3,442 research outputs found
Thermodynamics of the L\'evy spin glass
We investigate the L\'evy glass, a mean-field spin glass model with power-law
distributed couplings characterized by a divergent second moment. By combining
extensively many small couplings with a spare random backbone of strong bonds
the model is intermediate between the Sherrington-Kirkpatrick and the
Viana-Bray model. A truncated version where couplings smaller than some
threshold \eps are neglected can be studied within the cavity method
developed for spin glasses on locally tree-like random graphs. By performing
the limit \eps\to 0 in a well-defined way we calculate the thermodynamic
functions within replica symmetry and determine the de Almeida-Thouless line in
the presence of an external magnetic field. Contrary to previous findings we
show that there is no replica-symmetric spin glass phase. Moreover we determine
the leading corrections to the ground-state energy within one-step replica
symmetry breaking. The effects due to the breaking of replica symmetry appear
to be small in accordance with the intuitive picture that a few strong bonds
per spin reduce the degree of frustration in the system
Endo-cannibalism in the making of a recent British ancestor
Following his death in 1975, the ashes of Wally Hope, founder of Stonehenge People's Free Festival, were scattered in the centre of Stonehenge. When a child tasted the ashes the rest of the group followed this lead. In the following decades, as the festival increasingly became the site of contest about British heritage and culture, the story of Wally's ashes was told at significant times. His name continues to be invoked at gatherings today. This paper discusses these events as 'the making of an ancestor', and explores wider contexts in which they might be understood. These include Druidic involvement in the revival of cremation, Amazonian bone-ash endo-cannibalism, and popular means of speaking of and to dead relatives. In addition to considering the role of 'ancestors' in contemporary Britain, the paper contributes to considerations of 'ancestry' as a different way of being dead, of a particular moment in the evolution of an alternative religious neo-tribal movement, of the meanings of 'cannibalism', and of the ways in which human remains might be treated by the bereaved and by various other interested parties
Contribution of Filopodia to Cell Migration: A Mechanical Link between Protrusion and Contraction
Numerous F-actin containing structures are involved in regulating protrusion of membrane at the leading edge of motile cells. We have investigated the structure and dynamics of filopodia as they relate to events at the leading edge and the function of the trailing actin networks. We have found that although filopodia contain parallel bundles of actin, they contain a surprisingly nonuniform spatial and temporal distribution of actin binding proteins. Along the length of the actin filaments in a single filopodium, the most distal portion contains primarily T-plastin, while the proximal portion is primarily bound by α-actinin and coronin. Some filopodia are stationary, but lateral filopodia move with respect to the leading edge. They appear to form a mechanical link between the actin polymerization network at the front of the cell and the myosin motor activity in the cell body. The direction of lateral filopodial movement is associated with the direction of cell migration. When lateral filopodia initiate from and move toward only one side of a cell, the cell will turn opposite to the direction of filopodial flow. Therefore, this filopodia-myosin II system allows actin polymerization driven protrusion forces and myosin II mediated contractile force to be mechanically coordinated
Stability of the replica-symmetric saddle-point in general mean-field spin-glass models
Within the replica approach to mean-field spin-glasses the transition from
ergodic high-temperature behaviour to the glassy low-temperature phase is
marked by the instability of the replica-symmetric saddle-point. For general
spin-glass models with non-Gaussian field distributions the corresponding
Hessian is a matrix with the number of replicas tending to
zero eventually. We block-diagonalize this Hessian matrix using representation
theory of the permutation group and identify the blocks related to the
spin-glass susceptibility. Performing the limit within these blocks we
derive expressions for the de~Almeida-Thouless line of general spin-glass
models. Specifying these expressions to the cases of the
Sherrington-Kirkpatrick, Viana-Bray, and the L\'evy spin glass respectively we
obtain results in agreement with previous findings using the cavity approach
GLP-1 Agonists in Type 1 Diabetes Mellitus: A Review of the Literature
Objective: To review the use of GLP-1 agonists in patients with type 1 diabetes mellitus (T1DM). Data Sources: A search using the MEDLINE database, EMBASE, and Cochrane Database was performed through March 2016 using the search terms glucagon-like peptide 1 (GLP-1) agonists, incretin, liraglutide, exenatide, albiglutide, dulaglutide, type 1 diabetes mellitus. Study Selection and Data Extraction: All English-language trials that examined glycemic end points using GLP- 1 agonists in humans with T1DM were included. Data Synthesis: A total of 9 clinical trials examining the use of GLP-1 agonists in T1DM were identified. On average, hemoglobin A1C (A1C) was lower than baseline, with a maximal lowering of 0.6%. This effect was not significant when tested against a control group, with a relative decrease in A1C of 0.1% to 0.2%. In all trials examined, reported hypoglycemia was low, demonstrating no difference when compared with insulin monotherapy. Weight loss was seen in all trials, with a maximum weight loss of 6.4 kg over 24 weeks. Gastrointestinal adverse effects are potentially limiting, with a significant number of patients in trials reporting nausea. Conclusion: The use of GLP-1 agonists should be considered in T1DM patients who are overweight or obese and not at glycemic goals despite aggressive insulin therapy; however, tolerability of these agents is a potential concern. Liraglutide has the strongest evidence for use and would be the agent of choice for use in overweight or obese adult patients with uncontrolled T1DM
First IBEX observations of the terrestrial plasma sheet and a possible disconnection event
The Interstellar Boundary Explorer (IBEX) mission has recently provided the first all-sky maps of energetic neutral atoms (ENAs) emitted from the edge of the heliosphere as well as the first observations of ENAs from the Moon and from the magnetosheath stagnation region at the nose of the magnetosphere. This study provides the first IBEX images of the ENA emissions from the nightside magnetosphere and plasma sheet. We show images from two IBEX orbits: one that displays typical plasma sheet emissions, which correlate reasonably well with a model magnetic field, and a second that shows a significant intensification that may indicate a near-Earth (similar to 10 R(E) behind the Earth) disconnection event. IBEX observations from similar to 0.5-6 keV indicate the simultaneous addition of both a hot (several keV) and colder (similar to 700 eV) component during the intensification; if IBEX directly observed magnetic reconnection in the magnetotail, the hot component may signify the plasma energization
Evolving outer heliosphere: Large-scale stability and time variations observed by the Interstellar Boundary Explorer
The first all-sky maps of Energetic Neutral Atoms (ENAs) from the Interstellar Boundary Explorer (IBEX) exhibited smoothly varying, globally distributed flux and a narrow ribbon of enhanced ENA emissions. In this study we compare the second set of sky maps to the first in order to assess the possibility of temporal changes over the 6 months between views of each portion of the sky. While the large-scale structure is generally stable between the two sets of maps, there are some remarkable changes that show that the heliosphere is also evolving over this short timescale. In particular, we find that (1) the overall ENA emissions coming from the outer heliosphere appear to be slightly lower in the second set of maps compared to the first, (2) both the north and south poles have significantly lower (similar to 10-15%) ENA emissions in the second set of maps compared to the first across the energy range from 0.5 to 6 keV, and (3) the knot in the northern portion of the ribbon in the first maps is less bright and appears to have spread and/or dissipated by the time the second set was acquired. Finally, the spatial distribution of fluxes in the southernmost portion of the ribbon has evolved slightly, perhaps moving as much as 6 degrees (one map pixel) equatorward on average. The observed large-scale stability and these systematic changes at smaller spatial scales provide important new information about the outer heliosphere and its global interaction with the galaxy and help inform possible mechanisms for producing the IBEX ribbon
Limits on the HI content of the dwarf galaxy Hydra II
Sensitive 21cm HI observations have been made with the Green Bank Telescope
toward the newly-discovered Local Group dwarf galaxy Hydra II, which may lie
within the leading arm of the Magellanic Stream. No neutral hydrogen was
detected. Our 5-sigma limit of MHI < 210 solar masses for a 15 km/s linewidth
gives a gas-to-luminosity ratio MHI/L_V < 2.6 x 10^{-2} Mo / Lo. The limits on
HI mass and MHI/L_V are typical of dwarf galaxies found within a few hundred
kpc of the Milky Way. Whatever the origin of Hydra II, its neutral gas
properties are not unusual.Comment: Accepted for publication in Astronomy & Astrophysic
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