36,445 research outputs found
Troponins, Acute Coronary Syndrome and Renal Disease: From Acute Kidney Injury Through End-stage Kidney Disease
The diagnosis of acute coronary syndromes (ACS) is heavily dependent on cardiac biomarker assays, particularly cardiac troponins. ACS, particularly non-ST segment elevation MI, are more common in patients with acute kidney injury, chronic kidney disease (CKD) and end-stage kidney disease (ESKD), are associated with worse outcomes than in patients without kidney disease and are often difficult to diagnose and treat. Hence, early accurate diagnosis of ACS in kidney disease patients is important using easily available tools, such as cardiac troponins. However, the diagnostic reliability of cardiac troponins has been suboptimal in patients with kidney disease due to possible decreased clearance of troponin with acute and chronic kidney impairment and low levels of troponin secretion due to concomitant cardiac muscle injury related to left ventricular hypertrophy, inflammation and fibrosis. This article reviews the metabolism and utility of cardiac biomarkers in patients with acute and chronic kidney diseases. Cardiac troponins are small peptides that accumulate in both acute and chronic kidney diseases due to impaired excretion. Hence, troponin concentrations rise and fall with acute kidney injury and its recovery, limiting their use in the diagnosis of ACS. Troponin concentrations are chronically elevated in CKD and ESKD, are associated with poor prognosis and decrease the sensitivity and specificity for diagnosis of ACS. Yet, the evidence indicates that the use of high-sensitivity troponins can confirm or exclude a diagnosis of ACS in the emergency room in a significant proportion of kidney disease patients; those patients in whom the results are equivocal may need longer in-hospital assessment
Connecting anomaly and tunneling methods for Hawking effect through chirality
The role of chirality is discussed in unifying the anomaly and the tunneling
formalisms for deriving the Hawking effect. Using the chirality condition and
starting from the familiar form of the trace anomaly, the chiral
(gravitational) anomaly, manifested as a nonconservation of the stress tensor,
near the horizon of a black hole, is derived. Solution of this equation yields
the stress tensor whose asymptotic infinity limit gives the Hawking flux.
Finally, use of the same chirality condition in the tunneling formalism gives
the Hawking temperature that is compatible with the flux obtained by anomaly
method.Comment: LaTex, 8 pages, no figures, reformulation of tunneling mechanism, to
appear in Phys. Rev.
Artificial Life in an Exciton-Polariton Lattice
We show theoretically that a lattice of exciton-polaritons can behave as a
life-like cellular automaton when simultaneously excited by a continuous wave
coherent field and a time-periodic sequence of non-resonant pulses. This
provides a mechanism of realizing a range of highly sought spatiotemporal
structures under the same conditions, including: discrete solitons, oscillating
solitons, rotating solitons, breathers, soliton trains, guns, and choatic
behaviour. These structures can survive in the system indefinitely, despite the
presence of dissipation, and allow universal computation.Comment: 14 pages, 14 figure
Screening in three-dimensional QED with arbitrary fermion mass
We compute the quark--antiquark potential in three dimensional massive
Quantum Electrodynamics for arbitrary fermion mass. The result indicates that
screening prevails for any quark masses, contrary to the classical
expectations, generalizing our previous result obtained for large masses. We
also test the validity of several approximation schemes using a detailed
numerical analysis. The classical result is still reproduced for small
separation of the quarks.Comment: latex, 10 pages, 4 figures (6 ps-files
Duality and Topological Mass Generation in Diverse Dimensions
We shall discuss issues of duality and topological mass generation in diverse
dimensions. Particular emphasis will be given to the mass generation mechanism
from interference between self and anti self-dual components, as disclosed by
the soldering formalism. This is a gauge embedding procedure derived from an
old algorithm of second-class constraint conversion used by the author to
approach anomalous gauge theories. The problem of classification of the
electromagnetic duality groups, both massless and massive, that is closely
related will be discussed. Particular attention will be paid to a new approach
to duality based on the soldering embedding to tackle the problem of mass
generation by topological mechanisms in arbitrary dimensions including the
couplings to dynamical matter, nonlinear cases and nonabelian symmetries.Comment: 10 pages, invited talk at "Renormalization Group and Anomalies in
Gravity and Cosmology", Ouro Preto, Brazil, March 17-23, 200
Explicit Bosonization of the Massive Thirring Model in 3+1 Dimensions
We bosonize the Massive Thirring Model in 3+1D for small coupling constant
and arbitrary mass. The bosonized action is explicitly obtained both in terms
of a Kalb-Ramond tensor field as well as in terms of a dual vector field. An
exact bosonization formula for the current is derived. The small and large mass
limits of the bosonized theory are examined in both the direct and dual forms.
We finally obtain the exact bosonization of the free fermion with an arbitrary
mass.Comment: Latex, 7 page
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