@inproceedings{10903, abstract = {We propose a logic-based framework for automated reasoning about sequential programs manipulating singly-linked lists and arrays with unbounded data. We introduce the logic SLAD, which allows combining shape constraints, written in a fragment of Separation Logic, with data and size constraints. We address the problem of checking the entailment between SLAD formulas, which is crucial in performing pre-post condition reasoning. Although this problem is undecidable in general for SLAD, we propose a sound and powerful procedure that is able to solve this problem for a large class of formulas, beyond the capabilities of existing techniques and tools. We prove that this procedure is complete, i.e., it is actually a decision procedure for this problem, for an important fragment of SLAD including known decidable logics. We implemented this procedure and shown its preciseness and its efficiency on a significant benchmark of formulas.}, author = {Bouajjani, Ahmed and Dragoi, Cezara and Enea, Constantin and Sighireanu, Mihaela}, booktitle = {Automated Technology for Verification and Analysis}, isbn = {9783642333859}, issn = {1611-3349}, location = {Thiruvananthapuram, India}, pages = {167--182}, publisher = {Springer}, title = {{Accurate invariant checking for programs manipulating lists and arrays with infinite data}}, doi = {10.1007/978-3-642-33386-6_14}, volume = {7561}, year = {2012}, } @inproceedings{10905, abstract = {Energy games belong to a class of turn-based two-player infinite-duration games played on a weighted directed graph. It is one of the rare and intriguing combinatorial problems that lie in NP ∩ co−NP, but are not known to be in P. While the existence of polynomial-time algorithms has been a major open problem for decades, there is no algorithm that solves any non-trivial subclass in polynomial time. In this paper, we give several results based on the weight structures of the graph. First, we identify a notion of penalty and present a polynomial-time algorithm when the penalty is large. Our algorithm is the first polynomial-time algorithm on a large class of weighted graphs. It includes several counter examples that show that many previous algorithms, such as value iteration and random facet algorithms, require at least sub-exponential time. Our main technique is developing the first non-trivial approximation algorithm and showing how to convert it to an exact algorithm. Moreover, we show that in a practical case in verification where weights are clustered around a constant number of values, the energy game problem can be solved in polynomial time. We also show that the problem is still as hard as in general when the clique-width is bounded or the graph is strongly ergodic, suggesting that restricting graph structures need not help.}, author = {Chatterjee, Krishnendu and Henzinger, Monika H and Krinninger, Sebastian and Nanongkai, Danupon}, booktitle = {Algorithms – ESA 2012}, isbn = {9783642330896}, issn = {1611-3349}, location = {Ljubljana, Slovenia}, pages = {301--312}, publisher = {Springer}, title = {{Polynomial-time algorithms for energy games with special weight structures}}, doi = {10.1007/978-3-642-33090-2_27}, volume = {7501}, year = {2012}, } @inproceedings{10906, abstract = {HSF(C) is a tool that automates verification of safety and liveness properties for C programs. This paper describes the verification approach taken by HSF(C) and provides instructions on how to install and use the tool.}, author = {Grebenshchikov, Sergey and Gupta, Ashutosh and Lopes, Nuno P. and Popeea, Corneliu and Rybalchenko, Andrey}, booktitle = {Tools and Algorithms for the Construction and Analysis of Systems}, editor = {Flanagan, Cormac and König, Barbara}, isbn = {9783642287558}, issn = {1611-3349}, location = {Tallinn, Estonia}, pages = {549--551}, publisher = {Springer}, title = {{HSF(C): A software verifier based on Horn clauses}}, doi = {10.1007/978-3-642-28756-5_46}, volume = {7214}, year = {2012}, } @inbook{5745, author = {Gupta, Ashutosh}, booktitle = {Automated Technology for Verification and Analysis}, isbn = {9783642333859}, issn = {1611-3349}, location = {Thiruvananthapuram, Kerala, India}, pages = {107--121}, publisher = {Springer Berlin Heidelberg}, title = {{Improved Single Pass Algorithms for Resolution Proof Reduction}}, doi = {10.1007/978-3-642-33386-6_10}, volume = {7561}, year = {2012}, } @inproceedings{3251, abstract = {Many infinite state systems can be seen as well-structured transition systems (WSTS), i.e., systems equipped with a well-quasi-ordering on states that is also a simulation relation. WSTS are an attractive target for formal analysis because there exist generic algorithms that decide interesting verification problems for this class. Among the most popular algorithms are acceleration-based forward analyses for computing the covering set. Termination of these algorithms can only be guaranteed for flattable WSTS. Yet, many WSTS of practical interest are not flattable and the question whether any given WSTS is flattable is itself undecidable. We therefore propose an analysis that computes the covering set and captures the essence of acceleration-based algorithms, but sacrifices precision for guaranteed termination. Our analysis is an abstract interpretation whose abstract domain builds on the ideal completion of the well-quasi-ordered state space, and a widening operator that mimics acceleration and controls the loss of precision of the analysis. We present instances of our framework for various classes of WSTS. Our experience with a prototype implementation indicates that, despite the inherent precision loss, our analysis often computes the precise covering set of the analyzed system.}, author = {Zufferey, Damien and Wies, Thomas and Henzinger, Thomas A}, location = {Philadelphia, PA, USA}, pages = {445 -- 460}, publisher = {Springer}, title = {{Ideal abstractions for well structured transition systems}}, doi = {10.1007/978-3-642-27940-9_29}, volume = {7148}, year = {2012}, } @article{3157, abstract = {Colorectal tumours that are wild type for KRAS are often sensitive to EGFR blockade, but almost always develop resistance within several months of initiating therapy. The mechanisms underlying this acquired resistance to anti-EGFR antibodies are largely unknown. This situation is in marked contrast to that of small-molecule targeted agents, such as inhibitors of ABL, EGFR, BRAF and MEK, in which mutations in the genes encoding the protein targets render the tumours resistant to the effects of the drugs. The simplest hypothesis to account for the development of resistance to EGFR blockade is that rare cells with KRAS mutations pre-exist at low levels in tumours with ostensibly wild-type KRAS genes. Although this hypothesis would seem readily testable, there is no evidence in pre-clinical models to support it, nor is there data from patients. To test this hypothesis, we determined whether mutant KRAS DNA could be detected in the circulation of 28 patients receiving monotherapy with panitumumab, a therapeutic anti-EGFR antibody. We found that 9 out of 24 (38%) patients whose tumours were initially KRAS wild type developed detectable mutations in KRAS in their sera, three of which developed multiple different KRAS mutations. The appearance of these mutations was very consistent, generally occurring between 5 and 6months following treatment. Mathematical modelling indicated that the mutations were present in expanded subclones before the initiation of panitumumab treatment. These results suggest that the emergence of KRAS mutations is a mediator of acquired resistance to EGFR blockade and that these mutations can be detected in a non-invasive manner. They explain why solid tumours develop resistance to targeted therapies in a highly reproducible fashion.}, author = {Diaz Jr, Luis and Williams, Richard and Wu, Jian and Kinde, Isaac and Hecht, Joel and Berlin, Jordan and Allen, Benjamin and Božić, Ivana and Reiter, Johannes and Nowak, Martin and Kinzler, Kenneth and Oliner, Kelly and Vogelstein, Bert}, journal = {Nature}, number = {7404}, pages = {537 -- 540}, publisher = {Nature Publishing Group}, title = {{The molecular evolution of acquired resistance to targeted EGFR blockade in colorectal cancers}}, doi = {10.1038/nature11219}, volume = {486}, year = {2012}, } @article{3260, abstract = {Many scenarios in the living world, where individual organisms compete for winning positions (or resources), have properties of auctions. Here we study the evolution of bids in biological auctions. For each auction, n individuals are drawn at random from a population of size N. Each individual makes a bid which entails a cost. The winner obtains a benefit of a certain value. Costs and benefits are translated into reproductive success (fitness). Therefore, successful bidding strategies spread in the population. We compare two types of auctions. In “biological all-pay auctions”, the costs are the bid for every participating individual. In “biological second price all-pay auctions”, the cost for everyone other than the winner is the bid, but the cost for the winner is the second highest bid. Second price all-pay auctions are generalizations of the “war of attrition” introduced by Maynard Smith. We study evolutionary dynamics in both types of auctions. We calculate pairwise invasion plots and evolutionarily stable distributions over the continuous strategy space. We find that the average bid in second price all-pay auctions is higher than in all-pay auctions, but the average cost for the winner is similar in both auctions. In both cases, the average bid is a declining function of the number of participants, n. The more individuals participate in an auction the smaller is the chance of winning, and thus expensive bids must be avoided. }, author = {Chatterjee, Krishnendu and Reiter, Johannes and Nowak, Martin}, journal = {Theoretical Population Biology}, number = {1}, pages = {69 -- 80}, publisher = {Academic Press}, title = {{Evolutionary dynamics of biological auctions}}, doi = {10.1016/j.tpb.2011.11.003}, volume = {81}, year = {2012}, } @article{3258, abstract = {CA3 pyramidal neurons are important for memory formation and pattern completion in the hippocampal network. It is generally thought that proximal synapses from the mossy fibers activate these neurons most efficiently, whereas distal inputs from the perforant path have a weaker modulatory influence. We used confocally targeted patch-clamp recording from dendrites and axons to map the activation of rat CA3 pyramidal neurons at the subcellular level. Our results reveal two distinct dendritic domains. In the proximal domain, action potentials initiated in the axon backpropagate actively with large amplitude and fast time course. In the distal domain, Na+ channel–mediated dendritic spikes are efficiently initiated by waveforms mimicking synaptic events. CA3 pyramidal neuron dendrites showed a high Na+-to-K+ conductance density ratio, providing ideal conditions for active backpropagation and dendritic spike initiation. Dendritic spikes may enhance the computational power of CA3 pyramidal neurons in the hippocampal network.}, author = {Kim, Sooyun and Guzmán, José and Hu, Hua and Jonas, Peter M}, issn = {1546-1726}, journal = {Nature Neuroscience}, number = {4}, pages = {600 -- 606}, publisher = {Nature Publishing Group}, title = {{Active dendrites support efficient initiation of dendritic spikes in hippocampal CA3 pyramidal neurons}}, doi = {10.1038/nn.3060}, volume = {15}, year = {2012}, } @phdthesis{2964, abstract = {CA3 pyramidal neurons are important for memory formation and pattern completion in the hippocampal network. These neurons receive multiple excitatory inputs from numerous sources. Therefore, the rules of spatiotemporal integration of multiple synaptic inputs and propagation of action potentials are important to understand how CA3 neurons contribute to higher brain functions at cellular level. By using confocally targeted patch-clamp recording techniques, we investigated the biophysical properties of rat CA3 pyramidal neuron dendrites. We found two distinct dendritic domains critical for action potential initiation and propagation: In the proximal domain, action potentials initiated in the axon backpropagate actively with large amplitude and fast time course. In the distal domain, Na+-channel mediated dendritic spikes are efficiently evoked by local dendritic depolarization or waveforms mimicking synaptic events. These findings can be explained by a high Na+-to-K+ conductance density ratio of CA3 pyramidal neuron dendrites. The results challenge the prevailing view that proximal mossy fiber inputs activate CA3 pyramidal neurons more efficiently than distal perforant inputs by showing that the distal synapses trigger a different form of activity represented by dendritic spikes. The high probability of dendritic spike initiation in the distal area may enhance the computational power of CA3 pyramidal neurons in the hippocampal network. }, author = {Kim, Sooyun}, issn = {2663-337X}, pages = {65}, publisher = {Institute of Science and Technology Austria}, title = {{Active properties of hippocampal CA3 pyramidal neuron dendrites}}, year = {2012}, } @article{3246, abstract = {Visualizing and analyzing shape changes at various scales, ranging from single molecules to whole organisms, are essential for understanding complex morphogenetic processes, such as early embryonic development. Embryo morphogenesis relies on the interplay between different tissues, the properties of which are again determined by the interaction between their constituent cells. Cell interactions, on the other hand, are controlled by various molecules, such as signaling and adhesion molecules, which in order to exert their functions need to be spatiotemporally organized within and between the interacting cells. In this review, we will focus on the role of cell adhesion functioning at different scales to organize cell, tissue and embryo morphogenesis. We will specifically ask how the subcellular distribution of adhesion molecules controls the formation of cell-cell contacts, how cell-cell contacts determine tissue shape, and how tissue interactions regulate embryo morphogenesis.}, author = {Barone, Vanessa and Heisenberg, Carl-Philipp J}, journal = {Current Opinion in Cell Biology}, number = {1}, pages = {148 -- 153}, publisher = {Elsevier}, title = {{Cell adhesion in embryo morphogenesis}}, doi = {10.1016/j.ceb.2011.11.006}, volume = {24}, year = {2012}, } @article{12198, abstract = {The Arabidopsis thaliana central cell, the companion cell of the egg, undergoes DNA demethylation before fertilization, but the targeting preferences, mechanism, and biological significance of this process remain unclear. Here, we show that active DNA demethylation mediated by the DEMETER DNA glycosylase accounts for all of the demethylation in the central cell and preferentially targets small, AT-rich, and nucleosome-depleted euchromatic transposable elements. The vegetative cell, the companion cell of sperm, also undergoes DEMETER-dependent demethylation of similar sequences, and lack of DEMETER in vegetative cells causes reduced small RNA–directed DNA methylation of transposons in sperm. Our results demonstrate that demethylation in companion cells reinforces transposon methylation in plant gametes and likely contributes to stable silencing of transposable elements across generations.}, author = {Ibarra, Christian A. and Feng, Xiaoqi and Schoft, Vera K. and Hsieh, Tzung-Fu and Uzawa, Rie and Rodrigues, Jessica A. and Zemach, Assaf and Chumak, Nina and Machlicova, Adriana and Nishimura, Toshiro and Rojas, Denisse and Fischer, Robert L. and Tamaru, Hisashi and Zilberman, Daniel}, issn = {1095-9203}, journal = {Science}, keywords = {Multidisciplinary}, number = {6100}, pages = {1360--1364}, publisher = {American Association for the Advancement of Science}, title = {{Active DNA demethylation in plant companion cells reinforces transposon methylation in gametes}}, doi = {10.1126/science.1224839}, volume = {337}, year = {2012}, } @article{6588, abstract = {First we note that the best polynomial approximation to vertical bar x vertical bar on the set, which consists of an interval on the positive half-axis and a point on the negative half-axis, can be given by means of the classical Chebyshev polynomials. Then we explore the cases when a solution of the related problem on two intervals can be given in elementary functions.}, author = {Pausinger, Florian}, issn = {1812-9471}, journal = {Journal of Mathematical Physics, Analysis, Geometry}, number = {1}, pages = {63--78}, publisher = {B. Verkin Institute for Low Temperature Physics and Engineering}, title = {{Elementary solutions of the Bernstein problem on two intervals}}, volume = {8}, year = {2012}, } @inproceedings{3123, abstract = {We introduce the idea of using an explicit triangle mesh to track the air/fluid interface in a smoothed particle hydrodynamics (SPH) simulator. Once an initial surface mesh is created, this mesh is carried forward in time using nearby particle velocities to advect the mesh vertices. The mesh connectivity remains mostly unchanged across time-steps; it is only modified locally for topology change events or for the improvement of triangle quality. In order to ensure that the surface mesh does not diverge from the underlying particle simulation, we periodically project the mesh surface onto an implicit surface defined by the physics simulation. The mesh surface gives us several advantages over previous SPH surface tracking techniques. We demonstrate a new method for surface tension calculations that clearly outperforms the state of the art in SPH surface tension for computer graphics. We also demonstrate a method for tracking detailed surface information (like colors) that is less susceptible to numerical diffusion than competing techniques. Finally, our temporally-coherent surface mesh allows us to simulate high-resolution surface wave dynamics without being limited by the particle resolution of the SPH simulation.}, author = {Yu, Jihun and Wojtan, Christopher J and Turk, Greg and Yap, Chee}, booktitle = {Computer Graphics Forum}, issn = {1467-8659}, location = {Cagliari, Sardinia, Italy}, number = {2}, pages = {815 -- 824}, publisher = {Wiley}, title = {{Explicit mesh surfaces for particle based fluids}}, doi = {10.1111/j.1467-8659.2012.03062.x}, volume = {31}, year = {2012}, } @article{3244, abstract = {Bibliothekare haben die Aufgabe, sich mit neuen Medienformen auseinanderzusetzen. }, author = {Danowski, Patrick}, issn = {1869 -1137}, journal = {BuB - Forum Bibliothek und Information}, number = {4}, pages = {284}, publisher = {Fachzeitschrift des BIB – Berufsverband Information Bibliothek}, title = {{Die Zeit des Abwartens ist vorbei!}}, volume = {64}, year = {2012}, } @article{3243, abstract = {Wie wandelt sich das Berufsbild in Wissenschaftlichen Bibliotheken? Patrick Danowski gibt seine Einschätzung ab. }, author = {Danowski, Patrick}, issn = {1607-7172}, journal = {Büchereiperspektiven}, number = {1}, pages = {11}, publisher = {Büchereiverband Österreichs}, title = {{Zwischen Technologie und Information}}, volume = {2012}, year = {2012}, } @inproceedings{2915, author = {Kroemer, Oliver and Lampert, Christoph and Peters, Jan}, publisher = {Deutsches Zentrum für Luft und Raumfahrt}, title = {{Multi-modal learning for dynamic tactile sensing}}, year = {2012}, } @article{2912, author = {Edelsbrunner, Herbert and Strelkova, Nataliya}, journal = {Russian Mathematical Surveys}, number = {6}, pages = {1167–1168}, publisher = {Russian Academy of Sciences}, title = {{On the configuration space for the shortest networks}}, doi = {10.4213/rm9503}, volume = {67}, year = {2012}, } @inproceedings{3127, abstract = {When searching for characteristic subpatterns in potentially noisy graph data, it appears self-evident that having multiple observations would be better than having just one. However, it turns out that the inconsistencies introduced when different graph instances have different edge sets pose a serious challenge. In this work we address this challenge for the problem of finding maximum weighted cliques. We introduce the concept of most persistent soft-clique. This is subset of vertices, that 1) is almost fully or at least densely connected, 2) occurs in all or almost all graph instances, and 3) has the maximum weight. We present a measure of clique-ness, that essentially counts the number of edge missing to make a subset of vertices into a clique. With this measure, we show that the problem of finding the most persistent soft-clique problem can be cast either as: a) a max-min two person game optimization problem, or b) a min-min soft margin optimization problem. Both formulations lead to the same solution when using a partial Lagrangian method to solve the optimization problems. By experiments on synthetic data and on real social network data, we show that the proposed method is able to reliably find soft cliques in graph data, even if that is distorted by random noise or unreliable observations.}, author = {Quadrianto, Novi and Lampert, Christoph and Chen, Chao}, booktitle = {Proceedings of the 29th International Conference on Machine Learning}, location = {Edinburgh, United Kingdom}, pages = {211--218}, publisher = {ML Research Press}, title = {{The most persistent soft-clique in a set of sampled graphs}}, year = {2012}, } @article{2904, abstract = {Generalized van der Corput sequences are onedimensional, infinite sequences in the unit interval. They are generated from permutations in integer base b and are the building blocks of the multi-dimensional Halton sequences. Motivated by recent progress of Atanassov on the uniform distribution behavior of Halton sequences, we study, among others, permutations of the form P(i) = ai (mod b) for coprime integers a and b. We show that multipliers a that either divide b - 1 or b + 1 generate van der Corput sequences with weak distribution properties. We give explicit lower bounds for the asymptotic distribution behavior of these sequences and relate them to sequences generated from the identity permutation in smaller bases, which are, due to Faure, the weakest distributed generalized van der Corput sequences.}, author = {Pausinger, Florian}, issn = {2118-8572}, journal = {Journal de Theorie des Nombres des Bordeaux}, number = {3}, pages = {729 -- 749}, publisher = {Université de Bordeaux}, title = {{Weak multipliers for generalized van der Corput sequences}}, doi = {10.5802/jtnb.819}, volume = {24}, year = {2012}, } @article{2902, abstract = {We present an algorithm for simplifying linear cartographic objects and results obtained with a computer program implementing this algorithm. }, author = {Edelsbrunner, Herbert and Musin, Oleg and Ukhalov, Alexey and Yakimova, Olga and Alexeev, Vladislav and Bogaevskaya, Victoriya and Gorohov, Andrey and Preobrazhenskaya, Margarita}, journal = {Modeling and Analysis of Information Systems}, number = {6}, pages = {152 -- 160}, publisher = {Russian Academy of Sciences}, title = {{Fractal and computational geometry for generalizing cartographic objects}}, volume = {19}, year = {2012}, } @article{10389, abstract = {We perform numerical simulations to study self-assembly of nanoparticles mediated by an elastic planar surface. We show how the nontrivial elastic response to deformations of these surfaces leads to anisotropic interactions between the particles resulting in aggregates having different geometrical features. The morphology of the patterns can be controlled by the mechanical properties of the surface and the strength of the particle adhesion. We use simple scaling arguments to understand the formation of the different structures, and we show how the adhering particles can cause the underlying elastic substrate to wrinkle if two of its opposite edges are clamped. Finally, we discuss the implications of our results and suggest how elastic surfaces could be used in nanofabrication.}, author = {Šarić, Anđela and Cacciuto, Angelo}, issn = {1744-6848}, journal = {Soft Matter}, keywords = {condensed matter physics, general chemistry}, number = {18}, publisher = {Royal Society of Chemistry}, title = {{Soft elastic surfaces as a platform for particle self-assembly}}, doi = {10.1039/c1sm05773a}, volume = {7}, year = {2011}, } @article{1050, abstract = {We present experimentally derived potential curves 1?and spin-orbit interaction functions for the strongly perturbed AΣu+ 3?and bΠu states of the cesium dimer. The results are based on data from several sources. Laser-induced fluorescence Fourier transform spectroscopy (LIF FTS) was used some time ago in the Laboratoire Aimé Cotton primarily to study the XΣg+ state. More recent work at Tsinghua University provides information from moderate 3?resolution spectroscopy on the lowest levels of the bΠ0u± state as well as additional high-resolution data. From Innsbruck University, we have precision data obtained with cold Cs2 molecules. Recent data from Temple University was obtained using the optical-optical double resonance polarization spectroscopy technique, and finally, a group at the University of Latvia has added additional LIF FTS data. In the Hamiltonian matrix, we have used analytic potentials (the expanded Morse oscillator form) with both finite-difference (FD) coupled-channel and discrete variable representation (DVR) calculations of the term values. Fitted diagonal and off-diagonal spin-orbit functions are obtained and compared with ab initio results from Temple and Moscow State universities.}, author = {Bai, Jianmei and Ahmed, Ergin and Beser, Bediha and Guan, Yafei and Kotochigova, Svetlana and Lyyra, Marjatta and Ashman, Seth and Wolfe, Christopher and Huennekens, John and Xie, Feng and Li, Dan and Li, Li and Tamanis, Maris and Ferber, Ruvin and Drozdova, Anastasia and Pazyuk, Elena and Stolyarov, Andrey and Danzl, Johann G and Nägerl, Hanns and Bouloufa, Nadia and Dulieu, Olivier and Amiot, Claude and Salami, Houssam and Bergeman, Thomas}, journal = { Physical Review A - Atomic, Molecular, and Optical Physics}, number = {3}, publisher = {American Physical Society}, title = {{Global analysis of data on the spin-orbit-coupled A 1Σu+ and b 3Πu inf states of Cs2}}, doi = {10.1103/PhysRevA.83.032514}, volume = {83}, year = {2011}, } @article{1048, abstract = {We produce an ultracold and dense sample of rovibronic ground state Cs 2 molecules close to the regime of quantum degeneracy, in a single hyperfine level, in the presence of an optical lattice. The molecules are individually trapped, in the motional ground state of an optical lattice well, with a lifetime of 8 s. For preparation, we start with a zero-temperature atomic Mott-insulator state with optimized double-site occupancy and efficiently associate weakly-bound dimer molecules on a Feshbach resonance. Despite extremely weak Franck-Condon wavefunction overlap, the molecules are subsequently transferred with >50% efficiency to the rovibronic ground state by a stimulated four-photon process. Our results present a crucial step towards the generation of Bose-Einstein condensates of ground-state molecules and, when suitably generalized to polar heteronuclear molecules such as RbCs, the realization of dipolar many-body quantum-gas phases in periodic potentials.}, author = {Nägerl, Hanns and Mark, Manfred and Haller, Elmar and Gustavsson, Mattias and Hart, Russell and Danzl, Johann G}, journal = {Journal of Physics: Conference Series}, number = {1}, publisher = {IOP Publishing Ltd.}, title = {{Ultracold and dense samples of ground-state molecules in lattice potentials}}, doi = {10.1088/1742-6596/264/1/012015}, volume = {264}, year = {2011}, } @article{1052, abstract = {The present paper aims at finding optimal parameters for trapping of Cs 2 molecules in optical lattices, with the perspective of creating a quantum degenerate gas of ground-state molecules. We have calculated dynamic polarizabilities of Cs 2 molecules subject to an oscillating electric field, using accurate potential curves and electronic transition dipole moments. We show that for some particular wavelengths of the optical lattice, called "magic wavelengths", the polarizability of the ground-state molecules is equal to the one of a Feshbach molecule. As the creation of the sample of ground-state molecules relies on an adiabatic population transfer from weakly-bound molecules created on a Feshbach resonance, such a coincidence ensures that both the initial and final states are favorably trapped by the lattice light, allowing optimized transfer in agreement with the experimental observation.}, author = {Vexiau, Romain and Bouloufa, Nadia and Aymar, Mireille and Danzl, Johann G and Mark, Manfred and Nägerl, Hanns and Dulieu, Olivier}, journal = {European Physical Journal D}, number = {1-2}, pages = {243 -- 250}, publisher = {Springer}, title = {{Optimal trapping wavelengths of Cs 2 molecules in an optical lattice}}, doi = {10.1140/epjd/e2011-20085-4}, volume = {65}, year = {2011}, } @article{1051, abstract = {We demonstrate the temporal Talbot effect for trapped matter waves using ultracold atoms in an optical lattice. We investigate the phase evolution of an array of essentially non-interacting matter waves and observe matter-wave collapse and revival in the form of a Talbot interference pattern. By using long expansion times, we image momentum space with sub-recoil resolution, allowing us to observe fractional Talbot fringes up to tenth order.}, author = {Mark, Manfred and Haller, Elmar and Danzl, Johann G and Lauber, Katharina and Gustavsson, Mattias and Nägerl, Hanns}, journal = {New Journal of Physics}, publisher = {IOP Publishing Ltd.}, title = {{Demonstration of the temporal matter-wave Talbot effect for trapped matter waves}}, doi = {10.1088/1367-2630/13/8/085008}, volume = {13}, year = {2011}, } @article{1053, abstract = {We perform precision measurements on a Mott-insulator quantum state of ultracold atoms with tunable interactions. We probe the dependence of the superfluid-to-Mott-insulator transition on the interaction strength and explore the limits of the standard Bose-Hubbard model description. By tuning the on-site interaction energies to values comparable to the interband separation, we are able to quantitatively measure number-dependent shifts in the excitation spectrum caused by effective multibody interactions.}, author = {Mark, Manfred and Haller, Elmar and Lauber, Katharina and Danzl, Johann G and Daley, Andrew and Nägerl, Hanns}, journal = {Physical Review Letters}, number = {17}, publisher = {American Physical Society}, title = {{Precision measurements on a tunable Mott insulator of ultracold atoms}}, doi = {10.1103/PhysRevLett.107.175301}, volume = {107}, year = {2011}, } @article{1054, abstract = {We investigate local three-body correlations for bosonic particles in three dimensions and one dimension as a function of the interaction strength. The three-body correlation function g(3) is determined by measuring the three-body recombination rate in an ultracold gas of Cs atoms. In three dimensions, we measure the dependence of g(3) on the gas parameter in a BEC, finding good agreement with the theoretical prediction accounting for beyond-mean-field effects. In one dimension, we observe a reduction of g( 3) by several orders of magnitude upon increasing interactions from the weakly interacting BEC to the strongly interacting Tonks-Girardeau regime, in good agreement with predictions from the Lieb-Liniger model for all strengths of interaction.}, author = {Haller, Elmar and Rabie, Mahmoud and Mark, Manfred and Danzl, Johann G and Hart, Russell and Lauber, Katharina and Pupillo, Guido and Nägerl, Hanns}, journal = {Physical Review Letters}, number = {23}, publisher = {American Physical Society}, title = {{Three-body correlation functions and recombination rates for bosons in three dimensions and one dimension}}, doi = {10.1103/PhysRevLett.107.230404}, volume = {107}, year = {2011}, } @article{11094, abstract = {Nuclear pore complexes (NPCs) assemble at the end of mitosis during nuclear envelope (NE) reformation and into an intact NE as cells progress through interphase. Although recent studies have shown that NPC formation occurs by two different molecular mechanisms at two distinct cell cycle stages, little is known about the molecular players that mediate the fusion of the outer and inner nuclear membranes to form pores. In this paper, we provide evidence that the transmembrane nucleoporin (Nup), POM121, but not the Nup107–160 complex, is present at new pore assembly sites at a time that coincides with inner nuclear membrane (INM) and outer nuclear membrane (ONM) fusion. Overexpression of POM121 resulted in juxtaposition of the INM and ONM. Additionally, Sun1, an INM protein that is known to interact with the cytoskeleton, was specifically required for interphase assembly and localized with POM121 at forming pores. We propose a model in which POM121 and Sun1 interact transiently to promote early steps of interphase NPC assembly.}, author = {Talamas, Jessica A. and HETZER, Martin W}, issn = {1540-8140}, journal = {Journal of Cell Biology}, keywords = {Cell Biology}, number = {1}, pages = {27--37}, publisher = {Rockefeller University Press}, title = {{POM121 and Sun1 play a role in early steps of interphase NPC assembly}}, doi = {10.1083/jcb.201012154}, volume = {194}, year = {2011}, } @article{11096, abstract = {As the gatekeepers of the eukaryotic cell nucleus, nuclear pore complexes (NPCs) mediate all molecular trafficking between the nucleoplasm and the cytoplasm. In recent years, transport-independent functions of NPC components, nucleoporins, have been identified including roles in chromatin organization and gene regulation. Here, we summarize our current view of the NPC as a dynamic hub for the integration of chromatin regulation and nuclear trafficking and discuss the functional interplay between nucleoporins and the nuclear genome.}, author = {Liang, Yun and HETZER, Martin W}, issn = {0955-0674}, journal = {Current Opinion in Cell Biology}, keywords = {Cell Biology}, number = {1}, pages = {65--70}, publisher = {Elsevier}, title = {{Functional interactions between nucleoporins and chromatin}}, doi = {10.1016/j.ceb.2010.09.008}, volume = {23}, year = {2011}, } @article{11095, author = {HETZER, Martin W and Cavalli, Giacomo}, issn = {0955-0674}, journal = {Current Opinion in Cell Biology}, keywords = {Cell Biology}, number = {3}, pages = {255--257}, publisher = {Elsevier}, title = {{Editorial overview}}, doi = {10.1016/j.ceb.2011.04.013}, volume = {23}, year = {2011}, } @article{11100, abstract = {Eukaryotic cell function depends on the physical separation of nucleoplasmic and cytoplasmic components by the nuclear envelope (NE). Molecular communication between the two compartments involves active, signal-mediated trafficking, a function that is exclusively performed by nuclear pore complexes (NPCs). The individual NPC components and the mechanisms that are involved in nuclear trafficking are well documented and have become textbook knowledge. However, in addition to their roles as nuclear gatekeepers, NPC components-nucleoporins-have been shown to have critical roles in chromatin organization and gene regulation. These findings have sparked new enthusiasm to study the roles of this multiprotein complex in nuclear organization and explore novel functions that in some cases appear to go beyond a role in transport. Here, we discuss our present view of NPC biogenesis, which is tightly linked to proper cell cycle progression and cell differentiation. In addition, we summarize new data suggesting that NPCs represent dynamic hubs for the integration of gene regulation and nuclear transport processes.}, author = {Capelson, M. and Doucet, C. and HETZER, Martin W}, isbn = {9781936113071}, issn = {0091-7451}, journal = {Cold Spring Harbor Symposia on Quantitative Biology}, keywords = {Genetics, Molecular Biology, Biochemistry}, pages = {585--597}, publisher = {Cold Spring Harbor Laboratory Press}, title = {{Nuclear pore complexes: Guardians of the nuclear genome}}, doi = {10.1101/sqb.2010.75.059}, volume = {75}, year = {2011}, } @article{112, abstract = {Particle beams are important tools for probing atomic and molecular interactions. Here we demonstrate that particle beams also offer a unique opportunity to investigate interactions in macroscopic systems, such as granular media. Motivated by recent experiments on streams of grains that exhibit liquid-like breakup into droplets, we use molecular dynamics simulations to investigate the evolution of a dense stream of macroscopic spheres accelerating out of an opening at the bottom of a reservoir. We show how nanoscale details associated with energy dissipation during collisions modify the stream\'s macroscopic behavior. We find that inelastic collisions collimate the stream, while the presence of short-range attractive interactions drives structure formation. Parameterizing the collision dynamics by the coefficient of restitution (i.e., the ratio of relative velocities before and after impact) and the strength of the cohesive interaction, we map out a spectrum of behaviors that ranges from gaslike jets in which all grains drift apart to liquid-like streams that break into large droplets containing hundreds of grains. We also find a new, intermediate regime in which small aggregates form by capture from the gas phase, similar to what can be observed in molecular beams. Our results show that nearly all aspects of stream behavior are closely related to the velocity gradient associated with vertical free fall. Led by this observation, we propose a simple energy balance model to explain the droplet formation process. The qualitative as well as many quantitative features of the simulations and the model compare well with available experimental data and provide a first quantitative measure of the role of attractions in freely cooling granular streams.}, author = {Waitukaitis, Scott R and Grütjen, Helge and Royer, John and Jaeger, Heinrich}, journal = {Physical Review E}, number = {5}, publisher = {American Physical Society}, title = {{Droplet and cluster formation in freely falling granular streams}}, doi = {10.1103/PhysRevE.83.051302}, volume = {83}, year = {2011}, } @article{11673, abstract = {Given only the URL of a Web page, can we identify its topic? We study this problem in detail by exploring a large number of different feature sets and algorithms on several datasets. We also show that the inherent overlap between topics and the sparsity of the information in URLs makes this a very challenging problem. Web page classification without a page’s content is desirable when the content is not available at all, when a classification is needed before obtaining the content, or when classification speed is of utmost importance. For our experiments we used five different corpora comprising a total of about 3 million (URL, classification) pairs. We evaluated several techniques for feature generation and classification algorithms. The individual binary classifiers were then combined via boosting into metabinary classifiers. We achieve typical F-measure values between 80 and 85, and a typical precision of around 86. The precision can be pushed further over 90 while maintaining a typical level of recall between 30 and 40.}, author = {Baykan, Eda and Henzinger, Monika H and Marian, Ludmila and Weber, Ingmar}, issn = {1559-114X}, journal = {ACM Transactions on the Web}, keywords = {Topic classification, URL, ODP}, number = {3}, publisher = {Association for Computing Machinery}, title = {{A comprehensive study of features and algorithms for URL-based topic classification}}, doi = {10.1145/1993053.1993057}, volume = {5}, year = {2011}, } @article{11760, abstract = {We study a novel load balancing problem that arises in web search engines. The problem is a combination of an offline assignment problem, where files need to be (copied and) assigned to machines, and an online load balancing problem, where requests ask for specific files and need to be assigned to a corresponding machine, whose load is increased by this. We present simple deterministic algorithms for this problem and exhibit an interesting trade-off between the available space to make file copies and the obtainable makespan. We also give non-trivial lower bounds for a large class of deterministic algorithms and present a randomized algorithm that beats these bounds with high probability.}, author = {Dütting, Paul and Henzinger, Monika H and Weber, Ingmar}, issn = {0020-0190}, journal = {Information Processing Letters}, number = {4}, pages = {178--183}, publisher = {Elsevier}, title = {{Offline file assignments for online load balancing}}, doi = {10.1016/j.ipl.2010.11.022}, volume = {111}, year = {2011}, } @inproceedings{11796, abstract = {The design of truthful auctions that approximate the optimal expected revenue is a central problem in algorithmic mechanism design. 30 years after Myerson’s characterization of Bayesian optimal auctions in single-parameter domains [8], characterizing but also providing efficient mechanisms for multi-parameter domains still remains a very important unsolved problem. Our work improves upon recent results in this area, introducing new techniques for tackling the problem, while also combining and extending recently introduced tools. In particular we give the first approximation algorithms for Bayesian auctions with multiple heterogeneous items when bidders have additive valuations, budget constraints and general matroid feasibility constraints.}, author = {Henzinger, Monika H and Vidali, Angelina}, booktitle = {19th Annual European Symposium on Algorithms}, isbn = {9783642237188}, issn = {1611-3349}, location = {Saarbrücken, Germany}, pages = {192–202}, publisher = {Springer Nature}, title = {{Multi-parameter mechanism design under budget and matroid constraints}}, doi = {10.1007/978-3-642-23719-5_17}, volume = {6942}, year = {2011}, } @inproceedings{11864, abstract = {Auctions are widely used on the Web. Applications range from internet advertising to platforms such as eBay. In most of these applications the auctions in use are single/multi-item auctions with unit demand. The main drawback of standard mechanisms for this type of auctions, such as VCG and GSP, is the limited expressiveness that they offer to the bidders. The General Auction Mechanism (GAM) of [1] is taking a first step towards addressing the problem of limited expressiveness by computing a bidder optimal, envy free outcome for linear utility functions with identical slopes and a single discontinuity per bidder-item pair. We show that in many practical situations this does not suffice to adequately model the preferences of the bidders, and we overcome this problem by presenting the first mechanism for piece-wise linear utility functions with non-identical slopes and multiple discontinuities. Our mechanism runs in polynomial time. Like GAM it is incentive compatible for inputs that fulfill a certain non-degeneracy requirement, but our requirement is more general than the requirement of GAM. For discontinuous utility functions that are non-degenerate as well as for continuous utility functions the outcome of our mechanism is a competitive equilibrium. We also show how our mechanism can be used to compute approximately bidder optimal, envy free outcomes for a general class of continuous utility functions via piece-wise linear approximation. Finally, we prove hardness results for even more expressive settings.}, author = {Dütting, Paul and Henzinger, Monika H and Weber, Ingmar}, booktitle = {Proceedings of the 20th international conference on World wide web}, isbn = {978-145030632-4}, location = {Hyderabad, India}, pages = {127 -- 136}, publisher = {Association for Computing Machinery}, title = {{An expressive mechanism for auctions on the web}}, doi = {10.1145/1963405.1963427}, year = {2011}, } @article{12651, abstract = {Temperature data from three Automatic Weather Stations and twelve Temperature Loggers are used to investigate the spatiotemporal variability of temperature over a glacier, its main atmospheric controls, the suitability of extrapolation techniques and their effect on melt modeling. We use data collected on Juncal Norte Glacier, central Chile, during one ablation season. We examine temporal and spatial variability in lapse rates (LRs), together with alternative statistical interpolation methods. The main control over the glacier thermal regime is the development of a katabatic boundary layer (KBL). Katabatic wind occurs at night and in the morning and is eroded in the afternoon. LRs reveal strong diurnal variability, with steeper LRs during the day when the katabatic wind weakens and shallower LRs during the night and morning. We suggest that temporally variable LRs should be used to account for the observed change. They tend to be steeper than equivalent constant LRs, and therefore result in a reduction in simulated melt compared to use of constant LRs when extrapolating from lower to higher elevations. In addition to the temporal variability, the temperature-elevation relationship varies also in space. Differences are evident between local LRs and including such variability in melt modeling affects melt simulations. Extrapolation methods based on the spatial variability of the observations after removal of the elevation trend, such as Inverse Distance Weighting or Kriging, do not seem necessary for simulations of gridded temperature data over a glacier.}, author = {Petersen, L. and Pellicciotti, Francesca}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Paleontology, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Atmospheric Science, Earth-Surface Processes, Geochemistry and Petrology, Soil Science, Water Science and Technology, Ecology, Aquatic Science, Forestry, Oceanography, Geophysics}, number = {D23}, publisher = {American Geophysical Union}, title = {{Spatial and temporal variability of air temperature on a melting glacier: Atmospheric controls, extrapolation methods and their effect on melt modeling, Juncal Norte Glacier, Chile}}, doi = {10.1029/2011jd015842}, volume = {116}, year = {2011}, } @article{12649, abstract = {Physically based hydrological models describe natural processes more accurately than conceptual models but require extensive data sets to produce accurate results. To identify the value of different data sets for improving the performance of the distributed hydrological model TOPKAPI we combine a multivariable validation technique with Monte Carlo simulations. The study is carried out in the snow and ice-dominated Rhonegletscher basin, as these types of mountainous basins are generally the most critical with respect to data availability and sensitivity to climate fluctuations. Each observational data set is used individually and in combination with the other data sets to determine a subset of best parameter combinations out of 10,000 Monte Carlos runs performed with randomly generated parameter sets. We validate model results against discharge, glacier mass balance, and satellite snow cover images for a 14 year time period (1994–2007). While the use of all data sets combined provides the best overall model performance (defined by the concurrent best agreement of simulated discharge, snow cover and mass balance with their respective measurements), the use of one or two variables for constraining the model results in poorer performance. Using only one data set for constraining the model glacier mass balance proved to be the most efficient observation leading to the best overall model performance. Our main result is that a combination of discharge and satellite snow cover images is best for improving model performance, since the volumetric information of discharge data and the spatial information of snow cover images are complementary.}, author = {Finger, David and Pellicciotti, Francesca and Konz, Markus and Rimkus, Stefan and Burlando, Paolo}, issn = {0043-1397}, journal = {Water Resources Research}, number = {7}, publisher = {American Geophysical Union}, title = {{The value of glacier mass balance, satellite snow cover images, and hourly discharge for improving the performance of a physically based distributed hydrological model}}, doi = {10.1029/2010wr009824}, volume = {47}, year = {2011}, } @article{12652, abstract = {We explore the robustness and transferability of parameterizations of cloud radiative forcing used in glacier melt models at two sites in the Swiss Alps. We also look at the rationale behind some of the most commonly used approaches, and explore the relationship between cloud transmittance and several standard meteorological variables. The 2 m air-temperature diurnal range is the best predictor of variations in cloud transmittance. However, linear and exponential parameterizations can only explain 30–50% of the observed variance in computed cloud transmittance factors. We examine the impact of modelled cloud transmittance factors on both solar radiation and ablation rates computed with an enhanced temperature-index model. The melt model performance decreases when modelled radiation is used, the reduction being due to an underestimation of incoming solar radiation on clear-sky days. The model works well under overcast conditions. We also seek alternatives to the use of in situ ground data. However, outputs from an atmospheric model (2.2 km horizontal resolution) do not seem to provide an alternative to the parameterizations of cloud radiative forcing based on observations of air temperature at glacier automatic weather stations. Conversely, the correct definition of overcast conditions is important.}, author = {Pellicciotti, Francesca and Raschle, Thomas and Huerlimann, Thomas and Carenzo, Marco and Burlando, Paolo}, issn = {1727-5652}, journal = {Journal of Glaciology}, number = {202}, pages = {367--381}, publisher = {Cambridge University Press}, title = {{Transmission of solar radiation through clouds on melting glaciers: A comparison of parameterizations and their impact on melt modelling}}, doi = {10.3189/002214311796406013}, volume = {57}, year = {2011}, } @inbook{12650, abstract = {Streamflow is a hydrological variable measured at a defined river cross-section; it spatially integrates the runoff generating processes in the contributing watershed, including precipitation and air temperature. Trends in streamflow are progressive changes in the time series of streamflow that can be detected with statistical methods and their statistical significance can be assessed. Mountainous regions are particularly vulnerable to streamflow change because of their high specific runoff and the sensitivity to the distribution of precipitation and air temperature, and the processes of snow accumulation and melt.}, author = {Molnar, Peter and Burlando, Paolo and Pellicciotti, Francesca}, booktitle = {Encyclopedia of Snow, Ice and Glaciers}, editor = {Singh, Vijay and Singh, Pratap and Haritashya, Umesh}, isbn = {978-90-481-2641-5}, issn = {1871-756X}, pages = {1084--1089}, publisher = {Springer Nature}, title = {{Streamflow Trends in Mountainous Regions}}, doi = {10.1007/978-90-481-2642-2_543}, year = {2011}, } @article{1299, abstract = {Recent experiments have shown that motion detection in Drosophila starts with splitting the visual input into two parallel channels encoding brightness increments (ON) or decrements (OFF). This suggests the existence of either two (ON-ON, OFF-OFF) or four (for all pairwise interactions) separate motion detectors. To decide between these possibilities, we stimulated flies using sequences of ON and OFF brightness pulses while recording from motion-sensitive tangential cells. We found direction-selective responses to sequences of same sign (ON-ON, OFF-OFF), but not of opposite sign (ON-OFF, OFF-ON), refuting the existence of four separate detectors. Based on further measurements, we propose a model that reproduces a variety of additional experimental data sets, including ones that were previously interpreted as support for four separate detectors. Our experiments and the derived model mark an important step in guiding further dissection of the fly motion detection circuit.}, author = {Eichner, Hubert and Maximilian Jösch and Schnell, Bettina and Reiff, Dierk F and Borst, Alexander}, journal = {Neuron}, number = {6}, pages = {1155 -- 1164}, publisher = {Elsevier}, title = {{Internal structure of the fly elementary motion detector}}, doi = {10.1016/j.neuron.2011.03.028}, volume = {70}, year = {2011}, } @article{1467, abstract = {We propose a general conjecture for the mixed Hodge polynomial of the generic character varieties of representations of the fundamental group of a Riemann surface of genus g to GLn(C) with fixed generic semisimple conjugacy classes at k punctures. This conjecture generalizes the Cauchy identity for Macdonald polynomials and is a common generalization of two formulas that we prove in this paper. The first is a formula for the E-polynomial of these character varieties which we obtain using the character table of GLn(Fq). We use this formula to compute the Euler characteristic of character varieties. The second formula gives the Poincaré polynomial of certain associated quiver varieties which we obtain using the character table of gln(Fq). In the last main result we prove that the Poincaré polynomials of the quiver varieties equal certain multiplicities in the tensor product of irreducible characters of GLn(Fq). As a consequence we find a curious connection between Kac-Moody algebras associated with comet-shaped, and typically wild, quivers and the representation theory of GLn(Fq).}, author = {Tamas Hausel and Letellier, Emmanuel and Rodríguez Villegas, Fernando}, journal = {Duke Mathematical Journal}, number = {2}, pages = {323 -- 400}, publisher = {Duke University Press}, title = {{Arithmetic harmonic analysis on character and quiver varieties}}, doi = {10.1215/00127094-1444258}, volume = {160}, year = {2011}, } @article{1723, abstract = {The emergence of differences in the arrangement of cells is the first step towards the establishment of many organs. Understanding this process is limited by the lack of systematic characterization of epithelial organisation. Here we apply network theory at the scale of individual cells to uncover patterns in cell-to-cell contacts that govern epithelial organisation. We provide an objective characterisation of epithelia using network representation, where cells are nodes and cell contacts are links. The features of individual cells, together with attributes of the cellular network, produce a defining signature that distinguishes epithelia from different organs, species, developmental stages and genetic conditions. The approach permits characterization, quantification and classification of normal and perturbed epithelia, and establishes a framework for understanding molecular mechanisms that underpin the architecture of complex tissues.}, author = {Escudero, Luis M and Costa, Luciano and Anna Kicheva and Briscoe, James and Freeman, Matthew and Babu, Madan M}, journal = {Nature Communications}, number = {1}, publisher = {Nature Publishing Group}, title = {{Epithelial organisation revealed by a network of cellular contacts}}, doi = {10.1038/ncomms1536}, volume = {2}, year = {2011}, } @article{1724, abstract = {Morphogens, such as Decapentaplegic (Dpp) in the fly imaginal discs, form graded concentration profiles that control patterning and growth of developing organs. In the imaginal discs, proliferative growth is homogeneous in space, posing the conundrum of how morphogen concentration gradients could control position-independent growth. To understand the mechanism of proliferation control by the Dpp gradient, we quantified Dpp concentration and signaling levels during wing disc growth. Both Dpp concentration and signaling gradients scale with tissue size during development. On average, cells divide when Dpp signaling levels have increased by 50%. Our observations are consistent with a growth control mechanism based on temporal changes of cellular morphogen signaling levels. For a scaling gradient, this mechanism generates position-independent growth rates.}, author = {Wartlick, Ortrud and Mumcu, Peer and Anna Kicheva and Bittig, Thomas and Seum, Carole and Jülicher, Frank and González-Gaitán, Marcos A}, journal = {Science}, number = {6021}, pages = {1154 -- 1159}, publisher = {American Association for the Advancement of Science}, title = {{Dynamics of Dpp signaling and proliferation control}}, doi = {10.1126/science.1200037}, volume = {331}, year = {2011}, } @article{1754, abstract = {We report on a technique enabling electrical control of the contact silicidation process in silicon nanowire devices. Undoped silicon nanowires were contacted by pairs of nickel electrodes and each contact was selectively silicided by means of the Joule effect. By a realtime monitoring of the nanowire electrical resistance during the contact silicidation process we were able to fabricate nickel-silicide/silicon/nickel- silicide devices with controlled silicon channel length down to 8 nm. }, author = {Mongillo, Massimo and Spathis, Panayotis and Katsaros, Georgios and Gentile, Pascal and Sanquer, Marc and De Franceschi, Silvano}, journal = {ACS Nano}, number = {9}, pages = {7117 -- 7123}, publisher = {American Chemical Society}, title = {{Joule-assisted silicidation for short-channel silicon nanowire devices}}, doi = {10.1021/nn202524j}, volume = {5}, year = {2011}, } @article{1755, abstract = {Spin-selective tunneling of holes in SiGe nanocrystals contacted by normal-metal leads is reported. The spin selectivity arises from an interplay of the orbital effect of the magnetic field with the strong spin-orbit interaction present in the valence band of the semiconductor. We demonstrate both experimentally and theoretically that spin-selective tunneling in semiconductor nanostructures can be achieved without the use of ferromagnetic contacts. The reported effect, which relies on mixing the light and heavy holes, should be observable in a broad class of quantum-dot systems formed in semiconductors with a degenerate valence band.}, author = {Georgios Katsaros and Golovach, Vitaly N and Spathis, Panayotis N and Ares, Natalia and Stoffel, Mathieu and Fournel, Frank and Schmidt, Oliver G and Glazman, Leonid I and De Franceschi, Silvano}, journal = {Physical Review Letters}, number = {24}, publisher = {American Physical Society}, title = {{Observation of spin-selective tunneling in sige nanocrystals}}, doi = {10.1103/PhysRevLett.107.246601}, volume = {107}, year = {2011}, } @inproceedings{1776, abstract = {Superconducting circuits have been successfully established as systems to prepare and investigate microwave light fields at the quantum level. In contrast to optical experiments where light is detected using photon counters, microwaves are usually measured with well developed linear amplifiers. This makes measurements of correlation functions - one of the important tools in optics - harder to achieve because they traditionally rely on photon counters and beam splitters. Here, we demonstrate a system where we can prepare on demand single microwave photons in a cavity and detect them at the two outputs of the cavity using linear amplifiers. Together with efficient data processing, this allows us to measure different observables of the cavity photons, including the first-order correlation function. Using these techniques we demonstrate cooling of a thermal background field in the cavity.}, author = {Bozyigit, Deniz and Lang, C and Steffen, L. Kraig and Johannes Fink and Eichler, Christopher and Baur, Matthias P and Bianchetti, R and Leek, Peter J and Filipp, Stefan and Wallraff, Andreas and Da Silva, Marcus P and Blais, Alexandre}, number = {1}, publisher = {IOP Publishing Ltd.}, title = {{Correlation measurements of individual microwave photons emitted from a symmetric cavity}}, doi = {10.1088/1742-6596/264/1/012024}, volume = {264}, year = {2011}, } @article{1777, abstract = {A wide range of experiments studying microwave photons localized in superconducting cavities have made important contributions to our understanding of the quantum properties of radiation. Propagating microwave photons, however, have so far been studied much less intensely. Here we present measurements in which we reconstruct the quantum state of itinerant single photon Fock states and their superposition with the vacuum by analyzing moments of the measured amplitude distribution up to fourth order. Using linear amplifiers and quadrature amplitude detectors, we have developed efficient methods to separate the detected single photon signal from the noise added by the amplifier. From our measurement data we have also reconstructed the corresponding Wigner function.}, author = {Eichler, Christopher and Bozyigit, Deniz and Lang, C and Steffen, L. and Fink, Johannes M and Wallraff, Andreas}, journal = {Physical Review Letters}, number = {22}, publisher = {American Physical Society}, title = {{Experimental state tomography of itinerant single microwave photons}}, doi = {10.1103/PhysRevLett.106.220503}, volume = {106}, year = {2011}, } @article{1778, abstract = {Creating a train of single photons and monitoring its propagation and interaction is challenging in most physical systems, as photons generally interact very weakly with other systems. However, when confining microwave frequency photons in a transmission line resonator, effective photon-photon interactions can be mediated by qubits embedded in the resonator. Here, we observe the phenomenon of photon blockade through second-order correlation function measurements. The experiments clearly demonstrate antibunching in a continuously pumped source of single microwave photons measured by using microwave beam splitters, linear amplifiers, and quadrature amplitude detectors. We also investigate resonance fluorescence and Rayleigh scattering in Mollow-triplet-like spectra.}, author = {Lang, C and Bozyigit, Deniz and Eichler, Christopher and Steffen, L. Kraig and Johannes Fink and Abdumalikov, Abdufarrukh A and Baur, Matthias P and Filipp, Stefan and Da Silva, Marcus P and Blais, Alexandre and Wallraff, Andreas}, journal = {Physical Review Letters}, number = {24}, publisher = {American Physical Society}, title = {{Observation of resonant photon blockade at microwave frequencies using correlation function measurements}}, doi = {10.1103/PhysRevLett.106.243601}, volume = {106}, year = {2011}, } @article{1775, abstract = {At optical frequencies the radiation produced by a source, such as a laser, a black body or a single-photon emitter, is frequently characterized by analysing the temporal correlations of emitted photons using single-photon counters. At microwave frequencies, however, there are no efficient single-photon counters yet. Instead, well-developed linear amplifiers allow for efficient measurement of the amplitude of an electromagnetic field. Here, we demonstrate first- and second-order correlation function measurements of a pulsed microwave-frequency single-photon source integrated on the same chip with a 50/50 beam splitter followed by linear amplifiers and quadrature amplitude detectors. We clearly observe single-photon coherence in first-order and photon antibunching in second-order correlation function measurements of the propagating fields.}, author = {Bozyigit, Deniz and Lang, C and Steffen, L. Kraig and Johannes Fink and Eichler, Christopher and Baur, Matthias P and Bianchetti, R and Leek, Peter J and Filipp, Stefan and Da Silva, Marcus P and Blais, Alexandre and Wallraff, Andreas}, journal = {Nature Physics}, number = {2}, pages = {154 -- 158}, publisher = {Nature Publishing Group}, title = {{Antibunching of microwave-frequency photons observed in correlation measurements using linear detectors}}, doi = {10.1038/nphys1845}, volume = {7}, year = {2011}, }