Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network

Open Access. Powered by Scholars. Published by Universities.®

Physics

PDF

University of Massachusetts Amherst

Keyword
Publication Year
Publication

Articles 31 - 60 of 234

Full-Text Articles in Entire DC Network

Sum Rule For The Adm Mass And Tensions In Planar Ads Spacetimes, Basem M. El-Menoufi, Benjamin Ett, David Kastor, Jennie Traschen Sep 2013

Sum Rule For The Adm Mass And Tensions In Planar Ads Spacetimes, Basem M. El-Menoufi, Benjamin Ett, David Kastor, Jennie Traschen

David Kastor

An asymptotically planar AdS spacetimes is characterized by its ADM mass and tensions. We define an additional ADM charge Q associated with the scaling Killing vector of AdS, show that Q is given by a certain sum over the ADM mass and tensions and that Q vanishes on solutions to the Einstein equation with negative cosmological constant. The sum rule for the mass and tensions thus established corresponds in an AdS/CFT context to the vanishing of the trace of the boundary stress tensor. We also show that an analogous sum rule holds for local planar sources of stress-energy sources in …


Conformal Tensors Via Lovelock Gravity, David Kastor Sep 2013

Conformal Tensors Via Lovelock Gravity, David Kastor

David Kastor

Constructs from conformal geometry are important in low dimensional gravity models, while in higher dimensions the higher curvature interactions of Lovelock gravity are similarly prominent. Considering conformal invariance in the context of Lovelock gravity leads to natural, higher-curvature generalizations of the Weyl, Schouten, Cotton and Bach tensors, with properties that straightforwardly extend those of their familiar counterparts. As a first application, we introduce a new set of conformally invariant gravity theories in D=4k dimensions, based on the squares of the higher curvature Weyl tensors.


Self-Assembly On A Cylinder: A Model System For Understanding The Constrain Of Commensurability, D. A. Wood, Christian Santangelo, A. D. Dinsmore Aug 2013

Self-Assembly On A Cylinder: A Model System For Understanding The Constrain Of Commensurability, D. A. Wood, Christian Santangelo, A. D. Dinsmore

Christian Santangelo

A crystal lattice, when confined to the surface of a cylinder, must have a periodic structure that is commensurate with the cylinder circumference. This constraint can frustrate the system, leading to oblique crystal lattices or to structures with a chiral seam known as a ‘line slip’ phase, neither of which is stable for isotropic particles in equilibrium on flat surfaces. In this study, we use molecular dynamics simulations to find the steady-state structure of spherical particles with short-range repulsion and long-range attraction far below the melting temperature. We vary the range of attraction using the Lennard-Jones and Morse potentials and …


On The Universality Of Inner Black Hole Mechanics And Higher Curvature Gravity, Alejandra Castro, Nima Dehmami, Gaston Giribet, David Kastor Jul 2013

On The Universality Of Inner Black Hole Mechanics And Higher Curvature Gravity, Alejandra Castro, Nima Dehmami, Gaston Giribet, David Kastor

David Kastor

Black holes are famous for their universal behavior. New thermodynamic relations have been found recently for the product of gravitational entropies over all the horizons of a given stationary black hole. This product has been found to be independent of the mass for all such solutions of Einstein-Maxwell theory in d=4,5. We study the universality of this mass independence by introducing a number of possible higher curvature corrections to the gravitational action. We consider finite temperature black holes with both asymptotically flat and (A)dS boundary conditions. Although we find examples for which mass independence of the horizon entropy product continues …


Gravitational Tension And Thermodynamics Of Planar Ads Spacetimes, Basem M. El-Menoufi, Benjamin Ett, David Kastor, Jennie Traschen Jun 2013

Gravitational Tension And Thermodynamics Of Planar Ads Spacetimes, Basem M. El-Menoufi, Benjamin Ett, David Kastor, Jennie Traschen

David Kastor

We derive new thermodynamic relations for asymptotically planar AdS black hole and soliton solutions. In addition to the ADM mass, these spacetimes are characterized by gravitational tensions in each of the planar spatial directions. We show that with planar AdS asymptotics, the sum of the ADM mass and tensions necessarily vanishes, as one would expect from the AdS /CFT correspondence. Each Killing vector of such a spacetime leads to a Smarr formula relating the ADM mass and tensions, the black hole horizon and soliton bubble areas, and a set of thermodynamic volumes that arise due to the non-vanishing cosmological constant. …


Thermodynamic Volumes And Isoperimetric Inequalities For De Sitter Black Holes, Brian P. Dolan, David Kastor, David KubiznˇA´K, Robert B. Mann, Jennie Traschen May 2013

Thermodynamic Volumes And Isoperimetric Inequalities For De Sitter Black Holes, Brian P. Dolan, David Kastor, David KubiznˇA´K, Robert B. Mann, Jennie Traschen

David Kastor

We consider the thermodynamics of rotating and charged asymptotically de Sitter black holes. Using Hamiltonian perturbation theory techniques, we derive three different first law relations including variations in the cosmological constant, and associated Smarr formulas that are satisfied by such spacetimes. Each first law introduces a different thermodynamic volume conjugate to the cosmological constant. We examine the relation between these thermodynamic volumes and associated geometric volumes in a number of examples, including Kerr-dS black holes in all dimensions and Kerr-Newman-dS black holes in D=4. We also show that the Chong-Cvetic-Lu-Pope solution of D=5 minimal supergravity, analytically continued to positive cosmological …


On Random Time And On The Relation Between Wave And Telegraph Equations, Ramakrishna Janaswamy May 2013

On Random Time And On The Relation Between Wave And Telegraph Equations, Ramakrishna Janaswamy

Ramakrishna Janaswamy

Kac’s conjecture relating the solution of wave and telegraph equations in higher dimensions through a Poisson process-driven random time is established through the concepts of stochastic calculus. New expression is derived for the probability density function of the random time. We demonstrate how the relationship between the solution of a lossy wave- and that of a lossless wave equation can be exploited to derive some statistical identities. Relevance of the results presented to the study of pulse propagation in a dispersive medium characterized by a Lorentz or Drude model is discussed and new evolution equations for 2D Maxwell’s equations are …


Nambu-Goldstone Modes And Diffuse Deformations In Elastic Shells, Christian Santangelo Apr 2013

Nambu-Goldstone Modes And Diffuse Deformations In Elastic Shells, Christian Santangelo

Christian Santangelo

I consider the shape of a deformed elastic shell. Using the fact that the lowest-energy, small deformations are along infinitesimal isometries of the shell's mid-surface, I describe a class of weakly stretching deformations for thin shells based on the Nambu–Goldstone modes associated with those isometries. The main result is an effective theory to describe the diffuse deformations of thin shells that incorporate stretching and bending energies. The theory recovers previous results for the propagation of a “pinch” on a cylinder. A cone, on the other hand, has two length scales governing the persistence of a pinch: one governing the relaxation …


Chiral Cp^2 Skyrmions In Three-Band Superconductors, Garaud Julien, Johan CarlstrOm, Egor Babaev, Martin Speight Jan 2013

Chiral Cp^2 Skyrmions In Three-Band Superconductors, Garaud Julien, Johan CarlstrOm, Egor Babaev, Martin Speight

Egor Babaev

No abstract provided.


Stripe, Gossamer, And Glassy Phases In Systems With Strong Non-Pairwise Interactions, Karl A. H. Sellin, Egor Babaev Jan 2013

Stripe, Gossamer, And Glassy Phases In Systems With Strong Non-Pairwise Interactions, Karl A. H. Sellin, Egor Babaev

Egor Babaev

We study structure formation in systems of classical particles in two dimensions with long-range attractive short-range repulsive two-body interactions and repulsive three-body interactions. Stripe, gossamer, and glass phases are found as a result of nonpairwise interaction.


Hierarchical Structure Formation In Layered Superconducting Systems With Multi-Scale Inter-Vortex Interactions, Christopher N. Varney, Karl A. H. Sellin, Qing-Ze Wang, Hans Fangohr, Egor Babaev Jan 2013

Hierarchical Structure Formation In Layered Superconducting Systems With Multi-Scale Inter-Vortex Interactions, Christopher N. Varney, Karl A. H. Sellin, Qing-Ze Wang, Hans Fangohr, Egor Babaev

Egor Babaev

We demonstrate the formation of hierarchical structures in two-dimensional systems with multiple length scales in the inter-particle interaction. These include states such as clusters of clusters, concentric rings, clusters inside a ring, and stripes in a cluster. We propose to realize such systems in vortex matter (where a vortex is mapped onto a particle with multi-scale interactions) in layered superconducting systems with varying inter-layer thicknesses and different layer materials.


Freezing Of An Unconventional Two-Dimensional Plasma, Egil V. Herland, Egor Babaev, Parsa Bonderson, Victor Gurarie, Chetan Nayak, Leo Radzihovsky, Asle Sudbo Jan 2013

Freezing Of An Unconventional Two-Dimensional Plasma, Egil V. Herland, Egor Babaev, Parsa Bonderson, Victor Gurarie, Chetan Nayak, Leo Radzihovsky, Asle Sudbo

Egor Babaev

No abstract provided.


Correlations Between The Dynamics Of Parallel Tempering And The Free Energy Landscape In Spin Glasses, Burcu Yucesoy, Jonathan Machta, Helmut G. Katzgraber Jan 2013

Correlations Between The Dynamics Of Parallel Tempering And The Free Energy Landscape In Spin Glasses, Burcu Yucesoy, Jonathan Machta, Helmut G. Katzgraber

Jonathan Machta

We present the results of a large-scale numerical study of the equilibrium three-dimensional Edwards-Anderson Ising spin glass with Gaussian disorder. Using parallel tempering (replica exchange) Monte Carlo we measure various static, as well as dynamical quantities, such as the autocorrelation times and round-trip times for the parallel tempering Monte Carlo method. The correlation between static and dynamic observables for 5000 disorder realizations and up to 1000 spins down to temperatures at 20% of the critical temperature is examined. Our results show that autocorrelation times are directly correlated with the roughness of the free-energy landscape.


Classification Of Ground States And Normal Modes For Phase-Frustrated, Daniel Weston, Egor Babaev Jan 2013

Classification Of Ground States And Normal Modes For Phase-Frustrated, Daniel Weston, Egor Babaev

Egor Babaev

No abstract provided.


Phase Structure And Phase Transitions In A Three Dimensional Su(2) Superconductor, Egil V. Herland, Troels A. Bojesen, Egor Babaev, Asle Sudb Jan 2013

Phase Structure And Phase Transitions In A Three Dimensional Su(2) Superconductor, Egil V. Herland, Troels A. Bojesen, Egor Babaev, Asle Sudb

Egor Babaev

No abstract provided.


Nature Vs. Nurture: Predictability In Low-Temperature Ising Dynamics, J. Ye, Jonathan Machta, C. M. Newman, D. L. Stein Jan 2013

Nature Vs. Nurture: Predictability In Low-Temperature Ising Dynamics, J. Ye, Jonathan Machta, C. M. Newman, D. L. Stein

Jonathan Machta

Consider a dynamical many-body system with a random initial state subsequently evolving through stochastic dynamics. What is the relative importance of the initial state (“nature”) versus the realization of the stochastic dynamics (“nurture”) in predicting the final state? We examined this question for the two-dimensional Ising ferromagnet following an initial deep quench from T=∞ to T=0. We performed Monte Carlo studies on the overlap between “identical twins” raised in independent dynamical environments, up to size L=500. Our results suggest an overlap decaying with time as t−θh with θh=0.22±0.02; the same exponent holds for a quench to low but nonzero temperature. …


Time Reversal Symmetry Breakdown In Normal And Superconducting States In Frustrated Three-Band Systems, Troels Arnfred Bojesen, Egor Babaev, Asle Sudbo Jan 2013

Time Reversal Symmetry Breakdown In Normal And Superconducting States In Frustrated Three-Band Systems, Troels Arnfred Bojesen, Egor Babaev, Asle Sudbo

Egor Babaev

We discuss the phase diagram and phase transitions in U(1)×Z2 three-band superconductors with broken time reversal symmetry. We find that beyond mean-field approximation and for sufficiently strong frustration of interband interactions there appears an unusual metallic state precursory to a superconducting phase transition. In that state, the system is not superconducting. Nonetheless, it features a spontaneously broken Z2 time reversal symmetry. By contrast, for weak frustration of interband coupling the energy of a domain wall between different Z2 states is low and thus fluctuations restore broken time reversal symmetry in the superconducting state at low temperatures.


Unusual Mechanism Of Vortex Viscosity Generated By Mixed Normal Modes In Superconductors With Broken Time Reversal Symmetry, Mihail Silaev, Egor Babaev Jan 2013

Unusual Mechanism Of Vortex Viscosity Generated By Mixed Normal Modes In Superconductors With Broken Time Reversal Symmetry, Mihail Silaev, Egor Babaev

Egor Babaev

We show that under certain conditions, multiband superconductors with broken time reversal symmetry have a vortex viscosity-generating mechanism which is different from that in conventional superconductors. It appears due to the existence of a mixed superfluid phase-density mode inside the vortex core. This contribution is dominant near the time reversal symmetry-breaking phase transition. The results could be relevant for the three-band superconductor Ba1−xKxFe2As2.


The Shape And Mechanics Of Curved Fold Origami Structures, Marcelo A. Dias, Christian Santangelo Dec 2012

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 Oct 2012

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 Oct 2012

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 Oct 2012

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 Sep 2012

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 Aug 2012

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 Jul 2012

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 May 2012

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 May 2012

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 Apr 2012

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 Apr 2012

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 Mar 2012

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 …