El viaje de Pedro Montt por el sur de Perú y el norte de Chile (enero-marzo de 1880)

Indexación: Revista UNAB.En los años previos a que asumiese la presidencia de la República (1906- 1910), Pedro Montt había sido, desde 1876, diputado, senador, ministro de diversas carteras de gobierno, miembro de la Junta de Beneficencia de Santiago y de la Sociedad de Instrucción Primaria, director de la Casa de Orates y voluntario de la sexta Compañía de Bomberos de Santiago, entre otras actividades. Fue un mandatario que tuvo una prolongada trayectoria política, la que cimentó un camino expedito para llegar a La Moneda por la experiencia acumulada en todos esos años. Al mismo tiempo, era un político del cual se le reconocía su alta cultura y su pasión por acumular conocimientos acerca de las áreas públicas y privadas en las que se desempeñó. Tenía una especial cercanía con los libros, que lo llevó a poseer una importante biblioteca personal y a crear una para el Congreso Nacional. Sin embargo, sus viajes fueron los que marcaron una huella trascendental en su formación, pues lo llevaron a recorrer el mundo en compañía de su esposa, Sara del Campo

Coulomb's law modification driven by a logarithmic electrodynamics

We examine physical aspects for the electric version of a recently proposed logarithmic electrodynamics, for which the electric field of a point-like charge is finite at the origin. It is shown that this electrodynamics displays the vacuum birefringence phenomenon in the presence of external magnetic field. Afterwards we compute the lowest-order modification to the interaction energy by means of the gauge-invariant but path-dependent variables formalism. These are shown to result in a long-range ($1/r^3$-type) correction, in addition to a linear and another logarithmic correction, to the Coulomb potential.Comment: 4 pages. arXiv admin note: text overlap with arXiv:1709.0386

Remarks on Screening in a Gauge-Invariant Formalism

In this paper we display a direct and physically attractive derivation of the screening contribution to the interaction potential in the Chiral Schwinger model and generalized Maxwell-Chern-Simons gauge theory. It is shown that these results emerge naturally when a correct separation between gauge-invariant and gauge degrees of freedom is made. Explicit expressions for gauge-invariant fields are found.Comment: 13 pages, 1 figure, to appear in PR

The photino sector and a confining potential in a supersymetric Lorentz-symmetry-violating model

We study the spectrum of the minimal supersymmetric extension of the Carroll-Field-Jackiw model for Electrodynamics with a topological Chern-Simons-like Lorentz-symmetry violating term. We identify a number of independent background fermion condensates, work out the gaugino dispersion relation and propose a photonic effective action to consider aspects of confinement induced by the SUSY background fermion condensates, which also appear to signal Lorentz-symmetry violation in the photino sector of the action. Our calculations of the static potential are carried out within the framework of the gauge-invariant but path-dependent variables formalism which are alternative to the Wilson loop approach. Our results show that the interaction energy contains a linear term leading to the confinement of static probe charges.Comment: 11 pages, photino dispersion relation is extended to included the case the photino acquires mass through spontaneous SUSY breakin

Aspects of CPT-even Lorentz-symmetry violating physics in a supersymmetric scenario

Background fermion condensates in a landscape dominated by global SUSY are reassessed in connection with a scenario where Lorentz symmetry is violated in the bosonic sector (actually, the photon sector) by a $CPT$-even $k_F$-term. An effective photonic action is discussed that originates from the supersymmetric background fermion condensates. Also, the photino mass emerges in terms of a particular condensate contrary to what happens in the $k_{AF}$-violation. Finally, the interparticle potential induced by the effective photonic action is investigated and a confining profile is identified.Comment: 14 pages. arXiv admin note: text overlap with arXiv:1102.3777 by other author

Coulomb's law corrections from a gauge-kinetic mixing

We study the static quantum potential for a gauge theory which includes the mixing between the familiar photon $U(1)_{QED}$ and a second massive gauge field living in the so-called hidden-sector $U(1)_h$. Our discussion is carried out using the gauge-invariant but path-dependent variables formalism, which is alternative to the Wilson loop approach. Our results show that the static potential is a Yukawa correction to the usual static Coulomb potential. Interestingly, when this calculation is done inside a superconducting box, the Coulombic piece disappears leading to a screening phase.Comment: 4 page

High Power Ultrasound to Recover Fine Particles in Flotation Process

9 pages, 6 figures.-- Communication presented at: Forum Acusticum Sevilla 2002 (Sevilla, Spain, 16-20 Sep 2002), comprising: 3rd European Congress on Acoustics; XXXIII Spanish Congress on Acoustics (TecniAcústica 2002); European and Japanese Symposium on Acoustics; 3rd Iberian Congress on Acoustics.-- Special issue of the journal Revista de Acústica, Vol. XXXIII, year 2002.The flotation process to recover useful substances from minerals has been used for dozens of years. For the flotation, air bubbles in a water solution of finely ground mineral particles must be introduced. The particles were prepared with chemical substances (surfactants) to be caught by the bubbles.Some attempts were made to improve the whole process, the best results reported were obtained for a technique called the "high energy" flotation experiments, [1] [2][3]. It seems that the recovering of the useful substances can be improved if some energy can be injected to the reactor with the metallurgic pulp. This suggests that an ultrasonic field can also improve the recovering in flotation. In this paper an application of acoustic cavitation to the flotation process is explored.The authors would like to thank the financial support of project FONDECYT 1010243.Peer reviewe

The Montana Kaimin, May 14, 1918

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/1478/thumbnail.jp

Stress Inversion in a Gelatin Box: Testing Eruptive Vent Location Forecasts With Analog Models

Assessing volcanic hazard in regions of distributed volcanism is challenging because of the uncertain location of future vents. A statistical-mechanical strategy to forecast such locations was recently proposed: here, we further develop and test it with analog models. We stress a gelatin block laterally and with surface excavations, and observe air-filled crack trajectories. We use the observed surface arrivals to sample the distributions of parameters describing the stress state of the gelatin block, combining deterministic crack trajectory simulations with a Monte Carlo approach. While the individual stress parameters remain unconstrained, we effectively retrieve their ratio and successfully forecast the arrival points of subsequent cracks