1,065 research outputs found
Dusty, Radiation Pressure Dominated Photoionization. II. Multi-Wavelength Emission Line Diagnostics for Narrow Line Regions
Seyfert narrow line region (NLR) emission line ratios are remarkably uniform,
displaying only ~0.5 dex variation between galaxies, and even less within an
individual object. Previous photoionization and shock models of this region
were unable to explain this observation without the introduction of arbitrary
assumptions or additional parameters. Dusty, radiation pressure dominated
photoionization models provide a simple physical mechanism which can reproduce
this spectral uniformity between different objects. In the first paper of this
series we described this model and its implementation in detail, as well as
presenting grids of model emission lines and examining the model structures.
Here we explore these models further, demonstrating their ability to reproduce
the observed Seyfert line ratios on standard line diagnostic diagrams in both
the optical and UV. We also investigate the effects that the variation of
metallicity, density and ionizing spectrum have upon both the new paradigm and
the standard photoionization models used hitherto. Along with the standard
diagnostic diagrams we provide several new diagnostic diagrams in the UV,
Optical and IR. These new diagrams can provide further tests of the dusty,
radiation pressure photoionization paradigm as well as being used as
diagnostics of the metallicity, density and ionizing spectrum of the emission
line clouds.Comment: Accepted by ApJS, full pdf including figures can be obtained at
http://www.mso.anu.edu.au/~bgroves/Papers/ApJS2.pd
Electronic Structure of LuRh2Si2: "Small" Fermi Surface Reference to YbRh2Si2
We present band structure calculations and quantum oscillation measurements
on LuRh2Si2, which is an ideal reference to the intensively studied quantum
critical heavy-fermion system YbRh2Si2. Our band structure calculations show a
strong sensitivity of the Fermi surface on the position of the silicon atoms
zSi within the unit cell. Single crystal structure refinement and comparison of
predicted and observed quantum oscillation frequencies and masses yield zSi =
0.379c in good agreement with numerical lattice relaxation. This value of zSi
is suggested for future band structure calculations on LuRh2Si2 and YbRh2Si2.
LuRh2Si2 with a full f electron shell represents the "small" Fermi surface
configuration of YbRh2Si2. Our experimentally and ab initio derived quantum
oscillation frequencies of LuRh2Si2 show strong differences with earlier
measurements on YbRh2Si2. Consequently, our results confirm the contribution of
the f electrons to the Fermi surface of YbRh2Si2 at high magnetic fields. Yet
the limited agreement with refined fully itinerant local density approximation
calculations highlights the need for more elaborated models to describe the
Fermi surface of YbRh2Si2.Comment: 12 pages 10 figure
Thermodynamics of ideal quantum gas with fractional statistics in D dimensions
We present exact and explicit results for the thermodynamic properties
(isochores, isotherms, isobars, response functions, velocity of sound) of a
quantum gas in dimensions D>=1 and with fractional exclusion statistics 0<=g<=1
connecting bosons (g=0) and fermions (g=1). In D=1 the results are equivalent
to those of the Calogero-Sutherland model. Emphasis is given to the crossover
between boson-like and fermion-like features, caused by aspects of the
statistical interaction that mimic long-range attraction and short-range
repulsion. The full isochoric heat capacity and the leading low-T term of the
isobaric expansivity in D=2 are independent of g. The onset of Bose-Einstein
condensation along the isobar occurs at a nonzero transition temperature in all
dimensions. The T-dependence of the velocity of sound is in simple relation to
isochores and isobars. The effects of soft container walls are accounted for
rigorously for the case of a pure power-law potential.Comment: 15 pages, 31 figure
RANKL increases the level of Mcl-1 in osteoclasts and reduces bisphosphonate-induced osteoclast apoptosis in vitro
Peer reviewedPublisher PD
The MAPPINGS III Library of Fast Radiative Shock Models
We present a new library of fully-radiative shock models calculated with the
MAPPINGS III shock and photoionization code. The library consists of grids of
models with shock velocities in the range v=100-1000 km/s and magnetic
parameters B/sqrt(n) of 10^-4 - 10 muG cm^(3/2) for five different atomic
abundance sets, and for a pre-shock density of 1.0 cm^(-3). Additionally, Solar
abundance model grids have been calculated for densities of 0.01, 0.1, 10, 100,
and 1000 cm^(-3) with the same range in v and B/sqrt(n). Each model includes
components of both the radiative shock and its photoionized precursor, ionized
by the EUV and soft X-ray radiation generated in the radiative gas. We present
the details of the ionization structure, the column densities, and the
luminosities of the shock and its precursor. Emission line ratio predictions
are separately given for the shock and its precursor as well as for the
composite shock+precursor structure to facilitate comparison with observations
in cases where the shock and its precursor are not resolved. Emission line
ratio grids for shock and shock+precursor are presented on standard line ratio
diagnostic diagrams, and we compare these grids to observations of radio
galaxies and a sample of AGN and star forming galaxies from the Sloan Digital
Sky Survey. This library is available online, along with a suite of tools to
enable the analysis of the shocks and the easy creation of emission line ratio
diagnostic diagrams. These models represent a significant increase in parameter
space coverage over previously available models, and therefore provide a unique
tool in the diagnosis of emission by shocks.Comment: 39 pages, 34 figures, accepted for publication in ApJS, April 200
Magnitude effects for experienced rewards at short delays in the escalating interest task
A first-person shooter video game was adapted for the study of choice between smaller sooner and larger later rewards. Participants chose when to fire a weapon that increased in damage potential over a short interval. When the delay to maximum damage was shorter (5 – 8 s), people showed greater sensitivity to the consequences of their choices than when the delay was longer (17 – 20 s). Participants also evidenced a magnitude effect by waiting proportionally longer when the damage magnitudes were doubled for all rewards. The experiment replicated the standard magnitude effect with this new video game preparation over time scales similar to those typically used in nonhuman animal studies and without complications due to satiation or cost
Taxonomy of particles in Ising spin chains
The statistical mechanics of particles with shapes on a one-dimensional
lattice is investigated in the context of the Ising chain with uniform
nearest-neighbor coupling, quadratic single-site potential, and magnetic field,
which supports four distinct ground states:
, ,
, . The complete
spectrum is generated from each ground state by particles from a different set
of six or seven species. Particles and elements of pseudo-vacuum are
characterized by motifs (patterns of several consecutive site variables).
Particles are floating objects that can be placed into open slots on the
lattice. Open slots are recognized as permissible links between motifs. The
energy of a particle varies between species but is independent of where it is
placed. Placement of one particle changes the open-slot configuration for
particles of all species. This statistical interaction is encoded in a
generalized Pauli principle, from which the multiplicity of states for a given
particle combination is determined and used for the exact statistical
mechanical analysis. Particles from all species belong to one of four
categories: compacts, hosts, tags, or hybrids. Compacts and hosts find open
slots in segments of pseudo-vacuum. Tags find open slots inside hosts. Hybrids
are tags with hosting capability. In the taxonomy of particles proposed here,
`species' is indicative of structure and `category' indicative of function. The
hosting function splits the Pauli principle into exclusion and accommodation
parts. Near phase boundaries, the state of the Ising chain at low temperature
is akin to that of miscible or immiscible liquids with particles from one
species acting as surfactant molecules.Comment: 12 pages, 6 tables, 6 figure
Are the Narrow Line Regions in Active Galaxies Dusty and Radiation Pressure Dominated?
The remarkable similarity between emission spectra of narrow line regions
(NLR) in Seyfert Galaxies has long presented a mystery. In photoionization
models, this similarity implies that the ionization parameter is nearly always
the same, about U ~ 0.01. Here we present dusty, radiation-pressure dominated
photoionization models that can provide natural physical insight into this
problem. In these models, dust and the radiation pressure acting on it provide
the controlling factor in moderating the density, excitation and surface
brightness of photoionized NLR structures. Additionally, photoelectric heating
by the dust is important in determining the temperature structure of the
models. These models can also explain the coexistence of the low-,
intermediate- and coronal ionization zones within a single self-consistent
physical structure. The radiation pressure acting on dust may also be capable
of driving the fast (~3000 km/s) outflows such as are seen in the HST
observations of NGC 1068.Comment: 23 pages, 8 figures, Accepted by Ap
School-Based Relationships Among Children with or at Risk for Emotional and Behavioral Disorders
We investigated the influence of a teacher’s perceived emotional state (e.g., feeling emotionally exhausted; feeling accomplished) on the association between parent-teacher relationships and teacher-child conflict among young children. We used pretest data from a pilot study examining the efficacy of a socio-emotional learning intervention for children with or at risk for emotional or behavioral disorders (EBD). Twenty-six teachers and 45 children (Mean age= 7.46 years; SD = 1.21) participated in the intervention. Teachers rated their relationships with children and their parents using the Parent-Teacher Relationship Scale and Student-Teacher Relationship Scale. Multilevel models showed that teachers with a higher sense of personal accomplishment evidenced a negative association between parent-teacher relationships and teacher-child conflict. However, for teachers who felt emotionally exhausted or those who had a lower sense of personal achievement, the association between parent-teacher relationships and teacher-child conflict either remained unchanged or was positive. We conclude by discussing findings in relation to the importance of increasing teacher efficacy, reducing teacher burnout, and strengthening parent-teacher relationships in schools to improve teacher-child relationships and children’s psychosocial outcomes
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