@article{3760, abstract = {We introduce a method for efficiently animating a wide range of deformable materials. We combine a high resolution surface mesh with a tetrahedral finite element simulator that makes use of frequent re-meshing. This combination allows for fast and detailed simulations of complex elastic and plastic behavior. We significantly expand the range of physical parameters that can be simulated with a single technique, and the results are free from common artifacts such as volume-loss, smoothing, popping, and the absence of thin features like strands and sheets. Our decision to couple a high resolution surface with low-resolution physics leads to efficient simulation and detailed surface features, and our approach to creating the tetrahedral mesh leads to an order-of-magnitude speedup over previous techniques in the time spent re-meshing. We compute masses, collisions, and surface tension forces on the scale of the fine mesh, which helps avoid visual artifacts due to the differing mesh resolutions. The result is a method that can simulate a large array of different material behaviors with high resolution features in a short amount of time.}, author = {Wojtan, Christopher J and Turk, Greg}, journal = {ACM Transactions on Graphics}, number = {3}, publisher = {ACM}, title = {{Fast viscoelastic behavior with thin features}}, doi = {10.1145/1360612.1360646}, volume = {27}, year = {2008}, } @article{3769, abstract = {The geometrical representation of the space of phylogenetic trees implies a metric on the space of weighted trees. This metric, the geodesic distance, is the length of the shortest path through that space. We present an exact algorithm to compute this metric. For biologically reasonable trees, the implementation allows fast computations of the geodesic distance, although the running time of the algorithm is worst-case exponential. The algorithm was applied to pairs of 118 gene trees of the metazoa. The results show that a special path in tree space, the cone path, which can be computed in linear time, is a good approximation of the geodesic distance. The program GeoMeTree is a python implementation of the geodesic distance, and it is approximations and is available from www.cibiv.at/software/geometree.}, author = {Anne Kupczok and von Haeseler,Arndt and Klaere,Steffen}, journal = {Journal of Computational Biology}, number = {6}, pages = {577 -- 591}, publisher = {Mary Ann Liebert}, title = {{An Exact Algorithm for the Geodesic Distance between Phylogenetic Trees.}}, doi = {4200}, volume = {15}, year = {2008}, } @article{3822, abstract = {Dentate gyrus granule cells transmit action potentials (APs) along their unmyelinated mossy fibre axons to the CA3 region. Although the initiation and propagation of APs are fundamental steps during neural computation, little is known about the site of AP initiation and the speed of propagation in mossy fibre axons. To address these questions, we performed simultaneous somatic and axonal whole-cell recordings from granule cells in acute hippocampal slices of adult mice at approximately 23 degrees C. Injection of short current pulses or synaptic stimulation evoked axonal and somatic APs with similar amplitudes. By contrast, the time course was significantly different, as axonal APs had a higher maximal rate of rise (464 +/- 30 V s(-1) in the axon versus 297 +/- 12 V s(-1) in the soma, mean +/- s.e.m.). Furthermore, analysis of latencies between the axonal and somatic signals showed that APs were initiated in the proximal axon at approximately 20-30 mum distance from the soma, and propagated orthodromically with a velocity of 0.24 m s(-1). Qualitatively similar results were obtained at a recording temperature of approximately 34 degrees C. Modelling of AP propagation in detailed cable models of granule cells suggested that a approximately 4 times higher Na(+) channel density ( approximately 1000 pS mum(-2)) in the axon might account for both the higher rate of rise of axonal APs and the robust AP initiation in the proximal mossy fibre axon. This may be of critical importance to separate dendritic integration of thousands of synaptic inputs from the generation and transmission of a common AP output.}, author = {Schmidt-Hieber, Christoph and Peter Jonas and Bischofberger, Josef}, journal = {Journal of Physiology}, number = {7}, pages = {1849 -- 57}, publisher = {Wiley-Blackwell}, title = {{Action potential initiation and propagation in hippocampal mossy fibre axons}}, doi = {10.1113/jphysiol.2007.150151 }, volume = {586}, year = {2008}, } @article{3823, abstract = {Two studies in this issue of Neuron (Kwon and Castillo and Rebola et al.) show that the mossy fiber-CA3 pyramidal neuron synapse, a hippocampal synapse well known for its presynaptic plasticity, exhibits a novel form of long-term potentiation of NMDAR-mediated currents, which is induced and expressed postsynaptically.}, author = {Kerr, Angharad M and Peter Jonas}, journal = {Neuron}, number = {1}, pages = {5 -- 7}, publisher = {Elsevier}, title = {{The two sides of hippocampal mossy fiber plasticity (Review)}}, doi = {10.1016/j.neuron.2007.12.015}, volume = {57}, year = {2008}, } @article{3824, abstract = {It is generally thought that transmitter release at mammalian central synapses is triggered by Ca2+ microdomains, implying loose coupling between presynaptic Ca2+ channels and Ca2+ sensors of exocytosis. Here we show that Ca2+ channel subunit immunoreactivity is highly concentrated in the active zone of GABAergic presynaptic terminals of putative parvalbumin-containing basket cells in the hippocampus. Paired recording combined with presynaptic patch pipette perfusion revealed that GABA release at basket cell-granule cell synapses is sensitive to millimolar concentrations of the fast Ca2+ chelator BAPTA but insensitive to the slow Ca2+ chelator EGTA. These results show that Ca2+ source and Ca2+ sensor are tightly coupled at this synapse, with distances in the range of 10-20 nm. Models of Ca2+ inflow-exocytosis coupling further reveal that the tightness of coupling increases efficacy, speed, and temporal precision of transmitter release. Thus, tight coupling contributes to fast feedforward and feedback inhibition in the hippocampal network.}, author = {Bucurenciu, Iancu and Kulik, Ákos and Schwaller, Beat and Frotscher, Michael and Peter Jonas}, journal = {Neuron}, number = {4}, pages = {536 -- 45}, publisher = {Elsevier}, title = {{Nanodomain coupling between Ca(2+) channels and Ca2+ sensors promotes fast and efficient transmitter release at a cortical GABAergic synapse}}, doi = {10.1016/j.neuron.2007.12.026}, volume = {57}, year = {2008}, } @article{3825, abstract = {Fast-spiking parvalbumin-expressing basket cells (BCs) represent a major type of inhibitory interneuron in the hippocampus. These cells inhibit principal cells in a temporally precise manner and are involved in the generation of network oscillations. Although BCs show a unique expression profile of Ca(2+)-permeable receptors, Ca(2+)-binding proteins and Ca(2+)-dependent signalling molecules, physiological Ca(2+) signalling in these interneurons has not been investigated. To study action potential (AP)-induced dendritic Ca(2+) influx and buffering, we combined whole-cell patch-clamp recordings with ratiometric Ca(2+) imaging from the proximal apical dendrites of rigorously identified BCs in acute slices, using the high-affinity Ca(2+) indicator fura-2 or the low-affinity dye fura-FF. Single APs evoked dendritic Ca(2+) transients with small amplitude. Bursts of APs evoked Ca(2+) transients with amplitudes that increased linearly with AP number. Analysis of Ca(2+) transients under steady-state conditions with different fura-2 concentrations and during loading with 200 microm fura-2 indicated that the endogenous Ca(2+)-binding ratio was approximately 200 (kappa(S) = 202 +/- 26 for the loading experiments). The peak amplitude of the Ca(2+) transients measured directly with 100 microm fura-FF was 39 nm AP(-1). At approximately 23 degrees C, the decay time constant of the Ca(2+) transients was 390 ms, corresponding to an extrusion rate of approximately 600 s(-1). At 34 degrees C, the decay time constant was 203 ms and the corresponding extrusion rate was approximately 1100 s(-1). At both temperatures, continuous theta-burst activity with three to five APs per theta cycle, as occurs in vivo during exploration, led to a moderate increase in the global Ca(2+) concentration that was proportional to AP number, whereas more intense stimulation was required to reach micromolar Ca(2+) concentrations and to shift Ca(2+) signalling into a non-linear regime. In conclusion, dentate gyrus BCs show a high endogenous Ca(2+)-binding ratio, a small AP-induced dendritic Ca(2+) influx, and a relatively slow Ca(2+) extrusion. These specific buffering properties of BCs will sharpen the time course of local Ca(2+) signals, while prolonging the decay of global Ca(2+) signals.}, author = {Aponte, Yexica and Bischofberger, Josef and Peter Jonas}, journal = {Journal of Physiology}, number = {8}, pages = {2061 -- 75}, publisher = {Wiley-Blackwell}, title = {{Efficient Ca(2+) buffering in fast-spiking basket cells of rat hippocampus}}, doi = {10.1113/jphysiol.2007.147298}, volume = {586}, year = {2008}, } @article{3826, abstract = {Gamma frequency (30-100 Hz) oscillations in the mature cortex underlie higher cognitive functions. Fast signaling in GABAergic interneuron networks plays a key role in the generation of these oscillations. During development of the rodent brain, gamma activity appears at the end of the first postnatal week, but frequency and synchrony reach adult levels only by the fourth week. However, the mechanisms underlying the maturation of gamma activity are unclear. Here we demonstrate that hippocampal basket cells (BCs), the proposed cellular substrate of gamma oscillations, undergo marked changes in their morphological, intrinsic, and synaptic properties between postnatal day 6 (P6) and P25. During maturation, action potential duration, propagation time, duration of the release period, and decay time constant of IPSCs decreases by approximately 30-60%. Thus, postnatal development converts BCs from slow into fast signaling devices. Computational analysis reveals that BC networks with young intrinsic and synaptic properties as well as reduced connectivity generate oscillations with moderate coherence in the lower gamma frequency range. In contrast, BC networks with mature properties and increased connectivity generate highly coherent activity in the upper gamma frequency band. Thus, late postnatal maturation of BCs enhances coherence in neuronal networks and will thereby contribute to the development of cognitive brain functions.}, author = {Doischer, Daniel and Hosp, Jonas Aurel and Yanagawa, Yuchio and Obata, Kunihiko and Peter Jonas and Vida, Imre and Bartos, Marlene}, journal = {Journal of Neuroscience}, number = {48}, pages = {12956 -- 68}, publisher = {Society for Neuroscience}, title = {{Postnatal differentiation of basket cells from slow to fast signaling devices}}, doi = {10.1523/JNEUROSCI.2890-08.2008}, volume = {28}, year = {2008}, } @article{3827, abstract = {Previous studies revealed that synaptotagmin 1 is the major Ca(2+) sensor for fast synchronous transmitter release at excitatory synapses. However, the molecular identity of the Ca(2+) sensor at hippocampal inhibitory synapses has not been determined. To address the functional role of synaptotagmin 1 at identified inhibitory terminals, we made paired recordings from synaptically connected basket cells (BCs) and granule cells (GCs) in the dentate gyrus in organotypic slice cultures from wild-type and synaptotagmin 1-deficient mice. As expected, genetic elimination of synaptotagmin 1 abolished synchronous transmitter release at excitatory GC-BC synapses. However, synchronous release at inhibitory BC-GC synapses was maintained. Quantitative analysis revealed that elimination of synaptotagmin 1 reduced release probability and depression but maintained the synchrony of transmitter release at BC-GC synapses. Elimination of synaptotagmin 1 also increased the frequency of both miniature excitatory postsynaptic currents (measured in BCs) and miniature inhibitory postsynaptic currents (recorded in GCs), consistent with a clamping function of synaptotagmin 1 at both excitatory and inhibitory terminals. Single-cell reverse-transcription quantitative PCR analysis revealed that single BCs coexpressed multiple synaptotagmin isoforms, including synaptotagmin 1-5, 7, and 11-13. Our results indicate that, in contrast to excitatory synapses, synaptotagmin 1 is not absolutely required for synchronous release at inhibitory BC-GC synapses. Thus, alternative fast Ca(2+) sensors contribute to synchronous release of the inhibitory transmitter GABA in cortical circuits.}, author = {Kerr, Angharad M and Reisinger, Ellen and Peter Jonas}, journal = {PNAS}, number = {40}, pages = {15581 -- 6}, publisher = {National Academy of Sciences}, title = {{Differential dependence of phasic transmitter release on synaptotagmin 1 at GABAergic and glutamatergic hippocampal synapses}}, doi = {10.1073/pnas.0800621105}, volume = {105}, year = {2008}, } @inbook{3872, abstract = {We survey value iteration algorithms on graphs. Such algorithms can be used for determining the existence of certain paths (model checking), the existence of certain strategies (game solving), and the probabilities of certain events (performance analysis). We classify the algorithms according to the value domain (boolean, probabilistic, or quantitative); according to the graph structure (nondeterministic, probabilistic, or multi-player); according to the desired property of paths (Borel level 1, 2, or 3); and according to the alternation depth and convergence rate of fixpoint computations.}, author = {Krishnendu Chatterjee and Thomas Henzinger}, booktitle = {25 Years in Model Checking}, pages = {107 -- 138}, publisher = {Springer}, title = {{Value iteration}}, doi = {10.1007/978-3-540-69850-0_7}, volume = {5000}, year = {2008}, } @inproceedings{3873, abstract = {We study the controller synthesis problem under budget constraints. In this problem, there is a cost associated with making an observation, and a controller can make only a limited number of observations in each round so that the total cost of the observations does not exceed a given fixed budget. The controller must ensure some omega-regular requirement subject to the budget constraint. Budget constraints arise in designing and implementing controllers for resource-constrained embedded systems, where a controller may not have enough power, time, or bandwidth to obtain data from all sensors in each round. They lead to games of imperfect information, where the unknown information is not fixed a priori, but can vary from round to round, based on the choices made by the controller how to allocate its budget. We show that the budget-constrained synthesis problem for W-regular objectives is complete for exponential time. In addition to studying synthesis under a fixed budget constraint, we study the budget optimization problem, where given a plant, an objective, and observation costs, we have to find a controller that achieves the objective with minimal average accumulated cost (or minimal peak cost). We show that this problem is reducible to a game of imperfect information where the winning objective is a conjunction of an omega-regular condition and a long-run average condition (or a least max-cost condition), and this again leads to an exponential-time algorithm. Finally, we extend our results to games over infinite state spaces, and show that the budget-constrained synthesis problem is decidable for infinite state games with stable quotients of finite index. Consequently, the discrete time budget-constrained synthesis problem is decidable for rectangular hybrid automata.}, author = {Krishnendu Chatterjee and Majumdar, Ritankar S and Thomas Henzinger}, pages = {72 -- 86}, publisher = {Springer}, title = {{Controller synthesis with budget constraints}}, doi = {DOI: 10.1007/978-3-540-78929-1_6}, volume = {4981}, year = {2008}, } @inproceedings{3874, abstract = {We consider concurrent two-player timed automaton games with omega-regular objectives specified as parity conditions. These games offer an appropriate model for the synthesis of real-time controllers. Earlier works on timed games focused on pure strategies for each player. We study, for the first time, the use of randomized strategies in such games. While pure (i.e., nonrandomized) strategies in timed games require infinite memory for winning even with respect to reachability objectives, we show that randomized strategies can win with finite memory with respect to all parity objectives. Also, the synthesized randomized real-time controllers are much simpler in structure than the corresponding pure controllers, and therefore easier to implement. For safety objectives we prove the existence of pure finite-memory winning strategies. Finally, while randomization helps in simplifying the strategies required for winning timed parity games, we prove that randomization does not help in winning at more states.}, author = {Krishnendu Chatterjee and Thomas Henzinger and Prabhu, Vinayak S}, pages = {87 -- 100}, publisher = {Springer}, title = {{Trading infinite memory for uniform randomness in timed games}}, doi = {10.1007/978-3-540-78929-1_7}, volume = {4981}, year = {2008}, } @inproceedings{3875, abstract = {We study the problem of model checking Interval-valued Discrete-time Markov Chains (IDTMC). IDTMCs are discrete-time finite Markov Chains for which the exact transition probabilities are riot known. Instead in IDTMCs, each transition is associated with an interval in which the actual transition probability must lie. We consider two semantic interpretations for the uncertainty in the transition probabilities of an IDTMC. In the first interpretation, we think of an IDTMC as representing a (possibly uncountable) family of (classical) discrete-time Markov Chains, where each member of the family is a Markov Chain whose transition probabilities lie within the interval range given in the IDTMC. We call this semantic interpretation Uncertain Markov Chains (UMC). In the second semantics for an IDTMC, which we call Interval Markov Decision Process (IMDP), we view the uncertainty as being resolved through non-determinism. In other words, each time a state is visited, we adversarially pick a transition distribution that respects the interval constraints, and take a probabilistic step according to the chosen distribution. We introduce a logic omega-PCTL that can express liveness, strong fairness, and omega-regular properties (such properties cannot be expressed in PCTL). We show that the omega-PCTL model checking problem for Uncertain Markov Chain semantics is decidable in PSPACE (same as the best known upper bound for PCTL) and for Interval Markov Decision Process semantics is decidable in coNP (improving the previous known PSPACE bound for PCTL). We also show that the qualitative fragment of the logic can lie solved in coNP for the UMC interpretation, and can be solved in polynomial time for a sub-class of UMCs. We also prove lower bounds for these model checking problems. We show that the model checking problem of IDTMCs with LTL formulas can be solved for both UMC and IMDP semantics by reduction to the model checking problem of IDTMC with omega-PcTL formulas.}, author = {Krishnendu Chatterjee and Thomas Henzinger and Sen, Koushik}, pages = {302 -- 317}, publisher = {Springer}, title = {{Model-checking omega-regular properties of interval Markov chains}}, doi = {10.1007/978-3-540-78499-9_22}, volume = {4962}, year = {2008}, } @inproceedings{3876, abstract = {We consider two-player games played in real time on game structures with clocks and parity objectives. The games are concurrent in that at each turn, both players independently propose a time delay and an action, and the action with the shorter delay is chosen. To prevent a player from winning by blocking time, we restrict each player to strategies that ensure that the player cannot be responsible for causing a zeno run. First, we present an efficient reduction of these games to turn-based (i.e., nonconcurrent) finite-state (i.e., untimed) parity games. The states of the resulting game are pairs of clock regions of the original game. Our reduction improves the best known complexity for solving timed parity games. Moreover, the rich class of algorithms for classical parity games can now be applied to timed parity games. Second, we consider two restricted classes of strategies for the player that represents the controller in a real-time synthesis problem, namely, limit-robust and bounded-robust strategies. Using a limit-robust strategy, the controller cannot choose an exact real-valued time delay but must allow for some nonzero jitter in each of its actions. If there is a given lower bound on the jitter, then the strategy is bounded-robust. We show that exact strategies are more powerful than limit-robust strategies, which are more powerful than bounded-robust strategies for any bound. For both kinds of robust strategies, we present efficient reductions to standard timed automaton games. These reductions provide algorithms for the synthesis of robust real-time controllers.}, author = {Krishnendu Chatterjee and Thomas Henzinger and Prabhu, Vinayak S}, pages = {124 -- 140}, publisher = {Springer}, title = {{Timed parity games: complexity and robustness}}, doi = {10.1007/978-3-540-85778-5_10}, volume = {5215}, year = {2008}, } @inproceedings{3877, abstract = {The synthesis problem asks to construct a reactive finite-state system from an omega-regular specification. Initial specifications are often unrealizable, which means that there is no system that implements the specification. A common reason for unrealizability is that assumptions on the environment of the system are incomplete. We study the problem of correcting an unrealizable specification phi by computing an environment assumption psi such that the new specification psi -> phi is realizable. Our aim is to construct an assumption psi that constrains only the environment and is as weak as possible. We present a two-step algorithm for computing assumptions. The algorithm operates on the game graph that is used to answer the realizability question. First, we compute a safety assumption that removes a minimal set of environment edges from the graph. Second, we compute a liveness assumption that puts fairness conditions on some of the remaining environment edges. We show that the problem of finding a minimal set of fair edges is computationally hard, and we use probabilistic games to compute a locally minimal fairness assumption.}, author = {Krishnendu Chatterjee and Thomas Henzinger and Jobstmann, Barbara}, pages = {147 -- 161}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Environment assumptions for synthesis}}, doi = {10.1007/978-3-540-85361-9_14}, volume = {5201}, year = {2008}, } @inproceedings{3878, abstract = {We study the problem of generating a test sequence that achieves maximal coverage for a reactive system under test. We formulate the problem as a repeated game between the tester and the system, where the system state space is partitioned according to some coverage criterion and the objective of the tester is to maximize the set of partitions (or coverage goals) visited during the game. We show the complexity of the maximal coverage problem for non-deterministic systems is PSPACE-complete, but is NP-complete for deterministic systems. For the special case of non-deterministic systems with a re-initializing “reset” action, which represent running a new test input on a re-initialized system, we show that the complexity is coNP-complete. Our proof technique for reset games uses randomized testing strategies that circumvent the exponentially large memory requirement of deterministic testing strategies.}, author = {Krishnendu Chatterjee and de Alfaro, Luca and Majumdar, Ritankar S}, pages = {91 -- 106}, publisher = {Springer}, title = {{The complexity of coverage}}, doi = {10.1007/978-3-540-89330-1_7}, volume = {5356}, year = {2008}, } @inproceedings{3879, abstract = {Quantitative generalizations of classical languages, which assign to each word a real number instead of a boolean value, have applications in modeling resource-constrained computation. We use weighted automata (finite automata with transition weights) to define several natural classes of quantitative languages over finite and infinite words; in particular, the real value of an infinite run is computed as the maximum, limsup, liminf, limit average, or discounted sum of the transition weights. We define the classical decision problems of automata theory (emptiness, universality, language inclusion, and language equivalence) in the quantitative setting and study their computational complexity. As the decidability of language inclusion remains open for some classes of weighted automata, we introduce a notion of quantitative simulation that is decidable and implies language inclusion. We also give a complete characterization of the expressive power of the various classes of weighted automata. In particular, we show that most classes of weighted automata cannot be determinized.}, author = {Krishnendu Chatterjee and Doyen, Laurent and Thomas Henzinger}, pages = {385 -- 400}, publisher = {Springer}, title = {{Quantitative languages}}, doi = {10.1007/978-3-540-87531-4_28}, volume = {5213}, year = {2008}, } @inproceedings{3880, abstract = {We consider imperfect-information parity games in which strategies rely on observations that provide imperfect information about the history of a play. To solve such games, i.e., to determine the winning regions of players and corresponding winning strategies, one can use the subset construction to build an equivalent perfect-information game. Recently, an algorithm that avoids the inefficient subset construction has been proposed. The algorithm performs a fixed-point computation in a lattice of antichains, thus maintaining a succinct representation of state sets. However, this representation does not allow to recover winning strategies. In this paper, we build on the antichain approach to develop an algorithm for constructing the winning strategies in parity games of imperfect information. We have implemented this algorithm as a prototype. To our knowledge, this is the first implementation of a procedure for solving imperfect-information parity games on graphs.}, author = {Berwanger, Dietmar and Krishnendu Chatterjee and Doyen, Laurent and Thomas Henzinger and Raje, Sangram}, pages = {325 -- 339}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Strategy construction for parity games with imperfect information}}, doi = {10.1007/978-3-540-85361-9}, volume = {5201}, year = {2008}, } @article{3903, abstract = {Background The invasive garden ant, Lasius neglectus, is the most recently detected pest ant and the first known invasive ant able to become established and thrive in the temperate regions of Eurasia. In this study, we aim to reconstruct the invasion history of this ant in Europe analysing 14 populations with three complementary approaches: genetic microsatellite analysis, chemical analysis of cuticular hydrocarbon profiles and behavioural observations of aggression behaviour. We evaluate the relative informative power of the three methodological approaches and estimate both the number of independent introduction events from a yet unknown native range somewhere in the Black Sea area, and the invasive potential of the existing introduced populations. Results Three clusters of genetically similar populations were detected, and all but one population had a similar chemical profile. Aggression between populations could be predicted from their genetic and chemical distance, and two major clusters of non-aggressive groups of populations were found. However, populations of L. neglectus did not separate into clear supercolonial associations, as is typical for other invasive ants. Conclusion The three methodological approaches gave consistent and complementary results. All joint evidence supports the inference that the 14 introduced populations of L. neglectus in Europe likely arose from only very few independent introductions from the native range, and that new infestations were typically started through introductions from other invasive populations. This indicates that existing introduced populations have a very high invasive potential when the ants are inadvertently spread by human transport. }, author = {Ugelvig, Line V and Drijfhout, Falko and Kronauer, Daniel and Boomsma, Jacobus and Pedersen, Jes and Cremer, Sylvia}, journal = {BMC Biology}, number = {11}, publisher = {BioMed Central}, title = {{The introduction history of invasive garden ants in Europe: integrating genetic, chemical and behavioural approaches}}, doi = {10.1186/1741-7007-6-11}, volume = {6}, year = {2008}, } @article{3905, abstract = {Winged and wingless males coexist in the ant Cardiocondyla obscurior. Wingless (“ergatoid”) males never leave their maternal colony and fight remorselessly among each other for the access to emerging females. The peaceful winged males disperse after about 10 days, but beforehand also mate in the nest. In the first 5 days of their life, winged males perform a chemical female mimicry that protects them against attack and even makes them sexually attractive to ergatoid males. When older, the chemical profile of winged males no longer matches that of virgin females; nevertheless, they are still tolerated, which so far has been puzzling. Contrasting this general pattern, we have identified a single aberrant colony in which all winged males were attacked and killed by the ergatoid males. A comparative analysis of the morphology and chemical profile of these untypical attacked winged males and the tolerated males from several normal colonies revealed that normal old males are still performing some chemical mimicry to the virgin queens, though less perfect than in their young ages. The anomalous attacked winged males, on the other hand, had a very different odour to the females. Our study thus exemplifies that the analysis of rare malfunctioning can add valuable insight on functioning under normal conditions and allows the conclusion that older winged males from normal colonies of the ant C. obscurior are guarded through an imperfect chemical female mimicry, still close enough to protect against attacks by the wingless fighters yet dissimilar enough not to elicit their sexual interest.}, author = {Cremer, Sylvia and D'Ettorre, Patrizia and Drijfhout, Falko and Sledge, Matthew and Turillazzi, Stefano and Heinze, Jürgen}, journal = {Naturwissenschaften}, number = {11}, pages = {1101 -- 1105}, publisher = {Springer}, title = {{Imperfect chemical female mimicry in males of the ant Cardiocondyla obscurior}}, doi = {10.1007/s00114-008-0430-8}, volume = {95}, year = {2008}, } @article{3906, author = {Cremer, Sylvia and Ugelvig, Line V and Drijfhout, Falko and Schlick Steiner, Birgit and Steiner, Florian and Seifert, Bernhard and Hughes, David and Schulz, Andreas and Petersen, Klaus and Konrad, Heino and Stauffer, Christian and Kiran, Kadri and Espadaler, Xavier and D'Ettorre, Patrizia and Aktaç, Nihat and Eilenberg, Jørgen and Jones, Graeme and Nash, David and Pedersen, Jes and Boomsma, Jacobus}, journal = {PLoS One}, number = {12}, publisher = {Public Library of Science}, title = {{The evolution of invasiveness in garden ants}}, doi = {10.1371/journal.pone.0003838}, volume = {3}, year = {2008}, }