TY - JOUR AB - Nonreciprocal circuit elements form an integral part of modern measurement and communication systems. Mathematically they require breaking of time-reversal symmetry, typically achieved using magnetic materials and more recently using the quantum Hall effect, parametric permittivity modulation or Josephson nonlinearities. Here we demonstrate an on-chip magnetic-free circulator based on reservoir-engineered electromechanic interactions. Directional circulation is achieved with controlled phase-sensitive interference of six distinct electro-mechanical signal conversion paths. The presented circulator is compact, its silicon-on-insulator platform is compatible with both superconducting qubits and silicon photonics, and its noise performance is close to the quantum limit. With a high dynamic range, a tunable bandwidth of up to 30 MHz and an in situ reconfigurability as beam splitter or wavelength converter, it could pave the way for superconducting qubit processors with multiplexed on-chip signal processing and readout. AU - Barzanjeh, Shabir AU - Wulf, Matthias AU - Peruzzo, Matilda AU - Kalaee, Mahmoud AU - Dieterle, Paul AU - Painter, Oskar AU - Fink, Johannes M ID - 798 IS - 1 JF - Nature Communications SN - 20411723 TI - Mechanical on chip microwave circulator VL - 8 ER - TY - CONF AB - Consider the following random process: we are given n queues, into which elements of increasing labels are inserted uniformly at random. To remove an element, we pick two queues at random, and remove the element of lower label (higher priority) among the two. The cost of a removal is the rank of the label removed, among labels still present in any of the queues, that is, the distance from the optimal choice at each step. Variants of this strategy are prevalent in state-of-the-art concurrent priority queue implementations. Nonetheless, it is not known whether such implementations provide any rank guarantees, even in a sequential model. We answer this question, showing that this strategy provides surprisingly strong guarantees: Although the single-choice process, where we always insert and remove from a single randomly chosen queue, has degrading cost, going to infinity as we increase the number of steps, in the two choice process, the expected rank of a removed element is O(n) while the expected worst-case cost is O(n log n). These bounds are tight, and hold irrespective of the number of steps for which we run the process. The argument is based on a new technical connection between "heavily loaded" balls-into-bins processes and priority scheduling. Our analytic results inspire a new concurrent priority queue implementation, which improves upon the state of the art in terms of practical performance. AU - Alistarh, Dan-Adrian AU - Kopinsky, Justin AU - Li, Jerry AU - Nadiradze, Giorgi ID - 791 SN - 978-145034992-5 T2 - Proceedings of the ACM Symposium on Principles of Distributed Computing TI - The power of choice in priority scheduling VL - Part F129314 ER - TY - JOUR AB - The chaotic dynamics of low-dimensional systems, such as Lorenz or Rössler flows, is guided by the infinity of periodic orbits embedded in their strange attractors. Whether this is also the case for the infinite-dimensional dynamics of Navier–Stokes equations has long been speculated, and is a topic of ongoing study. Periodic and relative periodic solutions have been shown to be involved in transitions to turbulence. Their relevance to turbulent dynamics – specifically, whether periodic orbits play the same role in high-dimensional nonlinear systems like the Navier–Stokes equations as they do in lower-dimensional systems – is the focus of the present investigation. We perform here a detailed study of pipe flow relative periodic orbits with energies and mean dissipations close to turbulent values. We outline several approaches to reduction of the translational symmetry of the system. We study pipe flow in a minimal computational cell at Re=2500, and report a library of invariant solutions found with the aid of the method of slices. Detailed study of the unstable manifolds of a sample of these solutions is consistent with the picture that relative periodic orbits are embedded in the chaotic saddle and that they guide the turbulent dynamics. AU - Budanur, Nazmi B AU - Short, Kimberly AU - Farazmand, Mohammad AU - Willis, Ashley AU - Cvitanović, Predrag ID - 792 JF - Journal of Fluid Mechanics SN - 00221120 TI - Relative periodic orbits form the backbone of turbulent pipe flow VL - 833 ER - TY - JOUR AB - We present the fabrication and characterization of an aluminum transmon qubit on a silicon-on-insulator substrate. Key to the qubit fabrication is the use of an anhydrous hydrofluoric vapor process which selectively removes the lossy silicon oxide buried underneath the silicon device layer. For a 5.6 GHz qubit measured dispersively by a 7.1 GHz resonator, we find T1 = 3.5 μs and T∗2 = 2.2 μs. This process in principle permits the co-fabrication of silicon photonic and mechanical elements, providing a route towards chip-scale integration of electro-opto-mechanical transducers for quantum networking of superconducting microwave quantum circuits. The additional processing steps are compatible with established fabrication techniques for aluminum transmon qubits on silicon. AU - Keller, Andrew J AU - Dieterle, Paul AU - Fang, Michael AU - Berger, Brett AU - Fink, Johannes M AU - Painter, Oskar ID - 796 IS - 4 JF - Applied Physics Letters SN - 00036951 TI - Al transmon qubits on silicon on insulator for quantum device integration VL - 111 ER - TY - JOUR AB - Let P be a finite point set in the plane. A cordinary triangle in P is a subset of P consisting of three non-collinear points such that each of the three lines determined by the three points contains at most c points of P . Motivated by a question of Erdös, and answering a question of de Zeeuw, we prove that there exists a constant c > 0such that P contains a c-ordinary triangle, provided that P is not contained in the union of two lines. Furthermore, the number of c-ordinary triangles in P is Ω(| P |). AU - Fulek, Radoslav AU - Mojarrad, Hossein AU - Naszódi, Márton AU - Solymosi, József AU - Stich, Sebastian AU - Szedlák, May ID - 793 JF - Computational Geometry: Theory and Applications SN - 09257721 TI - On the existence of ordinary triangles VL - 66 ER - TY - JOUR AB - We show that c-planarity is solvable in quadratic time for flat clustered graphs with three clusters if the combinatorial embedding of the underlying graph is fixed. In simpler graph-theoretical terms our result can be viewed as follows. Given a graph G with the vertex set partitioned into three parts embedded on a 2-sphere, our algorithm decides if we can augment G by adding edges without creating an edge-crossing so that in the resulting spherical graph the vertices of each part induce a connected sub-graph. We proceed by a reduction to the problem of testing the existence of a perfect matching in planar bipartite graphs. We formulate our result in a slightly more general setting of cyclic clustered graphs, i.e., the simple graph obtained by contracting each cluster, where we disregard loops and multi-edges, is a cycle. AU - Fulek, Radoslav ID - 794 JF - Computational Geometry: Theory and Applications TI - C-planarity of embedded cyclic c-graphs VL - 66 ER - TY - JOUR AB - The neurotransmitter receptor subtype, number, density, and distribution relative to the location of transmitter release sites are key determinants of signal transmission. AMPA-type ionotropic glutamate receptors (AMPARs) containing GluA3 and GluA4 subunits are prominently expressed in subsets of neurons capable of firing action potentials at high frequencies, such as auditory relay neurons. The auditory nerve (AN) forms glutamatergic synapses on two types of relay neurons, bushy cells (BCs) and fusiform cells (FCs) of the cochlear nucleus. AN-BC and AN-FC synapses have distinct kinetics; thus, we investigated whether the number, density, and localization of GluA3 and GluA4 subunits in these synapses are differentially organized using quantitative freeze-fracture replica immunogold labeling. We identify a positive correlation between the number of AMPARs and the size of AN-BC and AN-FC synapses. Both types of AN synapses have similar numbers of AMPARs; however, the AN-BC have a higher density of AMPARs than AN-FC synapses, because the AN-BC synapses are smaller. A higher number and density of GluA3 subunits are observed at AN-BC synapses, whereas a higher number and density of GluA4 subunits are observed at AN-FC synapses. The intrasynaptic distribution of immunogold labeling revealed that AMPAR subunits, particularly GluA3, are concentrated at the center of the AN-BC synapses. The central distribution of AMPARs is absent in GluA3-knockout mice, and gold particles are evenly distributed along the postsynaptic density. GluA4 gold labeling was homogenously distributed along both synapse types. Thus, GluA3 and GluA4 subunits are distributed at AN synapses in a target-cell-dependent manner. AU - Rubio, María AU - Matsui, Ko AU - Fukazawa, Yugo AU - Kamasawa, Naomi AU - Harada, Harumi AU - Itakura, Makoto AU - Molnár, Elek AU - Abe, Manabu AU - Sakimura, Kenji AU - Shigemoto, Ryuichi ID - 736 IS - 8 JF - Brain Structure and Function SN - 18632653 TI - The number and distribution of AMPA receptor channels containing fast kinetic GluA3 and GluA4 subunits at auditory nerve synapses depend on the target cells VL - 222 ER - TY - JOUR AB - Developments in bioengineering and molecular biology have introduced a palette of genetically encoded probes for identification of specific cell populations in electron microscopy. These probes can be targeted to distinct cellular compartments, rendering them electron dense through a subsequent chemical reaction. These electron densities strongly increase the local contrast in samples prepared for electron microscopy, allowing three major advances in ultrastructural mapping of circuits: genetic identification of circuit components, targeted imaging of regions of interest and automated analysis of the tagged circuits. Together, the gains from these advances can decrease the time required for the analysis of targeted circuit motifs by over two orders of magnitude. These genetic encoded tags for electron microscopy promise to simplify the analysis of circuit motifs and become a central tool for structure‐function studies of synaptic connections in the brain. We review the current state‐of‐the‐art with an emphasis on connectomics, the quantitative analysis of neuronal structures and motifs. AU - Shigemoto, Ryuichi AU - Jösch, Maximilian A ID - 740 IS - 6 JF - WIREs Developmental Biology SN - 17597684 TI - The genetic encoded toolbox for electron microscopy and connectomics VL - 6 ER - TY - JOUR AB - We prove that a system of N fermions interacting with an additional particle via point interactions is stable if the ratio of the mass of the additional particle to the one of the fermions is larger than some critical m*. The value of m* is independent of N and turns out to be less than 1. This fact has important implications for the stability of the unitary Fermi gas. We also characterize the domain of the Hamiltonian of this model, and establish the validity of the Tan relations for all wave functions in the domain. AU - Moser, Thomas AU - Seiringer, Robert ID - 741 IS - 1 JF - Communications in Mathematical Physics SN - 00103616 TI - Stability of a fermionic N+1 particle system with point interactions VL - 356 ER - TY - JOUR AB - We study the norm approximation to the Schrödinger dynamics of N bosons in with an interaction potential of the form . Assuming that in the initial state the particles outside of the condensate form a quasi-free state with finite kinetic energy, we show that in the large N limit, the fluctuations around the condensate can be effectively described using Bogoliubov approximation for all . The range of β is expected to be optimal for this large class of initial states. AU - Nam, Phan AU - Napiórkowski, Marcin M ID - 739 IS - 5 JF - Journal de Mathématiques Pures et Appliquées SN - 00217824 TI - A note on the validity of Bogoliubov correction to mean field dynamics VL - 108 ER - TY - JOUR AB - We generalize Brazas’ topology on the fundamental group to the whole universal path space X˜ i.e., to the set of homotopy classes of all based paths. We develop basic properties of the new notion and provide a complete comparison of the obtained topology with the established topologies, in particular with the Lasso topology and the CO topology, i.e., the topology that is induced by the compact-open topology. It turns out that the new topology is the finest topology contained in the CO topology, for which the action of the fundamental group on the universal path space is a continuous group action. AU - Virk, Ziga AU - Zastrow, Andreas ID - 737 JF - Topology and its Applications SN - 01668641 TI - A new topology on the universal path space VL - 231 ER - TY - JOUR AB - Let A and B be two N by N deterministic Hermitian matrices and let U be an N by N Haar distributed unitary matrix. It is well known that the spectral distribution of the sum H = A + UBU∗ converges weakly to the free additive convolution of the spectral distributions of A and B, as N tends to infinity. We establish the optimal convergence rate in the bulk of the spectrum. AU - Bao, Zhigang AU - Erdös, László AU - Schnelli, Kevin ID - 733 JF - Advances in Mathematics TI - Convergence rate for spectral distribution of addition of random matrices VL - 319 ER - TY - JOUR AB - Heavy holes confined in quantum dots are predicted to be promising candidates for the realization of spin qubits with long coherence times. Here we focus on such heavy-hole states confined in germanium hut wires. By tuning the growth density of the latter we can realize a T-like structure between two neighboring wires. Such a structure allows the realization of a charge sensor, which is electrostatically and tunnel coupled to a quantum dot, with charge-transfer signals as high as 0.3 e. By integrating the T-like structure into a radiofrequency reflectometry setup, single-shot measurements allowing the extraction of hole tunneling times are performed. The extracted tunneling times of less than 10 μs are attributed to the small effective mass of Ge heavy-hole states and pave the way toward projective spin readout measurements. AU - Vukusic, Lada AU - Kukucka, Josip AU - Watzinger, Hannes AU - Katsaros, Georgios ID - 840 IS - 9 JF - Nano Letters SN - 15306984 TI - Fast hole tunneling times in germanium hut wires probed by single-shot reflectometry VL - 17 ER - TY - JOUR AB - Infections with potentially lethal pathogens may negatively affect an individual’s lifespan and decrease its reproductive value. The terminal investment hypothesis predicts that individuals faced with a reduced survival should invest more into reproduction instead of maintenance and growth. Several studies suggest that individuals are indeed able to estimate their body condition and to increase their reproductive effort with approaching death, while other studies gave ambiguous results. We investigate whether queens of a perennial social insect (ant) are able to boost their reproduction following infection with an obligate killing pathogen. Social insect queens are special with regard to reproduction and aging, as they outlive conspecific non-reproductive workers. Moreover, in the ant Cardiocondyla obscurior, fecundity increases with queen age. However, it remained unclear whether this reflects negative reproductive senescence or terminal investment in response to approaching death. Here, we test whether queens of C. obscurior react to infection with the entomopathogenic fungus Metarhizium brunneum by an increased egg-laying rate. We show that a fungal infection triggers a reinforced investment in reproduction in queens. This adjustment of the reproductive rate by ant queens is consistent with predictions of the terminal investment hypothesis and is reported for the first time in a social insect. AU - Giehr, Julia AU - Grasse, Anna V AU - Cremer, Sylvia AU - Heinze, Jürgen AU - Schrempf, Alexandra ID - 914 IS - 7 JF - Royal Society Open Science SN - 20545703 TI - Ant queens increase their reproductive efforts after pathogen infection VL - 4 ER - TY - JOUR AB - Frequency-independent selection is generally considered as a force that acts to reduce the genetic variation in evolving populations, yet rigorous arguments for this idea are scarce. When selection fluctuates in time, it is unclear whether frequency-independent selection may maintain genetic polymorphism without invoking additional mechanisms. We show that constant frequency-independent selection with arbitrary epistasis on a well-mixed haploid population eliminates genetic variation if we assume linkage equilibrium between alleles. To this end, we introduce the notion of frequency-independent selection at the level of alleles, which is sufficient to prove our claim and contains the notion of frequency-independent selection on haploids. When selection and recombination are weak but of the same order, there may be strong linkage disequilibrium; numerical calculations show that stable equilibria are highly unlikely. Using the example of a diallelic two-locus model, we then demonstrate that frequency-independent selection that fluctuates in time can maintain stable polymorphism if linkage disequilibrium changes its sign periodically. We put our findings in the context of results from the existing literature and point out those scenarios in which the possible role of frequency-independent selection in maintaining genetic variation remains unclear. AU - Novak, Sebastian AU - Barton, Nicholas H ID - 910 IS - 2 JF - Genetics TI - When does frequency-independent selection maintain genetic variation? VL - 207 ER - TY - JOUR AB - An outstanding question in animal development, tissue homeostasis and disease is how cell populations adapt to sensory inputs. During Drosophila larval development, hematopoietic sites are in direct contact with sensory neuron clusters of the peripheral nervous system (PNS), and blood cells (hemocytes) require the PNS for their survival and recruitment to these microenvironments, known as Hematopoietic Pockets. Here we report that Activin-β, a TGF-β family ligand, is expressed by sensory neurons of the PNS and regulates the proliferation and adhesion of hemocytes. These hemocyte responses depend on PNS activity, as shown by agonist treatment and transient silencing of sensory neurons. Activin-β has a key role in this regulation, which is apparent from reporter expression and mutant analyses. This mechanism of local sensory neurons controlling blood cell adaptation invites evolutionary parallels with vertebrate hematopoietic progenitors and the independent myeloid system of tissue macrophages, whose regulation by local microenvironments remain undefined. AU - Makhijani, Kalpana AU - Alexander, Brandy AU - Rao, Deepti AU - Petraki, Sophia AU - Herboso, Leire AU - Kukar, Katelyn AU - Batool, Itrat AU - Wachner, Stephanie AU - Gold, Katrina AU - Wong, Corinna AU - O'Connor, Michael AU - Brückner, Katja ID - 835 JF - Nature Communications SN - 20411723 TI - Regulation of Drosophila hematopoietic sites by Activin-β from active sensory neurons VL - 8 ER - TY - CONF AB - Recent research has examined how to study the topological features of a continuous self-map by means of the persistence of the eigenspaces, for given eigenvalues, of the endomorphism induced in homology over a field. This raised the question of how to select dynamically significant eigenvalues. The present paper aims to answer this question, giving an algorithm that computes the persistence of eigenspaces for every eigenvalue simultaneously, also expressing said eigenspaces as direct sums of “finite” and “singular” subspaces. AU - Ethier, Marc AU - Jablonski, Grzegorz AU - Mrozek, Marian ID - 836 SN - 978-331956930-7 T2 - Special Sessions in Applications of Computer Algebra TI - Finding eigenvalues of self-maps with the Kronecker canonical form VL - 198 ER - TY - CONF AB - We study the quadratic assignment problem, in computer vision also known as graph matching. Two leading solvers for this problem optimize the Lagrange decomposition duals with sub-gradient and dual ascent (also known as message passing) updates. We explore this direction further and propose several additional Lagrangean relaxations of the graph matching problem along with corresponding algorithms, which are all based on a common dual ascent framework. Our extensive empirical evaluation gives several theoretical insights and suggests a new state-of-the-art anytime solver for the considered problem. Our improvement over state-of-the-art is particularly visible on a new dataset with large-scale sparse problem instances containing more than 500 graph nodes each. AU - Swoboda, Paul AU - Rother, Carsten AU - Abu Alhaija, Carsten AU - Kainmueller, Dagmar AU - Savchynskyy, Bogdan ID - 916 SN - 978-153860457-1 TI - A study of lagrangean decompositions and dual ascent solvers for graph matching VL - 2017 ER - TY - CONF AB - We propose a dual decomposition and linear program relaxation of the NP-hard minimum cost multicut problem. Unlike other polyhedral relaxations of the multicut polytope, it is amenable to efficient optimization by message passing. Like other polyhedral relaxations, it can be tightened efficiently by cutting planes. We define an algorithm that alternates between message passing and efficient separation of cycle- and odd-wheel inequalities. This algorithm is more efficient than state-of-the-art algorithms based on linear programming, including algorithms written in the framework of leading commercial software, as we show in experiments with large instances of the problem from applications in computer vision, biomedical image analysis and data mining. AU - Swoboda, Paul AU - Andres, Bjoern ID - 915 SN - 978-153860457-1 TI - A message passing algorithm for the minimum cost multicut problem VL - 2017 ER - TY - CONF AB - We propose a general dual ascent framework for Lagrangean decomposition of combinatorial problems. Although methods of this type have shown their efficiency for a number of problems, so far there was no general algorithm applicable to multiple problem types. In this work, we propose such a general algorithm. It depends on several parameters, which can be used to optimize its performance in each particular setting. We demonstrate efficacy of our method on graph matching and multicut problems, where it outperforms state-of-the-art solvers including those based on subgradient optimization and off-the-shelf linear programming solvers. AU - Swoboda, Paul AU - Kuske, Jan AU - Savchynskyy, Bogdan ID - 917 SN - 978-153860457-1 TI - A dual ascent framework for Lagrangean decomposition of combinatorial problems VL - 2017 ER -