8,586 research outputs found
Violating Displaced Persons Human Rights And Impairing The Quality Of Human Resources
Each year wars force several millions of people to leave their homes to join the ranks of displaced persons (DPs). Displaced women and children are particularly vulnerable to risks of physical abuses. The loss in current and future human resource quality caused by abuses suffered by DPs is an extreme version of the well-known brain drain phenomenon. The paper considers the psychological damage inflicted upon DPs, the possible effects of Post-Traumatic Stress Disorder (PTSD) and the consequent damage to human resource quality
Impact of incomplete ionization of dopants on the electrical properties of compensated p-type silicon
This paper investigates the importance of incomplete ionization of dopants in compensated p-type Si and its impact on the majority-carrier density and mobility and thus on the resistivity. Both theoretical calculations and temperature-dependent Hall-effect measurements demonstrate that the carrier density is more strongly affected by incomplete ionization in compensated Si than in uncompensated Si with the same net doping. The previously suggested existence of a compensation-specific scattering mechanism to explain the reduction of mobility in compensated Si is shown not to be consistent with the T-dependence of the measuredcarrier mobility. The experiment also shows that, in the vicinity of 300 K, the resistivity of compensated Si has a much weaker dependence on temperature than that of uncompensated silicon
Fractional Operators, Dirichlet Averages, and Splines
Fractional differential and integral operators, Dirichlet averages, and
splines of complex order are three seemingly distinct mathematical subject
areas addressing different questions and employing different methodologies. It
is the purpose of this paper to show that there are deep and interesting
relationships between these three areas. First a brief introduction to
fractional differential and integral operators defined on Lizorkin spaces is
presented and some of their main properties exhibited. This particular approach
has the advantage that several definitions of fractional derivatives and
integrals coincide. We then introduce Dirichlet averages and extend their
definition to an infinite-dimensional setting that is needed to exhibit the
relationships to splines of complex order. Finally, we focus on splines of
complex order and, in particular, on cardinal B-splines of complex order. The
fundamental connections to fractional derivatives and integrals as well as
Dirichlet averages are presented
Heat transport of clean spin-ladders coupled to phonons: Umklapp scattering and drag
We study the low-temperature heat transport in clean two-leg spin ladder
compounds coupled to three-dimensional phonons. We argue that the very large
heat conductivities observed in such systems can be traced back to the
existence of approximate symmetries and corresponding weakly violated
conservation laws of the effective (gapful) low--energy model, namely
pseudo-momenta. Depending on the ratios of spin gaps and Debye energy and on
the temperature, the magnetic contribution to the heat conductivity can be
positive or negative, and exhibit an activated or anti-activated behavior. In
most regimes, the magnetic heat conductivity is dominated by the spin-phonon
drag: the excitations of the two subsystems have almost the same drift
velocity, and this allows for an estimate of the ratio of the magnetic and
phononic contributions to the heat conductivity.Comment: revised version, 8 pages, 3 figures, added appendi
Large thermomagnetic effects in weakly disordered Heisenberg chains
The interplay of different scattering mechanisms can lead to novel effects in
transport. We show theoretically that the interplay of weak impurity and
Umklapp scattering in spin-1/2 chains leads to a pronounced dip in the magnetic
field dependence of the thermal conductivity at a magnetic field . In sufficiently clean samples, the reduction of the magnetic
contribution to heat transport can easily become larger than 50% and the effect
is predicted to exist even in samples with a large exchange coupling, J >> B,
where the field-induced magnetization is small. Qualitatively, our theory might
explain dips at observed in recent heat transport measurements on
copper pyrazine dinitrate, but a fully quantitative description is not possible
within our model.Comment: 5 pages, 2 figure
On two pieces of folklore in the AdS/CFT duality
In the AdS/CFT duality, it is often said that a local symmetry in a bulk
theory corresponds to a global symmetry in the corresponding boundary theory,
but the global symmetry can become local when one couples with an external
source. As a result, the GKP-Witten relation gives a response function instead
of a Green function. We explore this point in details using the example of
holographic superconductors. We point out that these points play a crucial role
to interpret the holographic London equation properly.Comment: 11 pages, ReVTeX4.1; v2: added discussio
Self-consistent theory of turbulence
A new approach to the stochastic theory of turbulence is suggested. The
coloured noise that is present in the stochastic Navier-Stokes equation is
generated from the delta-correlated noise allowing us to avoid the nonlocal
field theory as it is the case in the conventional theory. A feed-back
mechanism is introduced in order to control the noise intensity.Comment: submitted to J.Tech. Phys.Letters (St. Petersburg
Morphology and scaling in the noisy Burgers equation: Soliton approach to the strong coupling fixed point
The morphology and scaling properties of the noisy Burgers equation in one
dimension are treated by means of a nonlinear soliton approach based on the
Martin-Siggia-Rose technique. In a canonical formulation the strong coupling
fixed point is accessed by means of a principle of least action in the
asymptotic nonperturbative weak noise limit. The strong coupling scaling
behaviour and the growth morphology are described by a gas of nonlinear soliton
modes with a gapless dispersion law and a superposed gas of linear diffusive
modes with a gap. The dynamic exponent is determined by the gapless soliton
dispersion law, whereas the roughness exponent and a heuristic expression for
the scaling function are given by the form factor in a spectral representation
of the interface slope correlation function. The scaling function has the form
of a Levy flight distribution.Comment: 5 pages, Revtex file, submitted to Phys. Rev. Let
- …