On the Collisional Damping of Giant Dipole Resonance

Collisional damping widths of giant dipole excitations are calculated in Thomas-Fermi approximation by employing the microscopic in-medium cross-sections of Li and Machleidt and the phenomenological Gogny force. The results obtained in both calculations compare well, but account for about 25-35% of the observed widths in $^{120}Sn$ and $^{208}Pb$ at finite temperatures.Comment: Latex, 13 pages, 4 figure

Measuring systemic risk: structural approaches

The financial crisis of 2007-2008 has demonstrated that factors for financial distress of large parts of the economy depend to a large extent on the interrelations between the financial institutions. Risks threatening the financial sector can be decomposed into risks based in the individual factors for single institutions and risks which can be attributed to the financial system as a whole. This part of the risks is called systemic risk. We review several approaches for quantifying systemic risk, most of them based on structural credit modeling. In particular, we present an approach that is inspired by the fact that the joint probability distributions can be represented by their individual marginals and the copula function, which represents the interrelations

Active laser frequency stabilization using neutral praseodymium (Pr)

We present a new possibility for the active frequency stabilization of a laser using transitions in neutral praseodymium. Because of its five outer electrons, this element shows a high density of energy levels leading to an extremely line-rich excitation spectrum with more than 25000 known spectral lines ranging from the UV to the infrared. We demonstrate the active frequency stabilization of a diode laser on several praseodymium lines between 1105 and 1123 nm. The excitation signals were recorded in a hollow cathode lamp and observed via laser-induced fluorescence. These signals are strong enough to lock the diode laser onto most of the lines by using standard laser locking techniques. In this way, the frequency drifts of the unlocked laser of more than 30 MHz/h were eliminated and the laser frequency stabilized to within 1.4(1) MHz for averaging times >0.2 s. Frequency quadrupling the stabilized diode laser can produce frequency-stable UV-light in the range from 276 to 281 nm. In particular, using a strong hyperfine component of the praseodymium excitation line E = 16 502.616_7/2 cm^-1 -> E' = 25 442.742_9/2 cm^-1 at lambda = 1118.5397(4) nm makes it possible - after frequency quadruplication - to produce laser radiation at lambda/4 = 279.6349(1) nm, which can be used to excite the D2 line in Mg^+.Comment: 10 pages, 14 figure

Stars of extragalactic origin in the solar neighborhood

We computed the spatial velocities and the galactic orbital elements using Hipparcos data for 77 nearest main-sequence F-G-stars with published the iron, magnesium, and europium abundances determined from high dispersion spectra and with the ages estimated from theoretical isochrones. A comparison with the orbital elements of the globular clusters that are known was accreted by our Galaxy in the past reveals stars of extragalactic origin. We show that the relative elemental abundance ratios of r- and \alpha- elements in all the accreted stars differ sharply from those in the stars that are genetically associated with the Galaxy. According to current theoretical models, europium is produced mainly in low mass Type II supernovae (SNe II), while magnesium is synthesized in larger amounts in high mass SN II progenitors. Since all the old accreted stars of our sample exhibit a significant Eu overabundance relative to Mg, we conclude that the maximum masses of the SNII progenitors outside the Galaxy were much lower than those inside it are. On the other hand, only a small number of young accreted stars exhibit low negative ratios $[Eu/Mg] < 0$. The delay of primordial star formation burst and the explosions of high mass SNe II in a relatively small part of extragalactic space can explain this situation. We provide evidence that the interstellar medium was weakly mixed at the early evolutionary stages of the Galaxy formed from a single proto-galactic cloud and that the maximum mass of the SN II progenitors increased in it with time simultaneously with the increase in mean metallicity.Comment: Accepted for 2004, Astronomy Letters, Vol. 30, No. 3, P.148-158 15 pages, 3 figure

O IMPACTO DAS REFLEXÕES INTERDISCIPLINARES NA TEORIA GERAL DO DIREITO DE HANS KELSEN

O impacto das reflexões interdisciplinares nas ciências sociais tem levado a diversas aéreas do conhecimento social a repensar seus pressupostos e possibilidades. A Teoria Geral do Direito, por outro lado, ainda não enfrentou tal debate de extrema relevância como suporte para repensar seus limites e possibilidades. A partir da proposição da cultura como elemento central para pensar o Direito é possível encontrar três limitações da teoria geral do Direito: a limitação temporal, a limitação geográfica e a limitação relacionada à diversidade dentro de uma mesma cultura

Encíclica Laudato Si’: elementos fundamentais para uma ética socioambiental

Este trabalho busca refletir sobre a ética socioambiental instigada pela Encíclica Laudato Si’ do Papa Francisco, que aborda o cuidado da casa comum no contexto hodierno. A Encíclica questiona o modo de vida do ser humano no planeta e contextualiza a situação em que se encontra a criação, com duras críticas ao sistema econômico, político e social que está conduzindo a humanidade a uma espiral de destruição. A abordagem do Sumo Pontífice acolhe dados científicos fornecidos por especialistas que se dedicam a pesquisas sobre os impactos causados pela ação humana no planeta e integra a visão teológica da tradição com as reflexões que fazem parte das pautas das Conferências Episcopais das diversas partes do mundo. A Igreja Católica, de modo especial depois do Vaticano II, vem refletindo sobre a dignidade humana por ocasião dos sinais dos tempos, na Doutrina Social da Igreja. A Laudato Si’ é um marco na reflexão sobre a ecologia no interior da Igreja Católica, que se abre ao diálogo com o mundo em crise sistêmica para construir um novo modelo de vida humana na face da terra.This work seeks to reflect on the socio-environmental ethics instigated by Pope Francis' Encyclical Laudato Si’, which addresses the care of the common home in today's context. The Encyclical questions the way of life of human beings on the planet and contextualizes the situation in which creation finds itself, with harsh criticisms of the economic, political and social system that is leading humanity into a spiral of destruction. The Supreme Pontiff's approach includes scientific data provided by specialists who are dedicated to research on the impacts caused by human action on the planet and integrates the theological vision of tradition with the reflections that are part of the agendas of Episcopal Conferences from different parts of the world. The Catholic Church, especially after Vatican II, has been reflecting on human dignity on the occasion of the signs of the times, in the Church's Social Doctrine. Laudato Si’ is a milestone in the reflection on ecology within the Catholic Church, which is open to dialogue with the world in systemic crisis to build a new model of human life on the face of the earth

Biotribology of articular cartilage

Táto bakalárska práca sa zaoberá biotribológiou kĺbnej chrupky. V prvej časti sa zaoberá analýzou jednotlivých stavebných zložiek chrupky. Ďalšia časť je venovaná definovaniu tribologických vlastností chrupky s ohľadom na trenie, opotrebenie aj mazanie. V práci sú tiež stručne analyzované vybrané publikácie zaoberajúce sa biotribológiou kĺbnej chrupky. Na základe spracovaných článkov boli formulované a overené dve hypotézy. Klesne pri väčšej záťaži koeficient trenia? Zväčší koeficient trenia hodnotu pri vyššej rýchlosti? Experimentálne bolo potvrdené, že hodnota koeficientu trenia rastie so zväčšujúcou sa rýchlosťou a zmenšujúcim sa zaťažením.This bachelor thesis deals with biotribology of articular cartilage. The first part deals with the analysis of individual building components of cartilage. Another part is devoted to the definition of the tribological properties of cartilage with regard to friction, wear and lubrication. The thesis also briefly analyses selected publications dealing with articular cartilage biotribology. Two hypotheses have been formulated and verified on the basis of the processed articles. Will the friction coefficient fall at a higher load? Will the friction coefficient increase at higher speed? It has been experimentally confirmed that the friction coefficient value increases with increasing speed and decreasing load.

EDUCAÇÃO HISTÓRICA E CULTURA POLÍTICA: PODE O ENSINO DE HISTÓRIA EVITAR QUE OS JOVENS VENDAM SEUS VOTOS?

Afinal de contas para que serve o ensino de História? Essa pergunta muitas vezes serviu de base para atacar a presença da disciplina História na escola. Isso porque muitos acreditavam na sua inutilidade para a vida prática dos alunos. A forma tradicional de se ensinar História foi a grande responsável para a disseminação dessa visão. Entretanto, novos olhares sobre a utilidade da História justificam sua existência no currículo escolar em todos os níveis. Esses novos olhares desenvolvem, por exemplo, o olhar dos alunos sobre a importância da História para entender e atuar na esfera pública. A História pode fundamentar uma nova cultura política que propicie um envolvimento político mais significativo e crítico dos alunos enquanto cidadãos

The effect of synovial fluid composition on friction of joint cartilage

Táto diplomová práca sa zaoberá analýzou vplyvu zloženia modelovej synoviálnej kvapaliny na trecie vlastnosti kĺbnej chrupky. V práci je pozorovaný vplyv zložiek, koncentrácie, rýchlosti a zaťaženia. Boli realizované experimenty v konfigurácii pin-on-plate na komerčnom tribometri. Na experimenty bolo zvolených niekoľko typov mazív obsahujúcich niektoré zo zložiek synoviálnej kvapaliny. Mazivá boli pripravené vo dvoch koncentráciách. V koncentrácii zdravých jedincov a v koncentrácii aká je typická pre pacientov trpiacich na osteartrózu. Všetky merania boli realizované pri rýchlostiach 5 a 10 mm/s a zaťažení 5 a 10 N. V práci je ukázané, že pri použití mazív obsahujúce iba proteíny nie je pozorovaný žiadny rozdiel v hodnotách súčiniteľa trenia, a nie je taktiež pozorovaný vplyv koncentrácie. Pridanie HA má synergický účinok s -globulínom, avšak v prípade mazív obsahujúce albumín je účinok opačný. Po pridaní fosfolipidov nie je v mazivách obsahujúcich -globulín pozorovaný žiadny výrazný vplyv. Pri zmene zaťaženia nie je pozorovaný žiadny významný vplyv zloženia a koncentrácii na trenie.This thesis deals with the study of the effect of the constituents of the model synovial fluid on the frictional properties of articular cartilage. The influence of constituents, concentration, speed and load is observed. Experiments were performed on a commercial tribometer at configuration pin-on-plate. Several types of lubricants containing synovial fluid constituents have been selected for the experiments. Lubricants were prepared at two concentrations, the concentration of healthy individuals and at a concentration typical of for osteoarthritic patients. Speeds 5 and 10 mm/s and 5 and 10 N loads were used for all experiments. It is shown that when using only lubricant containing proteins, no difference in the coefficient of friction is observed and the effect of concentration is also not observed. The addition of hyaluronic acid has a synergistic effect with -globulin, however in the case of lubricants containing albumin, the effect is opposite. After the addition of phospholipids, no significant effect on friction is observed in -globulin containing lubricants. No significant effect of the composition and concentration of the lubricants is observed with the load change.