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Constraints On The Variability Of Quark Masses From Nuclear Binding, Thibault Damour, John Donoghue
Constraints On The Variability Of Quark Masses From Nuclear Binding, Thibault Damour, John Donoghue
John Donoghue
Based on recent work on nuclear binding, we update and extend the anthropic constraints on the light quark masses, with results that are more tightly constrained than previously obtained. We find that heavy nuclei would fall apart (because the attractive nuclear central potential becomes too weak) if the sum of the light quark masses m_u+m_d would exceed their physical values by 64% (at 95% confidence level). We summarize the anthropic constraints that follow from requiring the existence both of heavy atoms and of hydrogen. With the additional assumption that the quark Yukawa couplings do not vary, these constraints provide a …
Complementary Dimerization Of Microtubule-Associated Protein Tau: Implications For Microtubule Bundling And Tau-Mediated Pathogensis, Jennifer Ross, Kenneth J. Rosenberg, H. Eric Feinstein, Stuart C. Feinstein, Jacob Israelachvili
Complementary Dimerization Of Microtubule-Associated Protein Tau: Implications For Microtubule Bundling And Tau-Mediated Pathogensis, Jennifer Ross, Kenneth J. Rosenberg, H. Eric Feinstein, Stuart C. Feinstein, Jacob Israelachvili
Jennifer Ross
Tau is an intrinsically unstructured microtubule (MT)-associated protein capable of binding to and organizing MTs into evenly spaced parallel assemblies known as “MT bundles.” How tau achieves MT bundling is enigmatic because each tau molecule possesses only one MT-binding region. To dissect this complex behavior, we have used a surface forces apparatus to measure the interaction forces of the six CNS tau isoforms when bound to mica substrates in vitro. Two types of measurements were performed for each isoform: symmetric configuration experiments measured the interactions between two tau-coated mica surfaces, whereas “asymmetric” experiments examined tau-coated surfaces interacting with a smooth …
A Scintillator Purification System For The Borexino Solar Neutrino Detector, Andrea Pocar
A Scintillator Purification System For The Borexino Solar Neutrino Detector, Andrea Pocar
Andrea Pocar
Purification of the 278 tons of liquid scintillator and 889 tons of buffer shielding for the Borexino solar neutrino detector was performed with a system that combined distillation, water extraction, gas stripping and filtration. The purification of the scintillator achieved unprecedented low backgrounds for the large scale liquid scintillation detector. This paper describes the principles of operation, design, construction and commissioning of the purification system, and reviews the requirements and methods to achieve system cleanliness and leak-tightness.
Superfluids, Superconductors And Supersolids: Macroscopic Manifestations Of The Microworld Laws, Egor Babaev
Superfluids, Superconductors And Supersolids: Macroscopic Manifestations Of The Microworld Laws, Egor Babaev
Egor Babaev
A superconductor is a state of matter in which electrons flow without. Resistance. A superfluid is a fluid devoid of viscosity. Superfluidity was first. Discovered in experiments on helium conducted by Petr Kapitsa in 1937.. The lack of viscosity is a phenomenon which is highly counterintuitive. From the point of view of the classical physics on which our intuition is. Based. This phenomenon has a quantum nature, i.e. it is related to the. Physics of the microworld, where particles are divided into two classes:. Bosons and fermions. One of the fundaAssistant Professor Egor Babaev. Number of particles ‘conspire’ to behave.
Multibody Interactions In Coarse-Graining Schemes For Extended Systems, S Are, Ma Katsoulakis, P Plechac, L Rey-Bellet
Multibody Interactions In Coarse-Graining Schemes For Extended Systems, S Are, Ma Katsoulakis, P Plechac, L Rey-Bellet
Luc Rey-Bellet
In this paper we address the role of multibody interactions for the coarse-grained approximation of stochastic lattice systems. Such interaction potentials are often not included in coarse-graining schemes, as they can be computationally expensive. The multibody interactions are obtained from the error expansion of the reference measure which is, in many cases, chosen as a Gibbs measure corresponding to a local mean-field approximation. We identify the parameter $\epsilon$ that characterizes the level of approximation and its relation to the underlying interaction potential. The error analysis suggests strategies to overcome the computational costs due to evaluations of multibody interactions by additional …
The Percolation Signature Of The Spin Glass Transition, Jonathan Machta, C. M. Newman, D. L. Stein
The Percolation Signature Of The Spin Glass Transition, Jonathan Machta, C. M. Newman, D. L. Stein
Jonathan Machta
Magnetic ordering at low temperature for Ising ferromagnets manifests itself within the associated Fortuin–Kasteleyn (FK) random cluster representation as the occurrence of a single positive density percolating network. In this paper we investigate the percolation signature for Ising spin glass ordering—both in short-range (EA) and infinite-range (SK) models—within a two-replica FK representation and also within the different Chayes–Machta–Redner two-replica graphical representation. Based on numerical studies of the ±J EA model in three dimensions and on rigorous results for the SK model, we conclude that the spin glass transition corresponds to the appearance of two percolating clusters of unequal densities.
High-Resolution Saturation Spectroscopy Of Singly-Ionized Iron With A Pulsed Uv Laser, M. Ascoli, E. E. Eyler, David Kawall, David Demille
High-Resolution Saturation Spectroscopy Of Singly-Ionized Iron With A Pulsed Uv Laser, M. Ascoli, E. E. Eyler, David Kawall, David Demille
David Kawall
We describe the design and realization of a scheme for UV laser spectroscopy of singly-ionized iron (Fe II) with very high resolution. A buffer-gas cooled laser ablation source is used to provide a room-temperature plasma with a high density of Fe II. We combine this with a scheme for pulsed-laser saturation spectroscopy to yield sub-Doppler resolution. In a demonstration experiment, we have examined an Fe II transition near 260 nm, attaining a linewidth of about 250 MHz. The method is well suited to measure transition frequencies and hyperfine structure. It could also be used to measure small isotope shifts in …
Percolation In The Sherrington-Kirkpatrick Spin Glass, Jonathan Machta, C. M. Newman, D. L. Stein
Percolation In The Sherrington-Kirkpatrick Spin Glass, Jonathan Machta, C. M. Newman, D. L. Stein
Jonathan Machta
We present extended versions and give detailed proofs of results about percolation (using various sets of two-replica bond occupation variables) in Sherrington-Kirkpatrick spin glasses (with zero external field) that were first given in an earlier paper by the same authors. We also explain how ultrametricity is manifested by the densities of large percolating clusters. Our main theorems concern the connection between these densities and the usual spin overlap distribution. Their corollaries are that the ordered spin glass phase is characterized by a unique percolating cluster of maximal density (normally coexisting with a second cluster of nonzero but lower density). The …