Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model

This article presents an original code for Big Bang Nucleosynthesis in a baryon inhomogeneous model of the universe. In this code neutron diffusion between high and low baryon density regions is calculated simultaneously with the nuclear reactions and weak decays that compose the nucleosynthesis process. The size of the model determines the time when neutron diffusion becomes significant. This article describes in detail how the time of neutron diffusion relative to the time of nucleosynthesis affects the final abundances of He4, deuterium and Li7. These results will be compared with the most recent observational constraints of He4, deuterium and Li7. This inhomogeneous model has He4 and deuterium constraints in concordance for baryon to photon ratio eta = (4.3 - 12.3) X 10^{-10} Li7 constraints are brought into concordance with the other isotope constraints by including a depletion factor as high as 5.9. These ranges for the baryon to photon ratio and for the depletion factor are larger than the ranges from a Standard Big Bang Nucleosynthesis model.Comment: 7/15, added reference

Broadband probing magnetization dynamics of the coupled vortex state permalloy layers in nanopillars

Broadband magnetization response of coupled vortex state magnetic dots in layered nanopillars was explored as a function of in-plane magnetic field and interlayer separation. For dipolarly coupled circular Py(25 nm)/Cu(20 nm)/Py(25 nm) nanopillars of 600 nm diameter, a small in-plane field splits the eigenfrequencies of azimuthal spin wave modes inducing an abrupt transition between in-phase and out-of-phase kinds of the low-lying coupled spin wave modes. The critical field for this splitting is determined by antiparallel chiralities of the vortices in the layers. Qualitatively similar (although more gradual) changes occur also in the exchange coupled Py(25 nm)/Cu(1 nm)/Py(25 nm) tri-layer nanopillars. These findings are in qualitative agreement with micromagnetic dynamic simulations

The Korean War Through the Eyes of Ray DeWeese

Ray DeWeese was born in Cleveland, TN on May 10, 1928 and has lived in Cleveland most of his life. He enlisted in the Marine Corps at 17 years old and fought towards the end of World War II and went off to be a pilot and officer during the Korean War. This interview depicts Mr.DeWeese’s experience during World War II but digs deeper into the difficulty of being a pilot during the brutal Korean War. As Mr. DeWeese recounts his traumatic experience he emphasizes how his diligent training, hardworking comrades, and his Faith in God got him through the ordeal. The interview was conducted November 4,10, and 13 at Bradley Healthcare & Rehab Center in Cleveland, TN

Opacity in compact extragalactic radio sources and its effect on radio-optical reference frame alignment

Accurate alignment of the radio and optical celestial reference frames requires detailed understanding of physical factors that may cause offsets between the positions of the same object measured in different spectral bands. Opacity in compact extragalactic jets (due to synchrotron self-absorption and external free-free absorption) is one of the key physical phenomena producing such an offset, and this effect is well-known in radio astronomy ("core shift"). We have measured the core shifts in a sample of 29 bright compact extragalactic radio sources observed using very long baseline interferometry (VLBI) at 2.3 and 8.6 GHz. We report the results of these measurements and estimate that the average shift between radio and optical positions of distant quasars would be of the order of 0.1-0.2 mas. This shift exceeds positional accuracy of GAIA and SIM. We suggest two possible approaches to carefully investigate and correct for this effect in order to align accurately the radio and optical positions. Both approaches involve determining a Primary Reference Sample of objects to be used for tying the radio and optical reference frames together.Comment: 4 pages, 1 figure; to appear in IAU Symposium 248 Proceedings, "A Giant Step: from Milli- to Micro-arcsecond Astrometry", eds. W.-J. Jin, I. Platais, M. Perryma

Models of environment and T_1 relaxation in Josephson Charge Qubits

A theoretical interpretation of the recent experiments of Astafiev et. al. on the T_1-relaxation rate in Josephson Charge Qubits is proposed. The experimentally observed reproducible nonmonotonic dependence of T_1 on the splitting E_J of the qubit levels suggests further specification of the previously proposed models of the background charge noise. From our point of view the most promising is the ``Andreev fluctuator'' model of the noise. In this model the fluctuator is a Cooper pair that tunnels from a superconductor and occupies a pair of localized electronic states. Within this model one can naturally explain both the average linear T_1(E_J) dependence and the irregular fluctuations. The role of fluctuators in the formation of strong resonant peaks in this dependence is also discussed.Comment: 4 pages, 3 figure

Amine-impregnated Alumina Solid Sorbents for CO2 Capture. Lessons Learned

The application of Amine-impregnated Alumina Solid Sorbent Carbon Capture is a suitable option to increase CO2 capture efficiency and to reduce by several percentage points the efficiency penalty of CCS in power plants. These sorbents require less regeneration energy due to the reduction in water content and the higher heat capacity of solids. The objective is to demonstrate that the use of amine-impregnated alumina solid sorbents is a suitable option to increase CO2 capture efficiency and to reduce several percentage points the efficiency penalty caused by the capture system in the power plant. The proposed innovative sorbent consists in amines supported on high surface area and high porosity solid materials, such as alumina and silica-alumina. Good results have been achieved. Important high porosity support makes possible to obtain high CO2 capture capacities over 50 mg CO2/g of sorbent. As a consequence, the combination of this CCS option with a coal power plant may reduce the efficiency penalty down to 7 efficiency points. This figure could make feasible the impregnated amine solid sorbent as a future and promising option for CO2 capture

On the Flexibility of Coal-fired Power Plants with Integrated Ca-looping CO2 Capture Process

The share of renewable energy production is growing quickly. The output and variability of renewable power will force to fossil fuel power plants to adapt its electricity production to variable demand. In a future scenario, with CO2 capture systems installed in power plants, the variable performance will affect not only to fossil fuel power plant but also to the CO2 capture behavior. The knowledge of part load performance of fossil fuel power plants with CO2 capture systems will be essential in a near future. This paper analyzes the integration between Ca-looping cycles and power plants to foresee the requirements derived from a flexible operation. With this goal, the performance of the integrated system under different load scenarios is studied. An integration scheme designed for nominal load is proposed under different load scenarios at steady state, to study their performance. Then, for each load scenario, the optimum integration is designed, to quantify the minimum energy penalty of each specific load level. Finally, a comparative analysis of the general integration against the optimum one for each scenario is performed

El águila bicéfala: belicismo y humanitarismo

El presente estudio analiza los recientes discursos sobre las guerras actuales. Hemos podido identificar dos tipos de argumentaciones, una proveniente del ámbito belicista y otro del ámbito humanitarista. El primero de estos discursos defiende explícitamente las intervenciones militares y recurre a nociones como el poder y la hegemonía. El segundo en cambio apela a la defensa de valores universales, la democracia y los derechos humanos. No obstante, aun partiendo de posturas teóricas opuestas (incluso enfrentadas), finalmente confluyen en la normalización y legitimación de los conflictos actuales. Así pues, en ambos casos, quedan legitimadas las guerras desde posiciones teóricas opuestas, y además bajo esas teorizaciones quedan relegadas otras opciones no bélicas. Por ello el propósito del presente texto es realizar un repaso y balance de esas teorizaciones, puesto que, aparte de animar el debate intelectual actual, tienen una importante influencia práctica en la forma de concebir los conflictos internacionales (e incluso los conflictos sociales), en los que se juegan la vida de miles de personas.This paper analyzes the recent discourses about the current wars. We identify two sorts of these discourses, one of them is linked to the warmongering realm and the other one is related to humanitarianism. The warmongering account supports the military interventions in an explicit way, and uses notions as power and hegemony. In contrast, humanitarianism calls for the protection of Human Rights and democracy as universal values. Although both positions come from different theoretical accounts, even opposed, they converge on to normalize and legitimize the ongoing wars. So, in both cases, wars are legitimized from opposed theoretical accounts, and given their prevalence not warmongering options are shifted. According to this, the aim of this paper is taking into account those theoretical positions because they are inspiring the current academic debate about wars and have an enormous practical influence on how to conceive international conflicts, but social also, in which the lives of thousands of people are at stake

Ressenyes

Index de les obres ressenyades: Immanuel WALLERSTEIN, L'universalisme europeu. La retòrica del poder ; Universalismo europeo. El discurso del pode