2,569 research outputs found
Near-Constant Mean Curvature Solutions of the Einstein Constraint Equations with Non-Negative Yamabe Metrics
We show that sets of conformal data on closed manifolds with the metric in
the positive or zero Yamabe class, and with the gradient of the mean curvature
function sufficiently small, are mapped to solutions of the Einstein constraint
equations. This result extends previous work which required the conformal
metric to be in the negative Yamabe class, and required the mean curvature
function to be nonzero.Comment: 15 page
Biologic therapies for systemic lupus erythematosus: where are we now?
PURPOSE OF REVIEW:
Conventional approaches using hydroxychloroquine, corticosteroids and immunosuppressives have improved the prognosis for systemic lupus erythematosus (SLE) patients. Unfortunately, they have reached the limits of what they can achieve and patients still die prematurely and/or find their quality of life greatly impaired. Here, we discuss the problems of assessing activity in SLE, optimizing clinical trial design and more recent biologic approaches.
RECENT FINDINGS:
The success of B-cell depletion using Rituximab in open clinical studies, the approval of Belimumab (blocks the B-cell activating factor BAFF) and improvements in clinical trial design, gives cause for hope. Approaches including the use of fully humanized anti-CD20 and CD19 monoclonals, blocking interferons, inhibiting Bruton's tyrosine kinase (BTK), blocking the CD40 ligand (CD40L), utilizing an analogue of the FcɣRIIB and an IL12-23 blocker and targeting the JAK-STAT pathway have met end points in phase II and III trials.
SUMMARY:
For 20 years, we hoped that the successes of the biologic therapies in rheumatoid arthritis and psoriatic arthritis would be replicated in SLE but we have been generally disappointed. However, the encouraging recent results with monoclonals that block interferon and fully humanized anti-CD20 in particular, offer the prospect of a real revolution in the treatment of SLE
Resonant Interactions Between Protons and Oblique Alfv\'en/Ion-Cyclotron Waves
Resonant interactions between ions and Alfv\'en/ion-cyclotron (A/IC) waves
may play an important role in the heating and acceleration of the fast solar
wind. Although such interactions have been studied extensively for "parallel"
waves, whose wave vectors are aligned with the background magnetic
field , much less is known about interactions between ions and
oblique A/IC waves, for which the angle between and is nonzero. In this paper, we present new numerical results on resonant
cyclotron interactions between protons and oblique A/IC waves in collisionless
low-beta plasmas such as the solar corona. We find that if some mechanism
generates oblique high-frequency A/IC waves, then these waves initially modify
the proton distribution function in such a way that it becomes unstable to
parallel waves. Parallel waves are then amplified to the point that they
dominate the wave energy at the large parallel wave numbers at which the waves
resonate with the particles. Pitch-angle scattering by these waves then causes
the plasma to evolve towards a state in which the proton distribution is
constant along a particular set of nested "scattering surfaces" in velocity
space, whose shapes have been calculated previously. As the distribution
function approaches this state, the imaginary part of the frequency of parallel
A/IC waves drops continuously towards zero, but oblique waves continue to
undergo cyclotron damping while simultaneously causing protons to diffuse
across these kinetic shells to higher energies. We conclude that oblique A/IC
waves can be more effective at heating protons than parallel A/IC waves,
because for oblique waves the plasma does not relax towards a state in which
proton damping of oblique A/IC waves ceases
Ricci flows, wormholes and critical phenomena
We study the evolution of wormhole geometries under Ricci flow using
numerical methods. Depending on values of initial data parameters, wormhole
throats either pinch off or evolve to a monotonically growing state. The
transition between these two behaviors exhibits a from of critical phenomena
reminiscent of that observed in gravitational collapse. Similar results are
obtained for initial data that describe space bubbles attached to
asymptotically flat regions. Our numerical methods are applicable to
"matter-coupled" Ricci flows derived from conformal invariance in string
theory.Comment: 8 pages, 5 figures. References added and minor changes to match
version accepted by CQG as a fast track communicatio
Computer analyses suggest interactions of non-muscle filamin with lipid membranes
AbstractIt is concluded from structure predictions of the primary amino acid sequence by computer analyses that two segments of non-muscle filamin could facilitate lipid membrane attachment or anchoring. Residues 49–71 of the amino-terminal may attach to phospholipid membranes, and residues 131–155 may anchor in the hydrophobic region of lipid membranes
Quasilinear hyperbolic Fuchsian systems and AVTD behavior in T2-symmetric vacuum spacetimes
We set up the singular initial value problem for quasilinear hyperbolic
Fuchsian systems of first order and establish an existence and uniqueness
theory for this problem with smooth data and smooth coefficients (and with even
lower regularity). We apply this theory in order to show the existence of
smooth (generally not analytic) T2-symmetric solutions to the vacuum Einstein
equations, which exhibit AVTD (asymptotically velocity term dominated) behavior
in the neighborhood of their singularities and are polarized or half-polarized.Comment: 78 page
Low-Energy Dynamics of String Solitons
The dynamics of a class of fivebrane string solitons is considered in the
moduli space approximation. The metric on moduli space is found to be flat.
This implies that at low energies the solitons do not interact, and their
scattering is trivial. The range of validity of the approximation is also
briefly discussed.Comment: 8 pages, Minor typos correcte
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