Competition and Innovation in a Technology Setting Software Duopoly

Recently the software industry has experienced fundamental changes in market structure through the entry of open source competitors, e.g. Linux's entry into the operating systems market. In a simple model we examine the effects of such a change in market structure from monopoly to duopoly under the assumption that software producers compete in technology rather than price or quantities. The model includes the presence of technological progress and menu costs of adjusting existing software, i.e. innovation. It is found that: (i) moving from monopoly to duopoly does increase the technology level set by firms in the software industry; (ii) a duopoly adjusts more readily to global technological progress than a monopolist. Furthermore, results are presented comparing open source versus for-profit firms in terms of technology levels and innovation.open source software, strategic interaction, duopoly, menu costs

Bug-Fixing and Code-Writing: The Private Provision of Open Source Software

Open source software (OSS) is a public good. A self-interested individual would consider providing such software, if the benefits he gained from having it justified the cost of programming. Nevertheless each agent is tempted to free ride and wait for others to develop the software instead. This problem is modelled as a war of attrition with complete information, job signaling, repeated contribution to the public good and uncertainty in programming. The resulting game does not feature any delay: software will be provided swiftly, by young, low-cost individuals who gain considerably by signaling their programming skills; the startup (and collapse) of an OSS project displays bandwagon dynamics.open source software, war of attrition, public goods

Orale Kontrazeptiva und Depression

Zusammenfassung: Orale hormonale Kontrazeptiva werden weltweit von Millionen Frauen zur Schwangerschaftsverhütung eingesetzt. Die Effizienz, die gesundheitlichen Risiken, die Kontraindikationen und der mögliche gesundheitliche Nutzen sind aus vielen Untersuchungen bekannt. Kontrovers diskutiert wird aber bis heute, ob orale hormonale Kontrazeptiva negative Nebenwirkungen im Bereich der psychischen oder affektiven Befindlichkeit haben und insbesondere ob depressive Symptome bei der Einnahme neu auftreten. Auf der biologischen Ebene scheinen sich die in kombinierten Präparaten enthaltenen Östrogene und Gestagene zu antagonisieren: Östrogene wirken eher serotonerg und damit antidepressiv, während Gestagene eine eher GABA-ähnliche Wirkung entfalten, die zumindest theoretisch mit einer Stimmungsverschlechterung verbunden sein kann. Aufgrund empirischer Untersuchungen kann man davon ausgehen, dass kombinierte Präparate bei gesunden Frauen keine neu auftretenden depressiven Symptome hervorrufen. Bei Frauen mit prämentstruellem Syndrom (PMS) oder prämenstrueller dysphorischer Störung (PMDS) sind die Effekte komplexer. Frauen mit einer "major depression", die ein Kombinationspräparat einnehmen, haben weniger depressive Symptome als Nichtanwenderinnen und weisen eine geringere Komorbidität auf. In Studien zur Verhütung mit reinen Gestagenpräparaten wurde beobachtet, dass unter Hormoneinnahme depressive Symptome häufiger auftrate

Online Discrimination of Nonlinear Dynamics with Switching Differential Equations

How to recognise whether an observed person walks or runs? We consider a dynamic environment where observations (e.g. the posture of a person) are caused by different dynamic processes (walking or running) which are active one at a time and which may transition from one to another at any time. For this setup, switching dynamic models have been suggested previously, mostly, for linear and nonlinear dynamics in discrete time. Motivated by basic principles of computations in the brain (dynamic, internal models) we suggest a model for switching nonlinear differential equations. The switching process in the model is implemented by a Hopfield network and we use parametric dynamic movement primitives to represent arbitrary rhythmic motions. The model generates observed dynamics by linearly interpolating the primitives weighted by the switching variables and it is constructed such that standard filtering algorithms can be applied. In two experiments with synthetic planar motion and a human motion capture data set we show that inference with the unscented Kalman filter can successfully discriminate several dynamic processes online

On the timing between terrestrial gamma ray flashes, radio atmospherics, and optical lightning emission

On 25 October 2012 the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) and the Tropical Rainfall Measuring Mission (TRMM) satellites passed over a thunderstorm on the coast of Sri Lanka. RHESSI observed a terrestrial gamma ray flash (TGF) originating from this thunderstorm. Optical measurements of the causative lightning stroke were made by the lightning imaging sensor (LIS) on board TRMM. The World Wide Lightning Location Network (WWLLN) detected the very low frequency (VLF) radio emissions from the lightning stroke. The geolocation from WWLLN, which we also assume is the TGF source location, was in the convective core of the cloud. By using new information about both RHESSI and LIS timing accuracy, we find that the peak in the TGF light curve occurs 230 $\mu$s before the WWLLN time. Analysis of the optical signal from LIS shows that within the uncertainties, we cannot conclude which comes first: the gamma emission or the optical emission. We have also applied the new information about the LIS timing on a previously published event by {\O}stgaard et al. (2012). Also for this event we are not able to conclude which signal comes first. More accurate instruments are needed in order to get the exact timing between the TGF and the optical signal

Sexualmedizin für Gynäkologen

Zusammenfassung: Die Sexualität der Frau ist ein Paradigma für das Zusammenwirken biologischer, psychologischer und sozialer Faktoren. Die wichtigsten Störungen sind Mangel an sexuellem Verlangen, Erregungsstörungen, Störungen des Orgasmus und Schmerzen bei sexueller Aktivität. Häufig kommen diese Störungen kombiniert vor. In den letzten Jahren hat sich das Wissen um die neurophysiologischen, neuroendokrinen, vasomotorischen Prozesse bei der sexuellen Reaktion enorm erweitert und zur Entwicklung neuer Medikamente geführt. Gleichzeitig haben sich die psychologischen und soziologischen Erkenntnisse entwickelt und gewandelt. Als oft erste Ansprechpartner müssen sich Gynäkologinnen und Gynäkologen kontinuierlich weiterbilden, gleichzeitig müssen sie ihre kommunikativen Fertigkeiten in diesem sensiblen Bereich schulen. Ärztliches Gespräch, Diagnostik und Therapie folgen dabei dem Modell einer biopsychosozialen Sexualmedizin, die biomedizinischen Fortschritt mit psychosozialen Interventionen verbindet, um Patientinnen bei der Entfaltung ihrer selbstbestimmten und selbstgewählten Sexualität zu helfe

Chronic Toxicity Testing In Mining Influenced Streams of West Virginia

Whole effluent toxicity (WET) tests have become a common tool in the evaluation of effluent for discharge acceptability. In this study, four years of toxicity data from 119 sampling locations were analyzed to determine relationships with ions and conductivity as indicators of toxicity. West Virginia Stream Condition Index (WVSCI) scores were also examined to evaluate correlations between stream scores, conductivity, and IC25 endpoints from toxicity results. Conductivity was not an indicator of toxicity in the range of conductivities tested. Streams dominated by mining effluent sometimes exhibited toxicity to Ceriodaphnia dubia; however, toxicity was not found to be related to ionic concentration in the range tested. Although mortality and reproductive impairment were often demonstrated in the mining effluent dominated streams, there were no relationships established between survival and reproductive endpoints and the ionic concentrations. Benthic macroinvertebrate communities in the streams sampled indicated some level of impairment. Only a weak relationship was demonstrated between habitat assessment scores and WVSCI scores. No apparent relationship between conductivity and WVSCI was observed

Intrinsic motivation in open source software development

This papers sheds light on the puzzling evidence that even though open source software (OSS) is a public good, it is developed for free by highly qualified, young and motivated individuals, and evolves at a rapid pace. We show that once OSS development is understood as the private provision of a public good, these features emerge quite naturally. We adapt a dynamic private-provision-of-public-goods model to reflect key aspects of the OSS phenomenon. In particular, instead of relying on extrinsic motives for programmers (e.g. signaling) the present model is driven by intrinsic motives of OSS programmers, such as user-programmers, play value or homo ludens payoff, and gift culture benefits. Such intrinsic motives feature extensively in the wider OSS literature and contribute new insights to the economic analysis. --open source software,public goods,homo ludens,war of attrition