508 research outputs found
Protein synthesis driven by dynamical stochastic transcription
In this manuscript we propose a mathematical framework to couple
transcription and translation in which mRNA production is described by a set of
master equations while the dynamics of protein density is governed by a random
differential equation. The coupling between the two processes is given by a
stochastic perturbation whose statistics satisfies the master equations. In
this approach, from the knowledge of the analytical time dependent distribution
of mRNA number, we are able to calculate the dynamics of the probability
density of the protein population.Comment: 20 pages, 3 figure
Multidimensional patterns of neuronal activity: how do we see them?
Poster presentation: Introduction The brain is a highly interconnected network of constantly interacting units. Understanding the collective behavior of these units requires a multi-dimensional approach. The results of such analyses are hard to visualize and interpret. Hence tools capable of dealing with such tasks become imperative. ...
Magnetic Phase Transitions in NdCoAsO
Magnetization measurements reveal that NdCoAsO undergoes three magnetic phase
transitions below room temperature. The crystal and magnetic structures of
NdCoAsO have been determined by powder neutron diffraction, and the effects of
the phase transitions on physical properties are reported. Near 69 K a
ferromagnetic state emerges with a small saturation moment of about 0.2 Bohr
magnetons, likely on Co atoms. At 14 K the material enters an antiferromagnetic
state with propagation vector (0 0 1/2) and small ordered moments (~0.4 Bohr
magnetons) on Co and Nd. Near 3.5 K a third transition is observed, and
corresponds to the antiferromagnetic ordering, with the same propagation
vector, of larger moments on Nd reaching 1.30(2) Bohr magnetons at 1.4 K. In
addition, transport properties and heat capacity results are presented, and
show anomalies at all three phase transitions.Comment: Some minor changes made, and lower temperature neutron diffraction
results are included. Accepted for publication in Physical Review
The Geometry of Warped Product Singularities
In this article the degenerate warped products of singular semi-Riemannian
manifolds are studied. They were used recently by the author to handle
singularities occurring in General Relativity, in black holes and at the
big-bang. One main result presented here is that a degenerate warped product of
semi-regular semi-Riemannian manifolds with the warping function satisfying a
certain condition is a semi-regular semi-Riemannian manifold. The connection
and the Riemann curvature of the warped product are expressed in terms of those
of the factor manifolds. Examples of singular semi-Riemannian manifolds which
are semi-regular are constructed as warped products. Applications include
cosmological models and black holes solutions with semi-regular singularities.
Such singularities are compatible with a certain reformulation of the Einstein
equation, which in addition holds at semi-regular singularities too.Comment: 14 page
Pheochromocytoma – clinical manifestations, diagnosis and current perioperative management
Pheochromocytoma is a neuroendocrine tumor characterized by the excessive production of catecholamines (epinephrine, norepinephrine, and dopamine). The diagnosis is suspected due to hypertensive paroxysms, associated with vegetative phenomena, due to the catecholaminergic hypersecretion. Diagnosis involves biochemical tests that reveal elevated levels of catecholamine metabolites (metanephrine and normetanephrine). Functional imaging, such as 123I-metaiodobenzylguanidine scintigraphy (123I-MIBG), has increased specificity in identifying the catecholamine-producing tumor and its metastases. The gold-standard treatment for patients with pheochromocytoma is represented by the surgical removal of the tumor. Before surgical resection, it is important to optimize blood pressure and intravascular volume in order to avoid negative hemodynamic events
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