Finite-size effects in low-density parity-check codes applied to cryptography

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On the compatibility of benevolence and self-interest:philanthropy and entrepreneurial orientation

This article explores the philanthropy of owner–managers of small- and medium-sized enterprises (SMEs) investigating whether and why more entrepreneurially oriented SMEs are also more likely to engage in philanthropic activities. We find support for a positive link between entrepreneurial orientation (EO) and philanthropy in a representative sample of 270 Lithuanian SMEs controlling for alternative explanations. We highlight that philanthropy is relatively common among SME owner–managers and thus complement existing research which views philanthropy as sequentially following wealth generation. In line with our theorizing, further qualitative findings point to drivers of philanthropy beyond those considered in the dominant strategic-instrumental perspective. Building on social-psychological theories of motivation, we argue and confirm that philanthropy can also be an expression of owner–managers’ altruistic values; these values can be compatible and even mutually reinforcing with entrepreneurship. Our study is set in a transition economy, Lithuania, facilitating the analysis of heterogeneity in attitudes toward philanthropy.

Typical performance of regular low-density parity-check codes over general symmetric channels

Typical performance of low-density parity-check (LDPC) codes over a general binary-input output-symmetric memoryless channel is investigated using methods of statistical mechanics. Relationship between the free energy in statistical-mechanics approach and the mutual information used in the information-theory literature is established within a general framework; Gallager and MacKay-Neal codes are studied as specific examples of LDPC codes. It is shown that basic properties of these codes known for particular channels, including their potential to saturate Shannon's bound, hold for general symmetric channels. The binary-input additive-white-Gaussian-noise channel and the binary-input Laplace channel are considered as specific channel models.

Critical noise levels for low-density parity check decoding

We determine the critical noise level for decoding low-density parity check error-correcting codes based on the magnetization enumerator (M), rather than on the weight enumerator (W) employed in the information theory literature. The interpretation of our method is appealingly simple, and the relation between the different decoding schemes such as typical pairs decoding, MAP, and finite temperature decoding (MPM) becomes clear. In addition, our analysis provides an explanation for the difference in performance between MN and Gallager codes. Our results are more optimistic than those derived using the methods of information theory and are in excellent agreement with recent results from another statistical physics approach.

Interest groups in multiple streams:specifying their involvement in the framework

Although interests inhabit a central place in the multiple streams framework (MSF), interest groups have played only a minor role in theoretical and empirical studies until now. In Kingdon’s original conception, organized interests are a key variable in the politics stream. Revisiting Kingdon’s concept with a particular focus on interest groups and their activities—in different streams and at various levels—in the policy process, we take this argument further. In particular, we argue that specifying groups’ roles in other streams adds value to the explanatory power of the framework. To do this, we look at how interest groups affect problems, policies, and politics. The influence of interest groups within the streams is explained by linking the MSF with literature on interest intermediation. We show that depending on the number of conditions and their activity level, interest groups can be involved in all three streams. We illustrate this in case studies reviewing labor market policies in Germany and chemicals regulation at the European level.

Short-horizon excess returns and exchange rate and interest rate effects

stocks. We examine the effects of foreign exchange (FX) and interest rate changes on the excess returns of U.S. stocks, for short-horizons of 1-40 days. Our new evidence shows a tendency for the volatility of both excess returns and FX rate changes to be negatively related with FX rate and interest rate effects. Both the number of firms with significant FX rate and interest rate effects and the magnitude of their exposures increase with the length of the return horizon. Our finding seems inconsistent with the view that firms hedge effectively at short-return horizons.

Plaintext Recovery in DES-like Cryptosystems Based on S-boxes with Embedded Parity Check

We describe an approach for recovering the plaintext in block ciphers having a design structure similar to the Data Encryption Standard but with improperly constructed S-boxes. The experiments with a backtracking search algorithm performing this kind of attack against modified DES/Triple-DES in ECB mode show that the unknown plaintext can be recovered with a small amount of uncertainty and this algorithm is highly efficient both in time and memory costs for plaintext sources with relatively low entropy. Our investigations demonstrate once again that modifications resulting to S-boxes which still satisfy some design criteria may lead to very weak ciphers. ACM Computing Classification System (1998): E.3, I.2.7, I.2.8.

An empirical examination of emotional and cognitive responses to threat appeals

Advertising and other forms of communications are often used by government bodies, non-government organisations, and other institutions to try to influence the population to either a) reduce some form of harmful behaviour (e.g. smoking, drunk- driving) or b) increase some more healthy behaviour (e.g. eating healthily). It is common for these messages to be predicated on the chances of some negative event occurring if the individual does not either a) stop the harmful behaviour, or b) start / increase the healthy behaviour. This design of communication is referred to by many names in the relevant literature, but for the purposes of this thesis, will be termed a ‘threat appeal’. Despite their widespread use in the public sphere, and concerted academic interest since the 1950s, the effectiveness of threat appeals in delivering their objective remains unclear in many ways. In a detailed, chronological and thematic examination of the literature, two assumptions are uncovered that have either been upheld despite little evidence to support them, or received limited attention at all, in the literature. Specifically, a) that threat appeal characteristics can be conflated with their intended responses, and b) that a threat appeal always and necessarily evokes a fear response in the subject. A detailed examination of these assumptions underpins this thesis. The intention is to take as a point of departure the equivocality of empirical results, and deliver a novel approach with the objective of reducing the confusion that is evident in existing work. More specifically, the present thesis frames cognitive and emotional responses to threat appeals as part of a decision about future behaviour. To further develop theory, a conceptual framework is presented that outlines the role of anticipated and anticipatory emotions, alongside subjective probabilities, elaboration and immediate visceral emotions, resultant from manipulation of the intrinsic message characteristics of a threat appeal (namely, message direction, message frame and graphic image). In doing so, the spectrum of relevant literature is surveyed, and used to develop a theoretical model which serves to integrate key strands of theory into a coherent model. In particular, the emotional and cognitive responses to the threat appeal manipulations are hypothesised to influence behaviour intentions and expectations pertaining to future behaviour. Using data from a randomised experiment with a sample of 681 participants, the conceptual model was tested using analysis of covariance. The results for the conceptual framework were encouraging overall, and also with regard to the individual hypotheses. In particular, empirical results showed clearly that emotional responses to the intrinsic message characteristics are not restricted to fear, and that different responses to threat appeals were clearly attributed to specific intrinsic message characteristics. In addition, the inclusion of anticipated emotions alongside cognitive appraisals in the framework generated interesting results. Specifically, immediate emotions did not influence key response variables related to future behaviour, in support of questioning the assumption of the prominent role of fear in the response process that is so prevalent in existing literature. The findings, theoretical and practical implications, limitations and directions for future research are discussed.

Graphical Approach to Teaching Compound Interest in High School Math Classes

Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2015