625 research outputs found
A Pitch Salience Function Derived from Harmonic Frequency Deviations for Polyphonic Music Analysis
In this paper, a novel approach for the computation of a pitch salience function is presented. The aim of a pitch (considered here as synonym for fundamental frequency) salience function is to es- timate the relevance of the most salient musical pitches that are present in a certain audio excerpt. Such a function is used in nu- merous Music Information Retrieval (MIR) tasks such as pitch, multiple-pitch estimation, melody extraction and audio features computation (such as chroma or Pitch Class Profiles). In order to compute the salience of a pitch candidate f , the classical approach uses the weighted sum of the energy of the short time spectrum at its integer multiples frequencies hf. In the present work, we pro- pose a different approach which does not rely on energy but only on frequency location. For this, we first estimate the peaks of the short time spectrum. From the frequency location of these peaks, we evaluate the likelihood that each peak is an harmonic of a given fundamental frequency. The specificity of our method is to use as likelihood the deviation of the harmonic frequency locations from the pitch locations of the equal tempered scale. This is used to cre- ate a theoretical sequence of deviations which is then compared to an observed one. The proposed method is then evaluated for a task of multiple-pitch estimation using the MAPS test-set
Perturbation theory for the one-dimensional optical polaron
The one-dimensional optical polaron is treated on the basis of the
perturbation theory in the weak coupling limit. A special matrix diagrammatic
technique is developed. It is shown how to evaluate all terms of the
perturbation theory for the ground-state energy of a polaron to any order by
means of this technique. The ground-state energy is calculated up to the eighth
order of the perturbation theory. The effective mass of an electron is obtained
up to the sixth order of the perturbation theory. The radius of convergence of
the obtained series is estimated. The obtained results are compared with the
results from the Feynman polaron theory.Comment: 9 pages, 2 figures, RevTeX, to be published in Phys. Rev. B (2001)
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Data from docking simulations to develop an efficient strategy able to evaluate the interactions between RAGE and MDA-induced albumin adducts
This data article contains the results of docking simulations performed in order to develop a suitable in silico strategy able to assess the stability of the putative complexes between RAGE and MDA induced adducts on human albumin as experimentally determined doi: 10.1016/j.redox.2016.12.017, (Degani et al., 2017) [1]. The docking simulations involved different approaches to give a simplified yet realistic representation of the protein adducts and their environment. With increasing complexity, simulations involved the corresponding albumin tripeptides and pentapeptides with the modified residue in the central position as well as pseudo-structures which were generated by collecting the albumin residues around the adducted residue within a sphere of 7.5 \uc5 and 5 \uc5 radius. The reliability of the tested approaches was assessed by monitoring the score differences between adducted and unmodified residues. The obtained results revealed the greater predictive power of the spherical pseudo-structures compared to the simple tri- or pentapeptidic sequences thus suggesting that RAGE recognition involves residues which are spatially close to the modified residue even though not necessarily adjacent in the primary sequence
Quantum control theory for coupled 2-electron dynamics in quantum dots
We investigate optimal control strategies for state to state transitions in a
model of a quantum dot molecule containing two active strongly interacting
electrons. The Schrodinger equation is solved nonperturbatively in conjunction
with several quantum control strategies. This results in optimized electric
pulses in the THz regime which can populate combinations of states with very
short transition times. The speedup compared to intuitively constructed pulses
is an order of magnitude. We furthermore make use of optimized pulse control in
the simulation of an experimental preparation of the molecular quantum dot
system. It is shown that exclusive population of certain excited states leads
to a complete suppression of spin dephasing, as was indicated in Nepstad et al.
[Phys. Rev. B 77, 125315 (2008)].Comment: 24 pages, 9 figure
Insights into the effects of N-glycosylation on the characteristics of the VC1 domain of the human receptor for advanced glycation end products (RAGE) secreted by Pichia pastoris
Advanced glycation end products (AGEs) and advanced lipoxidation end products (ALEs), resulting from non-enzymatic modifications of proteins, are potentially harmful to human health. They directly act on proteins, affecting structure and function, or through receptor-mediated mechanisms. RAGE, a type I transmembrane glycoprotein, was identified as a receptor for AGEs. RAGE is involved in chronic inflammation, oxidative stress-based diseases and ageing. The majority of RAGE ligands bind to the VC1 domain. This domain was successfully expressed and secreted by Pichia pastoris. Out of two N-glycosylation sites, one (Asn25) was fully occupied while the other (Asn81) was under-glycosylated, generating two VC1 variants, named p36 and p34. Analysis of N-glycans and of their influence on VC1 properties were here investigated. The highly sensitive procainamide labeling method coupled to ES-MS was used for N-glycan profiling. N-glycans released from VC1 ranged from Man9GlcNAc2- to Man15GlcNAc2- with major Man10GlcNAc2- and Man11GlcNAc2- species for p36 and p34, respectively. Circular dichroism spectra indicated that VC1 maintains the same conformation also after removal of N-glycans. Thermal denaturation curves showed that the carbohydrate moiety has a small stabilizing effect on VC1 protein conformation. The removal of the glycan moiety did not affect the binding of VC1 to sugar-derived AGE- or malondialdehyde-derived ALE-human serum albumin. Given the crucial role of RAGE in human pathologies, the features of VC1 from P. pastoris will prove useful in designing strategies for the enrichment of AGEs/ALEs from plasma, urine or tissues, and in characterizing the nature of the interaction
Shape-independent scaling of excitonic confinement in realistic quantum wires
The scaling of exciton binding energy in semiconductor quantum wires is
investigated theoretically through a non-variational, fully three-dimensional
approach for a wide set of realistic state-of-the-art structures. We find that
in the strong confinement limit the same potential-to-kinetic energy ratio
holds for quite different wire cross-sections and compositions. As a
consequence, a universal (shape- and composition-independent) parameter can be
identified that governs the scaling of the binding energy with size. Previous
indications that the shape of the wire cross-section may have important effects
on exciton binding are discussed in the light of the present results.Comment: To appear in Phys. Rev. Lett. (12 pages + 2 figures in postscript
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