TY - JOUR
AB - We prove optimal second order convergence of a modified lowest-order Brezzi-Douglas-Marini (BDM1) mixed finite element scheme for advection-diffusion problems in divergence form. If advection is present, it is known that the total flux is approximated only with first-order accuracy by the classical BDM1 mixed method, which is suboptimal since the same order of convergence is obtained if the computationally less expensive Raviart-Thomas (RT0) element is used. The modification that was first proposed by Brunner et al. [Adv. Water Res., 35 (2012),pp. 163-171] is based on the hybrid problem formulation and consists in using the Lagrange multipliers for the discretization of the advective term instead of the cellwise constant approximation of the scalar unknown.
AU - Brunner, Fabian
AU - Julian Fischer
AU - Knabner, Peter
ID - 1315
IS - 4
JF - SIAM Journal on Numerical Analysis
TI - Analysis of a modified second-order mixed hybrid BDM1 finite element method for transport problems in divergence form
VL - 54
ER -
TY - JOUR
AB - We analyze the behaviour of free boundaries in thin-film flow in the regime of strong slippage n∈[1,2) and in the regime of very weak slippage n∈,3) qualitatively and quantitatively. In the regime of strong slippage, we construct initial data which are bounded from above by the steady state but for which nevertheless instantaneous forward motion of the free boundary occurs. This shows that the initial behaviour of the free boundary is not determined just by the growth of the initial data at the free boundary. Note that this is a new phenomenon for degenerate parabolic equations which is specific for higher-order equations. Furthermore, this result resolves a controversy in the literature over optimality of sufficient conditions for the occurrence of a waiting time phenomenon. In contrast, in the regime of very weak slippage we derive lower bounds on free boundary propagation which are optimal in the sense that they coincide up to a constant factor with the known upper bounds. In particular, in this regime the growth of the initial data at the free boundary fully determines the initial behaviour of the interface.
AU - Julian Fischer
ID - 1317
IS - 5
JF - Annales de l'Institut Henri Poincare (C) Non Linear Analysis
TI - Behaviour of free boundaries in thin-film flow: The regime of strong slippage and the regime of very weak slippage
VL - 33
ER -
TY - JOUR
AB - We develop a large-scale regularity theory of higher order for divergence-form elliptic equations with heterogeneous coefficient fields a in the context of stochastic homogenization. The large-scale regularity of a-harmonic functions is encoded by Liouville principles: The space of a-harmonic functions that grow at most like a polynomial of degree k has the same dimension as in the constant-coefficient case. This result can be seen as the qualitative side of a large-scale Ck,α-regularity theory, which in the present work is developed in the form of a corresponding Ck,α-“excess decay” estimate: For a given a-harmonic function u on a ball BR, its energy distance on some ball Br to the above space of a-harmonic functions that grow at most like a polynomial of degree k has the natural decay in the radius r above some minimal radius r0. Though motivated by stochastic homogenization, the contribution of this paper is of purely deterministic nature: We work under the assumption that for the given realization a of the coefficient field, the couple (φ, σ) of scalar and vector potentials of the harmonic coordinates, where φ is the usual corrector, grows sublinearly in a mildly quantified way. We then construct “kth-order correctors” and thereby the space of a-harmonic functions that grow at most like a polynomial of degree k, establish the above excess decay, and then the corresponding Liouville principle.
AU - Julian Fischer
AU - Otto, Felix
ID - 1318
IS - 7
JF - Communications in Partial Differential Equations
TI - A higher-order large scale regularity theory for random elliptic operators
VL - 41
ER -
TY - CONF
AB - We present a novel optimization-based algorithm for the design and fabrication of customized, deformable input devices, capable of continuously sensing their deformation. We propose to embed piezoresistive sensing elements into flexible 3D printed objects. These sensing elements are then utilized to recover rich and natural user interactions at runtime. Designing such objects is a challenging and hard problem if attempted manually for all but the simplest geometries and deformations. Our method simultaneously optimizes the internal routing of the sensing elements and computes a mapping from low-level sensor readings to user-specified outputs in order to minimize reconstruction error. We demonstrate the power and flexibility of the approach by designing and fabricating a set of flexible input devices. Our results indicate that the optimization-based design greatly outperforms manual routings in terms of reconstruction accuracy and thus interaction fidelity.
AU - Bächer, Moritz
AU - Hepp, Benjamin
AU - Pece, Fabrizio
AU - Kry, Paul
AU - Bickel, Bernd
AU - Thomaszewski, Bernhard
AU - Hilliges, Otmar
ID - 1319
TI - DefSense: computational design of customized deformable input devices
ER -
TY - CONF
AB - In recent years, several biomolecular systems have been shown to be scale-invariant (SI), i.e. to show the same output dynamics when exposed to geometrically scaled input signals (u → pu, p > 0) after pre-adaptation to accordingly scaled constant inputs. In this article, we show that SI systems-as well as systems invariant with respect to other input transformations-can realize nonlinear differential operators: when excited by inputs obeying functional forms characteristic for a given class of invariant systems, the systems' outputs converge to constant values directly quantifying the speed of the input.
AU - Lang, Moritz
AU - Sontag, Eduardo
ID - 1320
TI - Scale-invariant systems realize nonlinear differential operators
VL - 2016-July
ER -
TY - JOUR
AB - Direct reciprocity is a major mechanism for the evolution of cooperation. Several classical studies have suggested that humans should quickly learn to adopt reciprocal strategies to establish mutual cooperation in repeated interactions. On the other hand, the recently discovered theory of ZD strategies has found that subjects who use extortionate strategies are able to exploit and subdue cooperators. Although such extortioners have been predicted to succeed in any population of adaptive opponents, theoretical follow-up studies questioned whether extortion can evolve in reality. However, most of these studies presumed that individuals have similar strategic possibilities and comparable outside options, whereas asymmetries are ubiquitous in real world applications. Here we show with a model and an economic experiment that extortionate strategies readily emerge once subjects differ in their strategic power. Our experiment combines a repeated social dilemma with asymmetric partner choice. In our main treatment there is one randomly chosen group member who is unilaterally allowed to exchange one of the other group members after every ten rounds of the social dilemma. We find that this asymmetric replacement opportunity generally promotes cooperation, but often the resulting payoff distribution reflects the underlying power structure. Almost half of the subjects in a better strategic position turn into extortioners, who quickly proceed to exploit their peers. By adapting their cooperation probabilities consistent with ZD theory, extortioners force their co-players to cooperate without being similarly cooperative themselves. Comparison to non-extortionate players under the same conditions indicates a substantial net gain to extortion. Our results thus highlight how power asymmetries can endanger mutually beneficial interactions, and transform them into exploitative relationships. In particular, our results indicate that the extortionate strategies predicted from ZD theory could play a more prominent role in our daily interactions than previously thought.
AU - Hilbe, Christian
AU - Hagel, Kristin
AU - Milinski, Manfred
ID - 1322
IS - 10
JF - PLoS One
TI - Asymmetric power boosts extortion in an economic experiment
VL - 11
ER -
TY - JOUR
AB - Mossy fiber synapses on CA3 pyramidal cells are 'conditional detonators' that reliably discharge postsynaptic targets. The 'conditional' nature implies that burst activity in dentate gyrus granule cells is required for detonation. Whether single unitary excitatory postsynaptic potentials (EPSPs) trigger spikes in CA3 neurons remains unknown. Mossy fiber synapses exhibit both pronounced short-term facilitation and uniquely large post-tetanic potentiation (PTP). We tested whether PTP could convert mossy fiber synapses from subdetonator into detonator mode, using a recently developed method to selectively and noninvasively stimulate individual presynaptic terminals in rat brain slices. Unitary EPSPs failed to initiate a spike in CA3 neurons under control conditions, but reliably discharged them after induction of presynaptic short-term plasticity. Remarkably, PTP switched mossy fiber synapses into full detonators for tens of seconds. Plasticity-dependent detonation may be critical for efficient coding, storage, and recall of information in the granule cell–CA3 cell network.
AU - Vyleta, Nicholas
AU - Borges Merjane, Carolina
AU - Jonas, Peter M
ID - 1323
JF - eLife
TI - Plasticity-dependent, full detonation at hippocampal mossy fiber–CA3 pyramidal neuron synapses
VL - 5
ER -
TY - CONF
AB - DEC-POMDPs extend POMDPs to a multi-agent setting, where several agents operate in an uncertain environment independently to achieve a joint objective. DEC-POMDPs have been studied with finite-horizon and infinite-horizon discounted-sum objectives, and there exist solvers both for exact and approximate solutions. In this work we consider Goal-DEC-POMDPs, where given a set of target states, the objective is to ensure that the target set is reached with minimal cost. We consider the indefinite-horizon (infinite-horizon with either discounted-sum, or undiscounted-sum, where absorbing goal states have zero-cost) problem. We present a new and novel method to solve the problem that extends methods for finite-horizon DEC-POMDPs and the RTDP-Bel approach for POMDPs. We present experimental results on several examples, and show that our approach presents promising results. Copyright
AU - Chatterjee, Krishnendu
AU - Chmelik, Martin
ID - 1324
T2 - Proceedings of the Twenty-Sixth International Conference on International Conference on Automated Planning and Scheduling
TI - Indefinite-horizon reachability in Goal-DEC-POMDPs
VL - 2016-January
ER -
TY - CONF
AB - We study graphs and two-player games in which rewards are assigned to states, and the goal of the players is to satisfy or dissatisfy certain property of the generated outcome, given as a mean payoff property. Since the notion of mean-payoff does not reflect possible fluctuations from the mean-payoff along a run, we propose definitions and algorithms for capturing the stability of the system, and give algorithms for deciding if a given mean payoff and stability objective can be ensured in the system.
AU - Brázdil, Tomáš
AU - Forejt, Vojtěch
AU - Kučera, Antonín
AU - Novotny, Petr
ID - 1325
TI - Stability in graphs and games
VL - 59
ER -
TY - CONF
AB - Energy Markov Decision Processes (EMDPs) are finite-state Markov decision processes where each transition is assigned an integer counter update and a rational payoff. An EMDP configuration is a pair s(n), where s is a control state and n is the current counter value. The configurations are changed by performing transitions in the standard way. We consider the problem of computing a safe strategy (i.e., a strategy that keeps the counter non-negative) which maximizes the expected mean payoff.
AU - Brázdil, Tomáš
AU - Kučera, Antonín
AU - Novotny, Petr
ID - 1326
TI - Optimizing the expected mean payoff in Energy Markov Decision Processes
VL - 9938
ER -
TY - CONF
AB - We consider partially observable Markov decision processes (POMDPs) with a set of target states and positive integer costs associated with every transition. The traditional optimization objective (stochastic shortest path) asks to minimize the expected total cost until the target set is reached. We extend the traditional framework of POMDPs to model energy consumption, which represents a hard constraint. The energy levels may increase and decrease with transitions, and the hard constraint requires that the energy level must remain positive in all steps till the target is reached. First, we present a novel algorithm for solving POMDPs with energy levels, developing on existing POMDP solvers and using RTDP as its main method. Our second contribution is related to policy representation. For larger POMDP instances the policies computed by existing solvers are too large to be understandable. We present an automated procedure based on machine learning techniques that automatically extracts important decisions of the policy allowing us to compute succinct human readable policies. Finally, we show experimentally that our algorithm performs well and computes succinct policies on a number of POMDP instances from the literature that were naturally enhanced with energy levels.
AU - Brázdil, Tomáš
AU - Chatterjee, Krishnendu
AU - Chmelik, Martin
AU - Gupta, Anchit
AU - Novotny, Petr
ID - 1327
T2 - Proceedings of the 15th International Conference on Autonomous Agents and Multiagent Systems
TI - Stochastic shortest path with energy constraints in POMDPs
ER -
TY - JOUR
AB - Hole spins have gained considerable interest in the past few years due to their potential for fast electrically controlled qubits. Here, we study holes confined in Ge hut wires, a so-far unexplored type of nanostructure. Low-temperature magnetotransport measurements reveal a large anisotropy between the in-plane and out-of-plane g-factors of up to 18. Numerical simulations verify that this large anisotropy originates from a confined wave function of heavy-hole character. A light-hole admixture of less than 1% is estimated for the states of lowest energy, leading to a surprisingly large reduction of the out-of-plane g-factors compared with those for pure heavy holes. Given this tiny light-hole contribution, the spin lifetimes are expected to be very long, even in isotopically nonpurified samples.
AU - Watzinger, Hannes
AU - Kloeffel, Christoph
AU - Vukusic, Lada
AU - Rossell, Marta
AU - Sessi, Violetta
AU - Kukucka, Josip
AU - Kirchschlager, Raimund
AU - Lausecker, Elisabeth
AU - Truhlar, Alisha
AU - Glaser, Martin
AU - Rastelli, Armando
AU - Fuhrer, Andreas
AU - Loss, Daniel
AU - Katsaros, Georgios
ID - 1328
IS - 11
JF - Nano Letters
TI - Heavy-hole states in germanium hut wires
VL - 16
ER -
TY - JOUR
AB - Daphnia species have become models for ecological genomics and exhibit interesting features, such as high phenotypic plasticity and a densely packed genome with many lineage-specific genes. They are also cyclic parthenogenetic, with alternating asexual and sexual cycles and environmental sex determination. Here, we present a de novo transcriptome assembly of over 32,000 D. galeata genes and use it to investigate gene expression in females and spontaneously produced males of two clonal lines derived from lakes in Germany and the Czech Republic. We find that only a low percentage (18%) of genes shows sex-biased expression and that there are many more female-biased gene (FBG) than male-biased gene (MBG). Furthermore, FBGs tend to be more conserved between species than MBGs in both sequence and expression. These patterns may be a consequence of cyclic parthenogenesis leading to a relaxation of purifying selection on MBGs. The two clonal lines show considerable differences in both number and identity of sex-biased genes, suggesting that they may have reproductive strategies differing in their investment in sexual reproduction. Orthologs of key genes in the sex determination and juvenile hormone pathways, which are thought to be important for the transition from asexual to sexual reproduction, are present in D. galeata and highly conserved among Daphnia species.
AU - Huylmans, Ann K
AU - López Ezquerra, Alberto
AU - Parsch, John
AU - Cordellier, Mathilde
ID - 1329
IS - 10
JF - Genome Biology and Evolution
TI - De novo transcriptome assembly and sex-biased gene expression in the cyclical parthenogenetic Daphnia galeata
VL - 8
ER -
TY - JOUR
AB - In this paper we investigate the existence of closed billiard trajectories in not necessarily smooth convex bodies. In particular, we show that if a body K ⊂ Rd has the property that the tangent cone of every non-smooth point q ∉ ∂K is acute (in a certain sense), then there is a closed billiard trajectory in K.
AU - Akopyan, Arseniy
AU - Balitskiy, Alexey
ID - 1330
IS - 2
JF - Israel Journal of Mathematics
TI - Billiards in convex bodies with acute angles
VL - 216
ER -
TY - JOUR
AB - Cytokinin is a phytohormone that is well known for its roles in numerous plant growth and developmental processes, yet it has also been linked to abiotic stress response in a less defined manner. Arabidopsis (Arabidopsis thaliana) Cytokinin Response Factor 6 (CRF6) is a cytokinin-responsive AP2/ERF-family transcription factor that, through the cytokinin signaling pathway, plays a key role in the inhibition of dark-induced senescence. CRF6 expression is also induced by oxidative stress, and here we show a novel function for CRF6 in relation to oxidative stress and identify downstream transcriptional targets of CRF6 that are repressed in response to oxidative stress. Analysis of transcriptomic changes in wild-type and crf6 mutant plants treated with H2O2 identified CRF6-dependent differentially expressed transcripts, many of which were repressed rather than induced. Moreover, many repressed genes also show decreased expression in 35S:CRF6 overexpressing plants. Together, these findings suggest that CRF6 functions largely as a transcriptional repressor. Interestingly, among the H2O2 repressed CRF6-dependent transcripts was a set of five genes associated with cytokinin processes: (signaling) ARR6, ARR9, ARR11, (biosynthesis) LOG7, and (transport) ABCG14. We have examined mutants of these cytokinin-associated target genes to reveal novel connections to oxidative stress. Further examination of CRF6-DNA interactions indicated that CRF6 may regulate its targets both directly and indirectly. Together, this shows that CRF6 functions during oxidative stress as a negative regulator to control this cytokinin-associated module of CRF6- dependent genes and establishes a novel connection between cytokinin and oxidative stress response.
AU - Zwack, Paul
AU - De Clercq, Inge
AU - Howton, Timothy
AU - Hallmark, H Tucker
AU - Hurny, Andrej
AU - Keshishian, Erika
AU - Parish, Alyssa
AU - Benková, Eva
AU - Mukhtar, M Shahid
AU - Van Breusegem, Frank
AU - Rashotte, Aaron
ID - 1331
IS - 2
JF - Plant Physiology
TI - Cytokinin response factor 6 represses cytokinin-associated genes during oxidative stress
VL - 172
ER -
TY - JOUR
AB - Antibiotic-sensitive and -resistant bacteria coexist in natural environments with low, if detectable, antibiotic concentrations. Except possibly around localized antibiotic sources, where resistance can provide a strong advantage, bacterial fitness is dominated by stresses unaffected by resistance to the antibiotic. How do such mixed and heterogeneous conditions influence the selective advantage or disadvantage of antibiotic resistance? Here we find that sub-inhibitory levels of tetracyclines potentiate selection for or against tetracycline resistance around localized sources of almost any toxin or stress. Furthermore, certain stresses generate alternating rings of selection for and against resistance around a localized source of the antibiotic. In these conditions, localized antibiotic sources, even at high strengths, can actually produce a net selection against resistance to the antibiotic. Our results show that interactions between the effects of an antibiotic and other stresses in inhomogeneous environments can generate pervasive, complex patterns of selection both for and against antibiotic resistance.
AU - Chait, Remy P
AU - Palmer, Adam
AU - Yelin, Idan
AU - Kishony, Roy
ID - 1332
JF - Nature Communications
TI - Pervasive selection for and against antibiotic resistance in inhomogeneous multistress environments
VL - 7
ER -
TY - JOUR
AB - Social dilemmas force players to balance between personal and collective gain. In many dilemmas, such as elected governments negotiating climate-change mitigation measures, the decisions are made not by individual players but by their representatives. However, the behaviour of representatives in social dilemmas has not been investigated experimentally. Here inspired by the negotiations for greenhouse-gas emissions reductions, we experimentally study a collective-risk social dilemma that involves representatives deciding on behalf of their fellow group members. Representatives can be re-elected or voted out after each consecutive collective-risk game. Selfish players are preferentially elected and are hence found most frequently in the "representatives" treatment. Across all treatments, we identify the selfish players as extortioners. As predicted by our mathematical model, their steadfast strategies enforce cooperation from fair players who finally compensate almost completely the deficit caused by the extortionate co-players. Everybody gains, but the extortionate representatives and their groups gain the most.
AU - Milinski, Manfred
AU - Hilbe, Christian
AU - Semmann, Dirk
AU - Sommerfeld, Ralf
AU - Marotzke, Jochem
ID - 1333
JF - Nature Communications
TI - Humans choose representatives who enforce cooperation in social dilemmas through extortion
VL - 7
ER -
TY - JOUR
AB - Hippocampal neurons encode a cognitive map of space. These maps are thought to be updated during learning and in response to changes in the environment through activity-dependent synaptic plasticity. Here we examine how changes in activity influence spatial coding in rats using halorhodopsin-mediated, spatially selective optogenetic silencing. Halorhoposin stimulation leads to light-induced suppression in many place cells and interneurons; some place cells increase their firing through disinhibition, whereas some show no effect. We find that place fields of the unaffected subpopulation remain stable. On the other hand, place fields of suppressed place cells were unstable, showing remapping across sessions before and after optogenetic inhibition. Disinhibited place cells had stable maps but sustained an elevated firing rate. These findings suggest that place representation in the hippocampus is constantly governed by activity-dependent processes, and that disinhibition may provide a mechanism for rate remapping.
AU - Schönenberger, Philipp
AU - O'Neill, Joseph
AU - Csicsvari, Jozsef L
ID - 1334
JF - Nature Communications
TI - Activity dependent plasticity of hippocampal place maps
VL - 7
ER -
TY - CONF
AB - In this paper we review various automata-theoretic formalisms for expressing quantitative properties. We start with finite-state Boolean automata that express the traditional regular properties. We then consider weighted ω-automata that can measure the average density of events, which finite-state Boolean automata cannot. However, even weighted ω-automata cannot express basic performance properties like average response time. We finally consider two formalisms of weighted ω-automata with monitors, where the monitors are either (a) counters or (b) weighted automata themselves. We present a translation result to establish that these two formalisms are equivalent. Weighted ω-automata with monitors generalize weighted ω-automata, and can express average response time property. They present a natural, robust, and expressive framework for quantitative specifications, with important decidable properties.
AU - Chatterjee, Krishnendu
AU - Henzinger, Thomas A
AU - Otop, Jan
ID - 1335
TI - Quantitative monitor automata
VL - 9837
ER -
TY - JOUR
AB - We present a microelectromechanical system, in which a silicon beam is attached to a comb-drive
actuator, which is used to tune the tension in the silicon beam and thus its resonance frequency. By
measuring the resonance frequencies of the system, we show that the comb-drive actuator and the
silicon beam behave as two strongly coupled resonators. Interestingly, the effective coupling rate
(1.5 MHz) is tunable with the comb-drive actuator (10%) as well as with a side-gate (10%)
placed close to the silicon beam. In contrast, the effective spring constant of the system is insensitive
to either of them and changes only by 60.5%. Finally, we show that the comb-drive actuator
can be used to switch between different coupling rates with a frequency of at least 10 kHz.
AU - Verbiest, Gerard
AU - Xu, Duo
AU - Goldsche, Matthias
AU - Khodkov, Timofiy
AU - Barzanjeh, Shabir
AU - Von Den Driesch, Nils
AU - Buca, Dan
AU - Stampfer, Christoph
ID - 1339
JF - Applied Physics Letter
TI - Tunable mechanical coupling between driven microelectromechanical resonators
VL - 109
ER -
TY - CONF
AB - We study repeated games with absorbing states, a type of two-player, zero-sum concurrent mean-payoff games with the prototypical example being the Big Match of Gillete (1957). These games may not allow optimal strategies but they always have ε-optimal strategies. In this paper we design ε-optimal strategies for Player 1 in these games that use only O(log log T) space. Furthermore, we construct strategies for Player 1 that use space s(T), for an arbitrary small unbounded non-decreasing function s, and which guarantee an ε-optimal value for Player 1 in the limit superior sense. The previously known strategies use space Ω(log T) and it was known that no strategy can use constant space if it is ε-optimal even in the limit superior sense. We also give a complementary lower bound. Furthermore, we also show that no Markov strategy, even extended with finite memory, can ensure value greater than 0 in the Big Match, answering a question posed by Neyman [11].
AU - Hansen, Kristoffer
AU - Ibsen-Jensen, Rasmus
AU - Koucký, Michal
ID - 1340
TI - The big match in small space
VL - 9928
ER -
TY - CONF
AB - In resource allocation games, selfish players share resources that are needed in order to fulfill their objectives. The cost of using a resource depends on the load on it. In the traditional setting, the players make their choices concurrently and in one-shot. That is, a strategy for a player is a subset of the resources. We introduce and study dynamic resource allocation games. In this setting, the game proceeds in phases. In each phase each player chooses one resource. A scheduler dictates the order in which the players proceed in a phase, possibly scheduling several players to proceed concurrently. The game ends when each player has collected a set of resources that fulfills his objective. The cost for each player then depends on this set as well as on the load on the resources in it – we consider both congestion and cost-sharing games. We argue that the dynamic setting is the suitable setting for many applications in practice. We study the stability of dynamic resource allocation games, where the appropriate notion of stability is that of subgame perfect equilibrium, study the inefficiency incurred due to selfish behavior, and also study problems that are particular to the dynamic setting, like constraints on the order in which resources can be chosen or the problem of finding a scheduler that achieves stability.
AU - Avni, Guy
AU - Henzinger, Thomas A
AU - Kupferman, Orna
ID - 1341
TI - Dynamic resource allocation games
VL - 9928
ER -
TY - JOUR
AB - A key aspect of bacterial survival is the ability to evolve while migrating across spatially varying environmental challenges. Laboratory experiments, however, often study evolution in well-mixed systems. Here, we introduce an experimental device, the microbial evolution and growth arena (MEGA)-plate, in which bacteria spread and evolved on a large antibiotic landscape (120 × 60 centimeters) that allowed visual observation of mutation and selection in a migrating bacterial front.While resistance increased consistently, multiple coexisting lineages diversified both phenotypically and genotypically. Analyzing mutants at and behind the propagating front,we found that evolution is not always led by the most resistant mutants; highly resistant mutants may be trapped behindmore sensitive lineages.TheMEGA-plate provides a versatile platformfor studying microbial adaption and directly visualizing evolutionary dynamics.
AU - Baym, Michael
AU - Lieberman, Tami
AU - Kelsic, Eric
AU - Chait, Remy P
AU - Gross, Rotem
AU - Yelin, Idan
AU - Kishony, Roy
ID - 1342
IS - 6304
JF - Science
TI - Spatiotemporal microbial evolution on antibiotic landscapes
VL - 353
ER -
TY - JOUR
AB - The Fermi-Hubbard model is one of the key models of condensed matter physics, which holds a
potential for explaining the mystery of high-temperature superconductivity. Recent progress in
ultracold atoms in optical lattices has paved the way to studying the model’s phase diagram using
the tools of quantum simulation, which emerged as a promising alternative to the numerical
calculations plagued by the infamous sign problem. However, the temperatures achieved using
elaborate laser cooling protocols so far have been too high to show the appearance of
antiferromagnetic (AF) and superconducting quantum phases directly. In this work, we demonstrate
that using the machinery of dissipative quantum state engineering, one can observe the emergence of
the AF order in the Fermi-Hubbard model with fermions in optical lattices. The core of the approach
is to add incoherent laser scattering in such a way that the AF state emerges as the dark state of
the driven-dissipative dynamics. The proposed controlled dissipation channels described in this work
are straightforward to add to already existing experimental setups.
AU - Kaczmarczyk, Jan
AU - Weimer, Hendrik
AU - Lemeshko, Mikhail
ID - 1343
IS - 9
JF - New Journal of Physics
TI - Dissipative preparation of antiferromagnetic order in the Fermi-Hubbard model
VL - 18
ER -
TY - JOUR
AB - Despite being composed of immobile cells, plants reorient along directional stimuli. The hormone auxin is redistributed in stimulated organs leading to differential growth and bending. Auxin application triggers rapid cell wall acidification and elongation of aerial organs of plants, but the molecular players mediating these effects are still controversial. Here we use genetically-encoded pH and auxin signaling sensors, pharmacological and genetic manipulations available for Arabidopsis etiolated hypocotyls to clarify how auxin is perceived and the downstream growth executed. We show that auxin-induced acidification occurs by local activation of H+-ATPases, which in the context of gravity response is restricted to the lower organ side. This auxin-stimulated acidification and growth require TIR1/AFB-Aux/IAA nuclear auxin perception. In addition, auxin-induced gene transcription and specifically SAUR proteins are crucial downstream mediators of this growth. Our study provides strong experimental support for the acid growth theory and clarified the contribution of the upstream auxin perception mechanisms.
AU - Fendrych, Matyas
AU - Leung, Jeffrey
AU - Friml, Jirí
ID - 1344
JF - eLife
TI - TIR1 AFB Aux IAA auxin perception mediates rapid cell wall acidification and growth of Arabidopsis hypocotyls
VL - 5
ER -
TY - JOUR
AB - The electrostatic charge at the inner surface of the plasma membrane is strongly negative in higher organisms. A new study shows that phosphatidylinositol-4-phosphate plays a critical role in establishing plasma membrane surface charge in Arabidopsis, which regulates the correct localization of signalling components.
AU - Molnar, Gergely
AU - Fendrych, Matyas
AU - Friml, Jirí
ID - 1345
JF - Nature Plants
TI - Plasma membrane: Negative attraction
VL - 2
ER -
TY - JOUR
AB - ATP production requires the establishment of an electrochemical proton gradient across the inner mitochondrial membrane. Mitochondrial uncouplers dissipate this proton gradient and disrupt numerous cellular processes, including vesicular trafficking, mainly through energy depletion. Here we show that Endosidin9 (ES9), a novel mitochondrial uncoupler, is a potent inhibitor of clathrin-mediated endocytosis (CME) in different systems and that ES9 induces inhibition of CME not because of its effect on cellular ATP, but rather due to its protonophore activity that leads to cytoplasm acidification. We show that the known tyrosine kinase inhibitor tyrphostinA23, which is routinely used to block CME, displays similar properties, thus questioning its use as a specific inhibitor of cargo recognition by the AP-2 adaptor complex via tyrosine motif-based endocytosis signals. Furthermore, we show that cytoplasm acidification dramatically affects the dynamics and recruitment of clathrin and associated adaptors, and leads to reduction of phosphatidylinositol 4,5-biphosphate from the plasma membrane.
AU - Dejonghe, Wim
AU - Kuenen, Sabine
AU - Mylle, Evelien
AU - Vasileva, Mina K
AU - Keech, Olivier
AU - Viotti, Corrado
AU - Swerts, Jef
AU - Fendrych, Matyas
AU - Ortiz Morea, Fausto
AU - Mishev, Kiril
AU - Delang, Simon
AU - Scholl, Stefan
AU - Zarza, Xavier
AU - Heilmann, Mareike
AU - Kourelis, Jiorgos
AU - Kasprowicz, Jaroslaw
AU - Nguyen, Le
AU - Drozdzecki, Andrzej
AU - Van Houtte, Isabelle
AU - Szatmári, Anna
AU - Majda, Mateusz
AU - Baisa, Gary
AU - Bednarek, Sebastian
AU - Robert, Stéphanie
AU - Audenaert, Dominique
AU - Testerink, Christa
AU - Munnik, Teun
AU - Van Damme, Daniël
AU - Heilmann, Ingo
AU - Schumacher, Karin
AU - Winne, Johan
AU - Friml, Jirí
AU - Verstreken, Patrik
AU - Russinova, Eugenia
ID - 1346
JF - Nature Communications
TI - Mitochondrial uncouplers inhibit clathrin-mediated endocytosis largely through cytoplasmic acidification
VL - 7
ER -
TY - JOUR
AB - During the past 70 years, the quantum theory of angular momentum has been successfully applied to describing the properties of nuclei, atoms, and molecules, and their interactions with each other as well as with external fields. Because of the properties of quantum rotations, the angular-momentum algebra can be of tremendous complexity even for a few interacting particles, such as valence electrons of an atom, not to mention larger many-particle systems. In this work, we study an example of the latter: A rotating quantum impurity coupled to a many-body bosonic bath. In the regime of strong impurity-bath couplings, the problem involves the addition of an infinite number of angular momenta, which renders it intractable using currently available techniques. Here, we introduce a novel canonical transformation that allows us to eliminate the complex angular-momentum algebra from such a class of many-body problems. In addition, the transformation exposes the problem's constants of motion, and renders it solvable exactly in the limit of a slowly rotating impurity. We exemplify the technique by showing that there exists a critical rotational speed at which the impurity suddenly acquires one quantum of angular momentum from the many-particle bath. Such an instability is accompanied by the deformation of the phonon density in the frame rotating along with the impurity.
AU - Schmidt, Richard
AU - Lemeshko, Mikhail
ID - 1347
IS - 1
JF - Physical Review X
TI - Deformation of a quantum many-particle system by a rotating impurity
VL - 6
ER -
TY - CONF
AB - A drawing in the plane (ℝ2) of a graph G = (V,E) equipped with a function γ : V → ℕ is x-bounded if (i) x(u) < x(v) whenever γ(u) < γ(v) and (ii) γ(u) ≤ γ(w) ≤ γ(v), where uv ∈ E and γ(u) ≤ γ(v), whenever x(w) ∈ x(uv), where x(.) denotes the projection to the xaxis.We prove a characterization of isotopy classes of embeddings of connected graphs equipped with γ in the plane containing an x-bounded embedding.Then we present an efficient algorithm, which relies on our result, for testing the existence of an x-bounded embedding if the given graph is a forest.This partially answers a question raised recently by Angelini et al.and Chang et al., and proves that c-planarity testing of flat clustered graphs with three clusters is tractable when the underlying abstract graph is a forest.
AU - Fulek, Radoslav
ID - 1348
TI - Bounded embeddings of graphs in the plane
VL - 9843
ER -
TY - CONF
AB - Crossing fitness valleys is one of the major obstacles to function optimization. In this paper we investigate how the structure of the fitness valley, namely its depth d and length ℓ, influence the runtime of different strategies for crossing these valleys. We present a runtime comparison between the (1+1) EA and two non-elitist nature-inspired algorithms, Strong Selection Weak Mutation (SSWM) and the Metropolis algorithm. While the (1+1) EA has to jump across the valley to a point of higher fitness because it does not accept decreasing moves, the non-elitist algorithms may cross the valley by accepting worsening moves. We show that while the runtime of the (1+1) EA algorithm depends critically on the length of the valley, the runtimes of the non-elitist algorithms depend crucially only on the depth of the valley. In particular, the expected runtime of both SSWM and Metropolis is polynomial in ℓ and exponential in d while the (1+1) EA is efficient only for valleys of small length. Moreover, we show that both SSWM and Metropolis can also efficiently optimize a rugged function consisting of consecutive valleys.
AU - Oliveto, Pietro
AU - Paixao, Tiago
AU - Heredia, Jorge
AU - Sudholt, Dirk
AU - Trubenova, Barbora
ID - 1349
T2 - Proceedings of the Genetic and Evolutionary Computation Conference 2016
TI - When non-elitism outperforms elitism for crossing fitness valleys
ER -
TY - JOUR
AB - The hippocampal CA3 region plays a key role in learning and memory. Recurrent CA3–CA3
synapses are thought to be the subcellular substrate of pattern completion. However, the
synaptic mechanisms of this network computation remain enigmatic. To investigate these mechanisms, we combined functional connectivity analysis with network modeling.
Simultaneous recording fromup to eight CA3 pyramidal neurons revealed that connectivity was sparse, spatially uniform, and highly enriched in disynaptic motifs (reciprocal, convergence,divergence, and chain motifs). Unitary connections were composed of one or two synaptic contacts, suggesting efficient use of postsynaptic space. Real-size modeling indicated that CA3 networks with sparse connectivity, disynaptic motifs, and single-contact connections robustly generated pattern completion.Thus, macro- and microconnectivity contribute to efficient
memory storage and retrieval in hippocampal networks.
AU - Guzmán, José
AU - Schlögl, Alois
AU - Frotscher, Michael
AU - Jonas, Peter M
ID - 1350
IS - 6304
JF - Science
TI - Synaptic mechanisms of pattern completion in the hippocampal CA3 network
VL - 353
ER -
TY - JOUR
AB - We study the interplay of nematic and superconducting order in the two-dimensional Hubbard model and show that they can coexist, especially when superconductivity is not the energetically dominant phase. Due to a breaking of the C4 symmetry, the coexisting phase inherently contains admixture of the s-wave pairing components. As a result, the superconducting gap exhibits nonstandard features including changed nodal directions. Our results also show that in the optimally doped regime the pure superconducting phase is typically unstable towards developing nematicity (breaking of the C4 symmetry). This has implications for the cuprate high-Tc superconductors, for which in this regime the so-called intertwined orders have recently been observed. Namely, the coexisting phase may be viewed as a precursor to such more involved patterns of symmetry breaking.
AU - Kaczmarczyk, Jan
AU - Schickling, Tobias
AU - Bünemann, Jörg
ID - 1352
IS - 8
JF - Physical Review B - Condensed Matter and Materials Physics
TI - Coexistence of nematic order and superconductivity in the Hubbard model
VL - 94
ER -
TY - JOUR
AB - We characterize absorption in finite idempotent algebras by means of Jónsson absorption and cube term blockers. As an application we show that it is decidable whether a given subset is an absorbing subuniverse of an algebra given by the tables of its basic operations.
AU - Barto, Libor
AU - Kazda, Alexandr
ID - 1353
IS - 5
JF - International Journal of Algebra and Computation
TI - Deciding absorption
VL - 26
ER -
TY - JOUR
AB - Fabrication processes involving anhydrous hydrofluoric vapor etching are developed to create high-Q aluminum superconducting microwave resonators on free-standing silicon membranes formed from a silicon-on-insulator wafer. Using this fabrication process, a high-impedance 8.9-GHz coil resonator is coupled capacitively with a large participation ratio to a 9.7-MHz micromechanical resonator. Two-tone microwave spectroscopy and radiation pressure backaction are used to characterize the coupled system in a dilution refrigerator down to temperatures of Tf=11 mK, yielding a measured electromechanical vacuum coupling rate of g0/2π=24.6 Hz and a mechanical resonator Q factor of Qm=1.7×107. Microwave backaction cooling of the mechanical resonator is also studied, with a minimum phonon occupancy of nm≈16 phonons being realized at an elevated fridge temperature of Tf=211 mK.
AU - Dieterle, Paul
AU - Kalaee, Mahmoud
AU - Fink, Johannes M
AU - Painter, Oskar
ID - 1354
IS - 1
JF - Physical Review Applied
TI - Superconducting cavity electromechanics on a silicon-on-insulator platform
VL - 6
ER -
TY - JOUR
AB - Radiation pressure has recently been used to effectively couple the quantum motion of mechanical elements to the fields of optical or microwave light. Integration of all three degrees of freedom—mechanical, optical and microwave—would enable a quantum interconnect between microwave and optical quantum systems. We present a platform based on silicon nitride nanomembranes for integrating superconducting microwave circuits with planar acoustic and optical devices such as phononic and photonic crystals. Using planar capacitors with vacuum gaps of 60 nm and spiral inductor coils of micron pitch we realize microwave resonant circuits with large electromechanical coupling to planar acoustic structures of nanoscale dimensions and femtoFarad motional capacitance. Using this enhanced coupling, we demonstrate microwave backaction cooling of the 4.48 MHz mechanical resonance of a nanobeam to an occupancy as low as 0.32. These results indicate the viability of silicon nitride nanomembranes as an all-in-one substrate for quantum electro-opto-mechanical experiments.
AU - Fink, Johannes M
AU - Kalaee, Mahmoud
AU - Pitanti, Alessandro
AU - Norte, Richard
AU - Heinzle, Lukas
AU - Davanço, Marcelo
AU - Srinivasan, Kartik
AU - Painter, Oskar
ID - 1355
JF - Nature Communications
TI - Quantum electromechanics on silicon nitride nanomembranes
VL - 7
ER -
TY - JOUR
AU - Barton, Nicholas H
ID - 1356
IS - 1
JF - Genetics
TI - Sewall Wright on evolution in Mendelian populations and the “Shifting Balance”
VL - 202
ER -
TY - JOUR
AU - Barton, Nicholas H
ID - 1357
IS - 3
JF - Genetics
TI - Richard Hudson and Norman Kaplan on the coalescent process
VL - 202
ER -
TY - JOUR
AB - Gene regulation relies on the specificity of transcription factor (TF)–DNA interactions. Limited specificity may lead to crosstalk: a regulatory state in which a gene is either incorrectly activated due to noncognate TF–DNA interactions or remains erroneously inactive. As each TF can have numerous interactions with noncognate cis-regulatory elements, crosstalk is inherently a global problem, yet has previously not been studied as such. We construct a theoretical framework to analyse the effects of global crosstalk on gene regulation. We find that crosstalk presents a significant challenge for organisms with low-specificity TFs, such as metazoans. Crosstalk is not easily mitigated by known regulatory schemes acting at equilibrium, including variants of cooperativity and combinatorial regulation. Our results suggest that crosstalk imposes a previously unexplored global constraint on the functioning and evolution of regulatory networks, which is qualitatively distinct from the known constraints that act at the level of individual gene regulatory elements.
AU - Friedlander, Tamar
AU - Prizak, Roshan
AU - Guet, Calin C
AU - Barton, Nicholas H
AU - Tkacik, Gasper
ID - 1358
JF - Nature Communications
TI - Intrinsic limits to gene regulation by global crosstalk
VL - 7
ER -
TY - JOUR
AB - The role of gene interactions in the evolutionary process has long
been controversial. Although some argue that they are not of
importance, because most variation is additive, others claim that
their effect in the long term can be substantial. Here, we focus on
the long-term effects of genetic interactions under directional
selection assuming no mutation or dominance, and that epistasis is
symmetrical overall. We ask by how much the mean of a complex
trait can be increased by selection and analyze two extreme
regimes, in which either drift or selection dominate the dynamics
of allele frequencies. In both scenarios, epistatic interactions affect
the long-term response to selection by modulating the additive
genetic variance. When drift dominates, we extend Robertson
’
s
[Robertson A (1960)
Proc R Soc Lond B Biol Sci
153(951):234
−
249]
argument to show that, for any form of epistasis, the total response
of a haploid population is proportional to the initial total genotypic
variance. In contrast, the total response of a diploid population is
increased by epistasis, for a given initial genotypic variance. When
selection dominates, we show that the total selection response can
only be increased by epistasis when s
ome initially deleterious alleles
become favored as the genetic background changes. We find a sim-
ple approximation for this effect and show that, in this regime, it is
the structure of the genotype - phenotype map that matters and not
the variance components of the population.
AU - Paixao, Tiago
AU - Barton, Nicholas H
ID - 1359
IS - 16
JF - PNAS
TI - The effect of gene interactions on the long-term response to selection
VL - 113
ER -
TY - JOUR
AB - We apply the technique of Károly Bezdek and Daniel Bezdek to study billiard trajectories in convex bodies, when the length is measured with a (possibly asymmetric) norm. We prove a lower bound for the length of the shortest closed billiard trajectory, related to the non-symmetric Mahler problem. With this technique we are able to give short and elementary proofs to some known results.
AU - Akopyan, Arseniy
AU - Balitskiy, Alexey
AU - Karasev, Roman
AU - Sharipova, Anastasia
ID - 1360
IS - 10
JF - Proceedings of the American Mathematical Society
TI - Elementary approach to closed billiard trajectories in asymmetric normed spaces
VL - 144
ER -
TY - CONF
AB - We propose a novel surface-only technique for simulating incompressible, inviscid and uniform-density liquids with surface tension in three dimensions. The liquid surface is captured by a triangle mesh on which a Lagrangian velocity field is stored. Because advection of the velocity field may violate the incompressibility condition, we devise an orthogonal projection technique to remove the divergence while requiring the evaluation of only two boundary integrals. The forces of surface tension, gravity, and solid contact are all treated by a boundary element solve, allowing us to perform detailed simulations of a wide range of liquid phenomena, including waterbells, droplet and jet collisions, fluid chains, and crown splashes.
AU - Da, Fang
AU - Hahn, David
AU - Batty, Christopher
AU - Wojtan, Christopher J
AU - Grinspun, Eitan
ID - 1361
IS - 4
TI - Surface only liquids
VL - 35
ER -
TY - CONF
AB - We present a boundary element based method for fast simulation of brittle fracture. By introducing simplifying assumptions that allow us to quickly estimate stress intensities and opening displacements during crack propagation, we build a fracture algorithm where the cost of each time step scales linearly with the length of the crackfront. The transition from a full boundary element method to our faster variant is possible at the beginning of any time step. This allows us to build a hybrid method, which uses the expensive but more accurate BEM while the number of degrees of freedom is low, and uses the fast method once that number exceeds a given threshold as the crack geometry becomes more complicated. Furthermore, we integrate this fracture simulation with a standard rigid-body solver. Our rigid-body coupling solves a Neumann boundary value problem by carefully separating translational, rotational and deformational components of the collision forces and then applying a Tikhonov regularizer to the resulting linear system. We show that our method produces physically reasonable results in standard test cases and is capable of dealing with complex scenes faster than previous finite- or boundary element approaches.
AU - Hahn, David
AU - Wojtan, Christopher J
ID - 1362
IS - 4
TI - Fast approximations for boundary element based brittle fracture simulation
VL - 35
ER -
TY - CONF
AB - When aiming to seamlessly integrate a fluid simulation into a larger scenario (like an open ocean), careful attention must be paid to boundary conditions. In particular, one must implement special "non-reflecting" boundary conditions, which dissipate out-going waves as they exit the simulation. Unfortunately, the state of the art in non-reflecting boundary conditions (perfectly-matched layers, or PMLs) only permits trivially simple inflow/outflow conditions, so there is no reliable way to integrate a fluid simulation into a more complicated environment like a stormy ocean or a turbulent river. This paper introduces the first method for combining nonreflecting boundary conditions based on PMLs with inflow/outflow boundary conditions that vary arbitrarily throughout space and time. Our algorithm is a generalization of stateof- the-art mean-flow boundary conditions in the computational fluid dynamics literature, and it allows for seamless integration of a fluid simulation into much more complicated environments. Our method also opens the door for previously-unseen postprocess effects like retroactively changing the location of solid obstacles, and locally increasing the visual detail of a pre-existing simulation.
AU - Bojsen-Hansen, Morten
AU - Wojtan, Christopher J
ID - 1363
IS - 4
TI - Generalized non-reflecting boundaries for fluid re-simulation
VL - 35
ER -
TY - CONF
AB - We present a computational method for designing wire sculptures consisting of interlocking wires. Our method allows the computation of aesthetically pleasing structures that are structurally stable, efficiently fabricatable with a 2D wire bending machine, and assemblable without the need of additional connectors. Starting from a set of planar contours provided by the user, our method automatically tests for the feasibility of a design, determines a discrete ordering of wires at intersection points, and optimizes for the rest shape of the individual wires to maximize structural stability under frictional contact. In addition to their application to art, wire sculptures present an extremely efficient and fast alternative for low-fidelity rapid prototyping because manufacturing time and required material linearly scales with the physical size of objects. We demonstrate the effectiveness of our approach on a varied set of examples, all of which we fabricated.
AU - Miguel Villalba, Eder
AU - Lepoutre, Mathias
AU - Bickel, Bernd
ID - 1364
IS - 4
TI - Computational design of stable planar-rod structures
VL - 35
ER -
TY - CONF
AB - A memory-hard function (MHF) f is equipped with a space cost σ and time cost τ parameter such that repeatedly computing fσ,τ on an application specific integrated circuit (ASIC) is not economically advantageous relative to a general purpose computer. Technically we would like that any (generalized) circuit for evaluating an iMHF fσ,τ has area × time (AT) complexity at Θ(σ2 ∗ τ). A data-independent MHF (iMHF) has the added property that it can be computed with almost optimal memory and time complexity by an algorithm which accesses memory in a pattern independent of the input value. Such functions can be specified by fixing a directed acyclic graph (DAG) G on n = Θ(σ ∗ τ) nodes representing its computation graph. In this work we develop new tools for analyzing iMHFs. First we define and motivate a new complexity measure capturing the amount of energy (i.e. electricity) required to compute a function. We argue that, in practice, this measure is at least as important as the more traditional AT-complexity. Next we describe an algorithm A for repeatedly evaluating an iMHF based on an arbitrary DAG G. We upperbound both its energy and AT complexities per instance evaluated in terms of a certain combinatorial property of G. Next we instantiate our attack for several general classes of DAGs which include those underlying many of the most important iMHF candidates in the literature. In particular, we obtain the following results which hold for all choices of parameters σ and τ (and thread-count) such that n = σ ∗ τ. -The Catena-Dragonfly function of [FLW13] has AT and energy complexities O(n1.67). -The Catena-Butterfly function of [FLW13] has complexities is O(n1.67). -The Double-Buffer and the Linear functions of [CGBS16] both have complexities in O(n1.67). -The Argon2i function of [BDK15] (winner of the Password Hashing Competition [PHC]) has complexities O(n7/4 log(n)). -The Single-Buffer function of [CGBS16] has complexities O(n7/4 log(n)). -Any iMHF can be computed by an algorithm with complexities O(n2/ log1 −ε(n)) for all ε > 0. In particular when τ = 1 this shows that the goal of constructing an iMHF with AT-complexity Θ(σ2 ∗ τ ) is unachievable. Along the way we prove a lemma upper-bounding the depth-robustness of any DAG which may prove to be of independent interest.
AU - Alwen, Joel F
AU - Blocki, Jeremiah
ID - 1365
TI - Efficiently computing data-independent memory-hard functions
VL - 9815
ER -
TY - CONF
AB - We study the problem of devising provably secure PRNGs with input based on the sponge paradigm. Such constructions are very appealing, as efficient software/hardware implementations of SHA-3 can easily be translated into a PRNG in a nearly black-box way. The only existing sponge-based construction, proposed by Bertoni et al. (CHES 2010), fails to achieve the security notion of robustness recently considered by Dodis et al. (CCS 2013), for two reasons: (1) The construction is deterministic, and thus there are high-entropy input distributions on which the construction fails to extract random bits, and (2) The construction is not forward secure, and presented solutions aiming at restoring forward security have not been rigorously analyzed. We propose a seeded variant of Bertoni et al.’s PRNG with input which we prove secure in the sense of robustness, delivering in particular concrete security bounds. On the way, we make what we believe to be an important conceptual contribution, developing a variant of the security framework of Dodis et al. tailored at the ideal permutation model that captures PRNG security in settings where the weakly random inputs are provided from a large class of possible adversarial samplers which are also allowed to query the random permutation. As a further application of our techniques, we also present an efficient sponge-based key-derivation function (which can be instantiated from SHA-3 in a black-box fashion), which we also prove secure when fed with samples from permutation-dependent distributions.
AU - Gazi, Peter
AU - Tessaro, Stefano
ID - 1366
TI - Provably robust sponge-based PRNGs and KDFs
VL - 9665
ER -
TY - JOUR
AB - Superconductivity in heavy-fermion systems has an unconventional nature and is considered to originate from the universal features of the electronic structure. Here, the Anderson lattice model is studied by means of the full variational Gutzwiller wave function incorporating nonlocal effects of the on-site interaction. We show that the d-wave superconducting ground state can be driven solely by interelectronic correlations. The proposed microscopic mechanism leads to a multigap superconductivity with the dominant contribution due to f electrons and in the dx2−y2-wave channel. Our results rationalize several important observations for CeCoIn5.
AU - Wysokiński, Marcin
AU - Kaczmarczyk, Jan
AU - Spałek, Jozef
ID - 1368
IS - 2
JF - Physical Review B - Condensed Matter and Materials Physics
TI - Correlation driven d wave superconductivity in Anderson lattice model: Two gaps
VL - 94
ER -
TY - CONF
AB - We introduce a new loss function for the weakly-supervised training of semantic image segmentation models based on three guiding principles: to seed with weak localization cues, to expand objects based on the information about which classes can occur in an image, and to constrain the segmentations to coincide with object boundaries. We show experimentally that training a deep convolutional neural network using the proposed loss function leads to substantially better segmentations than previous state-of-the-art methods on the challenging PASCAL VOC 2012 dataset. We furthermore give insight into the working mechanism of our method by a detailed experimental study that illustrates how the segmentation quality is affected by each term of the proposed loss function as well as their combinations.
AU - Kolesnikov, Alexander
AU - Lampert, Christoph
ID - 1369
TI - Seed, expand and constrain: Three principles for weakly-supervised image segmentation
VL - 9908
ER -
TY - JOUR
AB - We study coherent phonon oscillations and tunneling between two coupled nonlinear nanomechanical resonators. We show that the coupling between two nanomechanical resonators creates an effective phonon Josephson junction, which exhibits two different dynamical behaviors: Josephson oscillation (phonon-Rabi oscillation) and macroscopic self-trapping (phonon blockade). Self-trapping originates from mechanical nonlinearities, meaning that when the nonlinearity exceeds its critical value, the energy exchange between the two resonators is suppressed, and phonon Josephson oscillations between them are completely blocked. An effective classical Hamiltonian for the phonon Josephson junction is derived and its mean-field dynamics is studied in phase space. Finally, we study the phonon-phonon coherence quantified by the mean fringe visibility, and show that the interaction between the two resonators may lead to the loss of coherence in the phononic junction.
AU - Barzanjeh, Shabir
AU - Vitali, David
ID - 1370
IS - 3
JF - Physical Review A - Atomic, Molecular, and Optical Physics
TI - Phonon Josephson junction with nanomechanical resonators
VL - 93
ER -
TY - JOUR
AB - Living cells can maintain their internal states, react to changing environments, grow, differentiate, divide, etc. All these processes are tightly controlled by what can be called a regulatory program. The logic of the underlying control can sometimes be guessed at by examining the network of influences amongst genetic components. Some associated gene regulatory networks have been studied in prokaryotes and eukaryotes, unveiling various structural features ranging from broad distributions of out-degrees to recurrent "motifs", that is small subgraphs having a specific pattern of interactions. To understand what factors may be driving such structuring, a number of groups have introduced frameworks to model the dynamics of gene regulatory networks. In that context, we review here such in silico approaches and show how selection for phenotypes, i.e., network function, can shape network structure.
AU - Martin, Olivier
AU - Krzywicki, André
AU - Zagórski, Marcin P
ID - 1371
JF - Physics of Life Reviews
TI - Drivers of structural features in gene regulatory networks: From biophysical constraints to biological function
VL - 17
ER -