267 research outputs found
Canonical Quantization and Expanding Metrics
The canonical formalism for expanding metrics scenarios is presented.
Non-unitary time evolution implied by expanding geometry is described as a
trajectory over unitarily inequivalent representations at different times of
the canonical commutation relations. Thermal properties of inflating Universe
are also discussed.Comment: 10 pages, 2 figure
Opsin vs opsin: new materials for biotechnological applications
The need of new diagnostic methods satisfying, as an early detection, a low
invasive procedure and a cost-efficient value, is orienting the technological
research toward the use of bio-integrated devices, in particular bio-sensors.
The set of know-why necessary to achieve this goal is wide, from biochemistry
to electronics and is summarized in an emerging branch of electronics, called
\textit{proteotronics}. Proteotronics is here here applied to state a
comparative analysis of the electrical responses coming from type-1 and type-2
opsins. In particular, the procedure is used as an early investigation of a
recently discovered family of opsins, the proteorhodopsins activated by blue
light, BPRs. The results reveal some interesting and unexpected similarities
between proteins of the two families, suggesting the global electrical response
are not strictly linked to the class identity.Comment: 10 pages, 8 figures revised version with more figure
The dissipative quantum model of brain: how do memory localize in correlated neuronal domains
The mechanism of memory localization in extended domains is described in the
framework of the parametric dissipative quantum model of brain. The size of the
domains and the capability in memorizing depend on the number of links the
system is able to establish with the external world.Comment: 19 PostScript pages, in press on a special issue of Information
Science Journal, S. Kak and D. Ventura Ed
Formation and life-time of memory domains in the dissipative quantum model of brain
We show that in the dissipative quantum model of brain the time-dependence of
the frequencies of the electrical dipole wave quanta leads to the dynamical
organization of the memories in space (i.e. to their localization in more or
less diffused regions of the brain) and in time (i.e. to their longer or
shorter life-time). The life-time and the localization in domains of the memory
states also depend on internal parameters and on the number of links that the
brain establishes with the external world. These results agree with the
physiological observations of the dynamic formation of neural circuitry which
grows as brain develops and relates to external world.Comment: LaTex file, 4 figures, 19 page
Hierarchy and assortativity as new tools for affinity investigation: the case of the TBA aptamer-ligand complex
Aptamers are single stranded DNA, RNA or peptide sequences having the ability
to bind a variety of specific targets (proteins, molecules as well as ions).
Therefore, aptamer production and selection for therapeutic and diagnostic
applications is very challenging. Usually they are in vitro generated, but,
recently, computational approaches have been developed for the in silico
selection, with a higher affinity for the specific target. Anyway, the
mechanism of aptamer-ligand formation is not completely clear, and not obvious
to predict. This paper aims to develop a computational model able to describe
aptamer-ligand affinity performance by using the topological structure of the
corresponding graphs, assessed by means of numerical tools such as the
conventional degree distribution, but also the rank-degree distribution
(hierarchy) and the node assortativity. Calculations are applied to the
thrombin binding aptamer (TBA), and the TBA-thrombin complex, produced in the
presence of Na+ or K+. The topological analysis reveals different affinity
performances between the macromolecules in the presence of the two cations, as
expected by previous investigations in literature. These results nominate the
graph topological analysis as a novel theoretical tool for testing affinity.
Otherwise, starting from the graphs, an electrical network can be obtained by
using the specific electrical properties of amino acids and nucleobases.
Therefore, a further analysis concerns with the electrical response, which
reveals that the resistance sensitively depends on the presence of sodium or
potassium thus posing resistance as a crucial physical parameter for testing
affinity.Comment: 12 pages, 5 figure
Investigations on the electrical current-voltage response in protein light receptors
We report a theoretical/computational approach for modeling the
current-voltage characteristics of sensing proteins. The modeling is applied to
a couple of transmembrane proteins, bacteriorhodopsin and proteorhodopsin,
sensitive to visible light and promising biomaterials for the development of a
new generation of photo-transducers. The agreement between theory and
experiments sheds new light on the microscopic interpretation of charge
transfer in proteins and biological materials in general.Comment: 4 pages, 3 figures To be published in J Phys. C: Conf Ser. Proceeding
of the Conference IC-MCSQUARE, PRAGUE 201
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