20,296 research outputs found
The significance of ACTH for the process of formation of complex heparin compounds in the blood during immobilization stress
Adrenocorticotropin (ACTH) was administered to rats at different times following adrenalectomy. Adrenocorticotropin caused a significant increase in the formation of heparin complexes even in the absence of stress factor. When ACTH secretion is blocked, immobilization stress is not accompanied by an increase in the process of complex formation. The effect of ACTH on the formation of heparin complexes was mediated through its stimulation of the adrenal cortex
The role of ACTH and glucocorticoids in nonenzymatic fibrinolysis during immobilization stress in animals
The role of the altered hormonal status of an organism in the activation of the anticoagulative system during stress is investigated. The 30 minute immobilization stress was shown to raise significantly the nonenzymatic fibrinolytic activity of blood in rats. Combined with adrenocorticotropin (ACTH) the effect is still greater. Intravenous administration of 0.2 m1 0.01 percent solution of protamine sulphate prevented the nonenzymatic fibrinolysis induced by the stress. Administration of ACTH after protomine sulphate again raised the fibrinolysis. This suggests that ACTH stimulates the release of heparin
The effects of adrenalectomy and corticsteroid injection on the fibrinolytic activity of complex heparin compounds in the blood during immobilization
Total non-enzymatic fibrinolytic activity in the blood of rats increased three times in response to stress caused by 30 minute immobilization, and the activity of epinephrine-heparin complex increased nine times. In adrenalectomized animals, which showed a weak response to the same stress, intraperitoneal injection of hydrocortisone 30 minutes prior to immobilization normalized the response. Obtained results indicate that adrenalectomy leads to sharp reduction of heparin complexing with thromogenic proteins and epinephrine, while substitution therapy with hydrocortisone restores anticoagulation system function
Importance of cooling in triggering the collapse of hypermassive neutron stars
The inspiral and merger of a binary neutron star (NSNS) can lead to the
formation of a hypermassive neutron star (HMNS). As the HMNS loses thermal
pressure due to neutrino cooling and/or centrifugal support due to
gravitational wave (GW) emission, and/or magnetic breaking of differential
rotation it will collapse to a black hole. To assess the importance of
shock-induced thermal pressure and cooling, we adopt an idealized equation of
state and perform NSNS simulations in full GR through late inspiral, merger,
and HMNS formation, accounting for cooling. We show that thermal pressure
contributes significantly to the support of the HMNS against collapse and that
thermal cooling accelerates its "delayed" collapse. Our simulations demonstrate
explicitly that cooling can induce the catastrophic collapse of a hot
hypermassive neutron star formed following the merger of binary neutron stars.
Thus, cooling physics is important to include in NSNS merger calculations to
accurately determine the lifetime of the HMNS remnant and to extract
information about the NS equation of state, cooling mechanisms, bar
instabilities and B-fields from the GWs emitted during the transient phase
prior to BH formation.Comment: 13 pages, 7 figures, matches published versio
Complete transfer of populations from a single state to a pre-selected superposition of states using Piecewise Adiabatic Passage
We develop a method for executing robust and selective transfer of
populations between a single level and pre-selected superpositions of energy
eigenstates. Viewed in the frequency domain, our method amounts to executing a
series of simultaneous adiabatic passages into each component of the target
superposition state. Viewed in {the} time domain, the method works by
accumulating the wavefunction of the target wave packet as it revisits the
Franck Condon region, in what amounts to an extension of the Piecewise
Adiabatic Passage technique [ Shapiro et.al., Phys. Rev. Lett. 99, 033002
(2007)] to the multi-state regime. The viability of the method is verified by
performing numerical tests for the Na_2 molecule.Comment: 8 pages, 4 figure
Anderson localization of a Bose-Einstein condensate in a 3D random potential
We study the effect of Anderson localization on the expansion of a
Bose-Einstein condensate, released from a harmonic trap, in a 3D random
potential. We use scaling arguments and the self-consistent theory of
localization to show that the long-time behavior of the condensate density is
controlled by a single parameter equal to the ratio of the mobility edge and
the chemical potential of the condensate. We find that the two critical
exponents of the localization transition determine the evolution of the
condensate density in time and space.Comment: 4 pages, 2 figure
Scaling of the conductance distribution near the Anderson transition
The single parameter scaling hypothesis is the foundation of our
understanding of the Anderson transition. However, the conductance of a
disordered system is a fluctuating quantity which does not obey a one parameter
scaling law. It is essential to investigate the scaling of the full conductance
distribution to establish the scaling hypothesis. We present a clear cut
numerical demonstration that the conductance distribution indeed obeys one
parameter scaling near the Anderson transition
On Useful Conformal Tranformations In General Relativity
Local conformal transformations are known as a useful tool in various
applications of the gravitational theory, especially in cosmology. We describe
some new aspects of these transformations, in particular using them for
derivation of Einstein equations for the cosmological and Schwarzschild
metrics. Furthermore, the conformal transformation is applied for the
dimensional reduction of the Gauss-Bonnet topological invariant in to the
spaces of lower dimensions.Comment: 17 pages, LaTeX. The paper is intended mainly for pedagogical
purposes and represents a collection of exercises concerning local conformal
transformations and dimensional reduction. To be published in "Gravitation
and Cosmology
Model-independent view on the low-mass proton-antiproton enhancement
We present a simple interpretation of the recently observed near-threshold
proton-antiproton enhancement. It is described by a set of low-energy
parameters deduced from the analysis of NantiN experiments at LEAR. We predict
a related effect in photoproduction reaction under study by CLAS collaboration.Comment: 10 pages, 2 figure
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