757 research outputs found
Polarimetric Properties of Flux-Ropes and Sheared Arcades in Coronal Prominence Cavities
The coronal magnetic field is the primary driver of solar dynamic events.
Linear and circular polarization signals of certain infrared coronal emission
lines contain information about the magnetic field, and to access this
information, either a forward or an inversion method must be used. We study
three coronal magnetic configurations that are applicable to polar-crown
filament cavities by doing forward calculations to produce synthetic
polarization data. We analyze these forward data to determine the
distinguishing characteristics of each model. We conclude that it is possible
to distinguish between cylindrical flux ropes, spheromak flux ropes, and
sheared arcades using coronal polarization measurements. If one of these models
is found to be consistent with observational measurements, it will mean
positive identification of the magnetic morphology that surrounds certain
quiescent filaments, which will lead to a greater understanding of how they
form and why they erupt.Comment: 22 pages, 8 figures, Solar Physics topical issue: Coronal Magnetis
Dynamics of liquid He-4 in confined geometries from Time-Dependent Density Functional calculations
We present numerical results obtained from Time-Dependent Density Functional
calculations of the dynamics of liquid He-4 in different environments
characterized by geometrical confinement. The time-dependent density profile
and velocity field of He-4 are obtained by means of direct numerical
integration of the non-linear Schrodinger equation associated with a
phenomenological energy functional which describes accurately both the static
and dynamic properties of bulk liquid He-4. Our implementation allows for a
general solution in 3-D (i.e. no symmetries are assumed in order to simplify
the calculations). We apply our method to study the real-time dynamics of pure
and alkali-doped clusters, of a monolayer film on a weakly attractive surface
and a nano-droplet spreading on a solid surface.Comment: q 1 tex file + 9 Ps figure
ATLAS Pixel Opto-Electronics
We have developed two radiation-hard ASICs for optical data transmission in
the ATLAS pixel detector at the LHC at CERN: a driver chip for a Vertical
Cavity Surface Emitting Laser (VCSEL) diode for 80 Mbit/s data transmission
from the detector, and a Bi-Phase Mark decoder chip to recover the control data
and 40 MHz clock received optically by a PIN diode. We have successfully
implemented both ASICs in 0.25 micron CMOS technology using enclosed layout
transistors and guard rings for increased radiation hardness. We present
results of the performance of these chips, including irradiation with 24 GeV
protons up to 61 Mrad (2.3 x 10e15 p/cm^2).Comment: 17 pages, 23 figures, submitted to NIM Added references. Added figure
15. Moved sec. IV to sec. I
Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System
The exclusive reaction , at 18 GeV has been studied with a partial wave analysis on a sample
of 23~492 events from BNL experiment E852. A mass-dependent fit
is consistent with a resonant hypothesis for the wave, thus providing
evidence for a neutral exotic meson with , a mass of MeV, and a width of MeV. New
interpretations of the meson exotics in neutral system observed in
E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase
variations. p4, rewording paragrath "The second method ..." . p4, at the
bottom of paragrath "The third method ..." added consistent with the results
of methods 1 and 2
Experiencing the world with archetypal symbols: A new form of aesthetics.
According to the theories of symbolic interactionism, phenomenology of perception and archetypes, we argue that symbols play the key role in translating the information from the physical world to the human experience, and archetypes are the universal knowledge of cognition that generates the background of human experience (the life-world). Therefore, we propose a conceptual framework that depicts how people experience the world with symbols, and how archetypes relate the deepest level of human experience. This framework indicates a new direction of research on memory and emotion, and also suggests that archetypal symbolism can be a new resource of aesthetic experience design.Postprint (published version
Developmental social case work : a process model
Abstract: Social development has been adopted as South Africa’s social welfare approach and is increasingly being adopted in Africa and other parts of the developing world. The translation of developmental social welfare to social work has, however, been difficult for many social workers. A particularly challenging aspect of this translation concerns the practice of social case work within a social development approach, a topic that has received virtually no attention in the social development literature. This paper constructs a process model for a form of social case work that is informed by social development principles and priorities
Exotic Meson Production in the System observed in the Reaction at 18 GeV/c
This letter reports results from the partial wave analysis of the
final state in collisions at 18GeV/c.
Strong evidence is observed for production of two mesons with exotic quantum
numbers of spin, parity and charge conjugation, in the decay
channel . The mass MeV/c^2 and
width MeV/c^2 of the first state are consistent
with the parameters of the previously observed . The second
resonance with mass MeV/c^2 and width MeV/c^2 agrees very well with predictions from theoretical
models. In addition, the presence of is confirmed with mass MeV/c^2 and width MeV/c^2
and a new state, , is observed with mass
MeV/c^2 and width MeV/c^2. The decay properties of
these last two states are consistent with flux tube model predictions for
hybrid mesons with non-exotic quantum numbers
Observation of Pseudoscalar and Axial Vector Resonances in pi- p -> K+ K- pi0 n at 18 GeV
A new measurement of the reaction pi- p -> K+ K- pi0 n has been made at a
beam energy of 18 GeV. A partial wave analysis of the K+ K- pi0 system shows
evidence for three pseudoscalar resonances, eta(1295), eta(1416), and
eta(1485), as well as two axial vectors, f1(1285), and f1(1420). Their observed
masses, widths and decay properties are reported. No signal was observed for
C(1480), an IG J{PC} = 1+ 1{--} state previously reported in phi pi0 decay.Comment: 7 pages, 6 figs, to be submitted to Phys. Let
Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c
Results are presented on a partial wave analysis of the Omega Eta final state
produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0
-> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay
mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass
M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The
h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures
and 1 tabl
HI in the Outskirts of Nearby Galaxies
The HI in disk galaxies frequently extends beyond the optical image, and can
trace the dark matter there. I briefly highlight the history of high spatial
resolution HI imaging, the contribution it made to the dark matter problem, and
the current tension between several dynamical methods to break the disk-halo
degeneracy. I then turn to the flaring problem, which could in principle probe
the shape of the dark halo. Instead, however, a lot of attention is now devoted
to understanding the role of gas accretion via galactic fountains. The current
cold dark matter theory has problems on galactic scales, such as
the core-cusp problem, which can be addressed with HI observations of dwarf
galaxies. For a similar range in rotation velocities, galaxies of type Sd have
thin disks, while those of type Im are much thicker. After a few comments on
modified Newtonian dynamics and on irregular galaxies, I close with statistics
on the HI extent of galaxies.Comment: 38 pages, 17 figures, invited review, book chapter in "Outskirts of
Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and
Space Science Library, Springer, in pres
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