TY - JOUR AB - When two indistinguishable single photons impinge at the two inputs of a beam splitter they coalesce into a pair of photons appearing in either one of its two outputs. This effect is due to the bosonic nature of photons and was first experimentally observed by Hong, Ou and Mandel. Here, we present the observation of the Hong-Ou-Mandel effect with two independent single-photon sources in the microwave frequency domain. We probe the indistinguishability of single photons, created with a controllable delay, in time-resolved second-order cross- and auto-correlation function measurements. Using quadrature amplitude detection we are able to resolve different photon numbers and detect coherence in and between the output arms. This scheme allows us to fully characterize the two-mode entanglement of the spatially separated beam-splitter output modes. Our experiments constitute a first step towards using two-photon interference at microwave frequencies for quantum communication and information processing. AU - Lang, C AU - Eichler, Christopher AU - Steffen, L. Kraig AU - Johannes Fink AU - Woolley, Matthew J AU - Blais, Alexandre AU - Wallraff, Andreas ID - 1787 IS - 6 JF - Nature Physics TI - Correlations, indistinguishability and entanglement in Hong-Ou-Mandel experiments at microwave frequencies VL - 9 ER - TY - JOUR AB - We report the experimental observation and a theoretical explanation of collective suppression of linewidths for multiple superconducting qubits coupled to a good cavity. This demonstrates how strong qubit-cavity coupling can significantly modify the dephasing and dissipation processes that might be expected for individual qubits, and can potentially improve coherence times in many-body circuit QED. AU - Nissen, Felix AU - Johannes Fink AU - Mlynek, Jonas A AU - Wallraff, Andreas AU - Keeling, Jonathan M ID - 1786 IS - 20 JF - Physical Review Letters TI - Collective suppression of linewidths in circuit QED VL - 110 ER - TY - JOUR AB - In the September 12, 2013 issue of Nature, the Epi4K Consortium (. Allen etal., 2013) reported sequencing 264patient trios with epileptic encephalopathies. The Consortium focused on genes exceptionally intolerant to sequence variations and found substantial interconnections with autism and intellectual disability gene networks. AU - Gaia Novarino AU - Baek, SeungTae AU - Gleeson, Joseph G ID - 1790 IS - 1 JF - Neuron TI - The sacred disease: The puzzling genetics of epileptic disorders VL - 80 ER - TY - JOUR AB - Complex I (NADH:ubiquinone oxidoreductase) is central to cellular energy production, being the first and largest enzyme of the respiratory chain in mitochondria. It couples electron transfer from NADH to ubiquinone with proton translocation across the inner mitochondrial membrane and is involved in a wide range of human neurodegenerative disorders. Mammalian complex I is composed of 44 different subunits, whereas the 'minimal' bacterial version contains 14 highly conserved 'core' subunits. The L-shaped assembly consists of hydrophilic and membrane domains. We have determined all known atomic structures of complex I, starting from the hydrophilic domain of Thermus thermophilus enzyme (eight subunits, nine Fe-S clusters), followed by the membrane domains of the Escherichia coli (six subunits, 55 transmembrane helices) and T. thermophilus (seven subunits, 64 transmembrane helices) enzymes, and finally culminating in a recent crystal structure of the entire intact complex I from T. thermophilus (536 kDa, 16 subunits, nine Fe-S clusters, 64 transmembrane helices). The structure suggests an unusual and unique coupling mechanism via longrange conformational changes. Determination of the structure of the entire complex was possible only through this step-by-step approach, building on from smaller subcomplexes towards the entire assembly. Large membrane proteins are notoriously difficult to crystallize, and so various non-standard and sometimes counterintuitive approaches were employed in order to achieve crystal diffraction to high resolution and solve the structures. These steps, as well as the implications from the final structure, are discussed in the present review. AU - Leonid Sazanov AU - Baradaran, Rozbeh AU - Efremov, Rouslan G AU - Berrisford, John M AU - Minhas, Gurdeep S ID - 1977 IS - 5 JF - Biochemical Society Transactions TI - A long road towards the structure of respiratory complex I, a giant molecular proton pump VL - 41 ER - TY - JOUR AB - Complex I is the first and largest enzyme of the respiratory chain and has a central role in cellular energy production through the coupling of NADH:ubiquinone electron transfer to proton translocation. It is also implicated in many common human neurodegenerative diseases. Here, we report the first crystal structure of the entire, intact complex I (from Thermus thermophilus) at 3.3 Å resolution. The structure of the 536-kDa complex comprises 16 different subunits, with a total of 64 transmembrane helices and 9 iron-sulphur clusters. The core fold of subunit Nqo8 (ND1 in humans) is, unexpectedly, similar to a half-channel of the antiporter-like subunits. Small subunits nearby form a linked second half-channel, which completes the fourth proton-translocation pathway (present in addition to the channels in three antiporter-like subunits). The quinone-binding site is unusually long, narrow and enclosed. The quinone headgroup binds at the deep end of this chamber, near iron-sulphur cluster N2. Notably, the chamber is linked to the fourth channel by a 'funnel' of charged residues. The link continues over the entire membrane domain as a flexible central axis of charged and polar residues, and probably has a leading role in the propagation of conformational changes, aided by coupling elements. The structure suggests that a unique, out-of-the-membrane quinone-reaction chamber enables the redox energy to drive concerted long-range conformational changes in the four antiporter-like domains, resulting in translocation of four protons per cycle. AU - Baradaran, Rozbeh AU - Berrisford, John M AU - Minhas, Gurdeep S AU - Leonid Sazanov ID - 1978 IS - 7438 JF - Nature TI - Crystal structure of the entire respiratory complex i VL - 494 ER - TY - JOUR AB - Although transitions of sex-determination mechanisms are frequent in species with homomorphic sex chromosomes, heteromorphic sex chromosomes are thought to represent a terminal evolutionary stage owing to chromosome-specific adaptations such as dosage compensation or an accumulation of sex-specific mutations. Here we show that an autosome of Drosophila, the dot chromosome, was ancestrally a differentiated X chromosome. We analyse the whole genome of true fruitflies (Tephritidae), flesh flies (Sarcophagidae) and soldier flies (Stratiomyidae) to show that genes located on the dot chromosome of Drosophila are X-linked in outgroup species, whereas Drosophila X-linked genes are autosomal. We date this chromosomal transition to early drosophilid evolution by sequencing the genome of other Drosophilidae. Our results reveal several puzzling aspects of Drosophila dot chromosome biology to be possible remnants of its former life as a sex chromosome, such as its minor feminizing role in sex determination or its targeting by a chromosome-specific regulatory mechanism. We also show that patterns of biased gene expression of the dot chromosome during early embryogenesis, oogenesis and spermatogenesis resemble that of the current X chromosome. Thus, although sex chromosomes are not necessarily evolutionary end points and can revert back to an autosomal inheritance, the highly specialized genome architecture of this former X chromosome suggests that severe fitness costs must be overcome for such a turnover to occur. AU - Beatriz Vicoso AU - Bachtrog, Doris ID - 1991 IS - 7458 JF - Nature TI - Reversal of an ancient sex chromosome to an autosome in Drosophila VL - 499 ER - TY - JOUR AB - The rod-shaped bacterium Escherichia coli selects the cell center as site of division with the help of the proteins MinC, MinD, and MinE. This protein system collectively oscillates between the two cell poles by alternately binding to the membrane in one of the two cell halves. This dynamic behavior, which emerges from the interaction of the ATPase MinD and its activator MinE on the cell membrane, has become a paradigm for protein self-organization. Recently, it has been found that not only the binding of MinD to the membrane, but also interactions of MinE with the membrane contribute to Min-protein self-organization. Here, we show that by accounting for this finding in a computational model, we can comprehensively describe all observed Min-protein patterns in vivo and in vitro. Furthermore, by varying the system's geometry, our computations predict patterns that have not yet been reported. We confirm these predictions experimentally. AU - Bonny, Mike AU - Fischer-Friedrich, Elisabeth AU - Martin Loose AU - Schwille, Petra AU - Kruse, Karsten ID - 1988 IS - 12 JF - PLoS Computational Biology TI - Membrane binding of MinE allows for a comprehensive description of Min-protein pattern formation VL - 9 ER - TY - JOUR AB - Many algorithms for inferring causality rely heavily on the faithfulness assumption. The main justification for imposing this assumption is that the set of unfaithful distributions has Lebesgue measure zero, since it can be seen as a collection of hypersurfaces in a hypercube. However, due to sampling error the faithfulness condition alone is not sufficient for statistical estimation, and strong-faithfulness has been proposed and assumed to achieve uniform or high-dimensional consistency. In contrast to the plain faithfulness assumption, the set of distributions that is not strong-faithful has nonzero Lebesgue measure and in fact, can be surprisingly large as we show in this paper. We study the strong-faithfulness condition from a geometric and combinatorial point of view and give upper and lower bounds on the Lebesgue measure of strong-faithful distributions for various classes of directed acyclic graphs. Our results imply fundamental limitations for the PC-algorithm and potentially also for other algorithms based on partial correlation testing in the Gaussian case. AU - Uhler, Caroline AU - Raskutti, Garvesh AU - Bühlmann, Peter AU - Yu, Bin ID - 2010 IS - 2 JF - The Annals of Statistics TI - Geometry of the faithfulness assumption in causal inference VL - 41 ER - TY - JOUR AB - Traditional statistical methods for confidentiality protection of statistical databases do not scale well to deal with GWAS databases especially in terms of guarantees regarding protection from linkage to external information. The more recent concept of differential privacy, introduced by the cryptographic community, is an approach which provides a rigorous definition of privacy with meaningful privacy guarantees in the presence of arbitrary external information, although the guarantees may come at a serious price in terms of data utility. Building on such notions, we propose new methods to release aggregate GWAS data without compromising an individual’s privacy. We present methods for releasing differentially private minor allele frequencies, chi-square statistics and p-values. We compare these approaches on simulated data and on a GWAS study of canine hair length involving 685 dogs. We also propose a privacy-preserving method for finding genome-wide associations based on a differentially-private approach to penalized logistic regression. AU - Uhler, Caroline AU - Slavkovic, Aleksandra AU - Fienberg, Stephen ID - 2009 IS - 1 JF - Journal of Privacy and Confidentiality TI - Privacy-preserving data sharing for genome-wide association studies VL - 5 ER - TY - JOUR AB - Sex chromosomes originate from autosomes. The accumulation of sexually antagonistic mutations on protosex chromosomes selects for a loss of recombination and sets in motion the evolutionary processes generating heteromorphic sex chromosomes. Recombination suppression and differentiation are generally viewed as the default path of sex chromosome evolution, and the occurrence of old, homomorphic sex chromosomes, such as those of ratite birds, has remained a mystery. Here, we analyze the genome and transcriptome of emu (Dromaius novaehollandiae) and confirm that most genes on the sex chromosome are shared between the Z and W. Surprisingly, however, levels of gene expression are generally sex-biased for all sex-linked genes relative to autosomes, including those in the pseudoautosomal region, and the male-bias increases after gonad formation. This expression bias suggests that the emu sex chromosomes have become masculinized, even in the absence of ZW differentiation. Thus, birds may have taken different evolutionary solutions to minimize the deleterious effects imposed by sexually antagonistic mutations: some lineages eliminate recombination along the protosex chromosomes to physically restrict sexually antagonistic alleles to one sex, whereas ratites evolved sex-biased expression to confine the product of a sexually antagonistic allele to the sex it benefits. This difference in conflict resolution may explain the preservation of recombining, homomorphic sex chromosomes in other lineages and illustrates the importance of sexually antagonistic mutations driving the evolution of sex chromosomes. AU - Beatriz Vicoso AU - Kaiser, Vera B AU - Bachtrog, Doris ID - 2074 IS - 16 JF - PNAS TI - Sex biased gene expression at homomorphic sex chromosomes in emus and its implication for sex chromosome evolution VL - 110 ER - TY - JOUR AB - Snakes exhibit genetic sex determination, with female heterogametic sex chromosomes (ZZ males, ZW females). Extensive cytogenetic work has suggested that the level of sex chromosome heteromorphism varies among species, with Boidae having entirely homomorphic sex chromosomes, Viperidae having completely heteromorphic sex chromosomes, and Colubridae showing partial differentiation. Here, we take a genomic approach to compare sex chromosome differentiation in these three snake families. We identify homomorphic sex chromosomes in boas (Boidae), but completely heteromorphic sex chromosomes in both garter snakes (Colubridae) and pygmy rattlesnake (Viperidae). Detection of W-linked gametologs enables us to establish the presence of evolutionary strata on garter and pygmy rattlesnake sex chromosomes where recombination was abolished at different time points. Sequence analysis shows that all strata are shared between pygmy rattlesnake and garter snake, i.e., recombination was abolished between the sex chromosomes before the two lineages diverged. The sex-biased transmission of the Z and its hemizygosity in females can impact patterns of molecular evolution, and we show that rates of evolution for Z-linked genes are increased relative to their pseudoautosomal homologs, both at synonymous and amino acid sites (even after controlling for mutational biases). This demonstrates that mutation rates are male-biased in snakes (male-driven evolution), but also supports faster-Z evolution due to differential selective effects on the Z. Finally, we perform a transcriptome analysis in boa and pygmy rattlesnake to establish baseline levels of sex-biased expression in homomorphic sex chromosomes, and show that heteromorphic ZW chromosomes in rattlesnakes lack chromosome-wide dosage compensation. Our study provides the first full scale overview of the evolution of snake sex chromosomes at the genomic level, thus greatly expanding our knowledge of reptilian and vertebrate sex chromosomes evolution. AU - Beatriz Vicoso AU - Emerson, Jr J. AU - Zektser, Yulia AU - Mahajan, Shivani AU - Bachtrog, Doris ID - 2076 IS - 8 JF - PLoS Biology TI - Comparative sex chromosome genomics in snakes: Differentiation evolutionary strata and lack of global dosage compensation VL - 11 ER - TY - JOUR AB - We present an interactive design system that allows non-expert users to create animated mechanical characters. Given an articulated character as input, the user iteratively creates an animation by sketching motion curves indicating how different parts of the character should move. For each motion curve, our framework creates an optimized mechanism that reproduces it as closely as possible. The resulting mechanisms are attached to the character and then connected to each other using gear trains, which are created in a semi-automated fashion. The mechanical assemblies generated with our system can be driven with a single input driver, such as a hand-operated crank or an electric motor, and they can be fabricated using rapid prototyping devices. We demonstrate the versatility of our approach by designing a wide range of mechanical characters, several of which we manufactured using 3D printing. While our pipeline is designed for characters driven by planar mechanisms, significant parts of it extend directly to non-planar mechanisms, allowing us to create characters with compelling 3D motions. AU - Coros, Stelian AU - Thomaszewski, Bernhard AU - Noris, Gioacchino AU - Sueda, Shinjiro AU - Forberg, Moira AU - Sumner, Robert W AU - Matusik, Wojciech AU - Bernd Bickel ID - 2108 IS - 4 JF - ACM Transactions on Graphics TI - Computational design of mechanical characters VL - 32 ER - TY - JOUR AB - We present a method for practical physical reproduction and design of homogeneous materials with desired subsurface scattering. Our process uses a collection of different pigments that can be suspended in a clear base material. Our goal is to determine pigment concentrations that best reproduce the appearance and subsurface scattering of a given target material. In order to achieve this task we first fabricate a collection of material samples composed of known mixtures of the available pigments with the base material. We then acquire their reflectance profiles using a custom-built measurement device. We use the same device to measure the reflectance profile of a target material. Based on the database of mappings from pigment concentrations to reflectance profiles, we use an optimization process to compute the concentration of pigments to best replicate the target material appearance. We demonstrate the practicality of our method by reproducing a variety of different translucent materials. We also present a tool that allows the user to explore the range of achievable appearances for a given set of pigments. AU - Papas, Marios AU - Regg, Christian AU - Jarosz, Wojciech AU - Bernd Bickel AU - Jackson, Philip V AU - Matusik, Wojciech AU - Marschner, Steve AU - Groß, Markus S ID - 2110 IS - 4 JF - ACM Transactions on Graphics TI - Fabricating translucent materials using continuous pigment mixtures VL - 32 ER - TY - JOUR AB - Animated animatronic figures are a unique way to give physical presence to a character. However, their movement and expressions are often limited due to mechanical constraints. In this paper, we propose a complete process for augmenting physical avatars using projector-based illumination, significantly increasing their expressiveness. Given an input animation, the system decomposes the motion into low-frequency motion that can be physically reproduced by the animatronic head and high-frequency details that are added using projected shading. At the core is a spatio-temporal optimization process that compresses the motion in gradient space, ensuring faithful motion replay while respecting the physical limitations of the system. We also propose a complete multi-camera and projection system, including a novel defocused projection and subsurface scattering compensation scheme. The result of our system is a highly expressive physical avatar that features facial details and motion otherwise unattainable due to physical constraints. AU - Bermano, Amit H AU - Bruschweiler, Philipp AU - Grundhöfer, Anselm AU - Iwai, Daisuke AU - Bernd Bickel AU - Groß, Markus S ID - 2111 IS - 6 JF - ACM Transactions on Graphics TI - Augmenting physical avatars using projector-based illumination VL - 32 ER - TY - JOUR AB - Most additive manufacturing technologies work by layering, i.e. slicing the shape and then generating each slice independently. This introduces an anisotropy into the process, often as different accuracies in the tangential and normal directions, but also in terms of other parameters such as build speed or tensile strength and strain. We model this as an anisotropic cubic element. Our approach then finds a compromise between modeling each part of the shape individually in the best possible direction and using one direction for the whole shape part. In particular, we compute an orthogonal basis and consider only the three basis vectors as slice normals (i.e. fabrication directions). Then we optimize a decomposition of the shape along this basis so that each part can be consistently sliced along one of the basis vectors. In simulation, we show that this approach is superior to slicing the whole shape in one direction, only. It also has clear benefits if the shape is larger than the build volume of the available equipment. AU - Hildebrand, Kristian AU - Bernd Bickel AU - Alexa, Marc ID - 2109 IS - 6 JF - Computers and Graphics (Pergamon) TI - Orthogonal slicing for additive manufacturing VL - 37 ER - TY - JOUR AB - We present a method for fabrication-oriented design of actuated deformable characters that allows a user to automatically create physical replicas of digitally designed characters using rapid manufacturing technologies. Given a deformable character and a set of target poses as input, our method computes a small set of actuators along with their locations on the surface and optimizes the internal material distribution such that the resulting character exhibits the desired deformation behavior. We approach this problem with a dedicated algorithm that combines finite-element analysis, sparse regularization, and constrained optimization. We validate our pipeline on a set of two- and three-dimensional example characters and present results in simulation and physically-fabricated prototypes. AU - Skouras, Mélina AU - Thomaszewski, Bernhard AU - Coros, Stelian AU - Bernd Bickel AU - Groß, Markus S ID - 2107 IS - 4 JF - ACM Transactions on Graphics TI - Computational design of actuated deformable characters VL - 32 ER - TY - JOUR AB - Force-deformation measurements of cloth exhibit significant hysteresis, and many researchers have identified internal friction as the source of this effect. However, it has not been incorporated into computer animation models of cloth. In this paper, we propose a model of internal friction based on an augmented reparameterization of Dahl's model, and we show that this model provides a good match to several important features of cloth hysteresis even with a minimal set of parameters. We also propose novel parameter estimation procedures that are based on simple and inexpensive setups and need only sparse data, as opposed to the complex hardware and dense data acquisition of previous methods. Finally, we provide an algorithm for the efficient simulation of internal friction, and we demonstrate it on simulation examples that show disparate behavior with and without internal friction. AU - Miguel, Eder AU - Tamstorf, Rasmus AU - Bradley, Derek J AU - Schvartzman, Sara C AU - Thomaszewski, Bernhard AU - Bernd Bickel AU - Matusik, Wojciech AU - Marschner, Steve AU - Otaduy, Miguel A ID - 2112 IS - 6 JF - ACM Transactions on Graphics TI - Modeling and estimation of internal friction in cloth VL - 32 ER - TY - JOUR AB - We prove new upper and lower bounds for Banach space-valued stochastic integrals with respect to a compensated Poisson random measure. Our estimates apply to Banach spaces with non-trivial martingale (co)type and extend various results in the literature. We also develop a Malliavin framework to interpret Poisson stochastic integrals as vector-valued Skorohod integrals, and prove a Clark-Ocone representation formula. AU - Dirksen, Sjoerd AU - Jan Maas AU - van Neerven, Jan M ID - 2117 JF - Electronic Journal of Probability TI - Poisson stochastic integration in Banach spaces VL - 18 ER - TY - JOUR AB - A new method fabricates custom surface reflectance and spatially varying bidirectional reflectance distribution functions (svBRDFs). Researchers optimize a microgeometry for a range of normal distribution functions and simulate the resulting surface's effective reflectance. Using the simulation's results, they reproduce an input svBRDF's appearance by distributing the microgeometry on the printed material's surface. This method lets people print svBRDFs on planar samples with current 3D printing technology, even with a limited set of printing materials. It extends naturally to printing svBRDFs on arbitrary shapes. AU - Rouiller, Olivier AU - Bernd Bickel AU - Kautz, Jan AU - Matusik, Wojciech AU - Alexa, Marc ID - 2113 IS - 6 JF - IEEE Computer Graphics and Applications TI - 3D printing spatially varying BRDFs VL - 33 ER - TY - JOUR AB - 3D printing is considered a disruptive technology with a potentially tremendous socioeconomic impact. The three articles in this special issue illustrate how novel computer graphics approaches are advancing such digital fabrication. AU - Bernd Bickel AU - Alexa, Marc ID - 2114 IS - 6 JF - IEEE Computer Graphics and Applications TI - Computational aspects of fabrication: Modeling, design and 3d printing VL - 33 ER - TY - JOUR AB - This paper continues the investigation of `Wasserstein-like' transportation distances for probability measures on discrete sets. We prove that the discrete transportation metrics on the d-dimensional discrete torus with mesh size 1/N converge, when N→∞, to the standard 2-Wasserstein distance W_2 on the continuous torus in the sense of Gromov-Hausdorff. This is the first convergence result for the recently developed discrete transportation metrics. The result shows the compatibility between these metrics and the well-established 2-Wasserstein metric. AU - Gigli, Nicola AU - Jan Maas ID - 2129 IS - 2 JF - SIAM Journal on Mathematical Analysis TI - Gromov-Hausdorff convergence of discrete transportation metrics VL - 45 ER - TY - JOUR AB - Recently it has been shown that pairs of atoms can form metastable bonds due to non-conservative forces induced by dissipation [Lemeshko&Weimer, Nature Comm. 4, 2230 (2013)]. Here we study the dynamics of interaction-induced coherent population trapping - the process responsible for the formation of dissipatively bound molecules. We derive the effective dissipative potentials induced between ultracold atoms by laser light, and study the time evolution of the scattering states. We demonstrate that binding occurs on short timescales of ~10 microseconds, even if the initial kinetic energy of the atoms significantly exceeds the depth of the dissipative potential. Dissipatively-bound molecules with preordained bond lengths and vibrational wavefunctions can be created and detected in current experiments with ultracold atoms. AU - Mikhail Lemeshko ID - 2139 IS - 17 JF - Frontiers Physics TI - Manipulating scattering of ultracold atoms with light-induced dissipation VL - 1 ER - TY - CONF AB - There is a trade-off between performance and correctness in implementing concurrent data structures. Better performance may be achieved at the expense of relaxing correctness, by redefining the semantics of data structures. We address such a redefinition of data structure semantics and present a systematic and formal framework for obtaining new data structures by quantitatively relaxing existing ones. We view a data structure as a sequential specification S containing all "legal" sequences over an alphabet of method calls. Relaxing the data structure corresponds to defining a distance from any sequence over the alphabet to the sequential specification: the k-relaxed sequential specification contains all sequences over the alphabet within distance k from the original specification. In contrast to other existing work, our relaxations are semantic (distance in terms of data structure states). As an instantiation of our framework, we present two simple yet generic relaxation schemes, called out-of-order and stuttering relaxation, along with several ways of computing distances. We show that the out-of-order relaxation, when further instantiated to stacks, queues, and priority queues, amounts to tolerating bounded out-of-order behavior, which cannot be captured by a purely syntactic relaxation (distance in terms of sequence manipulation, e.g. edit distance). We give concurrent implementations of relaxed data structures and demonstrate that bounded relaxations provide the means for trading correctness for performance in a controlled way. The relaxations are monotonic which further highlights the trade-off: increasing k increases the number of permitted sequences, which as we demonstrate can lead to better performance. Finally, since a relaxed stack or queue also implements a pool, we actually have new concurrent pool implementations that outperform the state-of-the-art ones. AU - Henzinger, Thomas A AU - Kirsch, Christoph AU - Payer, Hannes AU - Sezgin, Ali AU - Sokolova, Ana ID - 2181 SN - 978-1-4503-1832-7 T2 - Proceedings of the 40th annual ACM SIGPLAN-SIGACT symposium on Principles of programming language TI - Quantitative relaxation of concurrent data structures ER - TY - CONF AB - We propose a general framework for abstraction with respect to quantitative properties, such as worst-case execution time, or power consumption. Our framework provides a systematic way for counter-example guided abstraction refinement for quantitative properties. The salient aspect of the framework is that it allows anytime verification, that is, verification algorithms that can be stopped at any time (for example, due to exhaustion of memory), and report approximations that improve monotonically when the algorithms are given more time. We instantiate the framework with a number of quantitative abstractions and refinement schemes, which differ in terms of how much quantitative information they keep from the original system. We introduce both state-based and trace-based quantitative abstractions, and we describe conditions that define classes of quantitative properties for which the abstractions provide over-approximations. We give algorithms for evaluating the quantitative properties on the abstract systems. We present algorithms for counter-example based refinements for quantitative properties for both state-based and segment-based abstractions. We perform a case study on worst-case execution time of executables to evaluate the anytime verification aspect and the quantitative abstractions we proposed. AU - Cerny, Pavol AU - Henzinger, Thomas A AU - Radhakrishna, Arjun ID - 2182 T2 - Proceedings of the 40th annual ACM SIGPLAN-SIGACT symposium on Principles of programming language TI - Quantitative abstraction refinement ER - TY - CONF AB - A straight skeleton is a well-known geometric structure, and several algorithms exist to construct the straight skeleton for a given polygon or planar straight-line graph. In this paper, we ask the reverse question: Given the straight skeleton (in form of a planar straight-line graph, with some rays to infinity), can we reconstruct a planar straight-line graph for which this was the straight skeleton? We show how to reduce this problem to the problem of finding a line that intersects a set of convex polygons. We can find these convex polygons and all such lines in $O(nlog n)$ time in the Real RAM computer model, where $n$ denotes the number of edges of the input graph. We also explain how our approach can be used for recognizing Voronoi diagrams of points, thereby completing a partial solution provided by Ash and Bolker in 1985. AU - Biedl, Therese AU - Held, Martin AU - Huber, Stefan ID - 2209 TI - Recognizing straight skeletons and Voronoi diagrams and reconstructing their input ER - TY - JOUR AB - We introduce a new platform for quantum simulation of many-body systems based on nonspherical atoms or molecules with zero dipole moments but possessing a significant value of electric quadrupole moments. We consider a quadrupolar Fermi gas trapped in a 2D square optical lattice, and show that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create a topological superfluid. Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at high densities. AU - Bhongale, Satyan AU - Mathey, Ludwig AU - Zhao, Erhai AU - Yelin, Susanne AU - Lemeshko, Mikhail ID - 2204 IS - 15 JF - Physical Review Letters TI - Quantum phases of quadrupolar fermi gases in optical lattices VL - 110 ER - TY - JOUR AB - Magnetic impurities embedded in inert solids can exhibit long coherence times and interact with one another via their intrinsic anisotropic dipolar interaction. We argue that, as a consequence of these properties, disordered ensembles of magnetic impurities provide an effective platform for realizing a controllable, tunable version of the dipolar quantum spin glass seen in LiHoxY1-xF4. Specifically, we propose and analyze a system composed of dysprosium atoms embedded in solid helium. We describe the phase diagram of the system and discuss the realizability and detectability of the quantum spin glass and antiglass phases. AU - Mikhail Lemeshko AU - Yao, Norman Y AU - Gorshkov, Alexey V AU - Weimer, Hendrik AU - Bennett, Steven D AU - Momose, Takamasa AU - Gopalakrishnan, Sarang ID - 2206 IS - 1 JF - Physical Review B - Condensed Matter and Materials Physics TI - Controllable quantum spin glasses with magnetic impurities embedded in quantum solids VL - 88 ER - TY - GEN AB - The goal of the present article is to review the major developments that have led to the current understanding of molecule-field interactions and experimental methods for manipulating molecules with electromagnetic fields. Molecule-field interactions are at the core of several, seemingly distinct areas of molecular physics. This is reflected in the organisation of this article, which includes sections on field control of molecular beams, external field traps for cold molecules, control of molecular orientation and molecular alignment, manipulation of molecules by non-conservative forces, ultracold molecules and ultracold chemistry, controlled many-body phenomena, entanglement of molecules and dipole arrays, and stability of molecular systems in high-frequency super-intense laser fields. The article contains 852 references. AU - Mikhail Lemeshko AU - Krems, Roman V AU - Doyle, John M AU - Kais, Sabre ID - 2205 IS - 12-13 T2 - Molecular Physics TI - Manipulation of molecules with electromagnetic fields VL - 111 ER - TY - JOUR AB - The formation of molecules and supramolecular structures results from bonding by conservative forces acting among electrons and nuclei and giving rise to equilibrium configurations defined by minima of the interaction potential. Here we show that bonding can also occur by the non-conservative forces responsible for interaction-induced coherent population trapping. The bound state arises in a dissipative process and manifests itself as a stationary state at a preordained interatomic distance. Remarkably, such a dissipative bonding is present even when the interactions among the atoms are purely repulsive. The dissipative bound states can be created and studied spectroscopically in present-day experiments with ultracold atoms or molecules and can potentially serve for cooling strongly interacting quantum gases. AU - Mikhail Lemeshko AU - Weimer, Hendrik ID - 2207 JF - Nature Communications TI - Dissipative binding of atoms by non-conservative forces VL - 4 ER - TY - CONF AB - A straight skeleton is a well-known geometric structure, and several algorithms exist to construct the straight skeleton for a given polygon. In this paper, we ask the reverse question: Given the straight skeleton (in form of a tree with a drawing in the plane, but with the exact position of the leaves unspecified), can we reconstruct the polygon? We show that in most cases there exists at most one polygon; in the remaining case there is an infinite number of polygons determined by one angle that can range in an interval. We can find this (set of) polygon(s) in linear time in the Real RAM computer model. AU - Biedl, Therese AU - Held, Martin AU - Huber, Stefan ID - 2210 T2 - 29th European Workshop on Computational Geometry TI - Reconstructing polygons from embedded straight skeletons ER - TY - CONF AB - We describe new extensions of the Vampire theorem prover for computing tree interpolants. These extensions generalize Craig interpolation in Vampire, and can also be used to derive sequence interpolants. We evaluated our implementation on a large number of examples over the theory of linear integer arithmetic and integer-indexed arrays, with and without quantifiers. When compared to other methods, our experiments show that some examples could only be solved by our implementation. AU - Blanc, Régis AU - Gupta, Ashutosh AU - Kovács, Laura AU - Kragl, Bernhard ID - 2237 TI - Tree interpolation in Vampire VL - 8312 ER - TY - CONF AB - We study the problem of achieving a given value in Markov decision processes (MDPs) with several independent discounted reward objectives. We consider a generalised version of discounted reward objectives, in which the amount of discounting depends on the states visited and on the objective. This definition extends the usual definition of discounted reward, and allows to capture the systems in which the value of different commodities diminish at different and variable rates. We establish results for two prominent subclasses of the problem, namely state-discount models where the discount factors are only dependent on the state of the MDP (and independent of the objective), and reward-discount models where they are only dependent on the objective (but not on the state of the MDP). For the state-discount models we use a straightforward reduction to expected total reward and show that the problem whether a value is achievable can be solved in polynomial time. For the reward-discount model we show that memory and randomisation of the strategies are required, but nevertheless that the problem is decidable and it is sufficient to consider strategies which after a certain number of steps behave in a memoryless way. For the general case, we show that when restricted to graphs (i.e. MDPs with no randomisation), pure strategies and discount factors of the form 1/n where n is an integer, the problem is in PSPACE and finite memory suffices for achieving a given value. We also show that when the discount factors are not of the form 1/n, the memory required by a strategy can be infinite. AU - Chatterjee, Krishnendu AU - Forejt, Vojtěch AU - Wojtczak, Dominik ID - 2238 TI - Multi-objective discounted reward verification in graphs and MDPs VL - 8312 ER - TY - CONF AB - We show that modal logic over universally first-order definable classes of transitive frames is decidable. More precisely, let K be an arbitrary class of transitive Kripke frames definable by a universal first-order sentence. We show that the global and finite global satisfiability problems of modal logic over K are decidable in NP, regardless of choice of K. We also show that the local satisfiability and the finite local satisfiability problems of modal logic over K are decidable in NEXPTIME. AU - Michaliszyn, Jakub AU - Otop, Jan ID - 2243 TI - Elementary modal logics over transitive structures VL - 23 ER - TY - CONF AB - We consider two systems (α1,...,αm) and (β1,...,βn) of curves drawn on a compact two-dimensional surface ℳ with boundary. Each αi and each βj is either an arc meeting the boundary of ℳ at its two endpoints, or a closed curve. The αi are pairwise disjoint except for possibly sharing endpoints, and similarly for the βj. We want to "untangle" the βj from the αi by a self-homeomorphism of ℳ; more precisely, we seek an homeomorphism φ: ℳ → ℳ fixing the boundary of ℳ pointwise such that the total number of crossings of the αi with the φ(βj) is as small as possible. This problem is motivated by an application in the algorithmic theory of embeddings and 3-manifolds. We prove that if ℳ is planar, i.e., a sphere with h ≥ 0 boundary components ("holes"), then O(mn) crossings can be achieved (independently of h), which is asymptotically tight, as an easy lower bound shows. In general, for an arbitrary (orientable or nonorientable) surface ℳ with h holes and of (orientable or nonorientable) genus g ≥ 0, we obtain an O((m + n)4) upper bound, again independent of h and g. AU - Matoušek, Jiří AU - Sedgwick, Eric AU - Tancer, Martin AU - Wagner, Uli ID - 2244 TI - Untangling two systems of noncrossing curves VL - 8242 ER - TY - CONF AB - The learning with rounding (LWR) problem, introduced by Banerjee, Peikert and Rosen at EUROCRYPT ’12, is a variant of learning with errors (LWE), where one replaces random errors with deterministic rounding. The LWR problem was shown to be as hard as LWE for a setting of parameters where the modulus and modulus-to-error ratio are super-polynomial. In this work we resolve the main open problem and give a new reduction that works for a larger range of parameters, allowing for a polynomial modulus and modulus-to-error ratio. In particular, a smaller modulus gives us greater efficiency, and a smaller modulus-to-error ratio gives us greater security, which now follows from the worst-case hardness of GapSVP with polynomial (rather than super-polynomial) approximation factors. As a tool in the reduction, we show that there is a “lossy mode” for the LWR problem, in which LWR samples only reveal partial information about the secret. This property gives us several interesting new applications, including a proof that LWR remains secure with weakly random secrets of sufficient min-entropy, and very simple constructions of deterministic encryption, lossy trapdoor functions and reusable extractors. Our approach is inspired by a technique of Goldwasser et al. from ICS ’10, which implicitly showed the existence of a “lossy mode” for LWE. By refining this technique, we also improve on the parameters of that work to only requiring a polynomial (instead of super-polynomial) modulus and modulus-to-error ratio. AU - Alwen, Joel F AU - Krenn, Stephan AU - Pietrzak, Krzysztof Z AU - Wichs, Daniel ID - 2259 IS - 1 TI - Learning with rounding, revisited: New reduction properties and applications VL - 8042 ER - TY - CONF AB - In a digital signature scheme with message recovery, rather than transmitting the message m and its signature σ, a single enhanced signature τ is transmitted. The verifier is able to recover m from τ and at the same time verify its authenticity. The two most important parameters of such a scheme are its security and overhead |τ| − |m|. A simple argument shows that for any scheme with “n bits security” |τ| − |m| ≥ n, i.e., the overhead is lower bounded by the security parameter n. Currently, the best known constructions in the random oracle model are far from this lower bound requiring an overhead of n + logq h , where q h is the number of queries to the random oracle. In this paper we give a construction which basically matches the n bit lower bound. We propose a simple digital signature scheme with n + o(logq h ) bits overhead, where q h denotes the number of random oracle queries. Our construction works in two steps. First, we propose a signature scheme with message recovery having optimal overhead in a new ideal model, the random invertible function model. Second, we show that a four-round Feistel network with random oracles as round functions is tightly “public-indifferentiable” from a random invertible function. At the core of our indifferentiability proof is an almost tight upper bound for the expected number of edges of the densest “small” subgraph of a random Cayley graph, which may be of independent interest. AU - Kiltz, Eike AU - Pietrzak, Krzysztof Z AU - Szegedy, Mario ID - 2258 TI - Digital signatures with minimal overhead from indifferentiable random invertible functions VL - 8042 ER - TY - JOUR AB - Linked (Open) Data - bibliographic data on the Semantic Web. Report of the Working Group on Linked Data to the plenary assembly of the Austrian Library Network (translation of the title). Linked Data stands for a certain approach to publishing data on the Web. The underlying idea is to harmonise heterogeneous data sources of different origin in order to improve their accessibility and interoperability, effectively making them queryable as a big distributed database. This report summarises relevant developments in Europe as well as the Linked Data Working Group‘s strategic and technical considerations regarding the publishing of the Austrian Library Network’s (OBV’s) bibliographic datasets. It concludes with the mutual agreement that the implementation of Linked Data principles within the OBV can only be taken into consideration accompanied by a discussion about the provision of the datasets under a free license. AU - Danowski, Patrick AU - Goldfarb, Doron AU - Schaffner, Verena AU - Seidler, Wolfram ID - 2256 IS - 3/4 JF - VÖB Mitteilungen TI - Linked (Open) Data - Bibliographische Daten im Semantic Web VL - 66 ER - TY - CONF AB - Direct Anonymous Attestation (DAA) is one of the most complex cryptographic protocols deployed in practice. It allows an embedded secure processor known as a Trusted Platform Module (TPM) to attest to the configuration of its host computer without violating the owner’s privacy. DAA has been standardized by the Trusted Computing Group and ISO/IEC. The security of the DAA standard and all existing schemes is analyzed in the random-oracle model. We provide the first constructions of DAA in the standard model, that is, without relying on random oracles. Our constructions use new building blocks, including the first efficient signatures of knowledge in the standard model, which have many applications beyond DAA. AU - Bernhard, David AU - Fuchsbauer, Georg AU - Ghadafi, Essam ID - 2260 TI - Efficient signatures of knowledge and DAA in the standard model VL - 7954 ER - TY - JOUR AB - Faithful progression through the cell cycle is crucial to the maintenance and developmental potential of stem cells. Here, we demonstrate that neural stem cells (NSCs) and intermediate neural progenitor cells (NPCs) employ a zinc-finger transcription factor specificity protein 2 (Sp2) as a cell cycle regulator in two temporally and spatially distinct progenitor domains. Differential conditional deletion of Sp2 in early embryonic cerebral cortical progenitors, and perinatal olfactory bulb progenitors disrupted transitions through G1, G2 and M phases, whereas DNA synthesis appeared intact. Cell-autonomous function of Sp2 was identified by deletion of Sp2 using mosaic analysis with double markers, which clearly established that conditional Sp2-null NSCs and NPCs are M phase arrested in vivo. Importantly, conditional deletion of Sp2 led to a decline in the generation of NPCs and neurons in the developing and postnatal brains. Our findings implicate Sp2-dependent mechanisms as novel regulators of cell cycle progression, the absence of which disrupts neurogenesis in the embryonic and postnatal brain. AU - Liang, Huixuan AU - Xiao, Guanxi AU - Yin, Haifeng AU - Hippenmeyer, Simon AU - Horowitz, Jonathan AU - Ghashghaei, Troy ID - 2264 IS - 3 JF - Development TI - Neural development is dependent on the function of specificity protein 2 in cell cycle progression VL - 140 ER - TY - JOUR AB - This paper presents a parallel, implementation-friendly analytic visibility method for triangular meshes. Together with an analytic filter convolution, it allows for a fully analytic solution to anti-aliased 3D mesh rendering on parallel hardware. Building on recent works in computational geometry, we present a new edge-triangle intersection algorithm and a novel method to complete the boundaries of all visible triangle regions after a hidden line elimination step. All stages of the method are embarrassingly parallel and easily implementable on parallel hardware. A GPU implementation is discussed and performance characteristics of the method are shown and compared to traditional sampling-based rendering methods. AU - Thomas Auzinger AU - Wimmer, Michael AU - Stefan Jeschke ID - 2269 IS - 124 JF - Computer Graphics Forum TI - Analytic Visibility on the GPU VL - 32 ER - TY - CONF AB - Representation languages for coalitional games are a key research area in algorithmic game theory. There is an inher- ent tradeoff between how general a language is, allowing it to capture more elaborate games, and how hard it is computationally to optimize and solve such games. One prominent such language is the simple yet expressive Weighted Graph Games (WGGs) representation (Deng and Papadimitriou 1994), which maintains knowledge about synergies between agents in the form of an edge weighted graph. We consider the problem of finding the optimal coalition structure in WGGs. The agents in such games are vertices in a graph, and the value of a coalition is the sum of the weights of the edges present between coalition members. The optimal coalition structure is a partition of the agents to coalitions, that maximizes the sum of utilities obtained by the coalitions. We show that finding the optimal coalition structure is not only hard for general graphs, but is also intractable for restricted families such as planar graphs which are amenable for many other combinatorial problems. We then provide algorithms with constant factor approximations for planar, minorfree and bounded degree graphs. AU - Bachrach, Yoram AU - Kohli, Pushmeet AU - Kolmogorov, Vladimir AU - Zadimoghaddam, Morteza ID - 2270 TI - Optimal Coalition Structures in Cooperative Graph Games ER - TY - GEN AB - We propose a new family of message passing techniques for MAP estimation in graphical models which we call Sequential Reweighted Message Passing (SRMP). Special cases include well-known techniques such as Min-Sum Diusion (MSD) and a faster Sequential Tree-Reweighted Message Passing (TRW-S). Importantly, our derivation is simpler than the original derivation of TRW-S, and does not involve a decomposition into trees. This allows easy generalizations. We present such a generalization for the case of higher-order graphical models, and test it on several real-world problems with promising results. AU - Vladimir Kolmogorov ID - 2273 TI - Reweighted message passing revisited ER - TY - JOUR AB - It is firmly established that interactions between neurons and glia are fundamental across species for the correct establishment of a functional brain. Here, we found that the glia of the Drosophila larval brain display an essential non-autonomous role during the development of the optic lobe. The optic lobe develops from neuroepithelial cells that proliferate by dividing symmetrically until they switch to asymmetric/differentiative divisions that generate neuroblasts. The proneural gene lethal of scute (l9sc) is transiently activated by the epidermal growth factor receptor (EGFR)-Ras signal transduction pathway at the leading edge of a proneural wave that sweeps from medial to lateral neuroepithelium, promoting this switch. This process is tightly regulated by the tissue-autonomous function within the neuroepithelium of multiple signaling pathways, including EGFR-Ras and Notch. This study shows that the Notch ligand Serrate (Ser) is expressed in the glia and it forms a complex in vivo with Notch and Canoe, which colocalize at the adherens junctions of neuroepithelial cells. This complex is crucial for interactions between glia and neuroepithelial cells during optic lobe development. Ser is tissue-autonomously required in the glia where it activates Notch to regulate its proliferation, and non-autonomously in the neuroepithelium where Ser induces Notch signaling to avoid the premature activation of the EGFR-Ras pathway and hence of L9sc. Interestingly, different Notch activity reporters showed very different expression patterns in the glia and in the neuroepithelium, suggesting the existence of tissue-specific factors that promote the expression of particular Notch target genes or/and a reporter response dependent on different thresholds of Notch signaling. AU - Pérez Gómez, Raquel AU - Slovakova, Jana AU - Rives Quinto, Noemí AU - Krejčí, Alena AU - Carmena, Ana ID - 2278 IS - 21 JF - Journal of Cell Science TI - A serrate-notch-canoe complex mediates essential interactions between glia and neuroepithelial cells during Drosophila optic lobe development VL - 126 ER - TY - CONF AB - The problem of minimizing the Potts energy function frequently occurs in computer vision applications. One way to tackle this NP-hard problem was proposed by Kovtun [19, 20]. It identifies a part of an optimal solution by running k maxflow computations, where k is the number of labels. The number of “labeled” pixels can be significant in some applications, e.g. 50-93% in our tests for stereo. We show how to reduce the runtime to O (log k) maxflow computations (or one parametric maxflow computation). Furthermore, the output of our algorithm allows to speed-up the subsequent alpha expansion for the unlabeled part, or can be used as it is for time-critical applications. To derive our technique, we generalize the algorithm of Felzenszwalb et al. [7] for Tree Metrics . We also show a connection to k-submodular functions from combinatorial optimization, and discuss k-submodular relaxations for general energy functions. AU - Gridchyn, Igor AU - Kolmogorov, Vladimir ID - 2276 TI - Potts model, parametric maxflow and k-submodular functions ER - TY - JOUR AB - The problem of packing ellipsoids of different sizes and shapes into an ellipsoidal container so as to minimize a measure of overlap between ellipsoids is considered. A bilevel optimization formulation is given, together with an algorithm for the general case and a simpler algorithm for the special case in which all ellipsoids are in fact spheres. Convergence results are proved and computational experience is described and illustrated. The motivating application-chromosome organization in the human cell nucleus-is discussed briefly, and some illustrative results are presented. AU - Uhler, Caroline AU - Wright, Stephen ID - 2280 IS - 4 JF - SIAM Review TI - Packing ellipsoids with overlap VL - 55 ER - TY - JOUR AB - Negative frequency-dependent selection should result in equal sex ratios in large populations of dioecious flowering plants, but deviations from equality are commonly reported. A variety of ecological and genetic factors can explain biased sex ratios, although the mechanisms involved are not well understood. Most dioecious species are long-lived and/or clonal complicating efforts to identify stages during the life cycle when biases develop. We investigated the demographic correlates of sex-ratio variation in two chromosome races of Rumex hastatulus, an annual, wind-pollinated colonizer of open habitats from the southern USA. We examined sex ratios in 46 populations and evaluated the hypothesis that the proximity of males in the local mating environment, through its influence on gametophytic selection, is the primary cause of female-biased sex ratios. Female-biased sex ratios characterized most populations of R. hastatulus (mean sex ratio = 0.62), with significant female bias in 89% of populations. Large, high-density populations had the highest proportion of females, whereas smaller, low-density populations had sex ratios closer to equality. Progeny sex ratios were more female biased when males were in closer proximity to females, a result consistent with the gametophytic selection hypothesis. Our results suggest that interactions between demographic and genetic factors are probably the main cause of female-biased sex ratios in R. hastatulus. The annual life cycle of this species may limit the scope for selection against males and may account for the weaker degree of bias in comparison with perennial Rumex species. AU - Pickup, Melinda AU - Barrett, Spencer ID - 2287 IS - 3 JF - Ecology and Evolution TI - The influence of demography and local mating environment on sex ratios in a wind-pollinated dioecious plant VL - 3 ER - TY - JOUR AB - Epithelial spreading is a common and fundamental aspect of various developmental and disease-related processes such as epithelial closure and wound healing. A key challenge for epithelial tissues undergoing spreading is to increase their surface area without disrupting epithelial integrity. Here we show that orienting cell divisions by tension constitutes an efficient mechanism by which the enveloping cell layer (EVL) releases anisotropic tension while undergoing spreading during zebrafish epiboly. The control of EVL cell-division orientation by tension involves cell elongation and requires myosin II activity to align the mitotic spindle with the main tension axis. We also found that in the absence of tension-oriented cell divisions and in the presence of increased tissue tension, EVL cells undergo ectopic fusions, suggesting that the reduction of tension anisotropy by oriented cell divisions is required to prevent EVL cells from fusing. We conclude that cell-division orientation by tension constitutes a key mechanism for limiting tension anisotropy and thus promoting tissue spreading during EVL epiboly. AU - Campinho, Pedro AU - Behrndt, Martin AU - Ranft, Jonas AU - Risler, Thomas AU - Minc, Nicolas AU - Heisenberg, Carl-Philipp J ID - 2282 JF - Nature Cell Biology TI - Tension-oriented cell divisions limit anisotropic tissue tension in epithelial spreading during zebrafish epiboly VL - 15 ER - TY - JOUR AB - Pathogens exert a strong selection pressure on organisms to evolve effective immune defences. In addition to individual immunity, social organisms can act cooperatively to produce collective defences. In many ant species, queens have the option to found a colony alone or in groups with other, often unrelated, conspecifics. These associations are transient, usually lasting only as long as each queen benefits from the presence of others. In fact, once the first workers emerge, queens fight to the death for dominance. One potential advantage of co-founding may be that queens benefit from collective disease defences, such as mutual grooming, that act against common soil pathogens. We test this hypothesis by exposing single and co-founding queens to a fungal parasite, in order to assess whether queens in co-founding associations have improved survival. Surprisingly, co-foundresses exposed to the entomopathogenic fungus Metarhizium did not engage in cooperative disease defences, and consequently, we find no direct benefit of multiple queens on survival. However, an indirect benefit was observed, with parasite-exposed queens producing more brood when they co-founded, than when they were alone. We suggest this is due to a trade-off between reproduction and immunity. Additionally, we report an extraordinary ability of the queens to tolerate an infection for long periods after parasite exposure. Our study suggests that there are no social immunity benefits for co-founding ant queens, but that in parasite-rich environments, the presence of additional queens may nevertheless improve the chances of colony founding success. AU - Pull, Christopher AU - Hughes, William AU - Brown, Markus ID - 2283 IS - 12 JF - Naturwissenschaften TI - Tolerating an infection: an indirect benefit of co-founding queen associations in the ant Lasius niger VL - 100 ER - TY - JOUR AB - The spatiotemporal control of cell divisions is a key factor in epithelial morphogenesis and patterning. Mao et al (2013) now describe how differential rates of proliferation within the Drosophila wing disc epithelium give rise to anisotropic tissue tension in peripheral/proximal regions of the disc. Such global tissue tension anisotropy in turn determines the orientation of cell divisions by controlling epithelial cell elongation. AU - Campinho, Pedro AU - Heisenberg, Carl-Philipp J ID - 2286 IS - 21 JF - EMBO Journal TI - The force and effect of cell proliferation VL - 32 ER - TY - JOUR AB - Formal verification aims to improve the quality of software by detecting errors before they do harm. At the basis of formal verification is the logical notion of correctness, which purports to capture whether or not a program behaves as desired. We suggest that the boolean partition of software into correct and incorrect programs falls short of the practical need to assess the behavior of software in a more nuanced fashion against multiple criteria. We therefore propose to introduce quantitative fitness measures for programs, specifically for measuring the function, performance, and robustness of reactive programs such as concurrent processes. This article describes the goals of the ERC Advanced Investigator Project QUAREM. The project aims to build and evaluate a theory of quantitative fitness measures for reactive models. Such a theory must strive to obtain quantitative generalizations of the paradigms that have been success stories in qualitative reactive modeling, such as compositionality, property-preserving abstraction and abstraction refinement, model checking, and synthesis. The theory will be evaluated not only in the context of software and hardware engineering, but also in the context of systems biology. In particular, we will use the quantitative reactive models and fitness measures developed in this project for testing hypotheses about the mechanisms behind data from biological experiments. AU - Henzinger, Thomas A ID - 2289 IS - 4 JF - Computer Science Research and Development TI - Quantitative reactive modeling and verification VL - 28 ER -