714 research outputs found
Propagating phonons coupled to an artificial atom
Quantum information can be stored in micromechanical resonators, encoded as
quanta of vibration known as phonons. The vibrational motion is then restricted
to the stationary eigenmodes of the resonator, which thus serves as local
storage for phonons. In contrast, we couple propagating phonons to an
artificial atom in the quantum regime, and reproduce findings from quantum
optics with sound taking over the role of light. Our results highlight the
similarities between phonons and photons, but also point to new opportunities
arising from the unique features of quantum mechanical sound. The low
propagation speed of phonons should enable new dynamic schemes for processing
quantum information, and the short wavelength allows regimes of atomic physics
to be explored which cannot be reached in photonic systems.Comment: 30 pages, 6 figures, 1 tabl
Algebras stratified for all linear orders
In this paper we describe several characterizations of basic
finite-dimensional -algebras stratified for all linear orders, and
classify their graded algebras as tensor algebras satisfying some extra
property. We also discuss whether for a given preorder ,
, the category of -modules with
-filtrations, is closed under cokernels of
monomorphisms, and classify quasi-hereditary algebras satisfying this property.Comment: Final version accepted by Alg. Repn. Theor
Tetrahedral and Triangular Deformations of Nuclei in Mass Region
We study static non-axial octupole deformations in proton-rich nuclei,
Ge, Se, Kr, Sr, Zr and Mo, by using
the Skyrme Hartree-Fock plus BCS calculation with no restrictions on the
nuclear shape. The calculation predicts that the oblate ground state in
Se is extremely soft for the triangular deformation, and that
in Zr the low-lying local minimum state coexisting with the prolate
ground state has the tetrahedral deformation.Comment: 8 pages, 4 Postscript figures, REVTE
The contribution of normal modes in the bottom to the acoustic field in the ocean
Also published as: Journal of the Acoustical Society of America 68 (1980): 602-612The effects of normal modes in the bottom on the acoustic field in the ocean are examined. The ocean bottom
model consists of a slow isovelocity layer overlying an isovelocity half-space to simulate the characteristic
sound velocity drop at the water-bottom interface. Attention is focused on the perfectly trapped modes which
are excited in the layer by inhomogeneous waves emitted by a point source in the water column. The relative
normal mode contribution to the total acoustic field in the water is calculated analytically for a near-bottom
source/receiver geometry and evaluated for representative ocean bottom examples. It is shown that, for
combined source/receiver heights less than a wavelength, the field is dominated by the leaky mode
contribution at short ranges ( $ 2 km) and the trapped mode contribution at long ranges ( ~ 2 km). For fixed
bottom parameters, the trapped mode contribution increases exponentially with decreasing combined
source/receiver height. It is also shown that, for a fixed layer wavenumber-thickness product and fixed layer
sound speed, the leaky mode fields at different frequencies are approximately range-scaled versions of the
same field.Prepared for the Office of Naval Research under Contract
N000 14-77-C-0196
Neutron-proton interaction in rare-earth nuclei: Role of tensor force
We investigate the role of the tensor force in the description of doubly odd
deformed nuclei within the framework of the particle-rotor model. We study the
rare-earth nuclei 174Lu, 180Ta, 182Ta, and 188Re using a finite-range
interaction, with and without tensor terms. Attention is focused on the lowest
K=0 and K=1 bands, where the effects of the residual neutron-proton interaction
are particularly evident. Comparison of the calculated results with
experimental data evidences the importance of the tensor-force effects.Comment: 8 pages, 5 figures, to be published on Physical Review
Submillimeter Emission from Water in the W3 Region
We have mapped the submillimeter emission from the 1(10)-1(01) transition of
ortho-water in the W3 star-forming region. A 5'x5' map of the W3 IRS4 and W3
IRS5 region reveals strong water lines at half the positions in the map. The
relative strength of the Odin lines compared to previous observations by SWAS
suggests that we are seeing water emission from an extended region. Across much
of the map the lines are double-peaked, with an absorption feature at -39 km/s;
however, some positions in the map show a single strong line at -43 km/s. We
interpret the double-peaked lines as arising from optically thick,
self-absorbed water emission near the W3 IRS5, while the narrower blue-shifted
lines originate in emission near W3 IRS4. In this model, the unusual appearance
of the spectral lines across the map results from a coincidental agreement in
velocity between the emission near W3 IRS4 and the blue peak of the more
complex lines near W3 IRS5. The strength of the water lines near W3 IRS4
suggests we may be seeing water emission enhanced in a photon-dominated region.Comment: Accepted to A&A Letters as part of the special Odin issue; 4 page
Periodic-Orbit Bifurcations and Superdeformed Shell Structure
We have derived a semiclassical trace formula for the level density of the
three-dimensional spheroidal cavity. To overcome the divergences occurring at
bifurcations and in the spherical limit, the trace integrals over the
action-angle variables were performed using an improved stationary phase
method. The resulting semiclassical level density oscillations and
shell-correction energies are in good agreement with quantum-mechanical
results. We find that the bifurcations of some dominant short periodic orbits
lead to an enhancement of the shell structure for "superdeformed" shapes
related to those known from atomic nuclei.Comment: 4 pages including 3 figure
Perceived barriers in family-based behavioural treatment of paediatric obesity â Results from the FABO study
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Background: To date, few studies have investigated perceived barriers among those who participate in and drop out of family-based behavioural treatment (FBT) for paediatric obesity. Examining experienced barriers during treatment, and their role in participation and completion of treatment has important implications for clinical practice.
Objectives: To compare perceived barriers to participating in a family-based behavioural social facilitation treatment (FBSFT) for obesity among families who completed and did not complete treatment.
Methods: Data were analysed from 90 families of children and adolescents (mean (M) age = 12.8 years, standard deviation (SD) = 3.05) with severe obesity enrolled in a 17-session FBSFT program. After completing 12 sessions or at the time of dropout, parents and therapists completed the Barriers to Treatment Participation Scale (BTPS), a 5-point Likert scale (1 = never a problem, 5 = very often a problem) which includes four subscales: 1. Stressors and obstacles that compete with treatment, 2. Treatment demands and issues, 3. Perceived relevance of treatment, 4. Relationship with the therapist.
Results: Families who did not complete treatment scored significantly higher on the BTPS subscales stressors and obstacles that compete with treatment (M = 2.03, SD = 0.53 vs. M = 1.70, SD = 0.42), p = 0.010 and perceived relevance of treatment (M = 2.27, SD = 0.48 vs. M = 1.80, SD = 0.50), p < 0.001 than families who completed treatment. No other significant differences between groups were observed.
Conclusion: Families are more likely to drop out of FBSFT when experiencing a high burden from life stressors or when treatment is not meeting the expectations and perceived needs of the family.publishedVersio
Chaos in Axially Symmetric Potentials with Octupole Deformation
Classical and quantum mechanical results are reported for the single particle
motion in a harmonic oscillator potential which is characterized by a
quadrupole deformation and an additional octupole deformation. The chaotic
character of the motion is srongly dependent on the quadrupole deformation in
that for a prolate deformation virtually no chaos is discernible while for the
oblate case the motion shows strong chaos when the octupole term is turned on.Comment: 6 pages LaTex plus 4 figures available by contacting the authors
directly, published in PHYS.REV.LETT. 72(1994) 235
First detection of NH3 (1,0 - 0,0) from a low mass cloud core: On the low ammonia abundance of the rho Oph A core
Odin has successfully observed the molecular core rho Oph A in the 572.5 GHz
rotational ground state line of ammonia, NH3 (J,K = 1,0 - 0,0). The
interpretation of this result makes use of complementary molecular line data
obtained from the ground (C17O and CH3OH) as part of the Odin preparatory work.
Comparison of these observations with theoretical model calculations of line
excitation and transfer yields a quite ordinary abundance of methanol, X(CH3OH)
= 3e-9. Unless NH3 is not entirely segregated from C17O and CH3OH, ammonia is
found to be significantly underabundant with respect to typical dense core
values, viz. X(NH3) = 8e-10.Comment: 4 pages, 2 figures, 2 tables, to appear in Astron. Astrophys. Letter
- âŠ