469 research outputs found
Welfare Effects of Union Bargaining Centralisation in a Two-Sector Economy
No full textThe paper analyses the welfare effects of union bargaining centralisation in a simple general equilibrium model. A two-sector model is developed where the wage rate in the first sector is either set decentralised by a small union at the firm level or centralised by a large union covering all workers. Worker's outside option is employment in the second sector with wages adjusting to clear the market. The paper shows that social welfare depends on (i) whether the union considers the connection between wages in both sectors, (ii) the structure of the union's objective function, and (iii) the elasticities of labour demand. The welfare maximising employment allocation can be obtained under a high degree of centralisation if the union maximises the total wage-bill. Otherwise, if the union is rent maximising, neither centralised nor decentralised wage setting yield the social optimum. A second best optimum can then be obtained under decentralised bargaining.Unions; Bargaining centralisation; Two-sector economy; Social welfare
A Dynamic Model of Union Behaviour. The Role of an Endogenous Outside Option and Bargaining Centralisation
No full textWe analyse the role of bargaining centralisation when both the union's outside option and union membership are endogenous and considered in a dynamic framework. A dynamic two-sector model is developed where the wage rate in the first sector is either set by a monopoly union or is the result of efficient bargaining between union and firm. The union's outside option is employment in the second, competitive sector. We extend the dynamic analysis by modelling the outside option as endogenous and show that dynamic models may also overstate employment distortions in this case if bargaining is conducted on a highly centralised stage. Additionally, we offer reflexions along the optimisation process in different scenarios and a comparative static analysis, thus presenting some new general insights into the topic. --Dynamic wage bargaining,unions,dual labour market,endogenous outside option,endogenous membership
Spillover Effects of Minimum Wages: Theory and Experimental Evidence
No full textWe study the spillover effects of minimum wages in a laboratory experiment. In a bilateral firm-worker bargaining setting, we find that the introduction of a minimum wage exerts upward pressure on wages even if the minimum wage is too low to be a binding restriction. Furthermore, raising the minimum wage to a binding level increases the bargained wage above the new minimum wage level. While the Nash solution cannot explain the existence of spillover effects, the Kalai-Smorodinsky solution yields results that are qualitatively more in line with our experimental findings.minimum wage, bargaining, Kalai-Smorodinsky solution, labor market experiments
Wage and Employment Effects of Non-Binding Minimum Wages
No full textCommon wisdom holds that the introduction of a non-binding minimum wage is irrelevant for actual wages and employment. Empirical and experimental research, however, has shown that the introduction of a minimum wage can raise even those wages that were already above the new minimum wage. In this paper, we analyze how these findings can be explained by theoretical wage bargaining models between unions and firms. While the Nash bargaining solution is unaffected by minimum wages below initially bargained wages, we show that such minimum wages can drive up wages – and be harmful to employment – when bargaining follows the Kalai-Smorodinsky solution.minimum wage, bargaining, Kalai-Smorodinsky solution
Semiotics, Human-Computer Interaction and End-User Development:Special Issue
No full textSemiotics has been an undercurrent in the discussions on HCI and Programming Languages since the early days of Computer Science. This does not come as surprise: reducing computation to algorithmic symbol manipulation starting with Leibniz can be described as the pre-history of computer science (Krämer 1988; Krämer 1993). The Turing Machine, still one of the basic theoretical models for computation, expresses computation as formal symbol manipulation (Turing 1936). Though rather caused by serendipitous collocation, the re-interpretation of Chomsky”s generative grammars, that were meant to describe human language, has been used as a theoretical base for programming languages and compiler construction (Chomsky 1956; Chomsky & Schützenberger 1963; Knuth 1963). Aspects of programming language were early on denoted using semiotic terms: syntax stands for the rules on how to formulate a computer program, semantics refers to studying the computation described by a program. Also the relationship between natural language and programming language has been the subject of reflection for programming language researchers time and again. Heinz Zemanek”s publications on Wittgenstein and programming languages (1966, 1993) can here stand as an example.
When it comes to Human Computer Interaction (HCI), the discussion around computing and Semiotics is more diverse. The semiotic and linguistic theories that are brought into play are as heterogeneous as the computer science subdisciplines. An editorial cannot provide a systematic literature review. Nonetheless we would like to provide the interested reader with a number of pointers that could be a starting point for further reading. We apologize to readers who do not find their favorite articles on Semiotics, HCI and End User Development, since our selection is due to limited space.
Winograd and Flores” book “Understanding Computers and Cognition” in 1986 triggered a controversial discussion of speech act theory and software design that went far beyond the US community (see e.g. (Ljungberg & Holm 1995)). The discussion on the politics of (speech act) categories (Suchman 1993) sharpened sensitivity to the descriptive and analytical usage of theoretical concepts and their prescriptive usage when informing software design.
In Scandinavia, linguists and computer scientists met to discuss ordinary language in relation to computers (Bøgh Andersen and Halskov Madsen 1988; Bøgh Andersen and Bratteteig 1989). These discussions resulted in a number of monographs and edited volumes exploring the application of semiotic and linguistic theories in the context of information systems development (Bøgh Andersen 1990; Bøgh Andersen et al. 1993; Holmqvist et al. 1996). The edited volumes also provided a base to connect researchers from The Netherlands (Stamper 1996) and the US (Klein & Truex 1996) exploring the connection of linguistics and information systems in a similar way.
In Germany, Frieder Nake already in the 70 referred to aesthetic theory connecting semiotics and human computer interaction (Nake 1994). In the article “Human–computer interaction viewed as pseudo-communication” Nake and Grabowski (2001) proposed understanding informatics as technical semiotics and suggested a conceptualization of Human Computer Interaction as an interface between technical symbol manipulation and human sense making. Dittrich (1997; 1998) elaborated the pragmatic dimension of the interaction between ordinary and formal language, when developing and using software referring to Wittgenstein”s Philosophical Investigations and Humboldt”s language philosophy. Christiane Floyd, who, since the 80, had researched participatory and evolutionary software engineering, conceptualized software engineering as being concerned with “Developing and Embedding Autooperational Forms” (1997; 2002), where the concept of autooperational form describes the formal symbol manipulation defined by the program.
Besides Peter Bøgh Andersen, Mihai Nadin (Nadin 2011) and Clarisse S De Souza (DeSouza 2005) contributed continuously to the discussion on Semiotics and Computers. De Souza started to develop her semiotic engineering approach in the 90. Semiotic engineering views the whole software program as a message sent from the developer to the user of a software system on how to relate to what the software is about and how to interact through the software system (DeSouza 2005). De Souza emphasises the openness of the interpretation that the software system as a semiotic artefact triggers in ongoing cultural discourse (De Souza 2013).
Though the idea of EUD can be traced back to the early days of computer science (Mehandjiev and Bottaci 1995), the systematic research of EUD only dates back to two parallel projects, one is the European Network of Excellence resulting in (Lieberman et al. 2016) and the other is a US NSF project on End User Software Engineering, whose members joined forces to author (Ko 2011). The research on End User Development (EUD) (Lieberman et al. 2016) and End User Software Engineering (EUSE) (Ko 2011) refers both to programming language techniques and principles and to Human Computer Interaction: users are provided with interfaces that allow them to change the software they are using. These interfaces can be described as (domain specific) programming languages. EUSE research encompasses activities that lead to the creation, modification or extension of software artifacts for personal use, only by primarily addressing quality aspects that are “individual EUD activities” (Cabitza et al., 2014). EUD covers methods, situations and socio-technical environments which enable conditions that put owners of problems in charge, by defining the technical and social conditions for broad participation in design activities [Fischer, 2013]. In a wider sense EUD does not focus only on software (as do EUP and EUSE), but it “encompasses methods, techniques, methodologies, situations, and socio-technical environments that allow end users to act as professionals in those domains in which they are not professionals” (Fischer et al., in print). A more recent and updated view on EUD is reported in the new book on End-User Development (Paternò and Wulf, in print).
Piero Mussio and his group in Brescia and Milano were to our knowledge the first to explicitly relate End User Development and a semiotic take on HCI (Marcante & Mussio 2016, Valtolina et al. 2012). In particular, they presented a computer semiotic approach to describe the digital communication process and the new characteristics that have evolved from the creation and the maintenance of e-documents and the interaction with them. In this view the HCI process is seen as exchanges of messages – physical representations of e-documents - and contrasts e-document features to those of oral and written ones.
Clearly EUD takes advantage of the semiotic character of software: the functionality and appearance of a program is defined by a textual representation, which in turn can be offered, in an adequate form, to the user for manipulation. Referring to De Souza”s (2005) semiotic engineering, EUD allows the user to comment the message of the software developers not only in the same medium, by changing the text, but also by commenting on the message in a different medium, e.g. in oral feedback or by using the system in an innovative manner. In other words, taking the step to become an End User Developer, the user becomes an author, who not only communicates through the system, but changes the program or medium and enters the design discourse on an equal footing. Here EUD provides a specific challenge for the interface design: not only does the interaction with the system to achieve a goal need to be designed, but also the formulation of a program needs to be supported. Can the semiotic take on design of a computer system inform also this design?
By editing a special issue connecting semiotics and End User Development, we have invited authors to explore this area and further develop both the understanding of software systems as semiotic artefacts and the design of EUD systems. As the description of the accepted papers below indicates, the contributions provide not only a documentation of existing research, but also provide important innovative stepping stones.
Initially we received 20 submissions from authors from 11 different countries all over the world (Italy, Bangladesh, The Netherlands, Brazil, the Russian Federation, Belgium, Australia, Denmark, the US, the UK and Finland). All the papers underwent a rigid review process. After two rounds of reviews, seven papers were accepted for publication in this special issue. Accepted papers come from 3 different countries (Italy 3, Brazil 3 and Belgium 1).
The special issue consists of seven excellent papers.
Rita Barricelli and Stefano Valtolina develop, implement and evaluate “A Visual Language and Interactive System for End-User Development of Internet of Things Ecosystems” that supports trainers and athletes to make use of wearable interactive devices that allow the formulation of complex temporal rules to support lifestyle change. The language is designed both to relate to the domain of training and to steer the underpinning network of interacting sensors and activators. The evaluation shows that semiotic design leads to understandable and useful interfaces for both End User Developers and users.
The paper “Self-expression and discourse continuity in a multilevel EUD environment: The case of Moodle” by Luciana da Silveira Espindola and Milene Selbach Silveira deals with Virtual Learning Environments as a platform, allowing multiple customizations through multiple layers of (distinct) users. In particular, they focus on verifying the discourse continuity after multiple customizations by many hands, looking at how it impacts on the teacher”s self-expression and how this expression is perceived by the students, while interacting with the product of their teacher”s effort.
The paper “An analysis of deictic signs in computer interfaces: contributions to the Semiotic Inspection Method” by Aron Daniel Lopes, Vinicius Carvalho Pereira and Cristiano Maciel analyses the concept of deictic signs in digital games. Deictic signs in this case are here signs that establish an indexical relation with the objects they refer to, placing them in terms of space, time and person with a reference to the communication through the interface. They are considered as a component of the conceptual framework of Linguistics and Semiotics that can be added to the Semiotic Inspection Method (SIM) when the method is adapted to approach digital games better.
The paper “The semiotics of configurations for the immanent design of interactive computational systems”, by Federico Cabitza and Alvise Mattozzi, proposes a novel semiotic approach to the design of interactive systems and computational systems, called Semiotics of Configurations (SoC). The approach has inspired a platform for user-driven development and the use of electronic documents and forms in cooperative and organizational domains, such as hospital work.
The article “Signifying Software Engineering to Computational Thinking Learners with AgentSheets and PoliFacets” by Ingrid Monteiro, Luciana Salgado, Marcelle Mota, Andreia Liborio Sampaio and Clarisse de Souza evaluates an approach to computational thinking acquisition (CTA) that is based on an understanding of programming as communication when it supports the core notions of (End User) Software Engineering: requirements, design, reuse testing and debugging. The result shows that a semiotic approach to End User Programming is compatible with the teaching and implementation of software engineering concepts, though it requires a knowledgeable teacher who can draw the connection between the features of the End User Programming environment and the software engineering concepts.
Daniela Fogli in her article “Weaving Semiotic Engineering in Meta-Design: A Case Study Analysis” takes the application of a semantic understanding of programs as communication between software engineers and users a step further. She uses it to explore the relationship between software engineers responsible for the design of an EUD environment (meta design) and the domain expert using that environment to implement concrete applications for other users. The message in meta-design seen as communication is therefore a message about what kind of messages can be designed to be communicated to the (other) users by the end user developer, and how the dialogue between users and end user developers is meant to evolve
Parents studying medicine : the dichotomy of studying with a family
No full textIntroduction: In this article the personal study and life situation of parents who are also medical students at the Medical School of the Goethe University Frankfurt am Main is discussed. There is a special focus on the topics "studying with children" and "family-friendly university", which have been present in discussions about university development and in the daily life of academics, especially during the last decade. The workgroup "Individual Student Services" at the medical faculty at the Goethe University tries to meet the necessities of the individual study courses and to support the study success with a new counselling and student service concept.
Methods: The experience of parents studying medicine was recorded in semi-structured interviews (Date: April 2010), which were held as part of the sponsored pilot project on part-time medical studies ("Pilot Project Part-time Medical Studies"). Additionally, study results from the Medical School of the Goethe University Frankfurt am Main were integrated as well as a literature analysis.
Results: It was found that the teaching demands and support services, which have been suggested and needed for years now, have been partially implemented and are without sufficient support at the faculty level to date. Thus the current situation of medical students with children is still difficult and seems a big challenge for everyone involved.
Solution: As part of the "Individual Student Services" a new pilot project on part-time medical studies was established in November 2009. Only the use of new, unconventional and innovative ideas allows universities to adequately support the changing and heterogeneous student population and support them to successfully completing their medical studies
Age-related and species-specific methylation changes in the protein-coding marmoset sperm epigenome
No full textThe sperm epigenome is thought to affect the developmental programming of the resulting embryo, influencing health and disease in later life. Age-related methylation changes in the sperm of old fathers may mediate the increased risks for reproductive and offspring medical problems. The impact of paternal age on sperm methylation has been extensively studied in humans and, to a lesser extent, in rodents and cattle. Here, we performed a comparative analysis of paternal age effects on protein-coding genes in the human and marmoset sperm methylomes. The marmoset has gained growing importance as a non-human primate model of aging and age-related diseases. Using reduced representation bisulfite sequencing, we identified age-related differentially methylated transcription start site (ageTSS) regions in 204 marmoset and 27 human genes. The direction of methylation changes was the opposite, increasing with age in marmosets and decreasing in humans. None of the identified ageTSS was differentially methylated in both species. Although the average methylation levels of all TSS regions were highly correlated between marmosets and humans, with the majority of TSS being hypomethylated in sperm, more than 300 protein-coding genes were endowed with species-specifically (hypo)methylated TSS. Several genes of the glycosphingolipid (GSL) biosynthesis pathway, which plays a role in embryonic stem cell differentiation and regulation of development, were hypomethylated (<5%) in human and fully methylated (>95%) in marmoset sperm. The expression levels and patterns of defined sets of GSL genes differed considerably between human and marmoset pre-implantation embryo stages and blastocyst tissues, respectively
Pokročilé in situ metody pro studium deformačních mechanismů hořčíkových slitin v specifických mikrostrukturálních stavech
No full textTitle: Advanced In situ Methods for Studying Deformation Mechanisms of Mag- nesium Alloys under Specic Microstructural Conditions Author: RNDr. Jan Dittrich Department: Department of Physics of Materials Supervisor: doc. RNDr. Peter Minárik, PhD., Department of Physics of Materials Abstract: A set of hcp and hcp + bcc alloys from the Mg-Li-Y ternary system with varying Li and Y alloying content, intended for the fabrication of temporary orthopedic implants, was investigated. The focus was placed on understanding the mechanical properties based on a detailed microstructural and textural characte- rization of the extruded and subsequently ECAP-processed states of the alloys. Furthermore, the application-relevant corrosion and cytocompatibility proper- ties were investigated as well. Advanced experimental techniques, including slip trace analysis, acoustic emission, and digital image correlation, were employed to explain the observed deformation behavior. The corrosion performance in a si- mulated physiological environment was evaluated and discussed based on the microstructural properties, and the cytocompatibility of the studied materials was successfully veried. Keywords: magnesium alloys, deformation mechanisms, ductility, corrosion, cytocompatibilityNázev práce: Pokročilé In situ metody pro studium deformačních mechanism· hořčíkových slitin v specických mikrostrukturálních stavech Autor: RNDr. Jan Dittrich Katedra: Katedra fyziky materiál· Vedoucí diplomové práce: doc. RNDr. Peter Minárik, PhD., Katedra fyziky ma- teriál· Abstrakt: Tématem výzkumu je sada hcp a hcp + bcc slitin z ternárního Mg- Li-Y systému s r·znými množstvími příměsí Li a Y, určená pro aplikaci coby přechodné ortopedické implantáty. Práce se věnuje zejména studiu mechanických vlastností, přičemž vychází z detailní mikrostrukturní a texturní analýzy těchto slitin po extruzi a následném zpracování metodou ECAP. Dále byly zkoumány i korozní vlastnosti a cytokompatibilita těchto materiál·, představující d·ležité aspekty pro zamýšlenou aplikaci. K objasnění deformačního chování byly využity pokročilé metody, včetně analýzy skluzových pás·, akustické emise či digitální korelace obrazu. Korozní odolnost byla testována simulovaném fyziologickém pro- středí a diskutována v kontextu popsané mikrostuktury. V neposladní řadě byla úspěsně prokázána i cytokompatibilita zkoumaných materiál·. Klíčová slova: hořčíkové slitiny, deformační mechanismy, tažnost, koroze, cyto- kompatibilitaKatedra fyziky materiálůDepartment of Physics of MaterialsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Studium deformačních mechanismů v hořčíkové slitině s texturou pomocí pokročilých in-situ metod
No full textNázev práce: Studium deformačních mechanism· v hořčíkové slitině s texturou pomocí pokročilých in-situ metod Autor: Bc. Jan Dittrich Katedra: Katedra fyziky materiál· Vedoucí diplomové práce: RNDr. Peter Minárik, PhD., Katedra fyziky materiál· Abstrakt: Cílem předkládané práce je zkoumání vzájemného vztahu textury a ak- tivace jednotlivých deformačních mechanism· během deformace válcované hořčí- kové slitiny AZ31. K dosažení uvedeného cíle byla využita kombinace pokročilých in-situ metod, poskytujících vzájemně se doplňující informace o procesech, pro- bíhajících uvnitř materiálu během jeho deformace. Využití kombinace neutronové difrakce a akustické emise umožnilo studovat jak náhlé, tak pozvolné procesy, související se změnami mikrostruktury materi- álu v d·sledku jeho deformace. In-situ deformace vzork· uvnitř vakuové komory skenovacího elektronového mikroskopu, doplněná o analýzu difrakce zpětně odra- žených elektron·, umožnila bezprostřednější sledování vývoje mikrostrukturních změn. Pozorování povrchu deformovaných vzork· vysokorychlostní kamerou poté umožnilo přímé a okamžité sledování náhlých proces·, k nimž během deformace docházelo. Výsledky provedených měření potvrdily očekávanou anizotropii mechanických vlastností vzork· r·zných orientací v·či experimentálně zjištěné textuře zkouma- ného...Title: Investigation of deformation mechanisms in textured magnesium alloy by advanced in-situ methods Author: Bc. Jan Dittrich Department: Department of Physics of Materials Supervisor: RNDr. Peter Minárik, PhD., Department of Physics of Materials Abstract: This thesis aims to investigate the correlation between texture and the activation of particular deformation mechanisms during the deformation of a rolled magnesium alloy AZ31. A combination of advanced in-situ techniques, providing complementary information about the processes within the material during its deformation, was employed to achieve this goal. The combination of neutron diraction and acoustic emission measurements allowed to investigate both rapid and continuous processes related to changes of the material microstructure resulting from its deformation. The in-situ loading of the sample inside the chamber of a scanning electron microscope, coupled with the electron backscatter diraction analysis, provided more direct observations of the microstructural evolution. Furthermore, the high-speed camera imaging of the deformed sample surface enabled a direct, real-time view of the occurring rapid processes. The results of the experiments conrmed the anisotropy of the mechanical behaviour of samples oriented diversely with respect to the...Department of Physics of MaterialsKatedra fyziky materiálůMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
Advanced In situ Methods for Studying Deformation Mechanisms of Magnesium Alloys under Specific Microstructural Conditions
No full textTitle: Advanced In situ Methods for Studying Deformation Mechanisms of Mag- nesium Alloys under Specic Microstructural Conditions Author: RNDr. Jan Dittrich Department: Department of Physics of Materials Supervisor: doc. RNDr. Peter Minárik, PhD., Department of Physics of Materials Abstract: A set of hcp and hcp + bcc alloys from the Mg-Li-Y ternary system with varying Li and Y alloying content, intended for the fabrication of temporary orthopedic implants, was investigated. The focus was placed on understanding the mechanical properties based on a detailed microstructural and textural characte- rization of the extruded and subsequently ECAP-processed states of the alloys. Furthermore, the application-relevant corrosion and cytocompatibility proper- ties were investigated as well. Advanced experimental techniques, including slip trace analysis, acoustic emission, and digital image correlation, were employed to explain the observed deformation behavior. The corrosion performance in a si- mulated physiological environment was evaluated and discussed based on the microstructural properties, and the cytocompatibility of the studied materials was successfully veried. Keywords: magnesium alloys, deformation mechanisms, ductility, corrosion, cytocompatibilit
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