605 research outputs found
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
Angular distributions of scattered excited muonic hydrogen atoms
Differential cross sections of the Coulomb deexcitation in the collisions of
excited muonic hydrogen with the hydrogen atom have been studied for the first
time. In the framework of the fully quantum-mechanical close-coupling approach
both the differential cross sections for the transitions and
-averaged differential cross sections have been calculated for exotic atom
in the initial states with the principle quantum number at relative
motion energies eV and at scattering angles
. The vacuum polarization shifts of the
-states are taken into account. The calculated in the same approach
differential cross sections of the elastic and Stark scattering are also
presented. The main features of the calculated differential cross sections are
discussed and a strong anisotropy of cross sections for the Coulomb
deexcitation is predicted.Comment: 5 pages, 9 figure
Influence of a Uniform Current on Collective Magnetization Dynamics in a Ferromagnetic Metal
We discuss the influence of a uniform current, , on the
magnetization dynamics of a ferromagnetic metal. We find that the magnon energy
has a current-induced contribution proportional to
, where is the spin-current, and
predict that collective dynamics will be more strongly damped at finite . 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 . 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
Chiral Anomaly and Spin Gap in One-Dimensional Interacting Fermions
Semiclassical approach has been developed for the one-dimensional interacting
fermion systems. Starting from the incommensurate spin density wave (SDW) mean
field state for the repulsive Hubbard model in 1D, the non-Abelian bosonized
Lagrangian describing the spin-charge separation is obtained. The Berry phase
term is derived from the chiral anomaly, and we obtain the massless
Tomonaga-Luttinger liquid in the single chain case while the spin gap opens in
the double-chain system. This approach offers a new method to identify the
strong-coupling fixed point, and its relation to the Abelian bosonization
formalism is discussed on the spin gap state. The generalization to higher
dimensions is also discussed.Comment: Revised and enlarged version. 16 pages in REVTE
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