27 resultados para Alternative solutions

em Helda - Digital Repository of University of Helsinki


Relevância:

60.00% 60.00%

Publicador:

Resumo:

Starting point in the European individualistic copyright ideology is that an individual author creates a work and controls the use of it. However, this paper argues that it is (and has always been) impossible to control the use of works after their publication. This has also been acknowledged by the legislator, who has introduced collective licensing agreements because of this impossibility. Since it is impossible to rigorously control the use of works this writing "Rough Justice or Zero Tolerance - Reassessing the Nature of Copyright in Light of Collective Licensing" examines what reality of copyright is actually about. Finding alternative (and hopefully more "true") ways to understand copyright helps us to create alternative solutions in order to solve possible problems we have as it comes e.g. to use of content in online environment. The paper makes a claim that copyright is actually about defining negotiation points for different stakeholders and that nothing in the copyright reality prevents us from defining e.g. a new negotiation point where representatives of consumers would meet representatives of right holders in order to agree on the terms of use for certain content types in online environment.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The new paradigm of connectedness and empowerment brought by the interactivity feature of the Web 2.0 has been challenging the traditional centralized performance of mainstream media. The corporation has been able to survive the strong winds by transforming itself into a global multimedia business network embedded in the network society. By establishing networks, e.g. networks of production and distribution, the global multimedia business network has been able to sight potential solutions by opening the doors to innovation in a decentralized and flexible manner. Under this emerging context of re-organization, traditional practices like sourcing need to be re- explained and that is precisely what this thesis attempts to tackle. Based on ICT and on the network society, the study seeks to explain within the Finnish context the particular case of Helsingin Sanomat (HS) and its relations with the youth news agency, Youth Voice Editorial Board (NÄT). In that sense, the study can be regarded as an explanatory embedded single case study, where HS is the principal unit of analysis and NÄT its embedded unit of analysis. The thesis was able to reach explanations through interrelated steps. First, it determined the role of ICT in HS’s sourcing practices. Then it mapped an overview of the HS’s sourcing relations and provided a context in which NÄT was located. And finally, it established conceptualized institutional relational data between HS and NÄT for their posterior measurement through social network analysis. The data set was collected via qualitative interviews addressed to online and offline editors of HS as well as interviews addressed to NÄT’s personnel. The study concluded that ICT’s interactivity and User Generated Content (UGC) are not sourcing tools as such but mechanism used by HS for getting ideas that could turn into potential news stories. However, when it comes to visual communication, some exemptions were found. The lack of official sources amidst the immediacy leads HS to rely on ICT’s interaction and UGC. More than meets the eye, ICT’s input into the sourcing practice may be more noticeable if the interaction and UGC is well organized and coordinated into proper and innovative networks of alternative content collaboration. Currently, HS performs this sourcing practice via two projects that differ, precisely, by the mode they are coordinated. The first project found, Omakaupunki, is coordinated internally by Sanoma Group’s owned media houses HS, Vartti and Metro. The second project found is coordinated externally. The external alternative sourcing network, as it was labeled, consists of three actors, namely HS, NÄT (professionals in charge) and the youth. This network is a balanced and complete triad in which the actors connect themselves in relations of feedback, recognition, creativity and filtering. However, as innovation is approached very reluctantly, this content collaboration is a laboratory of experiments; a ‘COLLABORATORY’.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This thesis combines a computational analysis of a comprehensive corpus of Finnish lake names with a theoretical background in cognitive linguistics. The combination results on the one hand in a description of the toponymic system and the processes involved in analogy-based naming and on the other hand some adjustments to Construction Grammar. Finnish lake names are suitable for this kind of study, as they are to a large extent semantically transparent even when relatively old. There is also a large number of them, and they are comprehensively collected in a computer database. The current work starts with an exploratory computational analysis of co-location patterns between different lake names. Such an analysis makes it possible to assess the importance of analogy and patterns in naming. Prior research has suggested that analogy plays an important role, often also in cases where there are other motivations for the name, and the current study confirms this. However, it also appears that naming patterns are very fuzzy and that their nature is somewhat hard to define in an essentially structuralist tradition. In describing toponymic structure and the processes involved in naming, cognitive linguistics presents itself as a promising theoretical basis. The descriptive formalism of Construction Grammar seems especially well suited for the task. However, now productivity becomes a problem: it is not nearly as clear-cut as the latter theory often assumes, and this is even more apparent in names than in more traditional linguistic material. The varying degree of productivity is most naturally described by a prototype-based theory. Such an approach, however, requires some adjustments to onstruction Grammar. Based on all this, the thesis proposes a descriptive model where a new name -- or more generally, a new linguistic expression -- can be formed by conceptual integration from either a single prior example or a construction generalised from a number of different prior ones. The new model accounts nicely for various aspects of naming that are problematic for the traditional description based on analogy and patterns.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The study is a philosophical analysis of Israel Scheffler’s philosophy of education, focusing on three crucial conceptions in his philosophy: the conception of rationality, the conception of human nature, and the conception of reality. The interrelations of these three concepts as well as their relations to educational theorizing are analysed and elaborated. A conceptual problem concerning Scheffler’s ideal of rationality derives from Scheffler’s supposition of the strong analogy between science education and moral education in terms of the ideal of rationality. This analogy is argued to be conceptually problematic, since the interconnections of rationality, objectivity, and truth, appear to differ from each other in the realms of ethics and science, given the presuppositions of ontological realism and ethical naturalism, to which Scheffler explicitly subscribes. This study considers two philosophical alternatives for solving this problem. The first alternative relates the analogy to the normative concept of personhood deriving from the teleological understanding of human nature. Nevertheless, this position turns out to be problematic for Scheffler, since he rejects all teleological thinking in his philosophy. The problem can be solved, as it is argued, by limiting Scheffler’s rejection of teleology – in light of his philosophical outlook on the whole – in a manner that allows a modest version of a teleological conception of human nature. The second alternative, based especially on Scheffler’s later contributions, is to suggest that reality is actually more complex and manifold than it appears to be in light of a contemporary naturalist worldview. This idea of plurealism – Scheffler’s synthesis of pluralism and realism – is represented especially in Scheffler’s contributions related to his debate with Nelson Goodman dealing with both constructivism and realism. The idea of plurealism is not only related to the ethics-science-distinction, but is more widely related to the relationship between ontological realism and the incommensurable systems of description in diverse realms of human understanding. The Scheffler-Goodman debate is also analysed in relation to the contemporary constructivism-realism debate in educational philosophy. In terms of educational questions, Scheffler’s plurealism is argued as offering a fruitful perspective. Scheffler’s philosophy of education can be interpreted as searching for solutions to the problems deriving from the tension between the tradition of analytical philosophy and the complexity and multiplicity of educational reality. The complexity of reality combined with the supposition of the limitedness of human knowledge does not lead Scheffler to relativism or particularism, but, in contrast, Schefflerian formulations of rationality and objectivity preserve the possibility for critical inquiry in all realms of educational reality. In light of this study, Scheffler’s philosophy of education provides an exceptional example of combining ontological realism, epistemological fallibilism, and the defence of the ideal of rationality, combined with a wide-ranging understanding of educational reality.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study analysed whether the land tenure insecurity problem has led to a decline in long-term land improvements (liming and phosphorus fertilization) under the Common Agricultural Policy (CAP) and Nordic production conditions in European Union (EU) countries such as Finland. The results suggests that under traditional cash lease contracts, which are encouraged by the existing land leasing regulations and agricultural subsidy programs, the land tenure insecurity problem on leased land reduces land improvements that have a long pay-back period. In particular, soil pH was found to be significantly lower on land cultivated under a lease contract compared to land owned by the farmers themselves. The results also indicate that land improvements could not be reversed by land markets, because land owners would otherwise have carried out land improvements even if not farming by themselves. To reveal the causality between land tenure and land improvements, the dynamic optimisation problem was solved by a stochastic dynamic programming routine with known parameters for one-period returns and transition equations. The model parameters represented Finnish soil quality and production conditions. The decision rules were solved for alternative likelihood scenarios over the continuation of the fixed-term lease contract. The results suggest that as the probability of non-renewal of the lease contract increases, farmers quickly reduce investments in irreversible land improvements and, thereafter, yields gradually decline. The simulations highlighted the observed trends of a decline in land improvements on land parcels that are cultivated under lease contracts. Land tenure has resulted in the neglect of land improvement in Finland. This study aimed to analyze whether these challenges could be resolved by a tax policy that encourages land sales. Using Finnish data, real estate tax and a temporal relaxation on the taxation of capital gains showed some potential for the restructuring of land ownership. Potential sellers who could not be revealed by traditional logit models were identified with the latent class approach. Those landowners with an intention to sell even without a policy change were sensitive to temporal relaxation in the taxation of capital gains. In the long term, productivity and especially productivity growth are necessary conditions for the survival of farms and the food industry in Finland. Technical progress was found to drive the increase in productivity. The scale had only a moderate effect and for the whole study period (1976–2006) the effect was close to zero. Total factor productivity (TFP) increased, depending on the model, by 0.6–1.7% per year. The results demonstrated that the increase in productivity was hindered by the policy changes introduced in 1995. It is also evidenced that the increase in land leasing is connected to these policy changes. Land institutions and land tenure questions are essential in agricultural and rural policies on all levels, from local to international. Land ownership and land titles are commonly tied to fundamental political, economic and social questions. A fair resolution calls for innovative and new solutions both on national and international levels. However, this seems to be a problem when considering the application of EU regulations to member states inheriting divergent landownership structures and farming cultures. The contribution of this study is in describing the consequences of fitting EU agricultural policy to Finnish agricultural land tenure conditions and heritage.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Achieving sustainable consumption patterns is a crucial step on the way towards sustainability. The scientific knowledge used to decide which priorities to set and how to enforce them has to converge with societal, political, and economic initiatives on various levels: from individual household decision-making to agreements and commitments in global policy processes. The aim of this thesis is to draw a comprehensive and systematic picture of sustainable consumption and to do this it develops the concept of Strong Sustainable Consumption Governance. In this concept, consumption is understood as resource consumption. This includes consumption by industries, public consumption, and household consumption. Next to the availability of resources (including the available sink capacity of the ecosystem) and their use and distribution among the Earth’s population, the thesis also considers their contribution to human well-being. This implies giving specific attention to the levels and patterns of consumption. Methods: The thesis introduces the terminology and various concepts of Sustainable Consumption and of Governance. It briefly elaborates on the methodology of Critical Realism and its potential for analysing Sustainable Consumption. It describes the various methods on which the research is based and sets out the political implications a governance approach towards Strong Sustainable Consumption may have. Two models are developed: one for the assessment of the environmental relevance of consumption activities, another to identify the influences of globalisation on the determinants of consumption opportunities. Results: One of the major challenges for Strong Sustainable Consumption is that it is not in line with the current political mainstream: that is, the belief that economic growth can cure all our problems. So, the proponents have to battle against a strong headwind. Their motivation however is the conviction that there is no alternative. Efforts have to be taken on multiple levels by multiple actors. And all of them are needed as they constitute the individual strings that together make up the rope. However, everyone must ensure that they are pulling in the same direction. It might be useful to apply a carrot and stick strategy to stimulate public debate. The stick in this case is to create a sense of urgency. The carrot would be to articulate better the message to the public that a shrinking of the economy is not as much of a disaster as mainstream economics tends to suggest. In parallel to this it is necessary to demand that governments take responsibility for governance. The dominant strategy is still information provision. But there is ample evidence that hard policies like regulatory instruments and economic instruments are most effective. As for Civil Society Organizations it is recommended that they overcome the habit of promoting Sustainable (in fact green) Consumption by using marketing strategies and instead foster public debate in values and well-being. This includes appreciating the potential of social innovation. A countless number of such initiatives are on the way but their potential is still insufficiently explored. Beyond the question of how to multiply such approaches, it is also necessary to establish political macro structures to foster them.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The molecular level structure of mixtures of water and alcohols is very complicated and has been under intense research in the recent past. Both experimental and computational methods have been used in the studies. One method for studying the intra- and intermolecular bindings in the mixtures is the use of the so called difference Compton profiles, which are a way to obtain information about changes in the electron wave functions. In the process of Compton scattering a photon scatters inelastically from an electron. The Compton profile that is obtained from the electron wave functions is directly proportional to the probability of photon scattering at a given energy to a given solid angle. In this work we develop a method to compute Compton profiles numerically for mixtures of liquids. In order to obtain the electronic wave functions necessary to calculate the Compton profiles we need some statistical information about atomic coordinates. Acquiring this using ab-initio molecular dynamics is beyond our computational capabilities and therefore we use classical molecular dynamics to model the movement of atoms in the mixture. We discuss the validity of the chosen method in view of the results obtained from the simulations. There are some difficulties in using classical molecular dynamics for the quantum mechanical calculations, but these can possibly be overcome by parameter tuning. According to the calculations clear differences can be seen in the Compton profiles of different mixtures. This prediction needs to be tested in experiments in order to find out whether the approximations made are valid.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The analysis of sequential data is required in many diverse areas such as telecommunications, stock market analysis, and bioinformatics. A basic problem related to the analysis of sequential data is the sequence segmentation problem. A sequence segmentation is a partition of the sequence into a number of non-overlapping segments that cover all data points, such that each segment is as homogeneous as possible. This problem can be solved optimally using a standard dynamic programming algorithm. In the first part of the thesis, we present a new approximation algorithm for the sequence segmentation problem. This algorithm has smaller running time than the optimal dynamic programming algorithm, while it has bounded approximation ratio. The basic idea is to divide the input sequence into subsequences, solve the problem optimally in each subsequence, and then appropriately combine the solutions to the subproblems into one final solution. In the second part of the thesis, we study alternative segmentation models that are devised to better fit the data. More specifically, we focus on clustered segmentations and segmentations with rearrangements. While in the standard segmentation of a multidimensional sequence all dimensions share the same segment boundaries, in a clustered segmentation the multidimensional sequence is segmented in such a way that dimensions are allowed to form clusters. Each cluster of dimensions is then segmented separately. We formally define the problem of clustered segmentations and we experimentally show that segmenting sequences using this segmentation model, leads to solutions with smaller error for the same model cost. Segmentation with rearrangements is a novel variation to the segmentation problem: in addition to partitioning the sequence we also seek to apply a limited amount of reordering, so that the overall representation error is minimized. We formulate the problem of segmentation with rearrangements and we show that it is an NP-hard problem to solve or even to approximate. We devise effective algorithms for the proposed problem, combining ideas from dynamic programming and outlier detection algorithms in sequences. In the final part of the thesis, we discuss the problem of aggregating results of segmentation algorithms on the same set of data points. In this case, we are interested in producing a partitioning of the data that agrees as much as possible with the input partitions. We show that this problem can be solved optimally in polynomial time using dynamic programming. Furthermore, we show that not all data points are candidates for segment boundaries in the optimal solution.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Mobile RFID services for the Internet of Things can be created by using RFID as an enabling technology in mobile devices. Humans, devices, and things are the content providers and users of these services. Mobile RFID services can be either provided on mobile devices as stand-alone services or combined with end-to-end systems. When different service solution scenarios are considered, there are more than one possible architectural solution in the network, mobile, and back-end server areas. Combining the solutions wisely by applying the software architecture and engineering principles, a combined solution can be formulated for certain application specific use cases. This thesis illustrates these ideas. It also shows how generally the solutions can be used in real world use case scenarios. A case study is used to add further evidence.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The respiratory chain is found in the inner mitochondrial membrane of higher organisms and in the plasma membrane of many bacteria. It consists of several membrane-spanning enzymes, which conserve the energy that is liberated from the degradation of food molecules as an electrochemical proton gradient across the membrane. The proton gradient can later be utilized by the cell for different energy requiring processes, e.g. ATP production, cellular motion or active transport of ions. The difference in proton concentration between the two sides of the membrane is a result of the translocation of protons by the enzymes of the respiratory chain, from the negatively charged (N-side) to the positively charged side (P-side) of the lipid bilayer, against the proton concentration gradient. The endergonic proton transfer is driven by the flow of electrons through the enzymes of the respiratory chain, from low redox-potential electron donors to acceptors of higher potential, and ultimately to oxygen. Cytochrome c oxidase is the last enzyme in the respiratory chain and catalyzes the reduction of dioxygen to water. The redox reaction is coupled to proton transport across the membrane by a yet unresolved mechanism. Cytochrome c oxidase has two proton-conducting pathways through which protons are taken up to the interior part of the enzyme from the N-side of the membrane. The K-pathway transfers merely substrate protons, which are consumed in the process of water formation at the catalytic site. The D-pathway transfers both substrate protons and protons that are pumped to the P-side of the membrane. This thesis focuses on the role of two conserved amino acids in proton translocation by cytochrome c oxidase, glutamate 278 and tryptophan 164. Glu278 is located at the end of the D-pathway and is thought to constitute the branching point for substrate and pumped protons. In this work, it was shown that although Glu278 has an important role in the proton transfer mechanism, its presence is not an obligatory requirement. Alternative structural solutions in the area around Glu278, much like the ones present in some distantly related heme-copper oxidases, could in the absence of Glu278 support the formation of a long hydrogen-bonded water chain through which proton transfer from the D-pathway to the catalytic site is possible. The other studied amino acid, Trp164, is hydrogen bonded to the ∆-propionate of heme a3 of the catalytic site. Mutation of this amino acid showed that it may be involved in regulation of proton access to a proton acceptor, a pump site, from which the proton later is expelled to the P-side of the membrane. The ion pair that is formed by the ∆-propionate of heme a3 and arginine 473 is likely to form a gate-like structure, which regulates proton mobility to the P-side of the membrane. The same gate may also be part of an exit path through which water molecules produced at the catalytically active site are removed towards the external side of the membrane. Time-resolved optical and electrometrical experiments with the Trp164 to phenylalanine mutant revealed a so far undetected step in the proton pumping mechanism. During the A to PR transition of the catalytic cycle, a proton is transferred from Glu278 to the pump site, located somewhere in the vicinity of the ∆-propionate of heme a3. A mechanism for proton pumping by cytochrome c oxidase is proposed on the basis of the presented results and the mechanism is discussed in relation to some relevant experimental data. A common proton pumping mechanism for all members of the heme-copper oxidase family is moreover considered.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Ongoing habitat loss and fragmentation threaten much of the biodiversity that we know today. As such, conservation efforts are required if we want to protect biodiversity. Conservation budgets are typically tight, making the cost-effective selection of protected areas difficult. Therefore, reserve design methods have been developed to identify sets of sites, that together represent the species of conservation interest in a cost-effective manner. To be able to select reserve networks, data on species distributions is needed. Such data is often incomplete, but species habitat distribution models (SHDMs) can be used to link the occurrence of the species at the surveyed sites to the environmental conditions at these locations (e.g. climatic, vegetation and soil conditions). The probability of the species occurring at unvisited location is next predicted by the model, based on the environmental conditions of those sites. The spatial configuration of reserve networks is important, because habitat loss around reserves can influence the persistence of species inside the network. Since species differ in their requirements for network configuration, the spatial cohesion of networks needs to be species-specific. A way to account for species-specific requirements is to use spatial variables in SHDMs. Spatial SHDMs allow the evaluation of the effect of reserve network configuration on the probability of occurrence of the species inside the network. Even though reserves are important for conservation, they are not the only option available to conservation planners. To enhance or maintain habitat quality, restoration or maintenance measures are sometimes required. As a result, the number of conservation options per site increases. Currently available reserve selection tools do however not offer the ability to handle multiple, alternative options per site. This thesis extends the existing methodology for reserve design, by offering methods to identify cost-effective conservation planning solutions when multiple, alternative conservation options are available per site. Although restoration and maintenance measures are beneficial to certain species, they can be harmful to other species with different requirements. This introduces trade-offs between species when identifying which conservation action is best applied to which site. The thesis describes how the strength of such trade-offs can be identified, which is useful for assessing consequences of conservation decisions regarding species priorities and budget. Furthermore, the results of the thesis indicate that spatial SHDMs can be successfully used to account for species-specific requirements for spatial cohesion - in the reserve selection (single-option) context as well as in the multi-option context. Accounting for the spatial requirements of multiple species and allowing for several conservation options is however complicated, due to trade-offs in species requirements. It is also shown that spatial SHDMs can be successfully used for gaining information on factors that drive a species spatial distribution. Such information is valuable to conservation planning, as better knowledge on species requirements facilitates the design of networks for species persistence. This methods and results described in this thesis aim to improve species probabilities of persistence, by taking better account of species habitat and spatial requirements. Many real-world conservation planning problems are characterised by a variety of conservation options related to protection, restoration and maintenance of habitat. Planning tools therefore need to be able to incorporate multiple conservation options per site, in order to continue the search for cost-effective conservation planning solutions. Simultaneously, the spatial requirements of species need to be considered. The methods described in this thesis offer a starting point for combining these two relevant aspects of conservation planning.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Eukaryotic cells are characterized by having a subset of internal membrane compartments, each one with a specifi c identity, structure and function. Proteins destined to be targeted to the exterior of the cell need to enter and progress through the secretory pathway. Transport of secretory proteins from the endoplasmic reticulum (ER) to the Golgi takes place by the selective packaging of proteins into COPII-coated vesicles at the ER membrane. Taking advantage of the extensive genetic tools available for S. cerevisiae we found that Hsp150, a yeast secretory glycoprotein, selectively exited the ER in the absence of any of the three Sec24p family members. Sec24p has been thought to be an essential component of the COPII coat and thus indispensable for exocytic membrane traffic. Next we analyzed the ability of Hsp150 to be secreted in mutants, where post-Golgi transport is temperature sensitive. We found that Hsp150 could be selectively secreted under conditions where the exocyst component Sec15p is defective. Analysis of the secretory vesicles revealed that Hsp150 was packaged into a subset of known secretory vesicles as well as in a novel pool of secretory vesicles at the level of the Golgi. Secretion of Hsp150 in the absence of Sec15p function was dependent of Mso1p, a protein capable of interacting with vesicles intended to fuse with the plasma membrane, with the SNARE machinery and with Sec1p. This work demonstrated that Hsp150 is capable of using alternative secretory pathways in ER-to-Golgi and Golgi-to-plasma membrane traffi c. The sorting signals, used at both stages of the secretory pathway, for secretion of Hsp150 were different, revealing the highly dynamic nature and spatial organization of the secretory pathway. Foreign proteins usually misfold in the yeast ER. We used Hsp150 as a carrier to assist folding and transport of heterologous proteins though the secretory pathway to the culture medium in both S. cerevisiae and P. pastoris. Using this technique we expressed Hsp150Δ-HRP and developed a staining procedure, which allowed the visualization of the organelles of the secretory pathway of S. cerevisiae.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

When organisms compete for mates and fertilisations, the process of sexual selection drives the evolution of traits that increase reproductive success. The traits targeted by selection, and the extent to which they change, are constrained by the local environment. Sexual selection due to female mate choice can be undermined by alternative reproductive tactics (ARTs), which refers to discontinuous variation in traits or behaviours used in reproduction. As human activities are rapidly changing our planet, this raises the question how ARTs will be affected. Fish show a bewildering diversity of ARTs, which make them good model organisms to answer these questions. One example of human-induced environmental change, which is affecting aquatic ecosystems around the world, is eutrophication, the over-enrichment of water bodies with nutrients. One of its effects is decreased underwater visibility due to increases in both turbidity and vegetation density. The aims of this thesis were to investigate the effects increased turbidity and vegetation density have on an ART in sticklebacks, a fish common to marine and fresh water bodies of the Northern hemisphere. I furthermore investigated how this affected sexual selection for male size, a trait commonly under selection. I used a combination of behavioural observations in microcosms, where I manipulated underwater visibility, with collection of genetic material to reconstruct parentage of broods, and thus identify sneak fertilisations. The results show that turbidity might have weak negative effects on the frequency of sneaking behaviour, although this behaviour was rather infrequent in these experiments, which complicates firm conclusions. In dense vegetation the number of sneak fertilisations decreased slightly, as fewer nesting males sneaked, while the number of non-nesting males sneaking remained constant. The paternity analyses revealed that a significantly smaller fraction of eggs was sneak fertilised under dense vegetation. Furthermore, amongst the nesting males that sneaked, the amount of eggs sneak fertilised correlated positively with courtship success. A reduction in sneaking by these males under dense vegetation equalised the distribution of fertilisation success, in turn contributing to a decrease in the opportunity for selection. Under dense vegetation significantly more males built nests, which has also been observed in previous field studies. In a separate experiment we addressed if such changes in the proportion of nesters and non-nesters, without changes in visibility, affected the incidence of sneak fertilisation. My results show this was not the case, likely because sneaking is an opportunistic tactic shown by both nesters and non-nesters. Non-nesters did sneak proportionately more when there were many of them, which could be due to changes in the cost-benefit ratio of sneaking. As nesters can only attack one intruder at a time, the costs and risks per sneaker will decrease as the number of sneakers increases. The defensive behaviours shown by the nesters before spawning shifted to a more aggressive form of nest defence. This could be because less aggressive behaviours lose their effectiveness when the number of intruders increases. It could also indicate that the risks associated with aggressive behaviours decrease when there are fewer fellow nesters, as other studies indicate nesters are competitive and aggressive individuals. Under turbid conditions I did not detect changes in the opportunity for selection, based on fertilisation success, nor was male size under significant selection under clear or turbid conditions. More thorough analyses under densely vegetated conditions across the nesting, courtship and fertilisation stages revealed a decrease in the opportunity for selection across all stages. A reduction in sneaking by nesters contributed to this. During the nesting stage, but not during later stages, body size was under significant directional selection under sparse, but not dense vegetation. This illustrates the importance of considering all selection stages to get a complete picture of how environmental changes affect sexual selection. Leaving out certain stages or subgroups can result in incomplete or misleading results.