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Translation in plastids : elucidation of decoding mechanisms and functions of ribosomal components
(2008)
Generalized Two-Level Grammar (GTWOL) provides a new method for compilation of parallel replacement rules into transducers. The current paper identifies the role of generalized lenient composition (GLC) in this method. Thanks to the GLC operation, the compilation method becomes bipartite and easily extendible to capture various application modes. In the light of three notions of obligatoriness, a modification to the compilation method is proposed. We argue that the bipartite design makes implementation of parallel obligatoriness, directionality, length and rank based application modes extremely easy, which is the main result of the paper.
Traffic of molecular motors
(2008)
We propose a network structure-based model for heterosis, and investigate it relying on metabolite profiles from Arabidopsis. A simple feed-forward two-layer network model (the Steinbuch matrix) is used in our conceptual approach. It allows for directly relating structural network properties with biological function. Interpreting heterosis as increased adaptability, our model predicts that the biological networks involved show increasing connectivity of regulatory interactions. A detailed analysis of metabolite profile data reveals that the increasing-connectivity prediction is true for graphical Gaussian models in our data from early development. This mirrors properties of observed heterotic Arabidopsis phenotypes. Furthermore, the model predicts a limit for increasing hybrid vigor with increasing heterozygosity—a known phenomenon in the literature.
Towards a financial perspective on virtual communities : the case of the Berlin Stock Exchange
(2008)
pH sensing in living cells represents one of the most prominent topics in biochemistry and physiology. In this study we performed one-photon and two-photon time-domain fluorescence lifetime imaging with a laser-scanning microscope using the time-correlated single-photon counting technique for imaging intracellular pH levels. The suitability of different commercial fluorescence dyes for lifetime-based pH sensing is discussed on the basis of in vitro as well of in situ measurements. Although the tested dyes are suitable for intensity-based ratiometric measurements, for lifetime- based techniques in the time-domain so far only BCECF seems to meet the requirements of reliable intracellular pH recordings in living cells.
It has always been enigmatic which processes control the accretion of the North American terranes towards the Pacific plate and the landward migration of the San Andreas plate boundary. One of the theories suggests that the Pacific plate first cools and captures the uprising mantle in the slab window, and then it causes the accretion of the continental crustal blocks. The alternative theory attributes the accretion to the capture of Farallon plate fragments (microplates) stalled in the ceased Farallon-North America subduction zone. Quantitative judgement between these two end-member concepts requires a 3D thermomechanical numerical modeling. However, the software tool required for such modeling is not available at present in the geodynamic modeling community. The major aim of the presented work is comprised basically of two interconnected tasks. The first task is the development and testing of the research Finite Element code with sufficiently advanced facilities to perform the three-dimensional geological time scale simulations of lithospheric deformation. The second task consists in the application of the developed tool to the Neogene deformations of the crust and the mantle along the San Andreas Fault System in Central and northern California. The geological time scale modeling of lithospheric deformation poses numerous conceptual and implementation challenges for the software tools. Among them is the necessity to handle the brittle-ductile transition within the single computational domain, adequately represent the rock rheology in a broad range of temperatures and stresses, and resolve the extreme deformations of the free surface and internal boundaries. In the framework of this thesis the new Finite Element code (SLIM3D) has been successfully developed and tested. This code includes a coupled thermo-mechanical treatment of deformation processes and allows for an elasto-visco-plastic rheology with diffusion, dislocation and Peierls creep mechanisms and Mohr-Coulomb plasticity. The code incorporates an Arbitrary Lagrangian Eulerian formulation with free surface and Winkler boundary conditions. The modeling technique developed is used to study the aspects influencing the Neogene lithospheric deformation in central and northern California. The model setup is focused on the interaction between three major tectonic elements in the region: the North America plate, the Pacific plate and the Gorda plate, which join together near the Mendocino Triple Junction. Among the modeled effects is the influence of asthenosphere upwelling in the opening slab window on the overlying North American plate. The models also incorporate the captured microplate remnants in the fossil Farallon subduction zone, simplified subducting Gorda slab, and prominent crustal heterogeneity such as the Salinian block. The results show that heating of the mantle roots beneath the older fault zones and the transpression related to fault stepping, altogether, render cooling in the slab window alone incapable to explain eastward migration of the plate boundary. From the viewpoint of the thermomechanical modeling, the results confirm the geological concept, which assumes that a series of microplate capture events has been the primary reason of the inland migration of the San Andreas plate boundary over the recent 20 Ma. The remnants of the Farallon slab, stalled in the fossil subduction zone, create much stronger heterogeneity in the mantle than the cooling of the uprising asthenosphere, providing the more efficient and direct way for transferring the North American terranes to Pacific plate. The models demonstrate that a high effective friction coefficient on major faults fails to predict the distinct zones of strain localization in the brittle crust. The magnitude of friction coefficient inferred from the modeling is about 0.075, which is far less than typical values 0.6 – 0.8 obtained by variety of borehole stress measurements and laboratory data. Therefore, the model results presented in this thesis provide additional independent constrain which supports the “weak-fault” hypothesis in the long-term ongoing debate over the strength of major faults in the SAFS.
Thermal radiation processes
(2008)
We discuss the different physical processes that are important to understand the thermal X-ray emission and absorption spectra of the diffuse gas in clusters of galaxies and the warm-hot intergalactic medium. The ionisation balance, line and continuum emission and absorption properties are reviewed and several practical examples are given that illustrate the most important diagnostic features in the X-ray spectra.
This text compares the special characteristics of the game space in computer-generated environments with that in non-computerized playing-situations. Herewith, the concept of the magic circle as a deliberately delineated playing sphere with specific rules to be upheld by the players, is challenged. Yet, computer games also provide a virtual playing environment containing the rules of the game as well as the various action possibilities. But both the hardware and software facilitate the player’s actions rather than constraining them. This makes computer games fundamentally different: in contrast to traditional game spaces or limits, the computer-generated environment does not rely on the awareness of the player in upholding these rules. – Thus, there is no magic circle.
Contents: Artem Polyvanny, Sergey Smirnow, and Mathias Weske The Triconnected Abstraction of Process Models 1 Introduction 2 Business Process Model Abstraction 3 Preliminaries 4 Triconnected Decomposition 4.1 Basic Approach for Process Component Discovery 4.2 SPQR-Tree Decomposition 4.3 SPQR-Tree Fragments in the Context of Process Models 5 Triconnected Abstraction 5.1 Abstraction Rules 5.2 Abstraction Algorithm 6 Related Work and Conclusions
Over the last decades Britain´s ethnic minorities have successfully established themselves in a multicultural society. In particular, Indian – Hindu communities generally improved their social and economic situation. In this context, the third generation of British Indians is now growing up. In contrast to the previous generation of the Indian diaspora, these children grow up in an established ethnic community, which learned to retain its religion, traditions and culture in a foreign environment. At the same time, these children are part of the multicultural British society. Based on the academic discussion about the second generation of immigrated ethnic communities, when the youth often suffered from cultural differences, racism and discrimination and therefore rejected aspects of their culture of origin, this paper assumes that the loss of the culture of origin further increases in the third generation. This thesis follows the main theories about the connection between generation and integration. It is believed that the preference of western culture influences the personal, ethnic and cultural identity of young people. This leads to the rejection of traditional bonds. Before introducing this thesis various theoretical concepts are discussed which are inevitable for the comprehension of the diasporic situation in which British Indian youngsters grow up. As part of the worldwide Asian Indian diaspora Indian families in Britain maintain manifold links to Indian communities in various countries. Particularly, the link to India plays a decisive role; the subcontinent is referred to as an abstract homeland, especially by the first generation. While the grandparents strongly adhere to their Indian culture and Hindu religion, the second generation already generated cultural change. In this process various cultural values of the Indian ethnic community have been questioned and modified. Further, the second generation pushed the integration into the British society by giving up the dependence on the ethnic network. This paper is based on a hybrid and fluent definition of culture. This definition also applies to the underlying understanding of identity and ethnicity. Due to migration, cultural contact and the multilocality of the diaspora, diasporic and post-diasporic identities and cultures are characterized by hybridity, heterogeneity, fragmentation and flexibility. Particularly, in the younger generation – though dependent on a number of social and structural factors - cultural change and mixture happen; in this process new ethnicities and identities evolve. In the second and third part of this paper the thesis of loss of culture of origin is refuted on the basis of findings from empirical research. British - Indian youngsters in London have been questioned for the study. Half of the youngsters are related to a sampradaya, a Hindu sect. This enables the author to compare youngsters who do not belong to a particular religious group with those who are included into a religious and / or ethnic community through a sampradaya. The analysis of the findings which are based on qualitative and quantitative social research shows that the young people have great interest in their culture of origin and that they aim to maintain this culture in the diaspora. They identify as Indian and are proud of their cultural differences. In this, they differ from the second generation. In contrast to the generation of their grandparents the Indian identity of the third generation is not based on nostalgic memories. They confirm and emphasize their postdiasporic difference in a western multicultural society. The findings from the survey hereby exceed the thesis from Hansen’s theory about the rediscovery of the culture of origin in the third generation. The comparison of both groups shows that in the context of the differentiation of postmodern and postcolonial communities also ethnic groups become increasingly differentiated. Therefore, the Indian heritage and culture does not play the same role for every young British Indian.
Plant population modelling has been around since the 1970s, providing a valuable approach to understanding plant ecology from a mechanistic standpoint. It is surprising then that this area of research has not grown in prominence with respect to other approaches employed in modelling plant systems. In this review, we provide an analysis of the development and role of modelling in the field of plant population biology through an exploration of where it has been, where it is now and, in our opinion, where it should be headed. We focus, in particular, on the role plant population modelling could play in ecological forecasting, an urgent need given current rates of regional and global environmental change. We suggest that a critical element limiting the current application of plant population modelling in environmental research is the trade-off between the necessary resolution and detail required to accurately characterize ecological dynamics pitted against the goal of generality, particularly at broad spatial scales. In addition to suggestions how to overcome the current shortcoming of data on the process-level we discuss two emerging strategies that may offer a way to overcome the described limitation: (1) application of a modern approach to spatial scaling from local processes to broader levels of interaction and (2) plant functional-type modelling. Finally we outline what we believe to be needed in developing these approaches towards a 'science of forecasting'.
The space-image
(2008)
In recent computer game research a paradigmatic shift is observable: Games today are first and foremost conceived as a new medium characterized by their status as an interactive image. The shift in attention towards this aspect becomes apparent in a new approach that is, first and foremost, aware of the spatiality of games or their spatial structures. This rejects traditional approaches on the basis that the medial specificity of games can no longer be reduced to textual or ludic properties, but has to be seen in medial constituted spatiality. For this purpose, seminal studies on the spatiality of computer games are resumed and their advantages and disadvantages are discussed. In connection with this, and against the background of the philosophical method of phenomenology, we propose three steps in describing computer games as space images: With this method it is possible to describe games with respect to the possible appearance of spatiality in a pictorial medium.
The South Chilean subduction zone between 41° and 43.5°S : seismicity, structure and state of stress
(2008)
While the northern and central part of the South American subduction zone has been intensively studied, the southern part has attracted less attention, which may be due to its difficult accessibility and lower seismic activity. However, the southern part exhibits strong seismic and tsunamogenic potential with the prominent example of the Mw=9.5 May 22, 1960 Valdivia earthquake. In this study data from an amphibious seismic array (Project TIPTEQ) is presented. The network reached from the trench to the active magmatic arc incorporating the Island of Chiloé and the north-south trending Liquiñe-Ofqui fault zone (LOFZ). 364 local events were observed in an 11-month period from November 2004 until October 2005. The observed seismicity allows to constrain for the first time the current state of stress of the subducting plate and magmatic arc, as well as the local seismic velocity structure. The downgoing Benioff zone is readily identifiable as an eastward dipping plane with an inclination of ~30°. Main seismic activity occurred predominantly in a belt parallel to the coast of Chiloé Island in a depth range of 12-30 km, which is presumably related to the plate interface. The down-dip termination of abundant intermediate depth seismicity at approximately 70 km depth seems to be related to the young age (and high temperature) of the oceanic plate. A high-quality subset of events was inverted for a 2-D velocity model. The vp model resolves the sedimentary basins and the downgoing slab. Increased velocities below the longitudinal valley and the eastern part of Chiloé Island suggest the existence of a mantle bulge. Apart from the events in the Benioff Zone, shallow crustal events were observed mainly in different clusters along the magmatic arc. These crustal clusters of seismicity are related to the LOFZ, as well as to the volcanoes Chaitén, Michinmahuida and Corcovado. Seismic activity up to a magnitude of 3.8 Mw reveals the recent activity of the fault zone. Focal mechanisms for the events along the LOFZ were calculated using a moment tensor inversion of amplitude spectra for body waves which mostly yield strike-slip mechanisms indicating a SW-NE striking of sigma_1 for the LOFZ. Focal mechanism stress inversion indicates a strike-slip regime along the arc and a thrust regime in the Benioff zone. The observed deformation - which is also revealed by teleseismic observations - suggests a confirmation for the proposed northward movement of a forearc sliver acting as a detached continental micro-plate.