64,493 research outputs found
Degeneracies when T=0 Two Body Interacting Matrix Elements are Set Equal to Zero : Talmi's method of calculating coefficients of fractional parentage to states forbidden by the Pauli principle
In a previous work we studied the effects of setting all two body T=0 matrix
elements to zero in shell model calculations for Ti (Sc) and
Ti. The results for Ti were surprisingly good despite the
severity of this approximation. In this approximation degeneracies arose in the
T=1/2 I= and states in Sc and the T=1/2
, , and in Sc. The T=0
, , , and states in Ti were degenerate as
well. The degeneracies can be explained by certain 6j symbols and 9j symbols
either vanishing or being equal as indeed they are. Previously we used Regge
symmetries of 6j symbols to explain these degeneracies. In this work a simpler
more physical method is used. This is Talmi's method of calculating
coefficients of fractional parentage for identical particles to states which
are forbidden by the Pauli principle. This is done for both one particle cfp to
handle 6j symbols and two particle cfp to handle 9j symbols. The states can be
classified by the dual quantum numbers ()
Kinematics of the Broad Line Region in M81
A new model is presented which explains the origin of the broad emission
lines observed in the LINER/Seyfert nucleus of M81 in terms of a steady state
spherically symmetric inflow, amounting to 1 x 10^-5 Msun/yr, which is
sufficient to explain the luminosity of the AGN. The emitting volume has an
outer radius of ~1 pc, making it the largest broad line region yet to be
measured, and it contains a total mass of ~ 5 x 10^-2 Msun of dense, ~ 10^8
cm^-3, ionized gas, leading to a very low filling factor of ~ 5 x 10^-9. The
fact that the BLR in M81 is so large may explain why the AGN is unable to
sustain the ionization seen there. Thus, the AGN in M81 is not simply a scaled
down quasar.Comment: Accepted for Publication in ApJ 7/21/0
Children's suggestibility in relation to their understanding about sources of knowledge
In the experiments reported here, children chose either to maintain their initial belief about an object's identity or to accept the experimenter's contradicting suggestion. Both 3– to 4–year–olds and 4– to 5–year–olds were good at accepting the suggestion only when the experimenter was better informed than they were (implicit source monitoring). They were less accurate at recalling both their own and the experimenter's information access (explicit recall of experience), though they performed well above chance. Children were least accurate at reporting whether their final belief was based on what they were told or on what they experienced directly (explicit source monitoring). Contrasting results emerged when children decided between contradictory suggestions from two differentially informed adults: Three– to 4–year–olds were more accurate at reporting the knowledge source of the adult they believed than at deciding which suggestion was reliable. Decision making in this observation task may require reflective understanding akin to that required for explicit source judgments when the child participates in the task
Brayton-cycle radioisotope heat-source design study. Phase II /preliminary design/ report
Brayton cycle radioisotope heat source desig
Some aspects of algorithm performance and modeling in transient analysis of structures
The status of an effort to increase the efficiency of calculating transient temperature fields in complex aerospace vehicle structures is described. The advantages and disadvantages of explicit algorithms with variable time steps, known as the GEAR package, is described. Four test problems, used for evaluating and comparing various algorithms, were selected and finite-element models of the configurations are described. These problems include a space shuttle frame component, an insulated cylinder, a metallic panel for a thermal protection system, and a model of the wing of the space shuttle orbiter. Results generally indicate a preference for implicit over explicit algorithms for solution of transient structural heat transfer problems when the governing equations are stiff (typical of many practical problems such as insulated metal structures)
EFOSC2 Spectroscopy of SWIRE-CDFS Galaxies
We present the optical spectra of a sample of 34 SWIRE-CDFS sources observed
with EFOSC2 on the ESO 3.6m Telescope. We have used the spectra and
spectroscopic redshifts to validate our photometric redshift codes and SED
template fitting methods. 12 of our sources are Infrared Luminous Galaxies. Of
these, five belong to the class of ULIRGs and one to the class of HLIRGs with
evidence of both an AGN and starburst component contributing to their extreme
infrared luminosity for 3, starburst contributing for 1 and AGN contributing
for 2 of them.Comment: 14 pages, 11 figures, 4 tables, accepted for publication in MNRA
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Portable technology and multi-domain energy practices
This article complements the concept of embedded security by proposing disembedded security to capture consumers’ energy practices when travelling across multiple domains of energy accessibility. Consumer mobility outside the home produces misalignments between infrastructure and portable technology experienced as ‘hysteresis of the battery’. Hysteresis captures how respondents are subject to ‘unpleasant unpredictability’ about battery-based technology and infrastructure, which spurs hermeneutic reflection about energy, location and sociality. Multi-domain energy practices therefore bring energy consumers to ‘reembed’ or create a sense of psychological comfort on the move. Charge levels on battery icons not only structure daily patterns of consumer life through planning efforts but become interpretively entangled in issues of duration, distance and sociality as energy demands in portable technology push consumers to avoid disruption
Lagrange Model for the Chiral Optical Properties of Stereometamaterials
We employ a general Lagrange model to describe the chiral optical properties
of stereometamaterials. We derive the elliptical eigenstates of a twisted
stacked split-ring resonator, taking phase retardation into account. Through
this approach, we obtain a powerful Jones matrix formalism which can be used to
calculate the polarization rotation, ellipticity, and circular dichroism of
transmitted waves through stereometamaterials at any incident polarization. Our
experimental measurements agree well with our model.Comment: 10 pages, 3 figures, Theory and experimen
Primordial Non-Gaussianity: Baryon Bias and Gravitational Collapse of Cosmic String Wakes
I compute the 3-D non-linear evolution of gas and dark matter fluids in the
neighbourhood of cosmic string wakes which are formed at high redshift
() for a ``realistic'' scenario of wake formation. These wakes
are the ones which stand out most prominently as cosmological sheets and are
expected to play a dominant r\^ole in the cosmic string model of structure
formation. Employing a high-resolution 3-D hydrodynamics code to evolve these
wakes until the present day yields results for the baryon bias generated in the
inner wake region. I find that today, wakes would be Mpc thick and
contain a 70% excess in the density of baryons over the dark matter density in
their centre. However, high density peaks in the wake region do not inherit a
baryon enhancement. I propose a mechanism for this erasure of the baryon excess
in spherically collapsed objects based on the geometry change around the
collapsing region. Further, I present heuristic arguments for the consequences
of this work for large scale structure in the cosmic string model and conclude
that the peculiarities of wake formation are unlikely to have significant
import on the discrepancy between power spectrum predictions and observations
in this model. If one invokes the nucleosynthesis bound on this
could be seen as strengthening the case against or for low Hubble
constants.Comment: 21 pages, 7 figures, 2 tables, prepared with the AASTeX package.
Minor modifications, results unchanged. ApJ in press, scheduled for Vol. 50
Vitrification and determination of the crystallization time scales of the bulk-metallic-glass-forming liquid Zr58.5Nb2.8Cu15.6Ni12.8Al10.3
The crystallization kinetics of Zr58.5Nb2.8Cu15.6Ni12.8Al10.3 were studied in an electrostatic levitation (ESL) apparatus. The measured critical cooling rate is 1.75 K/s. Zr58.5Nb2.8Cu15.6Ni12.8Al10.3 is the first bulk-metallic-glass-forming liquid that does not contain beryllium to be vitrified by purely radiative cooling in the ESL. Furthermore, the sluggish crystallization kinetics enable the determination of the time-temperature-transformation (TTT) diagram between the liquidus and the glass transition temperatures. The shortest time to reach crystallization in an isothermal experiment; i.e., the nose of the TTT diagram is 32 s. The nose of the TTT diagram is at 900 K and positioned about 200 K below the liquidus temperature
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