Fluctuation induced conductivity of superconductors above the transition temperature: Regularization of the Maki diagram

The Maki contribution to the conductivity above the superconducting transition temperature is regularized within the framework of the BCS theory. This is achieved through the renormalization of the impurity scattering vertex by inclusion of the effects of pair fluctuations. The conductivity is evaluated for a thin film. It depends only on the reduced temperature and the normal resistance per square. Fair agreement is found with Al films over a wide temperature range. Agreement is not found with experiments on Bi, Pb and Ga films, which apparently contain a strong additional pair-breaking effect. The temperature range in which interactions among fluctuations become important in the Maki conductivity is generally larger than that given by the Ginzburg criterion

Long- term poverty and child development in the United States: Results from the NLSY

The authors describe developmental deficits in early childhood associated with long-term poverty in the National Longitudinal Survey of Youth (NLSY). They compare estimates of the effects of long-term poverty (based on a thirteen-year average of income) to estimates of the effects of poverty based on a single year of income (at the time of developmental assessment). They find substantial developmental deficits among children who, on average, are poor over a number of years relative to those who are not. These deficits are approximately twice as large according to the long-term income measure as compared to those based on the single- year measure, and are not explained by differences in maternal education, family structure, maternal behaviors during pregnancy, infant health, nutritional status, or age of mother at first birth. However, an index of the home environment accounts for one-third to one-half of the developmental disadvantages (net of other factors) of children who experience long-term poverty.

First observation of two hyperfine transitions in antiprotonic He-3

We report on the first experimental results for microwave spectroscopy of the hyperfine structure of antiprotonic He-3. Due to the helium nuclear spin, antiprotonic He-3 has a more complex hyperfine structure than antiprotonic He-4 which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. Two out of four super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were observed. The measured frequencies of the individual transitions are 11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. Although the experimental uncertainty for the difference of these frequencies is still very large as compared to that of theory, its measured value agrees with theoretical calculations. This difference is crucial to be determined because it is proportional to the magnetic moment of the antiproton.Comment: 8 pages, 6 figures, just published (online so far) in Physics Letters

Quantum fields in disequilibrium: neutral scalar bosons with long-range, inhomogeneous perturbations

Using Schwinger's quantum action principle, dispersion relations are obtained for neutral scalar mesons interacting with bi-local sources. These relations are used as the basis of a method for representing the effect of interactions in the Gaussian approximation to field theory, and it is argued that a marked inhomogeneity, in space-time dependence of the sources, forces a discrete spectrum on the field. The development of such a system is characterized by features commonly associated with chaos and self-organization (localization by domain or cell formation). The Green functions play the role of an iterative map in phase space. Stable systems reside at the fixed points of the map. The present work can be applied to self-interacting theories by choosing suitable properties for the sources. Rapid transport leads to a second order phase transition and anomalous dispersion. Finally, it is shown that there is a compact representation of the non-equilibrium dynamics in terms of generalized chemical potentials, or equivalently as a pseudo-gauge theory, with an imaginary charge. This analogy shows, more clearly, how dissipation and entropy production are related to the source picture and transform a flip-flop like behaviour between two reservoirs into the Landau problem in a constant `magnetic field'. A summary of conventions and formalism is provided as a basis for future work.Comment: 23 pages revte

Influence of a Uniform Current on Collective Magnetization Dynamics in a Ferromagnetic Metal

We discuss the influence of a uniform current, $\vec{j}$, on the magnetization dynamics of a ferromagnetic metal. We find that the magnon energy $\epsilon(\vec{q})$ has a current-induced contribution proportional to $\vec{q}\cdot \vec{\cal J}$, where $\vec{\cal J}$ is the spin-current, and predict that collective dynamics will be more strongly damped at finite ${\vec j}$. We obtain similar results for models with and without local moment participation in the magnetic order. For transition metal ferromagnets, we estimate that the uniform magnetic state will be destabilized for $j \gtrsim 10^{9} {\rm A} {\rm cm}^{-2}$. We discuss the relationship of this effect to the spin-torque effects that alter magnetization dynamics in inhomogeneous magnetic systems.Comment: 12 pages, 2 figure

Improved Study of the Antiprotonic Helium Hyperfine Structure

We report the initial results from a systematic study of the hyperfine (HF) structure of antiprotonic helium (n,l) = (37,~35) carried out at the Antiproton Decelerator (AD) at CERN. We performed a laser-microwave-laser resonance spectroscopy using a continuous wave (cw) pulse-amplified laser system and microwave cavity to measure the HF transition frequencies. Improvements in the spectral linewidth and stability of our laser system have increased the precision of these measurements by a factor of five and reduced the line width by a factor of three compared to our previous results. A comparison of the experimentally measured transition frequencies with three body QED calculations can be used to determine the antiproton spin magnetic moment, leading towards a test of CPT invariance.Comment: 14 pages 9 figure

Gauge Field Formulation of Adiabatic Spin Torques

Previous calculation of spin torques for small-amplitude magnetization dynamics around a uniformly magnetized state [J. Phys. Soc. Jpn. {\bf 75} (2006) 113706] is extended here to the case of finite-amplitude dynamics. This is achieved by introducing an `` adiabatic'' spin frame for conduction electrons, and the associated SU(2) gauge field. In particular, the Gilbert damping is shown to arise from the time variation of the spin-relaxation source terms in this new frame, giving a new physical picture of the damping. The present method will allow a `` first-principle'' derivation of spin torques without any assumptions such as rotational symmetry in spin space.Comment: 4 pages, 3 figure

Preliminary Results from Recent Measurements of the Antiprotonic Helium Hyperfine Structure

We report on preliminary results from a systematic study of the hyperfine (HF) structure of antiprotonic helium. This precise measurement which was commenced in 2006, has now been completed. Our initial analysis shows no apparent density or power dependence and therefore the results can be averaged. The statistical error of the observable M1 transitions is a factor of 60 smaller than that of three body quantum electrodynamic (QED) calculations, while their difference has been resolved to a precision comparable to theory (a factor of 10 better than our first measurement). This difference is sensitive to the antiproton magnetic moment and agreement between theory and experiment would lead to an increased precision of this parameter, thus providing a test of CPT invariance.Comment: 6 pages, 4 figure

Is youth unemployment really the major worry? (AOM)

Youth unemployment is neither the only nor the basic problem of the European labour market. The comparative analysis of unemployment data demonstrates that the unemployment of older people is even more serious. The article proves that the weight of young people in total unemployment has as a tendency been declining in the “inner periphery” of the EU, among them in Central and Eastern European member states (CEECs). The trend is just the opposite in the developed or “core” countries of the Union where youngsters took a higher share in total unemployment in 2012 than 10-12 years ago. In Europe there are millions of young people beyond the active unemployed who do not want to work or think they cannot find a job that fulfils their expectations and refuse to take part in any kind of education or training (NEETs-“Not in Employment, Education or Training”). By estimating the rate of NEETs in the adult population the article claims that the NEETs-phenomenon is not the differentia specifica of the youth. At the end the article details two suggestions for the mitigation of the problem. It concludes that the joblessness in Europe is an old and tendencially worsening problem that cannot be solved by particular policies