Biomedical subjects

Marcelo Gleiser

Publications and source records attributed to Marcelo Gleiser.

5 recordsLinked to original sources

PubMed2006

Asymmetric spatiotemporal evolution of prebiotic homochirality.

The role of asymmetry on the evolution of prebiotic homochirality is investigated in the context of autocatalytic polymerization reaction networks. A model featuring enantiometric cross-inhibition and chiral bias is used to study the diffusion equations controlling the spatiotemporal development of left and right-handed domains. Bounds on the chiral bias are obtained based on present-day constraints on the emergence of life on early Earth. The viability of biasing mechanisms such as weak neutral currents and circularly polarized UV light is discussed. The results can be applied to any hypothetical planetary platform.

Catalysis↗

PubMed2006

Prebiotic homochirality as a critical phenomenon.

The development of prebiotic homochirality on early-Earth or another planetary platform may be viewed as a critical phenomenon. It is shown, in the context of spatio-temporal polymerization reaction networks, that environmental effects--be they temperature surges or other external disruptions--may destroy any net chirality previously produced. In order to understand the emergence of prebiotic homochirality it is important to model the coupling of polymerization reaction networks to different planetary environments.

Evolution, Chemical↗

PubMed2005

Resonant nucleation.

We investigate the role played by fast quenching on the decay of metastable (or false vacuum) states. Instead of the exponentially slow decay rate per unit volume, Gamma(HN) approximately exp([-E(b)/k(B)T] (E(b) is the free energy of the critical bubble), predicted by homogeneous nucleation theory, we show that under fast enough quenching the decay rate is a power law Gamma(RN) approximately [E(b)/k(B)T](-B), where B is weakly sensitive to the temperature. For a range of parameters, large-amplitude oscillations about the metastable state trigger the resonant emergence of coherent subcritical configurations. Decay mechanisms for different E(b) are proposed and illustrated in a (2+1)-dimensional scalar field model.

Journal Article↗

PubMed2003

Resonant emergence of global and local spatiotemporal order in a nonlinear field model.

We investigate the nonequilibrium evolution of a scalar field in (2+1) dimensions. The field is set in a double-well potential in contact (open) or not (closed) with a heat bath. For closed systems, we observe the synchronized emergence of coherent spatiotemporal configurations, identified with oscillons. This initial global ordering degenerates into localized order until all oscillons disappear. We show that the synchronization is driven by resonant parametric oscillations of the field's zero mode and that local ordering is only possible outside equipartition. None of these orderings occur for open systems.

Journal Article↗

PubMed2002

Nonequilibrium precursor model for the onset of percolation in a two-phase system.

Using a Boltzmann-like equation, we investigate the nonequilibrium dynamics of nonperturbative fluctuations within the context of Ginzburg-Landau models. As an illustration, we examine how a two-phase system initially prepared in a homogeneous, low-temperature phase becomes populated by precursors of the opposite phase as the temperature is increased. We compute the critical value of the order parameter for the onset of percolation, which signals the breakdown of the conventional dilute gas approximation.

Journal Article↗