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Full-Text Articles in Physics
The Shape And Mechanics Of Curved Fold Origami Structures, Marcelo A. Dias, Christian Santangelo
The Shape And Mechanics Of Curved Fold Origami Structures, Marcelo A. Dias, Christian Santangelo
Christian Santangelo
We develop recursion equations to describe the three-dimensional shape of a sheet upon which a series of concentric curved folds have been inscribed. In the case of no stretching outside the fold, the three-dimensional shape of a single fold prescribes the shape of the entire origami structure. To better explore these structures, we derive continuum equations, valid in the limit of vanishing spacing between folds, to describe the smooth surface intersecting all the mountain folds. We find that this surface has negative Gaussian curvature with magnitude equal to the square of the fold's torsion. A series of open folds with …
Evidence Of Non-Mean-Field-Like Low-Temperature Behavior In The Edwards-Anderson Spin-Glass Model, B. Yucesoy, Helmut G. Katzgraber, Jonathan Machta
Evidence Of Non-Mean-Field-Like Low-Temperature Behavior In The Edwards-Anderson Spin-Glass Model, B. Yucesoy, Helmut G. Katzgraber, Jonathan Machta
Jonathan Machta
The three-dimensional Edwards-Anderson and mean-field Sherrington-Kirkpatrick Ising spin glasses are studied via large-scale Monte Carlo simulations at low temperatures, deep within the spin-glass phase. Performing a careful statistical analysis of several thousand independent disorder realizations and using an observable that detects peaks in the overlap distribution, we show that the Sherrington-Kirkpatrick and Edwards-Anderson models have a distinctly different low-temperature behavior. The structure of the spin-glass overlap distribution for the Edwards-Anderson model suggests that its low-temperature phase has only a single pair of pure states.
Borexino Calibrations: Hardware, Methods, And Results, H. Back, G. Bellini, J. Benziger, D. Bick, G. Bonfini, D. Bravo, M. Buizza Avanzini, B. Caccianiga, L. Cadonati, F. Calaprice, C. Carraro, P. Cavalcante, A. Chavarria, D. D'Angelo, S. Davini, A. Derbin, A. Etenko, F. Von Feilitzsch, G. Fernandes, K. Fomenko, D. Franco, C. Galbiati, S. Gazzana, C. Ghiano, M. Giammarchi, M. Goeger-Neff, A. Goretti, L. Grandi, E. Guardincerri, S. Hardy, Aldo Ianni, Andrea Ianni, A. Kayunov, S. Kidner, V. Kobychev, D. Korablev, G. Korga, Y. Koshio, D. Kryn, M. Laubenstein, T. Lewke, E. Litvinovich, B. Loer, F. Lombardi, P. Lombardi, L. Ludhova, I. Machulin, S. Manecki, W. Maneschg, G. Manuzio, Q. Meindl, E. Meroni, L. Miramonti, M. Misiaszek, D. Montanari, P. Mosteiro, V. Muratova, L. Oberauer, M. Obolensky, F. Ortica, K. Otis, M. Pallavicini, L. Papp, L. Perasso, S. Perasso, Andrea Pocar, R. S. Raghavan, G. Ranucci, A. Razeto, A. Re, A. Romani, N. Rossi, D. Rountree, A. Sabelnikov, R. Saldanha, C. Salvo, S. Schönert, H. Simgen, M. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Sukhotin, Y. Suvorov, R. Tartaglia, G. Testera, D. Vignaud, R. B. Vogelaar, J. Winter, M. Wojcik, A. Wright, M. Wurm, J. Xu, O. Zaimidoroga, S. Zavatarelli, G. Zuzel
Borexino Calibrations: Hardware, Methods, And Results, H. Back, G. Bellini, J. Benziger, D. Bick, G. Bonfini, D. Bravo, M. Buizza Avanzini, B. Caccianiga, L. Cadonati, F. Calaprice, C. Carraro, P. Cavalcante, A. Chavarria, D. D'Angelo, S. Davini, A. Derbin, A. Etenko, F. Von Feilitzsch, G. Fernandes, K. Fomenko, D. Franco, C. Galbiati, S. Gazzana, C. Ghiano, M. Giammarchi, M. Goeger-Neff, A. Goretti, L. Grandi, E. Guardincerri, S. Hardy, Aldo Ianni, Andrea Ianni, A. Kayunov, S. Kidner, V. Kobychev, D. Korablev, G. Korga, Y. Koshio, D. Kryn, M. Laubenstein, T. Lewke, E. Litvinovich, B. Loer, F. Lombardi, P. Lombardi, L. Ludhova, I. Machulin, S. Manecki, W. Maneschg, G. Manuzio, Q. Meindl, E. Meroni, L. Miramonti, M. Misiaszek, D. Montanari, P. Mosteiro, V. Muratova, L. Oberauer, M. Obolensky, F. Ortica, K. Otis, M. Pallavicini, L. Papp, L. Perasso, S. Perasso, Andrea Pocar, R. S. Raghavan, G. Ranucci, A. Razeto, A. Re, A. Romani, N. Rossi, D. Rountree, A. Sabelnikov, R. Saldanha, C. Salvo, S. Schönert, H. Simgen, M. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Sukhotin, Y. Suvorov, R. Tartaglia, G. Testera, D. Vignaud, R. B. Vogelaar, J. Winter, M. Wojcik, A. Wright, M. Wurm, J. Xu, O. Zaimidoroga, S. Zavatarelli, G. Zuzel
Andrea Pocar
Borexino was the first experiment to detect solar neutrinos in real-time in the sub-MeV region. In order to achieve high precision in the determination of neutrino rates, the detector design includes an internal and an external calibration system. This paper describes both calibration systems and the calibration campaigns that were carried out in the period between 2008 and 2011. We discuss some of the results and show that the calibration procedures preserved the radiopurity of the scintillator. The calibrations provided a detailed understanding of the detector response and led to a significant reduction of the systematic uncertainties in the Borexino …
Angular Tension Of Black Holes, David Kastor, Jennie Traschen
Angular Tension Of Black Holes, David Kastor, Jennie Traschen
David Kastor
Angular tension is an Arnowitt-Deser-Misner charge that contributes a work term to the first law of black hole mechanics when the range of an angular coordinate is varied and leads to a new Smarr formula for stationary black holes. A phase diagram for singly spinning D=5 black holes shows that angular tension resolves the degeneracies between spherical black holes and (dipole) black rings and captures the physics of the black ring balance condition. Angular tension depends on the behavior of the metric at rotational axes and we speculate on its relation to rod/domain structure characterizations of higher-dimensional black holes and …
Slack Dynamics On An Unfurling String, J. A. Hanna, Christian Santangelo
Slack Dynamics On An Unfurling String, J. A. Hanna, Christian Santangelo
Christian Santangelo
An arch will grow on a rapidly deployed thin string in contact with a rigid plane. We present a qualitative model for the growing structure involving the amplification, rectification, and advection of slack in the presence of a steady stress field, validate our assumptions with numerical experiments, and pose new questions about the spatially developing motions of thin objects.
Smectic Pores And Defect Cores, Elisabetta A. Masumoto, Randall D. Kamien, Christian Santangelo
Smectic Pores And Defect Cores, Elisabetta A. Masumoto, Randall D. Kamien, Christian Santangelo
Christian Santangelo
Riemann's minimal surfaces, a one-parameter family of minimal surfaces, describe a bicontinuous lamellar system with pores connecting alternating layers. We demonstrate explicitly that Riemann's minimal surfaces are composed of a nonlinear sum of two oppositely handed helicoids.
Mass Flux Characteristics In Solid 4he For T > 100 Mk: Evidence For Bosonic Luttinger Liquid Behavior, Ye. Vekhov, Robert B. Hallock
Mass Flux Characteristics In Solid 4he For T > 100 Mk: Evidence For Bosonic Luttinger Liquid Behavior, Ye. Vekhov, Robert B. Hallock
Robert Hallock
At a pressure of ~25.7 bar, the flux F carried by solid 4_He for T > 100 mK depends on the net chemical potential difference between two reservoirs in series with the solid, ∆ u, and obeys F ~ (∆µ) b, where b ≈ 0.3 is independent of temperature. At fixed ∆µ the temperature dependence of the flux F can be adequately represented by F ~ - In(T/t), t ≈ 0.6 K, for 0.1 ≤ T ≤ 0.5 K. A single function F = F_0 (∆µ)b In(T/t) fits all of the available data sets in the range 25.6-25.8 bar reasonably well. …
Cosmic-Muon Flux And Annual Modulation In Borexino At 3800 M Water-Equivalent Depth, G. Bellini, J. Benziger, D. Bick, G. Bonfini, D. Bravo, M. Buizza Avanzini, B. Caccianiga, L. Cadonati, F. Calaprice, C. Carraro, P. Cavalcante, A. Chavarria, A. Chepurnov, D. D'Angelo, S. Davini, A. Derbin, A. Etenko, F. Von Feilitzsch, K. Fomenko, D. Franco, C. Galbiati, S. Gazzana, C. Ghiano, M. Giammarchi, M. Goeger-Neff, A. Goretti, L. Grandi, E. Guardincerri, C. Hagner, S. Hardy, Aldo Ianni, Andrea Ianni, D. Korablev, G. Korga, Y. Koshio, D. Kryn, M. Laubenstein, T. Lewke, E. Litvinovich, B. Loer, F. Lombardi, P. Lombardi, L. Ludhova, I. Machulin, S. Manecki, W. Maneschg, G. Manuzio, Q. Meindl, E. Meroni, L. Miramonti, M. Misiazek, D. Montanari, P. Mosteiro, V. Muratova, L. Oberauer, M. Obolensky, F. Ortica, K. Otis, M. Pallavicini, L. Papp, L. Perasso, S. Perasso, Andrea Pocar, R. S. Raghavan, G. Ranucci, A. Razeto, A. Re, A. Romani, A. Sabelnikov, R. Saldanha, C. Salvo, S. Schönert, H. Simgen, M. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Sukhotin, Y. Suvorov, R. Tartaglia, G. Testera, D. Vignaud, R. B. Vogelaar, J. Winter, M. Wojcik, A. Wright, M. Wurm, J. Xu, O. Zaimidoroga, S. Zavatarelli, G. Zuzel
Cosmic-Muon Flux And Annual Modulation In Borexino At 3800 M Water-Equivalent Depth, G. Bellini, J. Benziger, D. Bick, G. Bonfini, D. Bravo, M. Buizza Avanzini, B. Caccianiga, L. Cadonati, F. Calaprice, C. Carraro, P. Cavalcante, A. Chavarria, A. Chepurnov, D. D'Angelo, S. Davini, A. Derbin, A. Etenko, F. Von Feilitzsch, K. Fomenko, D. Franco, C. Galbiati, S. Gazzana, C. Ghiano, M. Giammarchi, M. Goeger-Neff, A. Goretti, L. Grandi, E. Guardincerri, C. Hagner, S. Hardy, Aldo Ianni, Andrea Ianni, D. Korablev, G. Korga, Y. Koshio, D. Kryn, M. Laubenstein, T. Lewke, E. Litvinovich, B. Loer, F. Lombardi, P. Lombardi, L. Ludhova, I. Machulin, S. Manecki, W. Maneschg, G. Manuzio, Q. Meindl, E. Meroni, L. Miramonti, M. Misiazek, D. Montanari, P. Mosteiro, V. Muratova, L. Oberauer, M. Obolensky, F. Ortica, K. Otis, M. Pallavicini, L. Papp, L. Perasso, S. Perasso, Andrea Pocar, R. S. Raghavan, G. Ranucci, A. Razeto, A. Re, A. Romani, A. Sabelnikov, R. Saldanha, C. Salvo, S. Schönert, H. Simgen, M. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Sukhotin, Y. Suvorov, R. Tartaglia, G. Testera, D. Vignaud, R. B. Vogelaar, J. Winter, M. Wojcik, A. Wright, M. Wurm, J. Xu, O. Zaimidoroga, S. Zavatarelli, G. Zuzel
Andrea Pocar
We have measured the muon flux at the underground Gran Sasso National Laboratory (3800 m w.e.) to be (3.41±0.01)⋅10−4m−2s−1 using four years of Borexino data. A modulation of this signal is observed with a period of (366±3) days and a relative amplitude of (1.29±0.07)%. The measured phase is (179±6) days, corresponding to a maximum on the 28th of June. Using the most complete atmospheric data models available, muon rate fluctuations are shown to be positively correlated with atmospheric temperature, with an effective coefficient αT = 0.93±0.04. This result represents the most precise study of the muon flux modulation for this …
Microtubule-Severing Enzymes At The Cutting Edge, Jennifer Ross, David J. Sharp
Microtubule-Severing Enzymes At The Cutting Edge, Jennifer Ross, David J. Sharp
Jennifer Ross
ATP-dependent severing of microtubules was first reported in Xenopus laevis egg extracts in 1991. Two years later this observation led to the purification of the first known microtubule-severing enzyme, katanin. Katanin homologs have now been identified throughout the animal kingdom and in plants. Moreover, members of two closely related enzyme subfamilies, spastin and fidgetin, have been found to sever microtubules and might act alongside katanins in some contexts (Roll-Mecak and McNally, 2010; Yu et al., 2008; Zhang et al., 2007). Over the past few years, it has become clear that microtubule-severing enzymes contribute to a wide range of cellular activities …
Dynamic Reorganization Of Eg5 In The Mammalian Spindle Throughout Mitosis Requires Dynein And Tpx2, Alyssa Gable, Minhua Qui, Janel Titus, Sai Balchand, Nick P. Ferenz, Nan Ma, Elizabeth S. Collins, Carey Fagersrom, Jennifer Ross, Ge Yang, Patricia Wadsworth
Dynamic Reorganization Of Eg5 In The Mammalian Spindle Throughout Mitosis Requires Dynein And Tpx2, Alyssa Gable, Minhua Qui, Janel Titus, Sai Balchand, Nick P. Ferenz, Nan Ma, Elizabeth S. Collins, Carey Fagersrom, Jennifer Ross, Ge Yang, Patricia Wadsworth
Jennifer Ross
Kinesin-5 is an essential mitotic motor. However, how its spatial–temporal distribution is regulated in mitosis remains poorly understood. We expressed localization and affinity purification–tagged Eg5 from a mouse bacterial artificial chromosome (this construct was called mEg5) and found its distribution to be tightly regulated throughout mitosis. Fluorescence recovery after photobleaching analysis showed rapid Eg5 turnover throughout mitosis, which cannot be accounted for by microtubule turnover. Total internal reflection fluorescence microscopy and high-resolution, single-particle tracking revealed that mEg5 punctae on both astral and midzone microtubules rapidly bind and unbind. mEg5 punctae on midzone microtubules moved transiently both toward and away from …
The Impacts Of Molecular Motor Traffic Jams, Jennifer Ross
The Impacts Of Molecular Motor Traffic Jams, Jennifer Ross
Jennifer Ross
Much of a modern person's day is spent trying to get from point A to point B. So, too, in the cell, much time and energy is expended on shuttling organelles, protein complexes, and mRNA, called “cargos,” from point A to point B. We know that vehicle traffic slows down when roads get jammed with high-volume congestion. The traffic analogy begs the question: Do cellular highways get jammed? This is the question being probed by Leduc et al. in PNAS (1). Efficient cellular transport is made along “cellular highways” in the form of a cytoskeletal network of proteinacous filaments called …
Computational Study Of A Multistep Height Model, Matthew Drake, Jonathan Machta, Youjin Deng, Douglas Abraham, Charles Newman
Computational Study Of A Multistep Height Model, Matthew Drake, Jonathan Machta, Youjin Deng, Douglas Abraham, Charles Newman
Jonathan Machta
An equilibrium random surface multistep height model proposed in [Abraham and Newman, EPL, 86, 16002 (2009)] is studied using a variant of the worm algorithm. In one limit, the model reduces to the two-dimensional Ising model in the height representation. When the Ising model constraint of single height steps is relaxed, the critical temperature and critical exponents are continuously varying functions of the parameter controlling height steps larger than one. Numerical estimates of the critical exponents can be mapped via a single parameter-- the Coulomb gas coupling-- to the exponents of the O(n) loop model on the honeycomb lattice with …
The Riemann-Lovelock Curvature Tensor, David Kastor
The Riemann-Lovelock Curvature Tensor, David Kastor
David Kastor
In order to study the properties of Lovelock gravity theories in low dimensions, we define the kth-order Riemann-Lovelock tensor as a certain quantity having a total 4k-indices, which is kth-order in the Riemann curvature tensor and shares its basic algebraic and differential properties. We show that the kth-order Riemann-Lovelock tensor is determined by its traces in dimensions 2k \le D <4k. In D=2k+1 this identity implies that all solutions of pure kth-order Lovelock gravity are `Riemann-Lovelock' flat. It is verified that the static, spherically symmetric solutions of these theories, which are missing solid angle space times, indeed satisfy this flatness property. This generalizes results from Einstein gravity in D=3, which corresponds to the k=1 case. We speculate about some possible further consequences of Riemann-Lovelock curvature.
The Ninja-2 Catalog Of Hybrid Post-Newtonian/Numerical-Relativity Waveforms For Non-Precessing Black-Hole Binaries, P. Ajith, Michael Boyle, Duncan A. Brown, Bernd Brügmann, Luisa T. Buchman, Laura Cadonati, Manuela Campanelli, Tony Chu, Zachariah B. Etienne, Stephen Fairhurst, Et. Al.
The Ninja-2 Catalog Of Hybrid Post-Newtonian/Numerical-Relativity Waveforms For Non-Precessing Black-Hole Binaries, P. Ajith, Michael Boyle, Duncan A. Brown, Bernd Brügmann, Luisa T. Buchman, Laura Cadonati, Manuela Campanelli, Tony Chu, Zachariah B. Etienne, Stephen Fairhurst, Et. Al.
Laura Cadonati
The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational wave data analysis communities. The purpose of NINJA is to study the sensitivity of existing gravitational-wave search and parameter-estimation algorithms using numerically generated waveforms, and to foster closer collaboration between the numerical relativity and data analysis communities. The first NINJA project used only a small number of injections of short numerical-relativity waveforms, which limited its ability to draw quantitative conclusions. The goal of the NINJA- 2 project is to overcome these limitations with long post-Newtonian--numerical relativity hybrid waveforms, large numbers of injections, …
Skyrmionic State And Stable Half-Quantum Vortices In Chiral P-Wave Superconductors, Julien Garaud, Egor Babaev
Skyrmionic State And Stable Half-Quantum Vortices In Chiral P-Wave Superconductors, Julien Garaud, Egor Babaev
Egor Babaev
Observability of half-quantum vortices and skyrmions in p-wave superconductors is an outstanding open question. Under the most common conditions, fractional flux vortices are not thermodynamically stable in bulk samples. Here we show that in chiral p-wave superconductors, there is a regime where, in contrast lattices of integer flux vortices are not thermodynamically stable. Instead skyrmions made of spatially separated half-quantum vortices are the topological defects produced by an applied external field.
Absence Of Day-Night Asymmetry Of 862 Kev Be-7 Solar Neutrino Rate In Borexino And Msw Oscillation Parameters
Laura Cadonati
We report on a search for the day-night asymmetry of the Be-7 solar neutrino rate measured by Borexino at the Laboratori Nazionali del Gran Sasso (LNGS), Italy. The measured value, Adn=0.001 +- 0.012 (stat) +- 0.007 (syst), shows the absence of a significant asymmetry. This result alone rejects the so-called LOW solution at more than 8.5 sigma. Combined with the other solar neutrino data, it isolates the Large Mixing Angle (LMA) -- MSW solution at DeltaChi2 > 190 without relying on the assumption of CPT symmetry in the neutrino sector. We also show that including the day-night asymmetry, data from Borexino …
Packing Squares In A Torus, D. W. Blair, C. Santangelo, Jonathan Machta
Packing Squares In A Torus, D. W. Blair, C. Santangelo, Jonathan Machta
Jonathan Machta
The densest packings of N unit squares in a torus are studied using analytical methods as well as simulated annealing. A rich array of dense packing solutions are found: density-one packings when N is the sum of two square integers; a family of 'gapped bricklayer' Bravais lattice solutions with density N/(N + 1); and some surprising non-Bravais lattice configurations, including lattices of holes as well as a configuration for N = 23 in which not all squares share the same orientation. The entropy of some of these configurations and the frequency and orientation of density-one solutions as N -> Infinity …
Developed Smectics: When Exact Solutions Agree, Gareth P. Alexander, Randall D. Kamien, Christian Santangelo
Developed Smectics: When Exact Solutions Agree, Gareth P. Alexander, Randall D. Kamien, Christian Santangelo
Christian Santangelo
In the limit where the bending modulus vanishes, we construct layer configurations with arbitrary dislocation textures by exploiting a connection between uniformly spaced layers in two dimensions and developable surfaces in three dimensions. We then show how these focal textures can be used to construct layer configurations with finite bending modulus.
Vortex Coalescence And Type-1.5 Superconductivity In Sr2ruo4, Egor Babaev
Vortex Coalescence And Type-1.5 Superconductivity In Sr2ruo4, Egor Babaev
Egor Babaev
Recently vortex coalescence was reported in superconducting Sr2RuO4 by several experimental groups for fields applied along the c axis. We argue that Sr2RuO4 is a type-1.5 superconductor with long-range attractive, short-range repulsive intervortex interaction. The type-1.5 behavior stems from an interplay of the two orbital degrees of freedom describing this chiral superconductor together with the multiband nature of the superconductivity. These multiple degrees of freedom give rise to multiple coherence lengths, some larger and some smaller than the magnetic field penetration length, resulting in nonmonotonic intervortex forces.
Geometric Mechanics Of Curved Crease Origami, Marcelo A. Dias, Levi H. Dudte, L. Mahadevan, Christian Santangelo
Geometric Mechanics Of Curved Crease Origami, Marcelo A. Dias, Levi H. Dudte, L. Mahadevan, Christian Santangelo
Christian Santangelo
Folding a sheet of paper along a curve can lead to structures seen in decorative art and utilitarian packing boxes. Here we present a theory for the simplest such structure: an annular circular strip that is folded along a central circular curve to form a three-dimensional buckled structure driven by geometrical frustration. We quantify this shape in terms of the radius of the circle, the dihedral angle of the fold, and the mechanical properties of the sheet of paper and the fold itself. When the sheet is isometrically deformed everywhere except along the fold itself, stiff folds result in creases …
Packing Squares In A Torus, D. W. Blair, Christian Santangelo, J. Machta
Packing Squares In A Torus, D. W. Blair, Christian Santangelo, J. Machta
Christian Santangelo
The densest packings of N unit squares in a torus are studied using analytical methods as well as simulated annealing. A rich array of dense packing solutions are found: density-one packings when N is the sum of two square integers; a family of 'gapped bricklayer' Bravais lattice solutions with density N/(N + 1); and some surprising non-Bravais lattice configurations, including lattices of holes as well as a configuration for N = 23 in which not all squares share the same orientation. The entropy of some of these configurations and the frequency and orientation of density-one solutions as N -> infinity …
Frustrated Order On Extrinsic Geometries, Badel L. Mbanga, Gregory M. Grason, Christian Santangelo
Frustrated Order On Extrinsic Geometries, Badel L. Mbanga, Gregory M. Grason, Christian Santangelo
Christian Santangelo
We study, numerically and theoretically, defects in an anisotropic liquid that couple to the extrinsic geometry of a surface. Though the intrinsic geometry tends to confine topological defects to regions of large Gaussian curvature, extrinsic couplings tend to orient the order along the local direction of maximum or minimum bending. This additional frustration is generically unavoidable, and leads to complex ground-state thermodynamics. Using the catenoid as a prototype, we show, in contradistinction to the well-known effects of intrinsic geometry, that extrinsic curvature expels disclinations from the region of maximum curvature above a critical coupling threshold. On catenoids lacking an “inside-outside” …