@article{336, abstract = {The growth kinetics of colloidal Bi2S3 nanorods was investigated. After nucleation, the length distribution of the growing Bi 2S3 nanorods narrows with the reaction time until a bimodal length distribution appears. From this critical reaction time on, the smallest nanorods of the ensemble dissolve, feeding with monomer the growth of the largest ones. A comprehensive characterization of the size-distribution evolution of Bi2S3 nanorods is used here to illustrate the dependences of the anisotropic growth rates of cylindrical nanoparticles on the nanoparticle dimensions and the monomer concentration in solution. With this goal in mind, a diffusion-reaction model is presented to explain the origin of the experimentally obtained length distribution focusing mechanism. The model is able to reproduce the decrease of the growth rate in the nanorod axial direction with both its thickness and length. On the other hand, low lateral reaction rates prevent the nanorod thickness distribution to be focused. In both crystallographic growth directions, a concentration-dependent critical thickness exists, which discriminates between nanorods with positive growth rates and those dissolving in the reaction solution. }, author = {Ibáñez, Maria and Guardia, Pablo and Shavel, Alexey and Cadavid, Doris and Arbiol, Jordi and Morante, Joan and Cabot, Andreu}, journal = {Journal of Physical Chemistry C}, number = {16}, pages = {7947 -- 7955}, publisher = {American Chemical Society}, title = {{Growth kinetics of asymmetric Bi2S3 nanocrystals: Size distribution focusing in nanorods}}, doi = {10.1021/jp2002904}, volume = {115}, year = {2011}, } @inproceedings{3360, abstract = {A discounted-sum automaton (NDA) is a nondeterministic finite automaton with edge weights, which values a run by the discounted sum of visited edge weights. More precisely, the weight in the i-th position of the run is divided by lambda^i, where the discount factor lambda is a fixed rational number greater than 1. Discounted summation is a common and useful measuring scheme, especially for infinite sequences, which reflects the assumption that earlier weights are more important than later weights. Determinizing automata is often essential, for example, in formal verification, where there are polynomial algorithms for comparing two deterministic NDAs, while the equivalence problem for NDAs is not known to be decidable. Unfortunately, however, discounted-sum automata are, in general, not determinizable: it is currently known that for every rational discount factor 1 < lambda < 2, there is an NDA with lambda (denoted lambda-NDA) that cannot be determinized. We provide positive news, showing that every NDA with an integral factor is determinizable. We also complete the picture by proving that the integers characterize exactly the discount factors that guarantee determinizability: we show that for every non-integral rational factor lambda, there is a nondeterminizable lambda-NDA. Finally, we prove that the class of NDAs with integral discount factors enjoys closure under the algebraic operations min, max, addition, and subtraction, which is not the case for general NDAs nor for deterministic NDAs. This shows that for integral discount factors, the class of NDAs forms an attractive specification formalism in quantitative formal verification. All our results hold equally for automata over finite words and for automata over infinite words. }, author = {Boker, Udi and Henzinger, Thomas A}, location = {Bergen, Norway}, pages = {82 -- 96}, publisher = {Springer}, title = {{Determinizing discounted-sum automata}}, doi = {10.4230/LIPIcs.CSL.2011.82}, volume = {12}, year = {2011}, } @inproceedings{3361, abstract = {In this paper, we investigate the computational complexity of quantitative information flow (QIF) problems. Information-theoretic quantitative relaxations of noninterference (based on Shannon entropy)have been introduced to enable more fine-grained reasoning about programs in situations where limited information flow is acceptable. The QIF bounding problem asks whether the information flow in a given program is bounded by a constant $d$. Our first result is that the QIF bounding problem is PSPACE-complete. The QIF memoryless synthesis problem asks whether it is possible to resolve nondeterministic choices in a given partial program in such a way that in the resulting deterministic program, the quantitative information flow is bounded by a given constant $d$. Our second result is that the QIF memoryless synthesis problem is also EXPTIME-complete. The QIF memoryless synthesis problem generalizes to QIF general synthesis problem which does not impose the memoryless requirement (that is, by allowing the synthesized program to have more variables then the original partial program). Our third result is that the QIF general synthesis problem is EXPTIME-hard.}, author = {Cerny, Pavol and Chatterjee, Krishnendu and Henzinger, Thomas A}, location = {Cernay-la-Ville, France}, pages = {205 -- 217}, publisher = {IEEE}, title = {{The complexity of quantitative information flow problems}}, doi = {10.1109/CSF.2011.21}, year = {2011}, } @inproceedings{3362, abstract = {State-transition systems communicating by shared variables have been the underlying model of choice for applications of model checking. Such formalisms, however, have difficulty with modeling process creation or death and communication reconfigurability. Here, we introduce “dynamic reactive modules” (DRM), a state-transition modeling formalism that supports dynamic reconfiguration and creation/death of processes. The resulting formalism supports two types of variables, data variables and reference variables. Reference variables enable changing the connectivity between processes and referring to instances of processes. We show how this new formalism supports parallel composition and refinement through trace containment. DRM provide a natural language for modeling (and ultimately reasoning about) biological systems and multiple threads communicating through shared variables.}, author = {Fisher, Jasmin and Henzinger, Thomas A and Nickovic, Dejan and Piterman, Nir and Singh, Anmol and Vardi, Moshe}, location = {Aachen, Germany}, pages = {404 -- 418}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Dynamic reactive modules}}, doi = {10.1007/978-3-642-23217-6_27}, volume = {6901}, year = {2011}, } @unpublished{3363, abstract = {We consider probabilistic automata on infinite words with acceptance defined by safety, reachability, Büchi, coBüchi, and limit-average conditions. We consider quantitative and qualitative decision problems. We present extensions and adaptations of proofs for probabilistic finite automata and present a complete characterization of the decidability and undecidability frontier of the quantitative and qualitative decision problems for probabilistic automata on infinite words.}, author = {Chatterjee, Krishnendu and Henzinger, Thomas A and Tracol, Mathieu}, pages = {19}, publisher = {ArXiv}, title = {{The decidability frontier for probabilistic automata on infinite words}}, doi = {10.48550/arXiv.1104.0127}, year = {2011}, } @article{3364, abstract = {Molecular noise, which arises from the randomness of the discrete events in the cell, significantly influences fundamental biological processes. Discrete-state continuous-time stochastic models (CTMC) can be used to describe such effects, but the calculation of the probabilities of certain events is computationally expensive. We present a comparison of two analysis approaches for CTMC. On one hand, we estimate the probabilities of interest using repeated Gillespie simulation and determine the statistical accuracy that we obtain. On the other hand, we apply a numerical reachability analysis that approximates the probability distributions of the system at several time instances. We use examples of cellular processes to demonstrate the superiority of the reachability analysis if accurate results are required.}, author = {Didier, Frédéric and Henzinger, Thomas A and Mateescu, Maria and Wolf, Verena}, journal = {Theoretical Computer Science}, number = {21}, pages = {2128 -- 2141}, publisher = {Elsevier}, title = {{Approximation of event probabilities in noisy cellular processes}}, doi = {10.1016/j.tcs.2010.10.022}, volume = {412}, year = {2011}, } @inproceedings{3365, abstract = {We present the tool Quasy, a quantitative synthesis tool. Quasy takes qualitative and quantitative specifications and automatically constructs a system that satisfies the qualitative specification and optimizes the quantitative specification, if such a system exists. The user can choose between a system that satisfies and optimizes the specifications (a) under all possible environment behaviors or (b) under the most-likely environment behaviors given as a probability distribution on the possible input sequences. Quasy solves these two quantitative synthesis problems by reduction to instances of 2-player games and Markov Decision Processes (MDPs) with quantitative winning objectives. Quasy can also be seen as a game solver for quantitative games. Most notable, it can solve lexicographic mean-payoff games with 2 players, MDPs with mean-payoff objectives, and ergodic MDPs with mean-payoff parity objectives.}, author = {Chatterjee, Krishnendu and Henzinger, Thomas A and Jobstmann, Barbara and Singh, Rohit}, location = {Saarbrucken, Germany}, pages = {267 -- 271}, publisher = {Springer}, title = {{QUASY: quantitative synthesis tool}}, doi = {10.1007/978-3-642-19835-9_24}, volume = {6605}, year = {2011}, } @inproceedings{3366, abstract = {We present an algorithmic method for the quantitative, performance-aware synthesis of concurrent programs. The input consists of a nondeterministic partial program and of a parametric performance model. The nondeterminism allows the programmer to omit which (if any) synchronization construct is used at a particular program location. The performance model, specified as a weighted automaton, can capture system architectures by assigning different costs to actions such as locking, context switching, and memory and cache accesses. The quantitative synthesis problem is to automatically resolve the nondeterminism of the partial program so that both correctness is guaranteed and performance is optimal. As is standard for shared memory concurrency, correctness is formalized "specification free", in particular as race freedom or deadlock freedom. For worst-case (average-case) performance, we show that the problem can be reduced to 2-player graph games (with probabilistic transitions) with quantitative objectives. While we show, using game-theoretic methods, that the synthesis problem is Nexp-complete, we present an algorithmic method and an implementation that works efficiently for concurrent programs and performance models of practical interest. We have implemented a prototype tool and used it to synthesize finite-state concurrent programs that exhibit different programming patterns, for several performance models representing different architectures. }, author = {Cerny, Pavol and Chatterjee, Krishnendu and Henzinger, Thomas A and Radhakrishna, Arjun and Singh, Rohit}, editor = {Gopalakrishnan, Ganesh and Qadeer, Shaz}, location = {Snowbird, USA}, pages = {243 -- 259}, publisher = {Springer}, title = {{Quantitative synthesis for concurrent programs}}, doi = {10.1007/978-3-642-22110-1_20}, volume = {6806}, year = {2011}, } @inproceedings{3367, abstract = {In this paper, we present the first output-sensitive algorithm to compute the persistence diagram of a filtered simplicial complex. For any Γ>0, it returns only those homology classes with persistence at least Γ. Instead of the classical reduction via column operations, our algorithm performs rank computations on submatrices of the boundary matrix. For an arbitrary constant δ ∈ (0,1), the running time is O(C(1-δ)ΓR(n)log n), where C(1-δ)Γ is the number of homology classes with persistence at least (1-δ)Γ, n is the total number of simplices, and R(n) is the complexity of computing the rank of an n x n matrix with O(n) nonzero entries. Depending on the choice of the rank algorithm, this yields a deterministic O(C(1-δ)Γn2.376) algorithm, a O(C(1-δ)Γn2.28) Las-Vegas algorithm, or a O(C(1-δ)Γn2+ε) Monte-Carlo algorithm for an arbitrary ε>0.}, author = {Chen, Chao and Kerber, Michael}, location = {Paris, France}, pages = {207 -- 216}, publisher = {ACM}, title = {{An output sensitive algorithm for persistent homology}}, doi = {10.1145/1998196.1998228}, year = {2011}, } @article{3369, abstract = {Rab3 interacting molecules (RIMs) are highly enriched in the active zones of presynaptic terminals. It is generally thought that they operate as effectors of the small G protein Rab3. Three recent papers, by Han et al. (this issue of Neuron), Deng et al. (this issue of Neuron), and Kaeser et al. (a recent issue of Cell), shed new light on the functional role of RIM in presynaptic terminals. First, RIM tethers Ca2+ channels to active zones. Second, RIM contributes to priming of synaptic vesicles by interacting with another presynaptic protein, Munc13.}, author = {Pernia-Andrade, Alejandro and Jonas, Peter M}, journal = {Neuron}, number = {2}, pages = {185 -- 187}, publisher = {Elsevier}, title = {{The multiple faces of RIM}}, doi = {10.1016/j.neuron.2011.01.010}, volume = {69}, year = {2011}, } @article{3370, abstract = {Supertree methods are widely applied and give rise to new conclusions about phylogenies (e.g., Bininda-Emonds et al. 2007). Although several desiderata for supertree methods exist (Wilkinson, Thorley, et al. 2004), only few of them have been studied in greater detail, examples include shape bias (Wilkinson et al. 2005) or pareto properties (Wilkinson et al. 2007). Here I look more closely at two matrix representation methods, matrix representation with compatibility (MRC) and matrix representation with parsimony (MRP). Different null models of random data are studied and the resulting tree shapes are investigated. Thereby I consider unrooted trees and a bias in tree shape is determined by a tree balance measure. The measure for unrooted trees is a modification of a tree balance measure for rooted trees. I observe that depending on the underlying null model of random data, the methods may resolve conflict in favor of more balanced tree shapes. The analyses refer only to trees with the same taxon set, also known as the consensus setting (e.g., Wilkinson et al. 2007), but I will be able to draw conclusions on how to deal with missing data.}, author = {Kupczok, Anne}, journal = {Systematic Biology}, number = {2}, pages = {218 -- 225}, publisher = {Oxford University Press}, title = {{Consequences of different null models on the tree shape bias of supertree methods}}, doi = {10.1093/sysbio/syq086}, volume = {60}, year = {2011}, } @article{3371, abstract = {The Minisymposium “Cell Migration and Motility” was attended by approximately 500 visitors and covered a broad range of questions in the field using diverse model systems. Topics comprised actin dynamics, cell polarity, force transduction, signal transduction, bar- rier transmigration, and chemotactic guidance.}, author = {Sixt, Michael K and Parent, Carole}, journal = {Molecular Biology and Evolution}, number = {6}, pages = {724}, publisher = {Oxford University Press}, title = {{Cells on the move in Philadelphia}}, doi = {10.1091/mbc.E10-12-0958}, volume = {22}, year = {2011}, } @article{3372, abstract = {Nowak et al.1 argue that inclusive fitness theory has been of little value in explaining the natural world, and that it has led to negligible progress in explaining the evolution of eusociality. However, we believe that their arguments are based upon a misunderstanding of evolutionary theory and a misrepresentation of the empirical literature. We will focus our comments on three general issues.}, author = {Abbot, Patrick and Abe, Jun and Alcock, John and Alizon, Samuel and Alpedrinha, Joao and Andersson, Malte and Andre, Jean and Van Baalen, Minus and Balloux, Francois and Balshine, Sigal and Barton, Nicholas H and Beukeboom, Leo and Biernaskie, Jay and Bilde, Trine and Borgia, Gerald and Breed, Michael and Brown, Sam and Bshary, Redouan and Buckling, Angus and Burley, Nancy and Burton Chellew, Max and Cant, Michael and Chapuisat, Michel and Charnov, Eric and Clutton Brock, Tim and Cockburn, Andrew and Cole, Blaine and Colegrave, Nick and Cosmides, Leda and Couzin, Iain and Coyne, Jerry and Creel, Scott and Crespi, Bernard and Curry, Robert and Dall, Sasha and Day, Troy and Dickinson, Janis and Dugatkin, Lee and El Mouden, Claire and Emlen, Stephen and Evans, Jay and Ferriere, Regis and Field, Jeremy and Foitzik, Susanne and Foster, Kevin and Foster, William and Fox, Charles and Gadau, Juergen and Gandon, Sylvain and Gardner, Andy and Gardner, Michael and Getty, Thomas and Goodisman, Michael and Grafen, Alan and Grosberg, Rick and Grozinger, Christina and Gouyon, Pierre and Gwynne, Darryl and Harvey, Paul and Hatchwell, Ben and Heinze, Jürgen and Helantera, Heikki and Helms, Ken and Hill, Kim and Jiricny, Natalie and Johnstone, Rufus and Kacelnik, Alex and Kiers, E Toby and Kokko, Hanna and Komdeur, Jan and Korb, Judith and Kronauer, Daniel and Kümmerli, Rolf and Lehmann, Laurent and Linksvayer, Timothy and Lion, Sébastien and Lyon, Bruce and Marshall, James and Mcelreath, Richard and Michalakis, Yannis and Michod, Richard and Mock, Douglas and Monnin, Thibaud and Montgomerie, Robert and Moore, Allen and Mueller, Ulrich and Noë, Ronald and Okasha, Samir and Pamilo, Pekka and Parker, Geoff and Pedersen, Jes and Pen, Ido and Pfennig, David and Queller, David and Rankin, Daniel and Reece, Sarah and Reeve, Hudson and Reuter, Max and Roberts, Gilbert and Robson, Simon and Roze, Denis and Rousset, Francois and Rueppell, Olav and Sachs, Joel and Santorelli, Lorenzo and Schmid Hempel, Paul and Schwarz, Michael and Scott Phillips, Tom and Shellmann Sherman, Janet and Sherman, Paul and Shuker, David and Smith, Jeff and Spagna, Joseph and Strassmann, Beverly and Suarez, Andrew and Sundström, Liselotte and Taborsky, Michael and Taylor, Peter and Thompson, Graham and Tooby, John and Tsutsui, Neil and Tsuji, Kazuki and Turillazzi, Stefano and Úbeda, Francisco and Vargo, Edward and Voelkl, Bernard and Wenseleers, Tom and West, Stuart and West Eberhard, Mary and Westneat, David and Wiernasz, Diane and Wild, Geoff and Wrangham, Richard and Young, Andrew and Zeh, David and Zeh, Jeanne and Zink, Andrew}, journal = {Nature}, number = {7339}, pages = {E1 -- E4}, publisher = {Nature Publishing Group}, title = {{Inclusive fitness theory and eusociality}}, doi = {10.1038/nature09831}, volume = {471}, year = {2011}, } @article{3374, abstract = {Genetic regulatory networks enable cells to respond to changes in internal and external conditions by dynamically coordinating their gene expression profiles. Our ability to make quantitative measurements in these biochemical circuits has deepened our understanding of what kinds of computations genetic regulatory networks can perform, and with what reliability. These advances have motivated researchers to look for connections between the architecture and function of genetic regulatory networks. Transmitting information between a network's inputs and outputs has been proposed as one such possible measure of function, relevant in certain biological contexts. Here we summarize recent developments in the application of information theory to gene regulatory networks. We first review basic concepts in information theory necessary for understanding recent work. We then discuss the functional complexity of gene regulation, which arises from the molecular nature of the regulatory interactions. We end by reviewing some experiments that support the view that genetic networks responsible for early development of multicellular organisms might be maximizing transmitted 'positional information'.}, author = {Tkacik, Gasper and Walczak, Aleksandra}, journal = {Journal of Physics: Condensed Matter}, number = {15}, publisher = {IOP Publishing}, title = {{Information transmission in genetic regulatory networks a review}}, doi = {10.1088/0953-8984/23/15/153102}, volume = {23}, year = {2011}, } @article{3376, abstract = {Regulatory conflicts occur when two signals that individually trigger opposite cellular responses are present simultaneously. Here, we investigate regulatory conflicts in the bacterial response to antibiotic combinations. We use an Escherichia coli promoter-GFP library to study the transcriptional response of many promoters to either additive or antagonistic drug pairs at fine two-dimensional (2D) resolution of drug concentration. Surprisingly, we find that this data set can be characterized as a linear sum of only two principal components. Component one, accounting for over 70% of the response, represents the response to growth inhibition by the drugs. Component two describes how regulatory conflicts are resolved. For the additive drug pair, conflicts are resolved by linearly interpolating the single drug responses, while for the antagonistic drug pair, the growth-limiting drug dominates the response. Importantly, for a given drug pair, the same conflict resolution strategy applies to almost all genes. These results provide a recipe for predicting gene expression responses to antibiotic combinations.}, author = {Bollenbach, Mark Tobias and Kishony, Roy}, journal = {Molecular Cell}, number = {4}, pages = {413 -- 425}, publisher = {Cell Press}, title = {{Resolution of gene regulatory conflicts caused by combinations of antibiotics}}, doi = {10.1016/j.molcel.2011.04.016}, volume = {42}, year = {2011}, } @article{3377, abstract = {By definition, transverse intersections are stable under in- finitesimal perturbations. Using persistent homology, we ex- tend this notion to sizeable perturbations. Specifically, we assign to each homology class of the intersection its robust- ness, the magnitude of a perturbation necessary to kill it, and prove that robustness is stable. Among the applications of this result is a stable notion of robustness for fixed points of continuous mappings and a statement of stability for con- tours of smooth mappings.}, author = {Edelsbrunner, Herbert and Morozov, Dmitriy and Patel, Amit}, journal = {Foundations of Computational Mathematics}, number = {3}, pages = {345 -- 361}, publisher = {Springer}, title = {{Quantifying transversality by measuring the robustness of intersections}}, doi = {10.1007/s10208-011-9090-8}, volume = {11}, year = {2011}, } @article{3378, abstract = {The theory of intersection homology was developed to study the singularities of a topologically stratified space. This paper in- corporates this theory into the already developed framework of persistent homology. We demonstrate that persistent intersec- tion homology gives useful information about the relationship between an embedded stratified space and its singularities. We give, and prove the correctness of, an algorithm for the computa- tion of the persistent intersection homology groups of a filtered simplicial complex equipped with a stratification by subcom- plexes. We also derive, from Poincare ́ Duality, some structural results about persistent intersection homology.}, author = {Bendich, Paul and Harer, John}, journal = {Foundations of Computational Mathematics}, number = {3}, pages = {305 -- 336}, publisher = {Springer}, title = {{Persistent intersection homology}}, doi = {10.1007/s10208-010-9081-1}, volume = {11}, year = {2011}, } @article{3380, abstract = {Linkage between markers and genes that affect a phenotype of interest may be determined by examining differences in marker allele frequency in the extreme progeny of a cross between two inbred lines. This strategy is usually employed when pooling is used to reduce genotyping costs. When the cross progeny are asexual, the extreme progeny may be selected by multiple generations of asexual reproduction and selection. We analyse this method of measuring phenotype in asexual progeny and examine the changes in marker allele frequency due to selection over many generations. Stochasticity in marker frequency in the selected population arises due to the finite initial population size. We derive the distribution of marker frequency as a result of selection at a single major locus, and show that in order to avoid spurious changes in marker allele frequency in the selected population, the initial population size should be in the low to mid hundreds.}, author = {Logeswaran, Sayanthan and Barton, Nicholas H}, journal = {Genetical Research}, number = {3}, pages = {221 -- 232}, publisher = {Cambridge University Press}, title = {{Mapping Mendelian traits in asexual progeny using changes in marker allele frequency}}, doi = {10.1017/S0016672311000115}, volume = {93}, year = {2011}, } @article{3381, abstract = {In this survey, we compare several languages for specifying Markovian population models such as queuing networks and chemical reaction networks. All these languages — matrix descriptions, stochastic Petri nets, stoichiometric equations, stochastic process algebras, and guarded command models — describe continuous-time Markov chains, but they differ according to important properties, such as compositionality, expressiveness and succinctness, executability, and ease of use. Moreover, they provide different support for checking the well-formedness of a model and for analyzing a model.}, author = {Henzinger, Thomas A and Jobstmann, Barbara and Wolf, Verena}, journal = {IJFCS: International Journal of Foundations of Computer Science}, number = {4}, pages = {823 -- 841}, publisher = {World Scientific Publishing}, title = {{Formalisms for specifying Markovian population models}}, doi = {10.1142/S0129054111008441}, volume = {22}, year = {2011}, } @article{3382, abstract = {Dynamic tactile sensing is a fundamental ability to recognize materials and objects. However, while humans are born with partially developed dynamic tactile sensing and quickly master this skill, today's robots remain in their infancy. The development of such a sense requires not only better sensors but the right algorithms to deal with these sensors' data as well. For example, when classifying a material based on touch, the data are noisy, high-dimensional, and contain irrelevant signals as well as essential ones. Few classification methods from machine learning can deal with such problems. In this paper, we propose an efficient approach to infer suitable lower dimensional representations of the tactile data. In order to classify materials based on only the sense of touch, these representations are autonomously discovered using visual information of the surfaces during training. However, accurately pairing vision and tactile samples in real-robot applications is a difficult problem. The proposed approach, therefore, works with weak pairings between the modalities. Experiments show that the resulting approach is very robust and yields significantly higher classification performance based on only dynamic tactile sensing.}, author = {Kroemer, Oliver and Lampert, Christoph and Peters, Jan}, journal = {IEEE Transactions on Robotics}, number = {3}, pages = {545 -- 557}, publisher = {IEEE}, title = {{Learning dynamic tactile sensing with robust vision based training}}, doi = {10.1109/TRO.2011.2121130}, volume = {27}, year = {2011}, }