Neural Activity in Quarks Language: Lattice Field Theory for a Network of Real Neurons.

Brain-computer interfaces have seen extraordinary surges in developments in recent years, and a significant discrepancy now exists between the abundance of available data and the limited headway made in achieving a unified theoretical framework. This discrepancy becomes particularly pronounced when examining the collective neural activity at the micro and meso scale, where a coherent formalization that adequately describes neural interactions is still lacking. Here, we introduce a mathematical framework to analyze systems of natural neurons and interpret the related empirical observations in terms of lattice field theory, an established paradigm from theoretical particle physics and statistical mechanics.

Large-deviation theory of increasing returns.

An influential theory of increasing returns was proposed by the economist W. B. Arthur in the 1980s to explain the lock-in phenomenon between two competing commercial products.

Energy of the interacting self-avoiding walk at the θ point.

We perform a numerical study of a new microcanonical polymer model on a three-dimensional cubic lattice, consisting of ideal chains whose range and number of nearest-neighbor contacts are fixed to given values. Our simulations suggest an interesting exact relation concerning the internal energy per monomer of the interacting self-avoiding walk at the θ point.

Pyruvate cellular uptake and enzymatic conversion probed by dissolution DNP-NMR: the impact of overexpressed membrane transporters.

Pyruvate membrane crossing and its lactate dehydrogenase-mediated conversion to lactate in cells featuring different levels of expression of membrane monocarboxylate transporters (MCT4) were probed by dissolution dynamic nuclear polarization-enhanced NMR. Hyperpolarized C-1-labeled pyruvate was transferred to suspensions of rodent tumor cell carcinoma, cell line 39. The pyruvate-to-lactate conversion rate monitored by dissolution dynamic nuclear polarization-NMR in carcinoma cells featuring native MCT4 expression level was lower than the rate observed for cells in which the human MCT4 gene was overexpressed.

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR.

The main limitation of NMR-based investigations is low sensitivity. This prompts for long acquisition times, thus preventing real-time NMR measurements of metabolic transformations. Hyperpolarization via dissolution DNP circumvents part of the sensitivity issues thanks to the large out-of-equilibrium nuclear magnetization stemming from the electron-to-nucleus spin polarization transfer.

Hyperpolarized (6)Li as a probe for hemoglobin oxygenation level.

Hyperpolarization by dissolution dynamic nuclear polarization (DNP) is a versatile technique to dramatically enhance the nuclear magnetic resonance (NMR) signal intensity of insensitive long-T1 nuclear spins such as (6)Li. The (6)Li longitudinal relaxation of lithium ions in aqueous solutions strongly depends on the concentration of paramagnetic species, even if they are present in minute amounts. We herein demonstrate that blood oxygenation can be readily detected by taking advantage of the (6)Li signal enhancement provided by dissolution DNP, together with the more than 10% decrease in (6)Li longitudinal relaxation as a consequence of the presence of paramagnetic deoxyhemoglobin.

Over 35% liquid-state 13C polarization obtained via dissolution dynamic nuclear polarization at 7 T and 1 K using ubiquitous nitroxyl radicals.

The most versatile method to increase liquid-state (13)C NMR sensitivity is dissolution dynamic nuclear polarization. The use of trityl radicals is usually required to obtain very large (13)C polarization via this technique. We herein demonstrate that up to 35% liquid-state (13)C polarization can be obtained in about 1.