Minor mergers and their impact on the kinematics of old and young stellar populations in disk galaxies

By means of N-body simulations we investigate the impact of minor mergers on the angular momentum and dynamical properties of the merger remnant. Our simulations cover a range of initial orbital characteristics and gas-to-stellar mass fractions (from 0 to 20%), and include star formation and supernova feedback. We confirm and extend previous results by showing that the specific angular momentum of the stellar component always decreases independently of the orbital parameters or morphology of the satellite, and that the decrease in the rotation velocity of the primary galaxy is accompanied by a change in the anisotropy of the orbits. However, the decrease affects only the old stellar population, and not the new population formed from gas during the merging process. This means that the merging process induces an increasing difference in the rotational support of the old and young stellar components, with the old one lagging with respect to the new. Even if our models are not intended specifically to reproduce the Milky Way and its accretion history, we find that, under certain conditions, the modeled rotational lag found is compatible with that observed in the Milky Way disk, thus indicating that minor mergers can be a viable way to produce it. The lag can increase with the vertical distance from the disk midplane, but only if the satellite is accreted along a direct orbit, and in all cases the main contribution to the lag comes from stars originally in the primary disk rather than from stars in the satellite galaxy. We also discuss the possibility of creating counter-rotating stars in the remnant disk, their fraction as a function of the vertical distance from the galaxy midplane, and the cumulative effect of multiple mergers on their creation.

Relation between the work function and Young's modulus of RhSi and estimate of Schottky-barrier height at RhSi/Si interface: An ab-initio study

Density-functional calculations are performed to explore the relationship between the work function and Young's modulus of RhSi, and to estimate the p-Schottky-barrier height (SBH) at the Si/RhSi(010) interface. It is shown that the Young's modulus and the workfunction of RhSi satisfy the generic sextic relation, proposed recently for elemental metals. The calculated p-SBH at the Si/RhSi interface is found to differ only by 0.04 eV in opposite limits, viz., no-pinning and strong pinning. We find that the p-SBH is reduced as much as by 0.28 eV due to vacancies at the interface. (C) 2012 American Institute of Physics. http://dx.doi.org/10.1063/1.4761994]

STM verification of the reduction of the Young's modulus of CdS nanoparticles at smaller sizes

We demonstrate the first STM evaluation of the Young's modulus (E) of nanoparticles (NPs) of different sizes. The sample deformation induced by tip-sample interaction has been determined using current-distance (I-Z) spectroscopy. As a result of tip-sample interaction, and the induced surface deformations, the I-z curves deviates from pure exponential dependence. Normally, in order to analyze the deformation quantitatively, the tip radius must be known. We show, that this necessity is eliminated by measuring the deformation on a substrate with a known Young's modulus (Au(111)) and estimating the tip radius, and afterwards, using the same tip (with a known radius) to measure the (unknown) Young's modulus of another sample (nanoparticles of CdS). The Young's modulus values found for 3 NP's samples of average diameters of 3.7, 6 and 7.5 nm, were E similar to 73%, 78% and 88% of the bulk value, respectively. These results are in a good agreement with the theoretically predicted reduction of the Young's modulus due to the changes in hydrostatic stresses which resulted from surface tension in nanoparticles with different sizes. Our calculation using third order elastic constants gives a reduction of E which scales linearly with 1/r (r is the NP's radius). This demonstrates the applicability of scanning tunneling spectroscopy for local mechanical characterization of nanoobjects. The method does not include a direct measurement of the tip-sample force but is rather based on the study of the relative elastic response. (C) 2014 Elsevier B.V. All rights reserved.

Evaluation of the Effectiveness of Representative Methods for Determining Young's Modulus and Hardness from Instrumented Indentation Data

The effectiveness of Oliver & Pharr's (O&P's) method, Cheng & Cheng's (C&C's) method, and a new method developed by our group for estimating Young's modulus and hardness based on instrumented indentation was evaluated for the case of yield stress to reduced Young's modulus ratio (sigma(y)/E-r) >= 4.55 x 10(-4) and hardening coefficient (n) <= 0.45. Dimensional theorem and finite element simulations were applied to produce reference results for this purpose. Both O&P's and C&C's methods overestimated the Young's modulus under some conditions, whereas the error can be controlled within +/- 16% if the formulation was modified with appropriate correction functions. Similar modification was not introduced to our method for determining Young's modulus, while the maximum error of results was around +/- 13%. The errors of hardness values obtained from all the three methods could be even larger and were irreducible with any correction scheme. It is therefore suggested that when hardness values of different materials are concerned, relative comparison of the data obtained from a single standard measurement technique would be more practically useful. It is noted that the ranges of error derived from the analysis could be different if different ranges of material parameters sigma(y)/E-r and n are considered.

“La Generación exiliada” y su imagen de Rosas a través de la prensa : comparación entre “El Grito Argentino y Muera Rosas!”

Resumen: El presente artículo analiza y compara el discurso verbal de El Grito Argentino (1839) y Muera Rosas! (1841-1842), dos periódicos antirrosistas publicados en Montevideo por jóvenes intelectuales emigrados de la “generación del 37”. Distribuidos secretamente en Buenos Aires y las provincias del litoral, su propósito era movilizar a los sectores antirrosistas en contextos de crisis del gobierno de Juan Manuel de Rosas. Este estudio focaliza especialmente en los distintos recursos proselitistas empleados así como el público al que ambos estaban destinados. Con el apoyo de fuentes históricas y correspondencia de la época, el artículo también aborda las relaciones que los jóvenes emigrados mantenían entre sí y con los dirigentes unitarios también exiliados en la Banda Oriental.

An Improved Energy Method For Determining Young'S Modulus By Instrumented Indentation Using A Berkovich Tip

We previously proposed a method for estimating Young's modulus from instrumented nanoindentation data based on a model assuming that the indenter had a spherical-capped Berkovich geometry to take account of the bluntness effect. The method is now further improved by releasing the constraint on the tip shape, allowing it to have a much broader arbitrariness to range from a conical-tipped shape to a flat-ended shape, whereas the spherical-capped shape is just a special case in between. This method requires two parameters to specify a tip geometry, namely, a volume bluntness ratio V-r and a height bluntness ratio h(r). A set of functional relationships correlating nominal hardness/reduced elastic modulus ratio (H-n/E-r) and elastic work/total work ratio (W-e/W) were established based on dimensional analysis and finite element simulations, with each relationship specified by a set of V-r and h(r). Young's modulus of an indented material can be estimated from these relationships. The method was shown to be valid when applied to S45C carbon steel and 6061 aluminum alloy.

Nanoindentation of thin-film-substrate system: Determination of film hardness and Young's modulus

In the present paper, the hardness and Young's modulus of film-substrate systems are determined by means of nanoindentation experiments and modified models. Aluminum film and two kinds of substrates; i.e. glass and silicon, are studied. Nanoindentation XP II and continuous stiffness mode are used during the experiments. In order to avoid the influence of the Oliver and Pharr method used in the experiments, the experiment data are analyzed with the constant Young's modulus assumption and the equal hardness assumption. The volume fraction model (CZ model) proposed by Fabes et al. (1992) is used and modified to analyze the measured hardness. The method proposed by Doerner and Nix (DN formula) (1986) is modified to analyze the measured Young's modulus. Two kinds of modified empirical formula are used to predict the present experiment results and those in the literature, which include the results of two kinds of systems, i.e., a soft film on a hard substrate and a hard film on a soft substrate. In the modified CZ model, the indentation influence angle, phi, is considered as a relevant physical parameter, which embodies the effects of the indenter tip radius, pile-up or sink-in phenomena and deformation of film and substrate.

关于Young-Laplace公式的吉布斯自由能证明

对于为论证球形液滴附加压强的Young-Laplace公式而设计的一个理想实验,有文献试图借助吉布斯自由能函数进行证明,本文给出符合这一条件的证明方法.

The Use of Herbicides to Control Hydrilla and the Effects on Young Largemouth Bass Population Characteristics and Aquatic Vegetation in Lake Seminole, Georgia

From 1997 to 2003, we examined the impacts of two aquatic herbicides, fluridone (Sonar; 1-methyl-3-phenyl-5-[3-(trifluromethl) phenyl]-4(1H)-pyridinone), and dipotassium salt of endothall (Aquathol K; 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid), used to control dense hydrilla (Hydrilla verticillata L. f. Royle), on population characteristics of juvenile largemouth bass (Micropterus salmoides Lacepede) in small coves (<10 ha) in Lake Seminole, Georgia. In addition, we estimated areal coverage and species composition of submersed aquatic vegetation (SAV) communities in each cove. Fish and plants were sampled in both control (hydrilla infested)and herbicide treated coves in November and March- April each year. Electrofishing catch-per-effort for both number and weight of age-0 and age-1 fish for the 1997 to 2002 year classes was either the same or higher (p < 0.05) in herbicide treated than in control coves. Age-0 fish were larger (p <0.05) in treated, than in control coves in November, but at age-1 in the following spring, fish were slightly longer (p <0.05) in the control coves. Higher age-0 catches were associated with greater percent reductions in numeric catch between age-0 and age-1 and reduced lengths of fish in November indicating density-dependent effects. Age-0 fish lengths were also negatively correlated to percent cover of both total and native SAV. Total or native SAV coverages were not associated with catch-per-unit effort for number and weight, but nearly all control and herbicide treated coves had total SAV coverage greater than 40%. Applications of both Sonar and Aquathol K reduced total SAV coverage and hydrilla, permitted the establishment of native SAVs, and had either neutral or positive impacts on young largemouth bass in small coves in Lake Seminole. (PDF contains 7 pages.)

Pamplona, toda ella un castillo, y más que ciudad, ciudadela. Construcción de la imagen de una ciudad, 1876-1941

[ES] Un estudio de Pamplona (España) como una de las ciudades decimonónicas europeas resueltas a resistirse al modelo de gran urbe universal despersonalizada y anómica. Comparación con Vitoria, inmersa en ese proceso.

História do movimento político, que no anno de 1842 teve lugar na provincia de Minas Geraes

José Antonio Marinho nasceu em Minas Gerais, em 1803, e morreu no Rio de Janeiro, em 1853. Em 1823, de passagem pela Bahia, envolveu-se nas lutas políticas daquele ano. Seguiu depois para Pernambuco, onde tomou parte, em 1824, na Confederação do Equador. Entrou para o Seminário de Olinda, mas denúncias de sua participação nos acontecimentos de 1824 impediram sua ordenação. Voltou, então, para Minas Gerais e conseguiu concluir sua formação sacerdotal. Ordenado em 1829, voltou às lides políticas, tornando-se advogado, jornalista e deputado provincial. Em 1836m elegeu-se deputado-geral por Minas Gerais, em 1842, tomou parte na Revolução Liberal, da qual foi primeiro historiador. Apesar de ter participado dos acontecimentos que historiou, tendo sido, por isso, acusado de parcial, o autor primou “pela verdade da exposição dos fatos”, como disse o Barão Homem de Melo. Com a autoridade de historiador da Revolução Liberal de 1842, Aluísio de Almeida afirmou que, sem a Historia do movimento politico, que no anno de 1842 teve lugar na Provincia de Minas Geraes, seria impossível escrever sobre aquele movimento. Obra rara, valorizada por treze litografias, que Aluísio de Almeida considera, com razão, “preciosas” : nove retratos, quatro vistas e uma planta, estas desdobradas. As litografias do primeiro volume se constituem de retratos do autor e de J. Feliciano, J. P. Dias de Carvalho e T. B. Ottoni, vistas da Praça de Barbacena, da Vila de Queluz e do Arraial da Lagoa Santa e planta do Arraial de Santa Luzia e suas imediações; e as do segundo volume de retratos de R. T. d’Aguiar, D.J. C. de Mendonça Franco, J. G. Teixeira de Carvalho, Diogo Antônio Feijó e Manuel Alves Branco e vista de Sabará.

Collecção das Leis do Imperio do Brasil de 1842

Parte 1 - Decisões