g., avatar) to VC members is a recent revenue generation method. This study examines how VC members decide to purchase digital items from the customer value perspective. Based on customer value theory, this study identifies six factors over three dimensions of customer value and examines their effects on VC members’ intention of purchasing digital items. Our finding suggests that the effect of value on members’ purchase intentions is significant in the functional (i.e., quality of digital items), social (i.e., social self-image), and emotional (i.e., playfulness) value dimensions. This study provides important implications for practitioners to understand how they can foster an ideal environment for customers to perceive more value in their digital items so that it would be more compelling to make purchases in a VC

Breaking Temporal Consistency: Generating Video Universal Adversarial Perturbations Using Image Models

As video analysis using deep learning models becomes more widespread, the vulnerability of such models to adversarial attacks is becoming a pressing concern. In particular, Universal Adversarial Perturbation (UAP) poses a significant threat, as a single perturbation can mislead deep learning models on entire datasets. We propose a novel video UAP using image data and image model. This enables us to take advantage of the rich image data and image model-based studies available for video applications. However, there is a challenge that image models are limited in their ability to analyze the temporal aspects of videos, which is crucial for a successful video attack. To address this challenge, we introduce the Breaking Temporal Consistency (BTC) method, which is the first attempt to incorporate temporal information into video attacks using image models. We aim to generate adversarial videos that have opposite patterns to the original. Specifically, BTC-UAP minimizes the feature similarity between neighboring frames in videos. Our approach is simple but effective at attacking unseen video models. Additionally, it is applicable to videos of varying lengths and invariant to temporal shifts. Our approach surpasses existing methods in terms of effectiveness on various datasets, including ImageNet, UCF-101, and Kinetics-400.Comment: ICCV 202

Bis­(methane­sulfonato-κO)(5,10,15,20-tetra­phenyl­porphyrinato-κ4 N,N′,N′′,N′′′)tin(IV) chloro­form tris­olvate

In the crystal structure of the title compound, [Sn(C44H28N4)(CH3O3S)2]·3CHCl3, the SnIV ion is located on an inversion center and is octa­hedrally coordinated. The porphyrin N atoms occupy the equatorial positions while the axial positions are occupied by the O atoms of the methane­sulfonate anions. The phenyl rings make dihedral angles of 77.02 (13) and 87.89 (14)° with the porphyrin ring. Of the three solvent chloro­form mol­ecules, one is disordered over a twofold rotation axis. In the crystal a three-dimensional assembly is accomplished via C—H⋯O hydrogen bonds between the H atoms of the phenyl groups in the porphyrin ring and the O atoms of the methane­sulfonate ligands

Topological Structure of Dense Hadronic Matter

We present a summary of work done on dense hadronic matter, based on the Skyrme model, which provides a unified approach to high density, valid in the large $N_c$ limit. In our picture, dense hadronic matter is described by the {\em classical} soliton configuration with minimum energy for the given baryon number density. By incorporating the meson fluctuations on such ground state we obtain an effective Lagrangian for meson dynamics in a dense medium. Our starting point has been the Skyrme model defined in terms of pions, thereafter we have extended and improved the model by incorporating other degrees of freedom such as dilaton, kaons and vector mesons.Comment: 13 pages, 8 figures, Talk given at the KIAS-APCTP Symposium in Astro-Hadron Physics "Compact Stars: Quest for New States of Dense Matter", November 10-14, 2003, Seoul, Korea, published by World Scientific. Based on talk by B.-Y. Par