Fetkin-hydro,a new thermo-hydrological algorithm for low-temperature thermochronological modeling

Despite two decades of major advances in the field of thermochronological modeling,state-of-the-art numerical implementations still rely mostly on burial and exhumation processes to explain radiometric measurements.Even though such an approach has proved valuable,failing to account for other first-order geological variables has led to misinterpretations and therefore,calls for a refinement.In this study a new version of the Fetkin(finite element temperature kinematics,Ecopetrol)program is presented.Its new algorithm couples time-dependent hydrological and thermal calculations,thus rendering thermochronological ages that,instead of being solely dependent on the kinematical evolution of a system,conditioning by the fluid flow is also present.In contrast with previous thermochronological models,this work considers the influence of effective stress on rock properties(porosity and permeability)and therefore,in thermal conductivity.Sensitivity analyses addressing relevant geological questions show not only the versatility of the code but also,new perspectives on forward low-temperature thermochronological modeling.Groundwater circulation through pure-sandstone settings produce colder thermal architectures than those obtained in impermeable domains.Differences in cooling ages from models with and without fluid circulation are up to 5 Myr.A 4-fold variation in thrusting rates(0.5 km/Myr to 2 km/Myr)produces a 15-Myr difference in cooling ages in models with fluid flow,which contrasts to much lower differences,only 2 Myr,in domains without(or minimal)fluid circulation.2D thermal solutions in fold-bend-fold thrust belts composed of sandstones remain static despite substantial relief development by kinematic folding.A case-study from Western Argentina,in the Andean Precordillera,confirms the plausibility of the numerical algorithm here posed and raises new questions on the first-order thermal controls in settings under deformation.

Approximation Method for the Relaxed Covariant Form of the Gravitational Field Equations for Particles

We present a study of the so called relaxed field equations of general relativity in terms of a decomposition of the metric;which is designed to deal with the notion of particles. Several known results are generalized to a coordinate free covariant discussion. We apply our techniques to the study of a particle up to second order.

Experimental and Computational Study of the Effect of Temperature on the Electro-Polymerization Process of Thiophene

Temperature effect on the nucleation and growth mechanisms (NGM) of poly(thiophene) (PTh) was investigated through experimental and computational tools. The computational simulation method was based on a kinetic Monte Carlo algorithm. It reproduced key processes such as diffusion, oligomerization, and the precipitation of oligomers onto the electrode surface. Electrochemical synthesis conditions at temperatures between 263 and 303 K were optimized. The deconvolution of the i-t transients reflected two contributions: a progressive nucleation with three-dimensional growth controlled by diffusion and the other by charge transfer, PN3Ddif and PN3Dct, respectively. As temperature decreased, a diminution of the charge associated to each contribution was observed and the nucleation induction time increased. Experimental and computational evidence indicated that temperature does not change the nucleation and growth mechanism (NGM). This effect was ascribed to kinetic factors rather than to film conductivity. This work contrasts simulation and experimental evidence and demonstrates how computational simulations can help to understand the electrochemical process of conducting polymers formation.

A compartmental model for antibiotic resistant,bacterial infections over networks

This paper presents a compartmental model for bacterial infections in a population distributed over a network of individuals.Within each node,individuals interact,bac­teria can be transmitted and the disease may be spread;moreover,the acquisition of bacterial antibiotic resistance is considered.In addition,nodes are connected through weighted edges,and consequently individuals from different nodes may interact.As a result,the infection may be propagated over the network.We perform an analysis on this propagation as well as numerical simulations in order to illustrate the validity of the model.

Composition of Fractional Orlicz Maximal Operators and A1-weights on Spaces of Homogeneous Type

For a Young function θ with 0 ≤α 〈 1, let Mα,θ be the fractional Orlicz maximal operator defined in the context of the spaces of homogeneous type （X, d, μ） by Mα,θf（x） = supx∈（B）α ｜｜f｜｜θ,B, where ｜｜f｜｜θ,B is the mean Luxemburg norm of f on a ball B. When α= 0 we simply denote it by Me. In this paper we prove that if Ф and ψare two Young functions, there exists a third Young function θ such that the composition Mα,ψ o MФ is pointwise equivalent to Mα,θ. As a consequence we prove that for some Young functions θ, if Mα,θf 〈∞a.e. and δ ∈（0,1） then （Mα,θf）δ is an A1-weight.

A kinetic model for horizontal transfer and bacterial antibiotic resistance

This paper presents a mathematical model for bacterial growth, mutations, horizontal transfer and development of antibiotic resistance. The model is based on the so-called kinetic theory for active particles that is able to capture the main complexity features of the system. Bacterial and immune cells are viewed as active particles whose microscopic state is described by a scalar variable. Particles interact among them and the temporal evolution of the system is described by a generalized distribution function over the microscopic state. The model is derived and tested in a couple of case studies in order to confirm its ability to describe one of the most fundamental problems of modern medicine, namely bacterial resistance to antibiotics.

Stable and Accurate Second-Order Formulation of the Shifted Wave Equation

High order finite difference approximations are derived for a one-dimensional model of the shifted wave equation written in second-order form. Thedomain is discretized using fully compatible summation by parts operators and theboundary conditions are imposed using a penalty method, leading to fully explicittime integration. This discretization yields a strictly stable and efficient scheme. Theanalysis is verified by numerical simulations in one-dimension. The present study isthe first step towards a strictly stable simulation of the second-order formulation ofEinstein’s equations in three spatial dimensions.