Social networks are everywhere, from face-to-face activities to online social networks such as Flickr, YouTube and Facebook. In social networks, ties (relationships) are connections between people. The change of social relationships over time consequently leads to the evolution of the social network structure. At the same time, ties serve as carriers to transfer pieces of information from one person to another. Studying social ties is critical to understanding the fundamental processes behind the network. Although many studies on social networks have been carried out over the last many decades, most of the work either used small in-lab datasets, or focused on directly connected static relations while ignoring indirect relations and the dynamic nature of real networks. Today, because of the emergence of online social networks, more and more large longitudinal social datasets are becoming available. The available real social datasets are fundamental to understanding evolution processes of networks in more depth. In this thesis, we study the role of social ties in dynamic networks using datasets from various domains of online social networks. Networks, especially social networks often exhibit dual dynamic nature: the structure of the graph changes (by node and edge insertion and removal), and information flows in the network. Our work focuses on both aspects of network dynamics. The purpose of this work is to better understand the role of social ties in network evolution and changes over time, and to determine what social factors help shape individuals’ choices in negative behavior. We first developed a metric that measures the strength of indirectly connected ties. We validated the accuracy of the measurement of indirect tie metric with real-world social datasets from four domains. Another important aspect of my research is the study of edge creation and forecast future graph structure in time evolving networks. We aim to develop algorithms that explain the edge formation properties and process which govern the network evolution. We also designed algorithms in the information propagation process to identify next spreaders several steps ahead, and use them to predict diffusion paths. Next, because different social ties or social ties in different contexts have different influence between people, we looked at the influence of social ties in behavior contagion, particularly in a negative behavior cheating. Our recent work included the study of social factors that motivate or limit the contagion of cheating in a large real-world online social network. We tested several factors drawn from sociology and psychology explaining cheating behavior but have remained untested outside of controlled laboratory experiments or only with small, survey based studies. In addition, this work analyzed online social networks with large datasets that certain inherent influences or patterns only emerge or become visible when dealing with massive data. We analyzed the world’s largest online gaming community, Steam Community, collected data with 3, 148, 289 users and 44, 725, 277 edges. We also made interesting observations of cheating influence that were not observed in previous in-lab experiments. Besides providing empirically based understanding of social ties and their influence in evolving networks at large scales, our work has high practical importance for using social influence to maintain a fair online community environment, and build systems to detect, prevent, and mitigate undesirable influence.

Resumé The thesis elaborates on the indirect purchaser's standing in disputes for damages caused by a breach of competition law. Its main purpose is to describe and, consecutively, compare the American and European approach to private enforcement of competition law or, more specifically, selected aspects of regulation relating to indirect purchasers. It should be noted that while the roots of the American model of private enforcement date back to the 19th and 20th century, Europe started to pay increased attention to this topic in the 21st century. This fact obviously raises the question of whether and to what extent was the EU inspired by the American model in forming a European approach to private competition law enforcement. For years, this issue has not been regulated on the European level at all. Nevertheless, this changed with the adoption of a landmark Directive 2014/104/EU which shed new light on European conception of private enforcement of competition law. The thesis is divided into three chapters. The first chapter introduces the subject and aims to put the topic at hand into broader context. The private pillar of competition law enforcement, its advantages and disadvantages as well as its relation to the public pillar are described on a few pages. Subsequently, the history and current state of...

Abstract The aims of this study were to explore different aspects of dental fear and their determinants among children at different ages. The study samples comprised 378 children from the Veneto region of Italy aged 3–13 years and 1474 children from Jyväskylä and Kuopio, Finland, aged 3, 6, 9, 12 and 15 years. In the Italian study, the child’s age, first dental visit, number of subsequent visits and dental fear, and the parent’s dental fear were asked in a questionnaire. In the Finnish study, a questionnaire was used that contained 11 dental fear-related questions and family member’s dental fear and questions on oral health habits and family characteristics. Dental status was determined clinically and information on treatment procedures from three preceding years was collected from patient records. A total of 21 to 36% of Finnish children were quite or very afraid of something in dental treatment. The prevalence of dental fear among Finnish children was not lower among older children but rather fluctuated among different ages. The characteristics of dental fear differed among children at different ages. Among Finnish children, four aspects of dental fear were revealed from the questionnaire, i.e. ‘Treatment of dental decay’, ‘Attending dentist’, ‘Peak value for dental fear’ and ‘Fear of dental treatment in general’. Correlations between the four abovementioned aspects, the differences between age groups separately for the above mentioned aspects, and the determinants of dental fear were studied. At younger ages, the dental fear was abstract, commonly related to attending dentist. At older ages, dental fear was often related to invasive treatment, such as fear of local anaesthesia and drilling. Fear of pain which was common among all age groups. Among Italian children, the first dental experiences were strong determinants of dental fear. Among Finnish children, dental fear among other members of the family was more often found among children with dental fear than among non-fearful children. 15-year-old girls were more likely to be afraid than boys of the same age but gender differences were not found at younger ages. The results indicated that dental fear is not solely based on direct conditioning but rather consists of child, family and environment related determinants. / Tiivistelmä Tutkimuksen tarkoituksena oli selvittää lasten hammashoitopelon piirteitä ja niihin liittyviä seikkoja eri-ikäisillä lapsilla. Tutkimuksessa käytettiin havaintoaineistoa, joka koostui 378:sta 3–13-vuotiaasta italialaisesta lapsesta Veneton maakunnan alueelta sekä 1474:stä 3-, 6-, 9-, 12- ja 15-vuotiaasta lapsesta Jyväskylästä ja Kuopiosta. Tutkimuksessa italialaisilla lapsilla vanhempi täytti kyselylomakkeen, joka sisälsi kysymyksiä lapsen iästä, hammashoitopelosta, ensimmäisestä hammashoitokäynnistä ja seuraavien hoitokäyntien lukumäärästä sekä vanhemman omasta hammashoitopelosta. Suomalaisilla lapsilla tutkimustiedot kerättiin kyselylomakkeella, joka sisälsi 11 kysymystä lapsen hammashoitopelosta ja kysymyksiä lapsen suun terveystottumuksista sekä perheeseen liittyvistä seikoista, kuten perheenjäsenten hammashoitopelosta. Hampaiden senhetkinen kliininen tila sekä kolmen tarkastusta edeltävän vuoden hoitokäynnit ja tuolloin tehdyt toimenpiteet otettiin mukaan tutkimukseen. Suomalaisista lapsista 21–36 % pelkäsi jonkin verran tai paljon jotain asiaa hammashoidossa. Suomalaisten lasten hammashoitopelko ei ollut alempi nuoremmilla lapsilla vaan vaihteli ikäryhmien välillä. Myös hammashoitopelon luonne vaihteli ikäluokittain. Suomalaisesta kyselystä löydettiin neljä pelon osa-aluetta: paikkaushoitoon liittyvä pelko, hammaslääkärissä käymiseen liittyvä pelko, yleinen hammashoitopelko sekä voimakkaimmaksi koettu hammashoitoon liittyvä yksittäinen pelko. Tutkimuksessa tutkittiin pelon osa-alueiden välisiä korrelaatioita ikäryhmittäin, erikseen yksittäisen pelon osa-alueen vaihtelua ikäryhmien välillä sekä hammashoitopelon liittyviä seikkoja ikäryhmittäin. Nuoremmilla lapsilla hammashoitopelko oli useammin abstraktia, yleensä hammashoidossa käymiseen liittyvää pelkoa. Vanhemmilla lapsilla hammashoitopelko oli usein hammashoitotoimenpiteisiin liittyvää pelkoa, esimerkiksi puudutuksen ja porauksen pelkoa. Kivun pelko oli yleistä kaikissa ikäryhmissä. Ensimmäiset hammashoitokokemukset olivat voimakkaita hammashoitopelon selittäjiä italialaisilla lapsilla. Suomalaisten lasten hammashoitopelko oli vahvasti yhteydessä muiden perheenjäsenten hammashoitopelkoon. 15-vuotiaat tytöt pelkäsivät hammashoitoa enemmän kuin pojat, mutta sukupuolten välisiä eroja ei havaittu nuoremmissa ikäryhmissä. Tutkimus osoittaa, että lasten hammashoitopelko ei ole ainoastaan seurausta suorasta ehdollistumisesta hammashoitokokemusten kautta vaan siihen vaikuttavat enemmänkin lapseen, perheeseen ja ympäristöön liittyvät seikat.

Introduction: Weight loss programs are based on inducing a negative energy balance by decreasing energy intake while increasing energy expenditure. Energy needs of obese patients are difficult to determine. The value of resting energy expenditure, as the largest component of the energy needs, is usually calculated to asses an adequate energy intake for obese patient. In clinical practice, predictive equations are most commonly used for this purpose, because of their simplicity, although many clinical studies have shown that in obese individuals they may generate errors large enough to impact the outcome of treatment. It leads to the prescription of an inadequate diet that does not meet the criterion of long-term sustainability. Objective: The aim of the thesis is to compare the values of resting energy expenditure (REE) measured by indirect calorimetry with values calculated with Harris-Benedict predictive equation in a selected group of obese individuals. Methods: The sample includes 38 subjects, 28 women and 10 men, patients of the General University Hospital in Prague. The average age is 48 ± 11,71 years, the mean BMI is 42,88 ± 9,09 kg/m2 . For each subject, resting energy expenditure was measured by indirect calorimetry and calculated by the Harris-Benedict predictive equation. Indirect...

This dissertation reports on an investigation of transition-to-proof students' understanding of proof by contradiction. A plethora of research on the construction aspect of proof by contradiction is available and suggests that the method is one of the most difficult for students to construct and comprehend. However, there is little research on the students' comprehension of proofs and, in particular, proofs by contradiction. This study aims to fill this gap in the literature. Applying the cognitive lens of Action-Process-Object-Schema (APOS) Theory to proof by contradiction, this study proposes a preliminary genetic decomposition for how a student might construct the concept `proof by contradiction' and a series of five teaching interventions based on this preliminary genetic decomposition. Data was analyzed in two ways: (1) group analysis of the first two teaching interventions to consider students' initial conceptions of the proof method and (2) case study analysis of two individuals to consider how students' understanding developed over time. The genetic decomposition and teaching interventions were then revised based on the results of the data analysis. This study concludes with implications for teaching the concept of proof by contradiction and suggestions for further research on the topic.

The past decade has seen a rise in research on social, relational and indirect aggression, with a burgeoning focus only recently on the psychosocial consequences of being a target of such behaviours. It is widely understood that experiencing social aggression can trigger internal distress for children and adolescents, but far less is known about the nature and extent of longer-term psychosocial consequences. In this qualitative study, I aim to begin filling this gap by exploring how young women make meaning from experiences of social aggression in adolescence, with a particular focus on how they understand the impact of these experiences on their sense of self and relation to others in adulthood. Seven women between the ages of 25 and 32 were interviewed using a modified collaborative narrative method (Arvay, 2003). Interviews were transcribed and interpreted in narrative form to preserve the unique voice and experience of each participant. Five themes emerged through a process of categorical-content analysis as described by Lieblich, Tuval-Mashiach & Zilber (1998). Themes address participants' meaning-making following experiences of social aggression in terms of the (1) struggle to understand, (2) loss of trust in relationship, (3) changes in sense of self, (4) psychosocial responses, and (5) process of reframing of the experience in adulthood. The themes are discussed within the context of relevant qualitative and quantitative literature on the psychosocial consequence of social, relational and indirect aggression in adolescence and adulthood. Implications for school and community counselling practice and suggestions for future research are examined. / Education, Faculty of / Educational and Counselling Psychology, and Special Education (ECPS), Department of / Graduate

Herbivory can have many effects on plant fitness, including altering plant-pollinator interactions and sexual reproduction in angiosperms. Pollinator-mediated interactions may be impacted when herbivores alter plant traits, such as floral display size, that can influence pollinator visitation rates, and, ultimately, the reproductive component of plant fitness. Here I describe an investigation into the indirect effects of feeding by beetles released as a biological control agent, Galerucella calmariensis and G. pusilla, on plant-pollinator interactions and reproductive output in the invasive plant Lythrum salicaria L. (purple loosestrife). During the summer of 2011, three treatments (low, ambient and mechanical herbivory) were applied to 105 plants during the pre-flowering period of growth. At the onset of flowering, a series of pollinator observations were conducted over the course of approximately 1.5 weeks. Several aspects of floral display were affected by the herbivory treatments, including increased inflorescence and flower production in the ambient and mechanical herbivory treatments, relative to the low herbivory treatment. Treatment type did not have a significant effect on the number of pollinator foraging bouts, but had marginally significant effects on the number of flowers probed per pollinator foraging bout and per 30-minutes. Moreover, treatment had a significant effect on the number of switches among the inflorescences on a single plant. I discuss the possibility that the differences in pollinator visitation were mediated by differences in the architecture and the size of floral display. There were no detectable differences in fruit or seed production (i.e., female fitness) among treatments. However, as I discuss, differences in pollinator visitation may affect other unmeasured aspects of fitness, such as the level of inbreeding or the number of seeds sired through male function.

Innovation is a critical factor of the economical development as it is the key source of a competitive advantage and brings an addend value of a concerete company (Zhang, 2O13); Technological innovation could be defined as an endogenous factor responding to economic challenges (McKenzie, 2OO8). Research and development provides innovations, whereas the production of research and development brings externalities. Externalities reduce the private return on investment as such, therefore research and development is an object of public support. Public support can be provided ether by direct or indirect form that includes primarily tax incentives. Small and medium-size enterprises play a key role in the innovation process, however they dispose limited resources for investments to research and development and also for administrative activities connected to tax incentive applications. Thus small and medium-size enterprises are more sensitive to associated administrative tasks. The objective of the thesis was set as follows: to contribute to the existing knowledge in the application of tax incentives and desing an appropriate tool for managerial support of tax incentives reporting in small and medium-size enterprises. This objective has been divided into the following sub-objectives: (1) identify issues related to the application of tax incentives for research and development in terms of small and medium-size enterprises and to compare them with reference research, carried out by Chittenden & Derregia (2O1O); (2) design a system to improve reporting of tax incentives in small and medium-size enterprises. A reference framework was provided to address the objective, the key findings are as follows: precise recognition of research and development activities and associated costs are crucial for an effective implementation of tax incentives (Billings et al., 2OO1); cost allocation in research and development activities is rather a complicated issue (Švejda et al., 2OO7, Godfrey & Hamilton, 2OO5), therefore a comprehensive reporting system shall be provided (Chittenden & Derregia, 2O1O) and these reporting systems should include accounting elements Bhiman (2OO6) and enable project division into phases (Jorgensen 2O1O). In accordance with the recommendation of Chittenden & Derregia (2O1O), Bourgeois and Eisenhardt (1988), Koners and Goffin (2OO7), Workman (1993) Singleton and Straits (2OO5), Morandi (2O11), Yin (2OO3) qualitative research based on structured questionnaires was chosen for exploring the first objective and case study for the second objective. The key findings of qualitative research based on structured questionnaires are: only top management and accountants were involved in the administration of tax incetives. Middle management and researchers were omitted, wherease in reporting of grant projects (realized with the direct support), they were fully involved. The case study research approved that a formalized system of management and reporting of research and development activities supports identification of a research project. Representative of a case company confirm that the formalized system of management and reporting supports decision making process and innovation performance, that corresponds to Bossink (2OO2). The main limitation of the research is the chosen method. The questionnaire survey was conducted in a selected sample of small and medium-size enterprises case study was carried out in a concrere company. The conclusions therefore can not be generalized. Further research can provide a more extensive survey that can be statistically generalize. Other possibity is the evaluation of a social impact as Galal & Wiener (2OO3) also suggest or description of differences in reporting research and development project realized without public support as Lokshin & Mohnen (2O12) recommend.

Value added tax is the tax of great relevance, it is the universal tax levied on general production. In practice people meet this tax very often a its theoretical knowledge is important. The VAT ranks among indirect taxes, of which the harmonization is most expanded and essential for formation of the united European market. The goal of the thesis is to give the overview of history, present and perspectives of the VAT in Europe. This thesis deals with the theory and function principles of the VAT. The first chapter refers to historic evolution of the VAT, arguments and process of introducing of this tax in Europe. Characteristics of inderect and general taxes are mentioned and the system of the VAT in Czech Republic is described in detail. The second chapter discusses the VAT harmonization, the tax competition, coordination and legislation in this branch. The third chapter examines the evolution of the VAT in European countries in recent years, concretely the evolution of the VAT revenue, the evolution of the VAT rates and differences in the base among countries in the EU.

Prevalence of obesity worldwide has increased rapidly in the last decade. In the Czech Republic, a similar trend has been observed. Every fifth adult has a problem with obesity, a fact which puts the Czech Republic among the countries with the highest obesity rates in European and global context. Obesity is a risk factor leading to a number of serious diseases. The growing prevalence of obesity is directly causing higher health care spending and also incurs costs indirectly, in terms of productivity losses. Present thesis is the first study in the Czech Republic, providing an estimate of both direct and indirect costs related to the obesity. Using a cost-of-illness method, the overall social costs of obesity in the Czech Republic for 2013 were estimated at 12.1 billion CZK which corresponds to 0.3% of GDP in the given year. Direct costs accounted for two thirds of this amount. The highest costs, attributable to the obesity, were inflicted by back pain diseases, arthritis, ischemic heart diseases and type 2 diabetes.