Isotope shifts and hyperfine structure of the laser cooling Fe I 358-nm line

We report on the measurement of the isotope shifts of the $3d^74s \,\, a \, {}^5\!F_5 - 3d^74p \,\, z \, {}^5\!G^o_6$ Fe~I line at 358~nm between all four stable isotopes ${}^{54}$Fe, ${}^{56}$Fe, ${}^{57}$Fe and ${}^{58}$Fe, as well as the hyperfine structure of that line for ${}^{57}$Fe, the only stable isotope having a nonzero nuclear spin. This line is of primary importance for laser cooling applications. In addition, an experimental value of the field and specific mass shift coefficients of the transition is reported as well as the hyperfine structure magnetic dipole coupling constant $A$ of the transition excited state in $^{57}$Fe, namely $A(3d^74p \,\, z \, {}^5\!G^o_6)=31.241(48)$ MHz. The measurements were carried out by means of laser-induced fluorescence spectroscopy performed on an isotope-enriched iron atomic beam. All measured frequency shifts are reported with uncertainties below the third percent level.Comment: 5 pages, 5 figure

La no-opresión y los estudios de paz

La paz es algo más que la mera ausencia de violencia. Construir una paz verdadera necesita del entendimiento profundo de los instintos humanos, y de las formas en que éstos nos pueden ayudar a crear, en lugar de determinarnos hacia la destrucción. Nuestra propia naturaleza y búsqueda de la libertad nos pueden llevar a la guerra o a la paz. En lugar de centrarnos únicamente en evitar la violencia, debemos empezar a entender sus causas: la opresión. Así, descubrimos un nuevo concepto, una capacidad inherente al ser humano: la no-opresión, o la facultad de conseguir la libertad con los demás

Electroweak Baryogenesis with dimension-6 Higgs interactions

We present the computation of the baryon asymmetry in the SM amplified by dimension-6 Higgs interactions using the WKB approximation. Analyzing the one-loop potential it turns out that the phase transition is strongly first order in a wide range of the parameters. It is ensured not to wash out the net baryon number gained previously even for Higgs masses up to at least 170 GeV. In addition dimension-6 operators induce new sources of CP violation. Novel source terms which enhance the generated baryon asymmetry emerge in the transport equations. This model predicts a baryon to entropy ratio close to the observed value for a large part of the parameter space.Comment: 10 pages, 4 figures, Talk given at the 8th International Moscow School of Physic

The Euler-Heisenberg Lagrangian beyond one loop

We review what is presently known about higher loop corrections to the Euler-Heisenberg Lagrangian and its Scalar QED analogue. The use of those corrections as a tool for the study of the properties of the QED perturbation series is outlined. As a further step in a long-term effort to prove or disprove the convergence of the N photon amplitudes in the quenched approximation, we present a parameter integral representation of the three-loop Euler-Heisenberg Lagrangian in 1+1 dimensional QED, obtained in the worldline formalism.Comment: 11 pages, 2 figures, talk given by Christian Schubert at QFEXT11, Benasque, Spain, Sept. 18-24, 2011, to appear in the conference proceeding

Generating TV summaries for CE-devices

Automatically generated summaries of TV content are indispensable for content selection and navigation in CE-devices. We show two types of summaries: Short video trailers and visual overviews consisting of representative frames. The demo does not only show the feasibility of the proposed algorithms, but also shows how different types of generated summaries can be used in future CE-devices

Quality Assurance System to monitor the teaching and learning process at the University of Aveiro (Portugal)

At the University of Aveiro (UA), in Portugal, institutional initiatives are being undertaken so that high levels of quality teaching and learning are achieved. This paper presents (a) the design of an evaluation model for quality assurance of teaching and learning and (b) the results of its application in a pilot study that ran in 2008/09 at the Departments of Electronics and Telecommunications, and Physics, of the UA. The Quality Assurance System (QAS) to monitor the process of teaching and learning at the UA emerges as extremely important, not only to regulate the teaching and learning process, following the quality assurance orientations at a national and international level, but also to reflect and share teaching practices that enhance the whole academic experience, both from students, teachers, and researchers‟ perspectives. The authors explore the design of the model and some findings of the pilot study, more specifically the identification of problematic and good practice situations identified by the students‟ survey and reports

Isotope shifts and hyperfine structure of the Fe I 372 nm resonance line

We report measurements of the isotope shifts of the $3d^64s^2 a ^5D_4 - 3d^64s4p z ^5F_5^o$ Fe I resonance line at 372 nm between all four stable isotopes $^{54}$Fe, $^{56}$Fe, $^{57}$Fe, and $^{58}$Fe, as well as the complete hyperfine structure of that line for $^{57}$Fe, the only stable isotope having a non-zero nuclear spin. The field and specific mass shift coefficients of the transition have been derived from the data, as well as the experimental value for the hyperfine structure magnetic dipole coupling constant $A$ of the excited state of the transition in $^{57}$Fe: $A(3d^64s4p z ^5F_5^o) = 81.69(86)$ MHz. The measurements were done by means of Doppler-free laser saturated-absorption spectroscopy in a Fe-Ar hollow cathode using both natural and enriched iron samples. The measured isotope shifts and hyperfine constants are reported with uncertainties at the percent level.Comment: 5 pages, 5 figure

Particle Currents in a Space-Time dependent and CP-violating Higgs Background: a Field Theory Approach

Motivated by cosmological applications like electroweak baryogenesis, we develop a field theoretic approach to the computation of particle currents on a space-time dependent and CP-violating Higgs background. We consider the Standard Model model with two Higgs doublets and CP violation in the scalar sector, and compute both fermionic and Higgs currents by means of an expansion in the background fields. We discuss the gauge dependence of the results and the renormalization of the current operators, showing that in the limit of local equilibrium, no extra renormalization conditions are needed in order to specify the system completely.Comment: 21 pages, LaTeX file, uses epsf.sty. 4 figures available as a compressed .ep