6,066 research outputs found
Dynamic elastic properties and magnetic susceptibility across the austenite-martensite transformation in site-disordered ferromagnetic Ni-Fe-Al alloy
Besides permitting an accurate determination of the
ferromagnetic-to-paramagnetic phase transition temperature and the
characteristic temperatures for the beginning and end of the growth of
martensite (austenite) phase at the expense of austenite (martensite) phase
while cooling (heating), the results of an extensive ac susceptibility, sound
velocity and internal friction investigation of the thermoelastic martensitic
transformation in melt-quenched (site-disordered) Ni55Fe20Al25 alloy provide a
clear experimental evidence for the following. Irreversible thermoelastic
changes (thermal hysteresis) occur in the austenite phase in the premartensitic
regime. In the heating cycle, the system retains the "memory" of the initiation
and subsequent growth of the martensitic phase (at the expense of the parent
austenite phase) that had taken place during the cooling cycle in the
austenite-martensite phase coexistence region. We report and discuss these
novel findings in this communication.Comment: 5 figure
Does land tenure insecurity discourage tree planting?: evolution of customary land tenure and agroforestry management in Sumatra
It is widely believed that land tenure insecurity under a customary tenure system leads to socially inefficient resource allocation. This article demonstrates that land tenure insecurity promotes tree planting, which is inefficient from the private point of view but could be relatively efficient from the viewpoint of the global environment. Regression analysis, based on primary data collected in Sumatra, indicates that tenure insecurity in fact leads to early tree planting. It is also found that customary land tenure institutions have been evolving towards greater tenure security responding to increasing scarcity of land.Land tenure., Sumatra., Tree planting.,
Description of superdeformed nuclei in the interacting boson model
The interacting boson model is extended to describe the spectroscopy of
superdeformed bands. Microscopic structure of the model in the second minimum
is discussed and superdeformed bosons are introduced as the new building
blocks. Solutions of a quadrupole Hamiltonian are implemented through the
expansion method. Effects of the quadrupole parameters on dynamic moment of
inertia and electric quadrupole transition rates are discussed and the results
are used in a description of superdeformed bands in the Hg-Pb and Gd-Dy
regions.Comment: 18 pages revtex, 9 figures available upon reques
Covariant density functional theory: The role of the pion
We investigate the role of the pion in Covariant Density Functional Theory.
Starting from conventional Relativistic Mean Field (RMF) theory with a
non-linear coupling of the -meson and without exchange terms we add
pions with a pseudo-vector coupling to the nucleons in relativistic
Hartree-Fock approximation. In order to take into account the change of the
pion field in the nuclear medium the effective coupling constant of the pion is
treated as a free parameter. It is found that the inclusion of the pion to this
sort of density functionals does not destroy the overall description of the
bulk properties by RMF. On the other hand, the non-central contribution of the
pion (tensor coupling) does have effects on single particle energies and on
binding energies of certain nuclei.Comment: 12 pages, 5 figure
Tests and applications of self-consistent cranking in the interacting boson model
The self-consistent cranking method is tested by comparing the cranking
calculations in the interacting boson model with the exact results obtained
from the SU(3) and O(6) dynamical symmetries and from numerical
diagonalization. The method is used to study the spin dependence of shape
variables in the and boson models. When realistic sets of parameters
are used, both models lead to similar results: axial shape is retained with
increasing cranking frequency while fluctuations in the shape variable
are slightly reduced.Comment: 9 pages, 3 ps figures, Revte
Full control of quadruple quantum dot circuit charge states in the single electron regime
We report the realization of an array of four tunnel coupled quantum dots in
the single electron regime, which is the first required step toward a scalable
solid state spin qubit architecture. We achieve an efficient tunability of the
system but also find out that the conditions to realize spin blockade readout
are not as straightforwardly obtained as for double and triple quantum dot
circuits. We use a simple capacitive model of the series quadruple quantum dots
circuit to investigate its complex charge state diagrams and are able to find
the most suitable configurations for future Pauli spin blockade measurements.
We then experimentally realize the corresponding charge states with a good
agreement to our model.Comment: 4 pages, 3 figure
CO J = 2 - 1 Emission from Evolved Stars in the Galactic Bulge
We observe a sample of 8 evolved stars in the Galactic Bulge in the CO J = 2
- 1 line using the Submillimeter Array (SMA) with angular resolution of 1 - 4
arcseconds. These stars have been detected previously at infrared wavelengths,
and several of them have OH maser emission. We detect CO J = 2 - 1 emission
from three of the sources in the sample: OH 359.943 +0.260, [SLO2003] A12, and
[SLO2003] A51. We do not detect the remaining 5 stars in the sample because of
heavy contamination from the galactic foreground CO emission. Combining CO data
with observations at infrared wavelengths constraining dust mass loss from
these stars, we determine the gas-to-dust ratios of the Galactic Bulge stars
for which CO emission is detected. For OH 359.943 +0.260, we determine a gas
mass-loss rate of 7.9 (+/- 2.2) x 10^-5 M_Sun/year and a gas-to-dust ratio of
310 (+/- 89). For [SLO2003] A12, we find a gas mass-loss rate of 5.4 (+/- 2.8)
x 10^-5 M_Sun/year and a gas-to-dust ratio of 220 (+/- 110). For [SLO2003] A51,
we find a gas mass-loss rate of 3.4 (+/- 3.0) x 10^-5 M_Sun/year and a
gas-to-dust ratio of 160 (+/- 140), reflecting the low quality of our tentative
detection of the CO J = 2 - 1 emission from A51. We find the CO J = 2 - 1
detections of OH/IR stars in the Galactic Bulge require lower average CO J = 2
- 1 backgrounds.Comment: 40 pages, 16 figures, appeared in the 1 March 2013 issue of the
Astrophysical Journa
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