@article{1040,
  abstract     = {Ultracold atomic physics offers myriad possibilities to study strongly correlated many-body systems in lower dimensions. Typically, only ground-state phases are accessible. Using a tunable quantum gas of bosonic cesium atoms, we realized and controlled in one-dimensional geometry a highly excited quantum phase that is stabilized in the presence of attractive interactions by maintaining and strengthening quantum correlations across a confinement-induced resonance. We diagnosed the crossover from repulsive to attractive interactions in terms of the stiffness and energy of the system. Our results open up the experimental study of metastable, excited, many-body phases with strong correlations and their dynamical properties.},
  author       = {Haller, Elmar and Gustavsson, Mattias and Mark, Manfred and Danzl, Johann G and Hart, Russell and Pupillo, Guido and Nägerl, Hanns},
  journal      = {Science},
  number       = {5945},
  pages        = {1224 -- 1227},
  publisher    = {American Association for the Advancement of Science},
  title        = {{Realization of an excited, strongly correlated quantum gas Phase}},
  doi          = {10.1126/science.1175850},
  volume       = {325},
  year         = {2009},
}

@article{1041,
  abstract     = {We demonstrate efficient transfer of ultracold molecules into a deeply bound rovibrational level of the singlet ground state potential in the presence of an optical lattice. The overall molecule creation efficiency is 25%, and the transfer efficiency to the rovibrational level |v = 73, J = 2) is above 80%. We find that the molecules in |v = 73, J = 2) are trapped in the optical lattice, and that the lifetime in the lattice is limited by optical excitation by the lattice light. The molecule trapping time for a lattice depth of 15 atomic recoil energies is about 20 ms. We determine the trapping frequency by the lattice phase and amplitude modulation technique. It will now be possible to transfer the molecules to the rovibrational ground state |v = 0, J = 0) in the presence of the optical lattice.},
  author       = {Danzl, Johann G and Mark, Manfred and Haller, Elmar and Gustavsson, Mattias and Hart, Russell and Liem, Andreas and Zellmer, Holger and Nägerl, Hanns},
  journal      = {New Journal of Physics},
  publisher    = {IOP Publishing Ltd.},
  title        = {{Deeply bound ultracold molecules in an optical lattice}},
  doi          = {10.1088/1367-2630/11/5/055036},
  volume       = {11},
  year         = {2009},
}

@article{1043,
  abstract     = {One possibility for the creation of ultracold, high phase space density quantum gases of molecules in the rovibronic ground state relies on first associating weakly-bound molecules from quantum-degenerate atomic gases on a Feshbach resonance and then transferring the molecules via several steps of coherent two-photon stimulated Raman adiabatic passage (STIRAP) into the rovibronic ground state. Here, in ultracold samples of Cs2 Feshbach molecules produced out of ultracold samples of Cs atoms, we observe several optical transitions to deeply-bound rovibrational levels of the excited 0 u+ molecular potentials with high resolution. At least one of these transitions, although rather weak, allows efficient STIRAP transfer into the deeply-bound vibrational level v = 73> of the singlet X 1Σg+ ground state potential, as recently demonstrated (J. G. Danzl, E. Haller, M. Gustavsson, M. J. Mark, R. Hart, N. Bouloufa, O. Dulieu, H. Ritsch, and H.-C. Nägerl, Science, 2008, 321, 1062). From this level, the rovibrational ground state v = 0, J = 0> can be reached with one more transfer step. In total, our results show that coherent ground state transfer for Cs2 is possible using a maximum of two successive two-photon STIRAP processes or one single four-photon STIRAP process.},
  author       = {Danzl, Johann G and Mark, Manfred and Haller, Elmar and Gustavsson, Mattias and Bouloufa, Nadia and Dulieu, Olivier and Ritsch, Helmut and Hart, Russell and Nägerl, Hanns},
  journal      = {Faraday Discussions},
  pages        = {283 -- 295},
  publisher    = {Royal Society of Chemistry},
  title        = {{Precision molecular spectroscopy for ground state transfer of molecular quantum gases}},
  doi          = {10.1039/b820542f},
  volume       = {142},
  year         = {2009},
}

@inproceedings{11912,
  abstract     = {As the World Wide Web is growing rapidly, it is getting increasingly challenging to gather representative information about it. Instead of crawling the web exhaustively one has to resort to other techniques like sampling to determine the properties of the web. A uniform random sample of the web would be useful to determine the percentage of web pages in a specific language, on a topic or in a top level domain. Unfortunately, no approach has been shown to sample the web pages in an unbiased way. Three promising web sampling algorithms are based on random walks. They each have been evaluated individually, but making a comparison on different data sets is not possible. We directly compare these algorithms in this paper. We performed three random walks on the web under the same conditions and analyzed their outcomes in detail. We discuss the strengths and the weaknesses of each algorithm and propose improvements based on experimental results.},
  author       = {Baykan,  Eda and Henzinger, Monika H and Keller, Stefan F. and de Castelberg, Sebastian and Kinzler, Markus},
  booktitle    = {26th International Symposium on Theoretical Aspects of Computer Science},
  isbn         = {978-3-939897-09-5},
  issn         = {1868-8969},
  location     = {Freiburg, Germany},
  pages        = {13--30},
  publisher    = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik},
  title        = {{A comparison of techniques for sampling web pages}},
  doi          = {10.4230/LIPICS.STACS.2009.1809},
  volume       = {3},
  year         = {2009},
}

@article{12654,
  abstract     = {We investigate the transferability of an enhanced temperature-index melt model that was developed and tested on Haut Glacier d’Arolla, Switzerland, in the 2001 season. The model’s empirical parameters (temperature factor, TF, and shortwave radiation factor, SRF) are recalibrated for: (1) other locations on Haut Glacier d’Arolla; (2) subperiods of distinct meteorological conditions; (3) different years on Haut Glacier d’Arolla; and (4) other glaciers in different years. The model parameters are optimized against simulations of an energy-balance model validated against ablation observations. Results are compared with those obtained with the original parameters. The model works very well when applied to other sites, seasons and glaciers, with the exception of overcast conditions. Differences are due to underestimation of high melt rates. The parameter values are associated with the prevailing energy-balance conditions, showing that high SRF are obtained on clear-sky days, whereas higher TF are typical of locations where glacier winds prevail and turbulent fluxes are high. We also provide a range of parameters clearly associated with the site’s location and its meteorological characteristics that could help to assign parameter values to sites where few data are available.},
  author       = {Carenzo, Marco and Pellicciotti, Francesca and Rimkus, Stefan and Burlando, Paolo},
  issn         = {1727-5652},
  journal      = {Journal of Glaciology},
  number       = {190},
  pages        = {258--274},
  publisher    = {Cambridge University Press},
  title        = {{Assessing the transferability and robustness of an enhanced temperature-index glacier-melt model}},
  doi          = {10.3189/002214309788608804},
  volume       = {55},
  year         = {2009},
}

@article{12655,
  abstract     = {We discuss the inclusion of the subsurface heat-conduction flux into the calculation of the energy balance and ablation at the glacier–atmosphere interface. Data from automatic weather stations are used to force an energy-balance model at several locations on alpine glaciers and at one site in the dry Andes of central Chile. The heat-conduction flux is computed using a two-layer scheme, assuming that 36% of the net shortwave radiation is absorbed by the surface layer and that the rest penetrates into the snowpack. We compare simulations conducted with and without subsurface heat flux. Results show that assuming a surface temperature of zero degrees leads to a larger overestimation of melt at the sites in the accumulation area (10.4–13.3%) than in the ablation area (0.5–2.8%), due to lower air temperatures and the presence of snow. The difference between simulations with and without heat conduction is also high at the beginning and end of the ablation season (up to 29% for the first 15 days of the season), when air temperatures are lower and snow covers the glacier surface, while they are of little importance during periods of sustained melt at all the locations investigated.},
  author       = {Pellicciotti, Francesca and Carenzo, Marco and Helbing, Jakob and Rimkus, Stefan and Burlando, Paolo},
  issn         = {1727-5644},
  journal      = {Annals of Glaciology},
  number       = {50},
  pages        = {16--24},
  publisher    = {International Glaciological Society},
  title        = {{On the role of subsurface heat conduction in glacier energy-balance modelling}},
  doi          = {10.3189/172756409787769555},
  volume       = {50},
  year         = {2009},
}

@inproceedings{3503,
  abstract     = {We give polynomial-time algorithms for computing the values of Markov decision processes (MDPs) with limsup and liminf objectives. A real-valued reward is assigned to each state, and the value of an infinite path in the MDP is the limsup (resp. liminf) of all rewards along the path. The value of an MDP is the maximal expected value of an infinite path that can be achieved by resolving the decisions of the MDP. Using our result on MDPs, we show that turn-based stochastic games with limsup and liminf objectives can be solved in NP ∩ coNP. },
  author       = {Krishnendu Chatterjee and Thomas Henzinger},
  pages        = {32 -- 45},
  publisher    = {Springer},
  title        = {{Probabilistic systems with limsup and liminf objectives}},
  doi          = {10.1007/978-3-642-03092-5_4},
  volume       = {5489},
  year         = {2009},
}

@unpublished{3732,
  abstract     = {Ising models with pairwise interactions are the least structured, or maximum-entropy, probability distributions that exactly reproduce measured pairwise correlations between spins. Here we use this equivalence to construct Ising models that describe the correlated spiking activity of populations of 40 neurons in the salamander retina responding to natural movies. We show that pairwise interactions between neurons account for observed higher-order correlations, and that for groups of 10 or more neurons pairwise interactions can no longer be regarded as small perturbations in an independent system. We then construct network ensembles that generalize the network instances observed in the experiment, and study their thermodynamic behavior and coding capacity. Based on this construction, we can also create synthetic networks of 120 neurons, and find that with increasing size the networks operate closer to a critical point and start exhibiting collective behaviors reminiscent of spin glasses. We examine closely two such behaviors that could be relevant for neural code: tuning of the network to the critical point to maximize the ability to encode diverse stimuli, and using the metastable states of the Ising Hamiltonian as neural code words.},
  author       = {Gasper Tkacik and Schneidman, Elad and Berry, Michael J and Bialek, William S},
  booktitle    = {ArXiv},
  publisher    = {ArXiv},
  title        = {{Spin glass models for a network of real neurons}},
  volume       = {q-bio.NC},
  year         = {2009},
}

@article{3775,
  abstract     = {There is a close analogy between statistical thermodynamics and the evolution of allele frequencies under mutation, selection and random drift. Wright's formula for the stationary distribution of allele frequencies is analogous to the Boltzmann distribution in statistical physics. Population size, 2N, plays the role of the inverse temperature, 1/kT, and determines the magnitude of random fluctuations. Log mean fitness, View the MathML source, tends to increase under selection, and is analogous to a (negative) energy; a potential function, U, increases under mutation in a similar way. An entropy, SH, can be defined which measures the deviation from the distribution of allele frequencies expected under random drift alone; the sum View the MathML source gives a free fitness that increases as the population evolves towards its stationary distribution. Usually, we observe the distribution of a few quantitative traits that depend on the frequencies of very many alleles. The mean and variance of such traits are analogous to observable quantities in statistical thermodynamics. Thus, we can define an entropy, SΩ, which measures the volume of allele frequency space that is consistent with the observed trait distribution. The stationary distribution of the traits is View the MathML source; this applies with arbitrary epistasis and dominance. The entropies SΩ, SH are distinct, but converge when there are so many alleles that traits fluctuate close to their expectations. Populations tend to evolve towards states that can be realised in many ways (i.e., large SΩ), which may lead to a substantial drop below the adaptive peak; we illustrate this point with a simple model of genetic redundancy. This analogy with statistical thermodynamics brings together previous ideas in a general framework, and justifies a maximum entropy approximation to the dynamics of quantitative traits.},
  author       = {Barton, Nicholas H and Coe, Jason},
  journal      = {Journal of Theoretical Biology},
  number       = {2},
  pages        = {317 -- 324},
  publisher    = {Elsevier},
  title        = {{On the application of statistical physics to evolutionary biology}},
  doi          = {10.1016/j.jtbi.2009.03.019},
  volume       = {259},
  year         = {2009},
}

@article{3780,
  abstract     = {Why are sinistral snails so rare? Two main hypotheses are that selection acts against the establishment of new coiling morphs, because dextral and sinistral snails have trouble mating, or else a developmental constraint prevents the establishment of sinistrals. We therefore used an isolate of the snail Lymnaea stagnalis, in which sinistrals are rare, and populations of Partula suturalis, in which sinistrals are common, as well as a mathematical model, to understand the circumstances by which new morphs evolve. The main finding is that the sinistral genotype is associated with reduced egg viability in L. stagnalis, but in P. suturalis individuals of sinistral and dextral genotype appear equally fecund, implying a lack of a constraint. As positive frequency-dependent selection against the rare chiral morph in P. suturalis also operates over a narrow range (< 3%), the results suggest a model for chiral evolution in snails in which weak positive frequency-dependent selection may be overcome by a negative frequency-dependent selection, such as reproductive character displacement. In snails, there is not always a developmental constraint. As the direction of cleavage, and thus the directional asymmetry of the entire body, does not generally vary in other Spiralia (annelids, echiurans, vestimentiferans, sipunculids and nemerteans), it remains an open question as to whether this is because of a constraint and/or because most taxa do not have a conspicuous external asymmetry (like a shell) upon which selection can act.},
  author       = {Davison, Angus and Barton, Nicholas H and Clarke, Bryan},
  journal      = {Journal of Evolutionary Biology},
  number       = {8},
  pages        = {1624 -- 1635},
  publisher    = {Wiley},
  title        = {{The effect of chirality phenotype and genotype on the fecundity and viability of Partula suturalis and Lymnaea stagnalis: Implications for the evolution of sinistral snails}},
  doi          = {10.1111/j.1420-9101.2009.01770.x},
  volume       = {22},
  year         = {2009},
}

@inproceedings{3837,
  abstract     = {In this paper we extend the work of Alfaro, Henzinger et al. on interface theories for component-based design. Existing interface theories often fail to capture functional relations between the inputs and outputs of an interface. For example, a simple synchronous interface that takes as input a number n ≥ 0 and returns, at the same time, as output n + 1, cannot be expressed in existing theories. In this paper we provide a theory of relational interfaces, where such input-output relations can be captured. Our theory supports synchronous interfaces, both stateless and stateful. It includes explicit notions of environments and pluggability, and satisfies fundamental properties such as preservation of refinement by composition, and characterization of pluggability by refinement. We achieve these properties by making reasonable restrictions on feedback loops in interface compositions.},
  author       = {Tripakis, Stavros and Lickly, Ben and Henzinger, Thomas A and Lee, Edward},
  booktitle    = {EMSOFT '09 Proceedings of the seventh ACM international conference on Embedded software},
  location     = {Grenoble, France},
  pages        = {67 -- 76},
  publisher    = {ACM},
  title        = {{On relational interfaces}},
  doi          = {10.1145/1629335.1629346},
  year         = {2009},
}

@inproceedings{3841,
  abstract     = {We compare several languages for specifying Markovian population models such as queuing networks and chemical reaction networks. These languages —matrix descriptions, stochastic Petri nets, stoichiometric equations, stochastic process algebras, and guarded command models— all describe continuous-time Markov chains, but they differ according to important properties, such as compositionality, expressiveness and succinctness, executability, ease of use, and the support they provide for checking the well-formedness of a model and for analyzing a model. },
  author       = {Henzinger, Thomas A and Jobstmann, Barbara and Wolf, Verena},
  location     = {Palaiseau, France},
  pages        = {3 -- 23},
  publisher    = {Springer},
  title        = {{Formalisms for specifying Markovian population models}},
  doi          = {10.1007/978-3-642-04420-5_2},
  volume       = {5797},
  year         = {2009},
}

@inproceedings{3843,
  abstract     = {Within systems biology there is an increasing interest in the stochastic behavior of biochemical reaction networks. An appropriate stochastic description is provided by the chemical master equation, which represents a continuous- time Markov chain (CTMC).
Standard Uniformization (SU) is an efficient method for the transient analysis of CTMCs. For systems with very different time scales, such as biochemical reaction networks, SU is computationally expensive. In these cases, a variant of SU, called adaptive uniformization (AU), is known to reduce the large number of iterations needed by SU. The additional difficulty of AU is that it requires the solution of a birth process.
In this paper we present an on-the-fly variant of AU, where we improve the original algorithm for AU at the cost of a small approximation error. By means of several examples, we show that our approach is particularly well-suited for biochemical reaction networks.},
  author       = {Didier, Frédéric and Henzinger, Thomas A and Mateescu, Maria and Wolf, Verena},
  location     = {Trento, Italy},
  number       = {6},
  pages        = {118 -- 127},
  publisher    = {IEEE},
  title        = {{Fast adaptive uniformization of the chemical master equation}},
  doi          = {10.1109/HiBi.2009.23},
  volume       = {4},
  year         = {2009},
}

@inproceedings{3844,
  abstract     = {The Hierarchical Timing Language (HTL) is a real-time coordination language for distributed control systems. HTL programs must be checked for well-formedness, race freedom, transmission safety (schedulability of inter-host communication), and time safety (schedulability of host computation). We present a modular abstract syntax and semantics for HTL, modular checks of well-formedness, race freedom, and transmission safety, and modular code distribution. Our contributions here complement previous results on HTL time safety and modular code generation. Modularity in HTL can be utilized in easy program composition as well as fast program analysis and code generation, but also in so-called runtime patching, where program components may be modified at runtime.},
  author       = {Henzinger, Thomas A and Kirsch, Christoph and Marques, Eduardo and Sokolova, Ana},
  location     = {Washington, DC, United States},
  pages        = {171 -- 180},
  publisher    = {IEEE},
  title        = {{Distributed, modular HTL}},
  doi          = {10.1109/RTSS.2009.9},
  year         = {2009},
}

@article{3870,
  abstract     = {Games on graphs with omega-regular objectives provide a model for the control and synthesis of reactive systems. Every omega-regular objective can be decomposed into a safety part and a liveness part. The liveness part ensures that something good happens “eventually.” Two main strengths of the classical, infinite-limit formulation of liveness are robustness (independence from the granularity of transitions) and simplicity (abstraction of complicated time bounds). However, the classical liveness formulation suffers from the drawback that the time until something good happens may be unbounded. A stronger formulation of liveness, so-called finitary liveness, overcomes this drawback, while still retaining robustness and simplicity. Finitary liveness requires that there exists an unknown, fixed bound b such that something good happens within b transitions. While for one-shot liveness (reachability) objectives, classical and finitary liveness coincide, for repeated liveness (Buchi) objectives, the finitary formulation is strictly stronger. In this work we study games with finitary parity and Streett objectives. We prove the determinacy of these games, present algorithms for solving these games, and characterize the memory requirements of winning strategies. We show that finitary parity games can be solved in polynomial time, which is not known for infinitary parity games. For finitary Streett games, we give an EXPTIME algorithm and show that the problem is NP-hard. Our algorithms can be used, for example, for synthesizing controllers that do not let the response time of a system increase without bound.},
  author       = {Chatterjee, Krishnendu and Henzinger, Thomas A and Horn, Florian},
  journal      = {ACM Transactions on Computational Logic (TOCL)},
  number       = {1},
  publisher    = {ACM},
  title        = {{Finitary winning in omega-regular games}},
  doi          = {10.1145/1614431.1614432},
  volume       = {11},
  year         = {2009},
}

@inproceedings{3871,
  abstract     = {Nondeterministic weighted automata are finite automata with numerical weights oil transitions. They define quantitative languages 1, that assign to each word v; a real number L(w). The value of ail infinite word w is computed as the maximal value of all runs over w, and the value of a run as the supremum, limsup liminf, limit average, or discounted sum of the transition weights. We introduce probabilistic weighted antomata, in which the transitions are chosen in a randomized (rather than nondeterministic) fashion. Under almost-sure semantics (resp. positive semantics), the value of a word v) is the largest real v such that the runs over w have value at least v with probability I (resp. positive probability). We study the classical questions of automata theory for probabilistic weighted automata: emptiness and universality, expressiveness, and closure under various operations oil languages. For quantitative languages, emptiness university axe defined as whether the value of some (resp. every) word exceeds a given threshold. We prove some, of these questions to he decidable, and others undecidable. Regarding expressive power, we show that probabilities allow its to define a wide variety of new classes of quantitative languages except for discounted-sum automata, where probabilistic choice is no more expressive than nondeterminism. Finally we live ail almost complete picture of the closure of various classes of probabilistic weighted automata for the following, provide, is operations oil quantitative languages: maximum, sum. and numerical complement.},
  author       = {Chatterjee, Krishnendu and Doyen, Laurent and Henzinger, Thomas A},
  location     = {Bologna, Italy},
  pages        = {244 -- 258},
  publisher    = {Springer},
  title        = {{Probabilistic weighted automata}},
  doi          = {10.1007/978-3-642-04081-8_17},
  volume       = {5710},
  year         = {2009},
}

@article{3946,
  abstract     = {We compare anti-parasite defences at the level of multicellular organisms and insect societies, and find that selection by parasites at these two organisational levels is often very similar and has created a number of parallel evolutionary solutions in the host's immune response. The defence mechanisms of both individuals and insect colonies start with border defences to prevent parasite intake and are followed by soma defences that prevent the establishment and spread of the parasite between the body's cells or the social insect workers. Lastly, germ line defences are employed to inhibit infection of the reproductive tissue of organisms or the reproductive individuals in colonies. We further find sophisticated self/non-self-recognition systems operating at both levels, which appear to be vital in maintaining the integrity of the body or colony as a reproductive entity. We then expand on the regulation of immune responses and end with a contemplation of how evolution may shape the different immune components, both within and between levels. The aim of this review is to highlight common evolutionary principles acting in disease defence at the level of both individual organisms and societies, thereby linking the fields of physiological and ecological immunology.},
  author       = {Cremer, Sylvia and Sixt, Michael K},
  journal      = {Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences},
  number       = {1513},
  pages        = {129 -- 142},
  publisher    = {Royal Society, The},
  title        = {{Analogies in the evolution of individual and social immunity}},
  doi          = {10.1098/rstb.2008.0166},
  volume       = {364},
  year         = {2009},
}

@inproceedings{3968,
  abstract     = {We describe an algorithm for segmenting three-dimensional medical imaging data modeled as a continuous function on a 3-manifold. It is related to watershed algorithms developed in image processing but is closer to its mathematical roots, which are Morse theory and homological algebra. It allows for the implicit treatment of an underlying mesh, thus combining the structural integrity of its mathematical foundations with the computational efficiency of image processing.},
  author       = {Edelsbrunner, Herbert and Harer, John},
  location     = {Zermatt, Switzerland},
  pages        = {36 -- 50},
  publisher    = {Springer},
  title        = {{The persistent Morse complex segmentation of a 3-manifold}},
  doi          = {10.1007/978-3-642-10470-1_4},
  volume       = {5903},
  year         = {2009},
}

@article{4136,
  abstract     = {Populations living in a spatially and temporally changing environment can adapt to the changing optimum and/or migrate toward favorable habitats. Here we extend previous analyses with a static optimum to allow the environment to vary in time as well as in space. The model follows both population dynamics and the trait mean under stabilizing selection, and the outcomes can be understood by comparing the loads due to genetic variance, dispersal, and temporal change. With fixed genetic variance, we obtain two regimes: (1) adaptation that is uniform along the environmental gradient and that responds to the moving optimum as expected for panmictic populations and when the spatial gradient is sufficiently steep, and (2) a population with limited range that adapts more slowly than the environmental optimum changes in both time and space; the population therefore becomes locally extinct and migrates toward suitable habitat. We also use a population‐genetic model with many loci to allow genetic variance to evolve, and we show that the only solution now has uniform adaptation.},
  author       = {Polechova, Jitka and Barton, Nicholas H and Marion, Glenn},
  journal      = {American Naturalist},
  number       = {5},
  pages        = {E186 -- E204},
  publisher    = {University of Chicago Press},
  title        = {{Species' range: Adaptation in space and time}},
  doi          = {10.1086/605958},
  volume       = {174},
  year         = {2009},
}

@article{4242,
  abstract     = {Felsenstein distinguished two ways by which selection can directly strengthen isolation. First, a modifier that strengthens prezygotic isolation can be favored everywhere. This fits with the traditional view of reinforcement as an adaptation to reduce deleterious hybridization by strengthening assortative mating. Second, selection can favor association between different incompatibilities, despite recombination. We generalize this “two allele” model to follow associations among any number of incompatibilities, which may include both assortment and hybrid inviability. Our key argument is that this process, of coupling between incompatibilities, may be quite different from the usual view of reinforcement: strong isolation can evolve through the coupling of any kind of incompatibility, whether prezygotic or postzygotic. Single locus incompatibilities become coupled because associations between them increase the variance in compatibility, which in turn increases mean fitness if there is positive epistasis. Multiple incompatibilities, each maintained by epistasis, can become coupled in the same way. In contrast, a single-locus incompatibility can become coupled with loci that reduce the viability of haploid hybrids because this reduces harmful recombination. We obtain simple approximations for the limits of tight linkage, and strong assortment, and show how assortment alleles can invade through associations with other components of reproductive isolation.},
  author       = {Barton, Nicholas H and De Cara, Maria},
  journal      = {Evolution; International Journal of Organic Evolution},
  number       = {5},
  pages        = {1171 -- 1190},
  publisher    = {Wiley},
  title        = {{The evolution of strong reproductive isolation}},
  doi          = {10.1111/j.1558-5646.2009.00622.x},
  volume       = {63},
  year         = {2009},
}