A Dual Model of Open Source License Growth

Every open source project needs to decide on an open source license. This decision is of high economic relevance: Just which license is the best one to help the project grow and attract a community? The most common question is: Should the project choose a restrictive (reciprocal) license or a more permissive one? As an important step towards answering this question, this paper analyses actual license choice and correlated project growth from ten years of open source projects. It provides closed analytical models and finds that around 2001 a reversal in license choice occurred from restrictive towards permissive licenses.Comment: 14 pages, 6 figure

Learning Machines Supporting Bankruptcy Prediction

In many economic applications it is desirable to make future predictions about the financial status of a company. The focus of predictions is mainly if a company will default or not. A support vector machine (SVM) is one learning method which uses historical data to establish a classification rule called a score or an SVM. Companies with scores above zero belong to one group and the rest to another group. Estimation of the probability of default (PD) values can be calculated from the scores provided by an SVM. The transformation used in this paper is a combination of weighting ranks and of smoothing the results using the PAV algorithm. The conversion is then monotone. This discussion paper is based on the Creditreform database from 1997 to 2002. The indicator variables were converted to financial ratios; it transpired out that eight of the 25 were useful for the training of the SVM. The results showed that those ratios belong to activity, profitability, liquidity and leverage. Finally, we conclude that SVMs are capable of extracting the necessary information from financial balance sheets and then to predict the future solvency or insolvent of a company. Banks in particular will benefit from these results by allowing them to be more aware of their risk when lending money.Support Vector Machine, Bankruptcy, Default Probabilities Prediction, Profitability

Interference Minimization in Asymmetric Sensor Networks

A fundamental problem in wireless sensor networks is to connect a given set of sensors while minimizing the \emph{receiver interference}. This is modeled as follows: each sensor node corresponds to a point in $\mathbb{R}^d$ and each \emph{transmission range} corresponds to a ball. The receiver interference of a sensor node is defined as the number of transmission ranges it lies in. Our goal is to choose transmission radii that minimize the maximum interference while maintaining a strongly connected asymmetric communication graph. For the two-dimensional case, we show that it is NP-complete to decide whether one can achieve a receiver interference of at most $5$. In the one-dimensional case, we prove that there are optimal solutions with nontrivial structural properties. These properties can be exploited to obtain an exact algorithm that runs in quasi-polynomial time. This generalizes a result by Tan et al. to the asymmetric case.Comment: 15 pages, 5 figure

Crystal Structure of Thermotoga maritima α-Glucosidase AglA Defines a New Clan of NAD+-dependent Glycosidases

Glycoside hydrolase family 4 represents an unusual group of glucosidases with a requirement for NAD(+), divalent metal cations, and reducing conditions. The family is also unique in its inclusion of both alpha- and beta-specific enzymes. The alpha-glucosidase A, AglA, from Thermotoga maritima is a typical glycoside hydrolase family 4 enzyme, requiring NAD(+) and Mn2+ as well as strongly reducing conditions for activity. Here we present the crystal structure of the protein complexed with NAD(+) and maltose, refined at a resolution of 1.9 Angstrom. The NAD(+) is bound to a typical Rossman fold NAD(+)-binding site, and the nicotinamide moiety is localized close to the maltose substrate. Within the active site the conserved Cys-174 and surrounding histidines are positioned to play a role in the hydrolysis reaction. The electron density maps indicate that Cys-174 is oxidized to a sulfinic acid. Most likely, the strongly reducing conditions are necessary to reduce the oxidized cysteine side chain. Notably, the canonical set of catalytic acidic residues common to other glucosidases is not present in the active site. This, combined with a high structural homology to NAD-dependent dehydrogenases, suggests an unusual and possibly unique mechanism of action for a glycoside-hydrolyzing enzyme

Endoreversible Thermodynamics: A Tool for Simulating and Comparing Processes of Discrete Systems

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Endoreversible thermodynamics is concerned with reversible sub-systems that are in irreversible interaction with each other. Consequently, endoreversible thermodynamics represents the analogue for discrete systems to the local equilibrium hypothesis in continuum thermodynamics. Here a real cyclic 2-reservoir process is simulated by different endoreversible model processes. Simulation means that the simulating process has the same net heat exchanges, cycle time, power, entropy production, and efficiency as the original one. By introducing process-independent simulation parameters as constraints for the irreversible interaction, a family of comparative endoreversible processes is generated including the simulation of the original process. This procedure allows the process parameters of the family of comparative processes to be compared to those of the original one. The fraction “power of the real process over the maximal power inbetween the comparative family” is introduced as a parameter describing the process excellence

Finanzierung von Studenten in ausgewählten Ländern

Im internationalen Standortwettbewerb bildet ein hohes Ausbildungsniveau der Bevölkerung einen wichtigen Standortfaktor. Einen bedeutenden Beitrag zur Qualifizierung der Bevölkerung leistet die akademische Ausbildung. Mit der Hochschulausbildung sind Kosten verbunden, welche durch den Betrieb der Universitäten und die Lebenshaltung der Studenten entstehen. Diese Kosten können entweder vom Staat durch direkte Finanzierung der Hochschulen und Stipendien für Studenten getragen werden. Oder aber die Kosten werden durch die Studenten und ihre Eltern selbst finanziert. In der Realität findet sich keines der beiden Finanzierungssysteme in Reinform. Vielmehr werden die Studiengebühren und Lebenshaltungskosten der Studenten in der Regel sowohl durch Beihilfen und Darlehen des Staates als auch durch Eigenmittel der Studenten und ihrer Eltern finanziert. Der Beitrag gibt einen Überblick über Finanzierungskonzepte, staatliche Darlehen und Stipendien sowie Rückzahlungsmodalitäten in verschiedenen Ländern.Studienfinanzierung, Vergleich

El Nou paper de la televisió pública a Europa occidental: reptes i perspectives

Les televisions públiques de tota l'Europa occidental s'enfronten al formidable repte de redefinir el seu paper per l'aparició d'economies de radiodifusió mixta multicanal. El model que els autors proposen es basa en: a) complementar la televisió comercial; b) la qualitat de les prioritats de programació, i c) el caràcter social de la radiodifusió pública, que comporta una important funció cultural, política i social. En preguntar-se si aquest model és viable, els autors conclouen que depèn de com la televisió pública se'n surti a l'hora de competir amb la televisió comercial per a configurar les expectatives de programació dels televidents. Donen raons de per què es pot aconseguir i, d'aquesta manera, servir de model a altres democràcies, alhora que s'adonen que la televisió comercial tota sola cada vegada satisfà menys les necessitats de comunicació d'una societat.Due to the emergence of mixed broadcasting economies in multichannel conditions, public television throughout Western Europe faces a formidable challenge of role redefinition. The authors’ proposed approach to this is based on: (a) a competitive complementarity with commercial television; (b) a qualitative sense of programming priorities; and (c) the social character of public broadcasting which entails major cultural, political, and social functions. Asking whether such a recipe is viable, the authors conclude that it depends on how public television fares in its competition with commercial television to shape viewers’ expectations of programming. They give reasons why this can be waged successfully, thus serving as a model for other democracies, as they increasingly realize that commercial television alone cannot satisfy a society’s communication needs