16 research outputs found
Canonical differential geometry of string backgrounds
String backgrounds and D-branes do not possess the structure of Lorentzian
manifolds, but that of manifolds with area metric. Area metric geometry is a
true generalization of metric geometry, which in particular may accommodate a
B-field. While an area metric does not determine a connection, we identify the
appropriate differential geometric structure which is of relevance for the
minimal surface equation in such a generalized geometry. In particular the
notion of a derivative action of areas on areas emerges naturally. Area metric
geometry provides new tools in differential geometry, which promise to play a
role in the description of gravitational dynamics on D-branes.Comment: 20 pages, no figures, improved journal versio
Area metric gravity and accelerating cosmology
Area metric manifolds emerge as effective classical backgrounds in quantum
string theory and quantum gauge theory, and present a true generalization of
metric geometry. Here, we consider area metric manifolds in their own right,
and develop in detail the foundations of area metric differential geometry.
Based on the construction of an area metric curvature scalar, which reduces in
the metric-induced case to the Ricci scalar, we re-interpret the
Einstein-Hilbert action as dynamics for an area metric spacetime. In contrast
to modifications of general relativity based on metric geometry, no continuous
deformation scale needs to be introduced; the extension to area geometry is
purely structural and thus rigid. We present an intriguing prediction of area
metric gravity: without dark energy or fine-tuning, the late universe exhibits
a small acceleration.Comment: 52 pages, 1 figure, companion paper to hep-th/061213
MARS therapy, the bridging to liver retransplantation-Three cases from the Hungarian liver transplant program
Besides orthotopic liver transplantation (OLT) there is no long-term and effective replacement therapy for severe liver failure. Artificial extracorporeal liver supply devices are able to reduce blood toxin levels, but do not replace any synthetic function of the liver. Molecular adsorbent recirculating system (MARS) is one of the methods that can be used to treat fulminant acute liver failure (ALF) or acute on chronic liver failure (AoCLF). The primary non-function (PNF) of the newly transplanted liver manifests in the clinical settings exactly like acute liver failure. MARS treatment can reduce the severity of complications by eliminating blood toxins, so that it can help hepatic encephalopathy (HE), hepatorenal syndrome (HRS), and the high rate mortality of cerebral herniation. This might serve as a bridging therapy before orthotopic liver retransplantation (reOLT). Three patients after a first liver transplantation became candidate for urgent MARS treatment as a bridging solution prior to reOLT in our center. Authors report these three cases, focusing on indications, MARS sessions, clinical courses, and final outcomes. © 2013 Akadémiai Kiadó, Budapest
Super-Luminal Effects for Finsler Branes as a Way to Preserve the Paradigm of Relativity Theories
Using Finsler brane solutions [see details and methods in: S. Vacaru, Class.
Quant. Grav. 28 (2011) 215001], we show that neutrinos may surpass the speed of
light in vacuum which can be explained by trapping effects from gravity
theories on eight dimensional (co) tangent bundles on Lorentzian manifolds to
spacetimes in general and special relativity. In nonholonomic variables, the
bulk gravity is described by Finsler modifications depending on velocity/
momentum coordinates. Possible super-luminal phenomena are determined by the
width of locally anisotropic brane (spacetime) and induced by generating
functions and integration functions and constants in coefficients of metrics
and nonlinear connections. We conclude that Finsler brane gravity trapping
mechanism may explain neutrino super-luminal effects and almost preserve the
paradigm of Einstein relativity as the standard one for particle physics and
gravity.Comment: latex2e, 15 pages, v3, accepted to: Foundations of Physics 43 (2013