@book{3899, abstract = {Combining concepts from topology and algorithms, this book delivers what its title promises: an introduction to the field of computational topology. Starting with motivating problems in both mathematics and computer science and building up from classic topics in geometric and algebraic topology, the third part of the text advances to persistent homology. This point of view is critically important in turning a mostly theoretical field of mathematics into one that is relevant to a multitude of disciplines in the sciences and engineering. The main approach is the discovery of topology through algorithms. The book is ideal for teaching a graduate or advanced undergraduate course in computational topology, as it develops all the background of both the mathematical and algorithmic aspects of the subject from first principles. Thus the text could serve equally well in a course taught in a mathematics department or computer science department.}, author = {Edelsbrunner, Herbert and Harer, John}, isbn = {978-0-8218-4925-5}, pages = {XII, 241}, publisher = {American Mathematical Society}, title = {{Computational Topology: An Introduction}}, doi = {10.1090/mbk/069}, volume = {69}, year = {2010}, } @article{3901, abstract = {We are interested in 3-dimensional images given as arrays of voxels with intensity values. Extending these values to acontinuous function, we study the robustness of homology classes in its level and interlevel sets, that is, the amount of perturbationneeded to destroy these classes. The structure of the homology classes and their robustness, over all level and interlevel sets, can bevisualized by a triangular diagram of dots obtained by computing the extended persistence of the function. We give a fast hierarchicalalgorithm using the dual complexes of oct-tree approximations of the function. In addition, we show that for balanced oct-trees, thedual complexes are geometrically realized in $R^3$ and can thus be used to construct level and interlevel sets. We apply these tools tostudy 3-dimensional images of plant root systems.}, author = {Bendich, Paul and Edelsbrunner, Herbert and Kerber, Michael}, journal = {IEEE Transactions of Visualization and Computer Graphics}, number = {6}, pages = {1251 -- 1260}, publisher = {IEEE}, title = {{Computing robustness and persistence for images}}, doi = {10.1109/TVCG.2010.139}, volume = {16}, year = {2010}, } @article{3904, abstract = {Social organisms are constantly exposed to infectious agents via physical contact with conspecifics. While previous work has shown that disease susceptibility at the individual and group level is influenced by gen- etic diversity within and between group members, it remains poorly understood how group-level resistance to pathogens relates directly to individual physiology, defence behaviour and social interactions. We investigated the effects of high versus low genetic diversity on both the individual and collective disease defences in the ant Cardiocondyla obscurior. We compared the antiseptic behaviours (grooming and hygienic behaviour) of workers from genetically homogeneous and diverse colonies after exposure of their brood to the entomopathogenic fungus Metarhizium anisopliae. While workers from diverse colonies performed intensive allogrooming and quickly removed larvae covered with live fungal spores from the nest, workers from homogeneous colonies only removed sick larvae late after infection. This difference was not caused by a reduced repertoire of antiseptic behaviours or a generally decreased brood care activity in ants from homogeneous colonies. Our data instead suggest that reduced genetic diversity compromises the ability of Cardiocondyla colonies to quickly detect or react to the presence of pathogenic fungal spores before an infection is established, thereby affecting the dynamics of social immunity in the colony.}, author = {Ugelvig, Line V and Kronauer, Daniel and Schrempf, Alexandra and Heinze, Jürgen and Cremer, Sylvia}, journal = {Proceedings of the Royal Society of London Series B Biological Sciences}, number = {1695}, pages = {2821 -- 2828}, publisher = {Royal Society, The}, title = {{Rapid anti-pathogen response in ant societies relies on high genetic diversity}}, doi = {10.1098/rspb.2010.0644}, volume = {277}, year = {2010}, } @article{3956, abstract = {The shuttling of leukocytes between the bloodstream and interstitial tissues involves different locomotion strategies that are governed by locally presented soluble and cell-bound signals. Recent studies have furthered our understanding of the rapidly advancing field of leukocyte migration, particularly regarding cellular and subcellular events at the level of the venular wall. Furthermore, emerging cellular models are now addressing the transition from an adherent mode to a non-adherent state, incorporating mechanisms that support an efficient migratory profile of leukocytes in the interstitial tissue beyond the venular wall.}, author = {Nourshargh, Sussan and Hordijk, Peter L and Michael Sixt}, journal = {Nature Reviews Molecular Cell Biology}, number = {5}, pages = {366 -- 378}, publisher = {Nature Publishing Group}, title = {{Breaching multiple barriers: leukocyte motility through venular walls and the interstitium}}, doi = {10.1038/nrm2889}, volume = {11}, year = {2010}, } @article{3957, author = {Riedl, Julia and Flynn, Kevin C and Raducanu, Aurelia and Florian Gärtner and Beck, Gisela and Bosl, Michael and Bradke, Frank and Massberg, Steffen and Aszodi, Attila and Michael Sixt and Wedlich-Söldner, Roland}, journal = {Nature Methods}, number = {3}, pages = {168 -- 169}, publisher = {Nature Publishing Group}, title = {{Lifeact mice for studying F-actin dynamics}}, doi = {10.1038/nmeth0310-168}, volume = {7}, year = {2010}, } @article{3958, abstract = {Extracellular matrix (ECM) proteins can modify immune reactions, e.g. by sequestering or displaying growth factors and by interacting with immune and glial cells. Here we quantified by quantitative polymerase chain reaction (qPCR) expression of 50 ECM components and 34 ECM degrading enzymes in multiple sclerosis (MS) active and inactive white matter lesions. COL1A1, COL3A1, COL5A1 and COL5A2 chains were induced strongly in active lesions and even more in inactive lesions. These chains interact to form collagen types I, III and V, which are fibrillar collagens. Biglycan and decorin, which can decorate fibrillar collagens, were also induced strongly. The fibrillar collagens, biglycan and decorin were largely found between the endothelium and astrocytic glia limitans in the perivascular space where they formed a meshwork which was closely associated with infiltrating immune cells. In active lesions collagen V was also seen in the heavily infiltrated parenchyma. Fibrillar collagens I and III inhibited in vitro human monocyte production of CCL2 (MCP-1), an inflammatory chemokine involved in recruitment of immune cells. Together, ECM changes in lesions with different activities were quantified and proteins forming a perivascular fibrosis were identified. Induced fibrillar collagens may contribute to limiting enlargement of MS lesions by inhibiting the production of CCL2 by monocytes.}, author = {Mohan, Hema and Krumbholz, Markus and Sharma, Rakhi and Eisele, Sylvia and Junker, Andreas and Michael Sixt and Newcombe, Jia and Wekerle, Hartmut and Hohlfeld, Reinhard and Lassmann, Hans and Meinl, Edgar}, journal = {Brain Pathology}, number = {5}, pages = {966 -- 975}, publisher = {Wiley-Blackwell}, title = {{Extracellular matrix in multiple sclerosis lesions: fibrillar collagens, biglycan and decorin are upregulated and associated with infiltrating immune cells}}, doi = {10.1111/j.1750-3639.2010.00399.x}, volume = {20}, year = {2010}, } @article{3959, abstract = {Chemokines orchestrate immune cell trafficking by eliciting either directed or random migration and by activating integrins in order to induce cell adhesion. Analyzing dendritic cell (DC) migration, we showed that these distinct cellular responses depended on the mode of chemokine presentation within tissues. The surface-immobilized form of the chemokine CCL21, the heparan sulfate-anchoring ligand of the CC-chemokine receptor 7 (CCR7), caused random movement of DCs that was confined to the chemokine-presenting surface because it triggered integrin-mediated adhesion. Upon direct contact with CCL21, DCs truncated the anchoring residues of CCL21, thereby releasing it from the solid phase. Soluble CCL21 functionally resembles the second CCR7 ligand, CCL19, which lacks anchoring residues and forms soluble gradients. Both soluble CCR7 ligands triggered chemotactic movement, but not surface adhesion. Adhesive random migration and directional steering cooperate to produce dynamic but spatially restricted locomotion patterns closely resembling the cellular dynamics observed in secondary lymphoid organs.}, author = {Schumann, Kathrin and Lämmermann, Tim and Bruckner, Markus and Legler, Daniel and Polleux, Julien and Spatz, Joachim and Schuler, Gerold and Förster, Reinhold and Lutz, Manfred and Sorokin, Lydia and Sixt, Michael K}, journal = {Immunity}, number = {5}, pages = {703 -- 713}, publisher = {Cell Press}, title = {{Immobilized chemokine fields and soluble chemokine gradients cooperatively shape migration patterns of dendritic cells}}, doi = {10.1016/j.immuni.2010.04.017}, volume = {32}, year = {2010}, } @article{3960, abstract = {When lymphocytes follow chemotactic cues, they can adopt different migratory modes depending on the geometry and molecular composition of their extracellular environment. In this issue of The EMBO Journal, Klemke et al (2010) describe a novel Ras-dependent chemokine receptor signalling pathway that leads to activation of cofilin, which in turn amplifies actin turnover. This signalling module is exclusively required for lymphocyte migration in three-dimensional (3D) environments, but not for locomotion on two-dimensional (2D) surfaces.}, author = {Michele Weber and Michael Sixt}, journal = {EMBO Journal}, number = {17}, pages = {2861 -- 2863}, publisher = {Wiley-Blackwell}, title = {{MEK signalling tunes actin treadmilling for interstitial lymphocyte migration}}, doi = {10.1038/emboj.2010.183}, volume = {29}, year = {2010}, } @article{3961, abstract = {For innate and adaptive immune responses it is essential that inflammatory cells use quick and flexible locomotion strategies. Accordingly, most leukocytes can efficiently infiltrate and traverse almost every physiological or artificial environment. Here, we review how leukocytes might achieve this task mechanistically, and summarize recent findings on the principles of cytoskeletal force generation and transduction at the leading edge of leukocytes. We propose a model in which the cells switch between adhesion-receptor-mediated force transmission and locomotion modes that are based on cellular deformations, but independent of adhesion receptors. This plasticity in migration strategies allows leukocytes to adapt to the geometry and molecular composition of their environment.}, author = {Jörg Renkawitz and Michael Sixt}, journal = {EMBO Reports}, number = {10}, pages = {744 -- 750}, publisher = {Wiley-Blackwell}, title = {{Mechanisms of force generation and force transmission during interstitial leukocyte migration}}, doi = {10.1038/embor.2010.147}, volume = {11}, year = {2010}, } @phdthesis{3962, author = {Pflicke, Holger}, issn = {2663-337X}, publisher = {Institute of Science and Technology Austria}, title = {{Dendritic cell migration across basement membranes in the skin}}, year = {2010}, } @article{3963, abstract = {Almost all species of the orchid genus Ophrys are pollinated by sexual deception. The orchids mimic the sex pheromone of receptive female insects, mainly hymenopterans, in order to attract males seeking to copulate. Most Ophrys species have achromatic flowers, but some exhibit a coloured perianth and a bright, conspicuous labellum pattern. We recently showed that the pink perianth of Ophrys heldreichii flowers increases detectability by its pollinator, males of the long-horned bee Eucera berlandi. Here we tested the hypothesis that the bright, complex labellum pattern mimics the female of the pollinator to increase attractiveness toward males. In a dual-choice test we offered E. berlandi males an O. heldreichii flower and a flower from O. dictynnae, which also exhibits a pinkish perianth but no conspicuous labellum pattern. Both flowers were housed in UV-transmitting acrylic glass boxes to exclude olfactory signals. Males significantly preferred O. heldreichii to O. dictynnae flowers. In a second experiment, we replaced the perianth of both flowers with identical artificial perianths made from pink card, so that only the labellum differed between the two flower stimuli. Males then chose between both stimuli at random, suggesting that the presence of a labellum pattern does not affect their choice. Spectral measurements revealed higher colour contrast with the background of the perianth of O. heldreichii compared to O. dictynnae, but no difference in green receptor-specific contrast or brightness. Our results show that male choice is guided by the chromatic contrast of the perianth during the initial flower approach but is not affected by the presence of a labellum pattern. Instead, we hypothesise that the labellum pattern is involved in aversive learning during post-copulatory behaviour and used by the orchid as a strategy to increase outcrossing.}, author = {Streinzer, M. and Ellis, Thomas and Paulus, H. and Spaethe, J.}, journal = {Arthropod-Plant Interactions}, number = {3}, pages = {141 -- 148}, publisher = {Springer}, title = {{Visual discrimination between two sexually deceptive Ophrys species by a bee pollinator}}, doi = {10.1007/s11829-010-9093-4}, volume = {4}, year = {2010}, } @article{3964, abstract = {We prove two stability results for Lipschitz functions on triangulable, compact metric spaces and consider applications of both to problems in systems biology. Given two functions, the first result is formulated in terms of the Wasserstein distance between their persistence diagrams and the second in terms of their total persistence.}, author = {Cohen-Steiner, David and Herbert Edelsbrunner and Harer, John and Mileyko, Yuriy}, journal = {Foundations of Computational Mathematics}, number = {2}, pages = {127 -- 139}, publisher = {Springer}, title = {{Lipschitz functions have L_p-stable persistence}}, doi = {10.1007/s10208-010-9060-6}, volume = {10}, year = {2010}, } @article{4134, abstract = {All species are restricted in their distribution. Currently, ecological models can only explain such limits if patches vary in quality, leading to asymmetrical dispersal, or if genetic variation is too low at the margins for adaptation. However, population genetic models suggest that the increase in genetic variance resulting from dispersal should allow adaptation to almost any ecological gradient. Clearly therefore, these models miss something that prevents evolution in natural populations. We developed an individual-based simulation to explore stochastic effects in these models. At high carrying capacities, our simulations largely agree with deterministic predictions. However, when carrying capacity is low, the population fails to establish for a wide range of parameter values where adaptation was expected from previous models. Stochastic or transient effects appear critical around the boundaries in parameter space between simulation behaviours. Dispersal, gradient steepness, and population density emerge as key factors determining adaptation on an ecological gradient. }, author = {Bridle, Jon and Polechova, Jitka and Kawata, Masakado and Butlin, Roger}, journal = {Ecology Letters}, number = {4}, pages = {485 -- 494}, publisher = {Wiley-Blackwell}, title = {{Why is adaptation prevented at ecological margins? New insights from individual-based simulations}}, doi = {10.1111/j.1461-0248.2010.01442.x}, volume = {13}, year = {2010}, } @article{4157, abstract = {Integrin- and cadherin-mediated adhesion is central for cell and tissue morphogenesis, allowing cells and tissues to change shape without loosing integrity. Studies predominantly in cell culture showed that mechanosensation through adhesion structures is achieved by force-mediated modulation of their molecular composition. The specific molecular composition of adhesion sites in turn determines their signalling activity and dynamic reorganization. Here, we will review how adhesion sites respond to mecanical stimuli, and how spatially and temporally regulated signalling from different adhesion sites controls cell migration and tissue morphogenesis.}, author = {Papusheva, Ekaterina and Heisenberg, Carl-Philipp J}, journal = {EMBO Journal}, number = {16}, pages = {2753 -- 2768}, publisher = {Wiley-Blackwell}, title = {{Spatial organization of adhesion: force-dependent regulation and function in tissue morphogenesis}}, doi = {10.1038/emboj.2010.182}, volume = {29}, year = {2010}, } @article{4163, abstract = {Organ formation requires the precise assembly of progenitor cells into a functional multicellular structure. Mechanical forces probably participate in this process but how they influence organ morphogenesis is still unclear. Here, we show that Wnt11- and Prickle1a-mediated planar cell polarity (PCP) signalling coordinates the formation of the zebrafish ciliated laterality organ (Kupffer's vesicle) by regulating adhesion properties between organ progenitor cells (the dorsal forerunner cells, DFCs). Combined inhibition of Wnt11 and Prickle1a reduces DFC cell-cell adhesion and impairs their compaction and arrangement during vesicle lumen formation. This leads to the formation of a mis-shapen vesicle with small fragmented lumina and shortened cilia, resulting in severely impaired organ function and, as a consequence, randomised laterality of both molecular and visceral asymmetries. Our results reveal a novel role for PCP-dependent cell adhesion in coordinating the supracellular organisation of progenitor cells during vertebrate laterality organ formation.}, author = {Oteíza, Pablo and Koeppen, Mathias and Krieg, Michael and Pulgar, Eduardo and Farias, Cecilia and Melo, Cristina and Preibisch, Steffen and Mueller, Daniel and Tada, Masazumi and Hartel, Steffen and Heisenberg, Carl-Philipp J and Concha, Miguel}, journal = {Development}, number = {20}, pages = {3459 -- 3468}, publisher = {Company of Biologists}, title = {{Planar cell polarity signalling regulates cell adhesion properties in progenitors of the zebrafish laterality organ}}, doi = {10.1242/dev.049981}, volume = {137}, year = {2010}, } @article{4187, abstract = {Cell migration is central to embryonic development, homeostasis and disease(1), processes in which cells move as part of a group or individually. Whereas the mechanisms controlling single-cell migration in vitro are relatively well understood(2-4), less is known about the mechanisms promoting the motility of individual cells in vivo. In particular, it is not clear how cells that form blebs in their migration use those protrusions to bring about movement in the context of the three-dimensional cellular environment(5,6). Here we show that the motility of chemokine-guided germ cells within the zebrafish embryo requires the function of the small Rho GTPases Rac1 and RhoA, as well as E-cadherin-mediated cell-cell adhesion. Using fluorescence resonance energy transfer we demonstrate that Rac1 and RhoA are activated in the cell front. At this location, Rac1 is responsible for the formation of actin-rich structures, and RhoA promotes retrograde actin flow. We propose that these actin-rich structures undergoing retrograde flow are essential for the generation of E-cadherin-mediated traction forces between the germ cells and the surrounding tissue and are therefore crucial for cell motility in vivo.}, author = {Kardash, Elena and Reichman-Fried, Michal and Maître, Jean-Léon and Boldajipour, Bijan and Ekaterina Papusheva and Messerschmidt, Esther-Maria and Heisenberg, Carl-Philipp and Raz, Erez}, journal = {Nature Cell Biology}, number = {1}, pages = {47 -- 53}, publisher = {Nature Publishing Group}, title = {{A role for Rho GTPases and cell-cell adhesion in single-cell motility in vivo}}, doi = {10.1038/ncb2003}, volume = {12}, year = {2010}, } @article{4221, abstract = {Collective cell migration, the simultaneous movement of multiple cells that are connected by cell-cell adhesion, is ubiquitous in development, tissue repair, and tumor metastasis [1, 2]. It has been hypothesized that the directionality of cell movement during collective migration emerges as a collective property [3, 4]. Here we determine how movement directionality is established in collective mesendoderm migration during zebrafish gastrulation. By interfering with two key features of collective migration, (1) having neighboring cells and (2) adhering to them, we show that individual mesendoderm cells are capable of normal directed migration when moving as single cells but require cell-cell adhesion to participate in coordinated and directed migration when moving as part of a group. We conclude that movement directionality is not a de novo collective property of mesendoderm cells but rather a property of single mesendoderm cells that requires cell-cell adhesion during collective migration.}, author = {Arboleda Estudillo, Yohanna and Krieg, Michael and Stuehmer, Jan and Licata, Nicholas and Mueller, Daniel and Heisenberg, Carl-Philipp J}, journal = {Current Biology}, number = {2}, pages = {161 -- 169}, publisher = {Cell Press}, title = {{Movement directionality in collective migration of germ layer progenitors}}, doi = {10.1016/j.cub.2009.11.036}, volume = {20}, year = {2010}, } @article{4243, abstract = {We investigate a new model for populations evolving in a spatial continuum. This model can be thought of as a spatial version of the Lambda-Fleming-Viot process. It explicitly incorporates both small scale reproduction events and large scale extinction-recolonisation events. The lineages ancestral to a sample from a population evolving according to this model can be described in terms of a spatial version of the Lambda-coalescent. Using a technique of Evans (1997), we prove existence and uniqueness in law for the model. We then investigate the asymptotic behaviour of the genealogy of a finite number of individuals sampled uniformly at random (or more generally `far enough apart') from a two-dimensional torus of sidelength L as L tends to infinity. Under appropriate conditions (and on a suitable timescale) we can obtain as limiting genealogical processes a Kingman coalescent, a more general Lambda-coalescent or a system of coalescing Brownian motions (with a non-local coalescence mechanism).}, author = {Barton, Nicholas H and Etheridge, Alison and Véber, Amandine}, journal = {Electronic Journal of Probability}, number = {7}, pages = {162 -- 216}, publisher = {Institute of Mathematical Statistics}, title = {{A new model for evolution in a spatial continuum}}, doi = {10.1214/EJP.v15-741}, volume = {15}, year = {2010}, } @inbook{4339, abstract = {Mit diesem Buch möchten wir einen Überblick der aktuellen Diskussion zum Thema Bibliothek 2.0 geben und den Stand der tatsächlichen Umsetzung der Web 2.0-Ansätze in deutschsprachigen Bibliotheken beleuchten. An dieser Stelle ist die Frage erlaubt, warum es zu einer Zeit, in der es bereits die ersten "Web 3.0"- Konferenzen gibt, eines Handbuches der Bibliothek 2.0 noch bedarf. Und warum es überhaupt ein deutschsprachiges Handbuch zur Bibliothek 2.0 braucht, wo es doch bereits verschiedenste Publikationen zu diesem Thema aus anderen Ländern, insbesondere des angloamerikanischen Raums gibt. Ist dazu nicht bereits alles gesagt?}, author = {Bergmann, Julia and Danowski, Patrick}, booktitle = {Handbuch Bibliothek 2.0}, editor = {Bergmann, Julia and Danowski, Patrick}, pages = {5 -- 20}, publisher = {De Gruyter}, title = {{Ist Bibliothek 2.0 überhaupt noch relevant? – Eine Einleitung in das Handbuch}}, doi = {10.1515/9783110232103}, year = {2010}, } @misc{4340, abstract = {More and more libraries starting semantic web projects. The question about the license of the data is not discussed or the discussion is deferred to the end of project. in this paper is discussed why the question of the license is so important in context of the semantic web that is should be one of the first aspects in a semantic web project. Also it will be shown why a public domain weaver is the only solution that fulfill the the special requirements of the semantic web and that guaranties the reuseablitly of semantic library data for a sustainability of the projects. }, author = {Danowski, Patrick}, booktitle = {European Library Automation Group (ELAG) 2010}, publisher = {Elsevier}, title = {{Open bibliographic data}}, year = {2010}, }