The effect of cyber-attacks on stock returns

A widely debated issue in recent years is cybercrime. Breaches in the security of accessibility, integrity and confidentiality of information involve potentially high explicit and implicit costs for firms. This paper investigates the impact of information security breaches on stock returns. Using event-study methodology, the study provides empirical evidence on the effect of announcements of cyber-attacks on the market value of firms from 1995 to 2015. Results show that substantial negative market returns occur following announcements of cyber-attacks. Financial entities often suffer greater negative effects than other companies and non-confidential cyber-attacks are the most dangerous, especially for the financial sector. Overall findings seem to show a link between cybercrime and insider trading

A Survey on Continuous Time Computations

We provide an overview of theories of continuous time computation. These theories allow us to understand both the hardness of questions related to continuous time dynamical systems and the computational power of continuous time analog models. We survey the existing models, summarizing results, and point to relevant references in the literature

Empirical analysis of credit relationships in small firms financing : sampling design and descriptive statistics

Despite the relevance of credit financing for the profit and risk situation of commercial banks only little empirical evidence on the initial credit decision and monitoring process exists due to the lack of appropriate data on bank debt financing. The present paper provides a systematic overview of a data set generated during the Center for Financial Studies research project on "Credit Management" which was designed to fill this empirical void. The data set contains a broad list of variables taken from the credit files of five major German banks. It is a random sample drawn from all customers which have engaged in some form of borrowing from the banks in question between January 1992 and January 1997 and which meet a number of selection criteria. The sampling design and data collection procedure are discussed in detail. Additionally, the project's research agenda is described and some general descriptive statistics of the firms in our sample are provided

Quantum noise, entanglement and chaos in the quantum field theory of mind/brain states

We review the dissipative quantum model of brain and present recent developments related with the r\^ole of entanglement, quantum noise and chaos in the model.Comment: 15 page

Abstract State Machines 1988-1998: Commented ASM Bibliography

An annotated bibliography of papers which deal with or use Abstract State Machines (ASMs), as of January 1998.Comment: Also maintained as a BibTeX file at http://www.eecs.umich.edu/gasm

A model for hypermedia learning environments based on electronic books

Designers of hypermedia learning environments could take advantage of a theoretical scheme which takes into account various kinds of learning activities and solves some of the problems associated with them. In this paper, we present a model which inherits a number of characteristics from hypermedia and electronic books. It can provide designers with the tools for creating hypermedia learning systems, by allowing the elements and functions involved in the definition of a specific application to be formally represented A practical example, CESAR, a hypermedia learning environment for hearing‐impaired children, is presented, and some conclusions derived from the use of the model are also shown

Computational capacity of the universe

Merely by existing, all physical systems register information. And by evolving dynamically in time, they transform and process that information. The laws of physics determine the amount of information that a physical system can register (number of bits) and the number of elementary logic operations that a system can perform (number of ops). The universe is a physical system. This paper quantifies the amount of information that the universe can register and the number of elementary operations that it can have performed over its history. The universe can have performed no more than $10^{120}$ ops on $10^{90}$ bits.Comment: 17 pages, TeX. submitted to Natur

Generating indicative-informative summaries with SumUM

We present and evaluate SumUM, a text summarization system that takes a raw technical text as input and produces an indicative informative summary. The indicative part of the summary identifies the topics of the document, and the informative part elaborates on some of these topics according to the reader's interest. SumUM motivates the topics, describes entities, and defines concepts. It is a first step for exploring the issue of dynamic summarization. This is accomplished through a process of shallow syntactic and semantic analysis, concept identification, and text regeneration. Our method was developed through the study of a corpus of abstracts written by professional abstractors. Relying on human judgment, we have evaluated indicativeness, informativeness, and text acceptability of the automatic summaries. The results thus far indicate good performance when compared with other summarization technologies