1,928 research outputs found
The volume of Gaussian states by information geometry
We formulate the problem of determining the volume of the set of Gaussian
physical states in the framework of information geometry. That is, by
considering phase space probability distributions parametrized by the
covariances and supplying this resulting statistical manifold with the
Fisher-Rao metric. We then evaluate the volume of classical, quantum and
quantum entangled states for two-mode systems showing chains of strict
inclusion
Analysis of food supplement with unusual raspberry ketone content
In recent years food supplement market increased constantly, including slimming products and against obesity. The case of rasberry ketone (RK) is here reported. HPTLC and HPLC-DAD analyses on a marketed product containing raspberry juice evidenced an abnormal quantity of RK, not in accordance with the juice natural content. The reported data confirm the need of adequate controls on marketed food supplements and the necessity of a complete adherence between labelling and real constitution of the product. Practical Applications: Determining the natural origin and assuring the consumers' safety for raspberry-based food supplement
J-factors of short DNA molecules
The propensity of short DNA sequences to convert to the circular form is
studied by a mesoscopic Hamiltonian method which incorporates both the bending
of the molecule axis and the intrinsic twist of the DNA strands. The base pair
fluctuations with respect to the helix diameter are treated as path
trajectories in the imaginary time path integral formalism. The partition
function for the sub-ensemble of closed molecules is computed by imposing chain
ends boundary conditions both on the radial fluctuations and on the angular
degrees of freedom. The cyclization probability, the J-factor, proves to be
highly sensitive to the stacking potential, mostly to its nonlinear parameters.
We find that the J-factor generally decreases by reducing the sequence length (
N ) and, more significantly, below N = 100 base pairs. However, even for very
small molecules, the J-factors remain sizeable in line with recent experimental
indications. Large bending angles between adjacent base pairs and anharmonic
stacking appear as the causes of the helix flexibility at short length scales.Comment: The Journal of Chemical Physics - May 2016 ; 9 page
Sensitivity-bandwidth limit in a multi-mode opto-electro-mechanical transducer
An opto--electro--mechanical system formed by a nanomembrane capacitively
coupled to an LC resonator and to an optical interferometer has been recently
employed for the high--sensitive optical readout of radio frequency (RF)
signals [T. Bagci, \emph{et~al.}, Nature {\bf 507}, 81 (2013)]. Here we propose
and experimentally demonstrate how the bandwidth of such kind of transducer can
be increased by controlling the interference between two--electromechanical
interaction pathways of a two--mode mechanical system. With a
proof--of--principle device \new{operating at room temperature, we achieve a
sensitivity of 300 nV/Hz^(1/2) over a bandwidth of 15 kHz in the presence of
radiofrequency noise, and an optimal shot-noise limited sensitivity of 10
nV/Hz^(1/2) over a bandwidth of 5 kHz. We discuss strategies for improving the
performance of the device, showing that, for the same given sensitivity, a
mechanical multi--mode transducer can achieve a bandwidth} significantly larger
than that of a single-mode one
Retrieval-induced forgetting as motivated cognition
Recalling information from a particular category can reduce one's memory capability for related, non-retrieved information. This is known as the retrieval-induced forgetting effect (RIF; Anderson et al., 1994). The present paper reviews studies that show that the RIF effect is motivated. More specifically, we describe research showing that the need for closure (NFC; the motivation to attain epistemic certainty; Kruglanski and Webster, 1996) generally enhances the RIF, because this prevents uncertainty and confusion from the intrusion of unwanted memories during selective-retrieval. However, when the content of the to-be-forgotten information serves the retriever's goals, NFC reduces RIF. Overall, the present findings are consistent with the view that motivation can affect the magnitude of RIF effects which, in turn, can serve as a mechanism for reaching preferred conclusion
On the spectrum of the transfer operators of a one-parameter family with intermittency transition
We study the transfer operators for a family depending
on the parameter , which interpolates between the tent map and the
Farey map. In particular, considering the action of the transfer operator on a
suitable Hilbert space, we can define a family of infinite matrices associated
to the operators and study their spectrum by numerical methods.Comment: 6 pages, 3 figure
Bone computed tomography mineral content evaluation in chickens: Effects of substances in homeopathic concentration
Ninety-six cobb race chickens were equally divided in 4 groups and randomly
assigned to receive a standard treatment feed + homeopathic concentrations of Symphytum
(S.) officinalis (9CH), or standard treatment feed + homeopathic concentrations
of Tricalcarea (4CH), or standard treatment feed + homeopathic concentrations of Calcarea
(C.) carbonica (30CH) or a placebo (the same feed but without any homeopathic
compound) in order to assess the ability of the homeopathic compounds to increase
the concentration of calcium hydroxyapatite in the sternal spongy bone tissue. We
measured the concentration of calciumhydroxyapatite in the sternal spongy bone tissue
of all chickens by means of a computed tomography (CT).
Results: 30%, 36% and 63% increase of sternum spongy-bone mineralization was
observed after a 2 years period in the treatment groups with S. officinalis (9CH), Tricalcarea
(4CH) (*P < 0.05) and C. carbonica (30CH) (***P < 0.001) respectively.
Conclusion: Bone mineralization is usually low in battery chickens reared in commercial
poultry-sheds, creating a weakness of the whole animal supporting apparatus. Homeopathic
preparations with bone-tissue tropism may improve their health
quality
Heat, temperature and Clausius inequality in a model for active brownian particles
Methods of stochastic thermodynamics and hydrodynamics are applied to the a
recently introduced model of active particles. The model consists of an
overdamped particle subject to Gaussian coloured noise. Inspired by stochastic
thermodynamics, we derive from the system's Fokker-Planck equation the average
exchanges of heat and work with the active bath and the associated entropy
production. We show that a Clausius inequality holds, with the local
(non-uniform) temperature of the active bath replacing the uniform temperature
usually encountered in equilibrium systems. Furthermore, by restricting the
dynamical space to the first velocity moments of the local distribution
function we derive a hydrodynamic description where local pressure, kinetic
temperature and internal heat fluxes appear and are consistent with the
previous thermodynamic analysis. The procedure also shows under which
conditions one obtains the unified coloured noise approximation (UCNA): such an
approximation neglects the fast relaxation to the active bath and therefore
yields detailed balance and zero entropy production. In the last part, by using
multiple time-scale analysis, we provide a constructive method (alternative to
UCNA) to determine the solution of the Kramers equation and go beyond the
detailed balance condition determining negative entropy production.Comment: 19 pages, 1 figure. Major changes in the text. 1 figure has been
replace
Algorithmic complexity of quantum capacity
Recently the theory of communication developed by Shannon has been extended
to the quantum realm by exploiting the rules of quantum theory. This latter
stems on complex vector spaces. However complex (as well as real) numbers are
just idealizations and they are not available in practice where we can only
deal with rational numbers. This fact naturally leads to the question of
whether the developed notions of capacities for quantum channels truly catch
their ability to transmit information. Here we answer this question for the
quantum capacity. To this end we resort to the notion of semi-computability in
order to approximately (by rational numbers) describe quantum states and
quantum channel maps. Then we introduce algorithmic entropies (like algorithmic
quantum coherent information) and derive relevant properties for them. Finally
we define algorithmic quantum capacity and prove that it equals the standard
one
Multiscale Bone Remodelling with Spatial P Systems
Many biological phenomena are inherently multiscale, i.e. they are
characterized by interactions involving different spatial and temporal scales
simultaneously. Though several approaches have been proposed to provide
"multilayer" models, only Complex Automata, derived from Cellular Automata,
naturally embed spatial information and realize multiscaling with
well-established inter-scale integration schemas. Spatial P systems, a variant
of P systems in which a more geometric concept of space has been added, have
several characteristics in common with Cellular Automata. We propose such a
formalism as a basis to rephrase the Complex Automata multiscaling approach
and, in this perspective, provide a 2-scale Spatial P system describing bone
remodelling. The proposed model not only results to be highly faithful and
expressive in a multiscale scenario, but also highlights the need of a deep and
formal expressiveness study involving Complex Automata, Spatial P systems and
other promising multiscale approaches, such as our shape-based one already
resulted to be highly faithful.Comment: In Proceedings MeCBIC 2010, arXiv:1011.005
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