Local uncertainty relations serving as measures of entanglement in a bipartite two-level system

We comment on the recent suggestion to use a family of local uncertainty relations as a standard way of quantifying entanglement in two-qubit systems. Some statements made on the applicability of the proposed "measures" are overly optimistic. We exemplify how these specific "measures" fall short, and present a minor modification of the general theory which uses the same experimentally gathered information, but in a slightly different, better way.Comment: 5 pages, 1 figur

Carter's constant revealed

A new formulation of Carter's constant for geodesic motion in Kerr black holes is given. It is shown that Carter's constant corresponds to the total angular momentum plus a precisely defined part which is quadratic in the linear momenta. The characterization is exact in the weak field limit obtained by letting the gravitational constant go to zero. It is suggested that the new form can be useful in current studies of the dynamics of extreme mass ratio inspiral (EMRI) systems emitting gravitational radiation.Comment: Minor changes to match published versio

Elastic Stars in General Relativity: II. Radial perturbations

We study radial perturbations of general relativistic stars with elastic matter sources. We find that these perturbations are governed by a second order differential equation which, along with the boundary conditions, defines a Sturm-Liouville type problem that determines the eigenfrequencies. Although some complications arise compared to the perfect fluid case, leading us to consider a generalisation of the standard form of the Sturm-Liouville equation, the main results of Sturm-Liouville theory remain unaltered. As an important consequence we conclude that the mass-radius curve for a one-parameter sequence of regular equilibrium models belonging to some particular equation of state can be used in the same well-known way as in the perfect fluid case, at least if the energy density and the tangential pressure of the background solutions are continuous. In particular we find that the fundamental mode frequency has a zero for the maximum mass stars of the models with solid crusts considered in Paper I of this series.Comment: 22 pages, no figures, final version accepted for publication in Class. Quantum Grav. The treatment of the junction conditions has been improve

Longitudinal Waves in a Rod in an Elastic Medium

The general equations for the propagation of longitudinal waves in an infinite cylindrical rod including the effect of a surrounding elastic medium have been derived in order to obtain the relationship between the circular frequency and the wave number. A comparison has then been made with the Smith model in order to investigate the limits of the model and to refine the expressions for the spring and damming constants

Useful ‘junk': Alu RNAs in the human transcriptome

Abstract.: Alu elements are the most abundant repetitive elements in the human genome; they have amplified by retrotransposition to reach the present number of more than one million copies. Alu elements can be transcribed in two different ways, by two independent polymerases. ‘Free Alu RNAs' are transcribed by Pol III from their own promoter, while ‘embedded Alu RNAs' are transcribed by Pol II as part of protein- and non-protein-coding RNAs. Recent studies have demonstrated that both free and embedded Alu RNAs play a major role in post transcriptional regulation of gene expression, for example by affecting protein translation, alternative splicing and mRNA stability. These discoveries illustrate how a part of the ‘junk DNA' content of the human genome has been recruited to important functions in regulation of gene expressio

Quantum state tomography with quantum shotnoise

We propose a scheme for a complete reconstruction of one- and two-particle orbital quantum states in mesoscopic conductors. The conductor in the transport state continuously emits orbital quantum states. The orbital states are manipulated by electronic beamsplitters and detected by measurements of average currents and zero frequency current shotnoise correlators. We show how, by a suitable complete set of measurements, the elements of the density matrices of the one- and two-particle states can be directly expressed in terms of the currents and current correlators.Comment: 4 pages, 2 figure

An energy-dependent, transient peak in the minute range decay of luminescence, present in CO2-accumulating cells of Scenedesmus obliquus

AbstractPhotosynthetic O2 evolution in the green alga, Scenedesmus obliquus, was shown to be more sensitive to the uncoupler FCCP when assayed in a low Ci medium than in a high Ci medium, indicating the action of an energy-dependent mechanism for Ci uptake. Low Ci adapted algae exhibited characteristic luminescence decay kinetics with a transient peak 20–60 s after excitation. This peak was abolished by addition of FCCP and HCO−3. The effect caused by HCO−3 was partially reversed by methyl viologen. In view of the results obtained, a model is presented in order to discuss the origin of the transient luminescence peak