31 research outputs found
Psychosocial Treatment of Children in Foster Care: A Review
A substantial number of children in foster care exhibit psychiatric difficulties. Recent epidemiologi-cal and historical trends in foster care, clinical findings about the adjustment of children in foster care, and adult outcomes are reviewed, followed by a description of current approaches to treatment and extant empirical support. Available interventions for these children can be categorized as either symptom-focused or systemic, with empirical support for specific methods ranging from scant to substantial. Even with treatment, behavioral and emotional problems often persist into adulthood, resulting in poor functional outcomes. We suggest that self-regulation may be an important mediat-ing factor in the appearance of emotional and behavioral disturbance in these children
HST-COS Observations of Hydrogen, Helium, Carbon and Nitrogen Emission from the SN 1987A Reverse Shock
We present the most sensitive ultraviolet observations of Supernova 1987A to
date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins
Spectrograph shows many narrow (dv \sim 300 km/s) emission lines from the
circumstellar ring, broad (dv \sim 10 -- 20 x 10^3 km/s) emission lines from
the reverse shock, and ultraviolet continuum emission. The high signal-to-noise
(> 40 per resolution element) broad LyA emission is excited by soft X-ray and
EUV heating of mostly neutral gas in the circumstellar ring and outer supernova
debris. The ultraviolet continuum at \lambda > 1350A can be explained by HI
2-photon emission from the same region. We confirm our earlier, tentative
detection of NV \lambda 1240 emission from the reverse shock and we present the
first detections of broad HeII \lambda1640, CIV \lambda1550, and NIV]
\lambda1486 emission lines from the reverse shock. The helium abundance in the
high-velocity material is He/H = 0.14 +/- 0.06. The NV/H-alpha line ratio
requires partial ion-electron equilibration (T_{e}/T_{p} \approx 0.14 - 0.35).
We find that the N/C abundance ratio in the gas crossing the reverse shock is
significantly higher than that in the circumstellar ring, a result that may be
attributed to chemical stratification in the outer envelope of the supernova
progenitor. The N/C abundance ratio may have been stratified prior to the ring
expulsion, or this result may indicate continued CNO processing in the
progenitor subsequent to the expulsion of the circumstellar ring.Comment: 12 pages, 8 figures. ApJ - accepte
The Connection Between Thermal and Non-Thermal Emission in Gamma-ray Bursts: General Considerations and GRB090902B as a Case Study
Photospheric (thermal) emission is inherent to the gamma-ray burst (GRB)
"fireball" model. We show here, that inclusion of this component in the
analysis of the GRB prompt emission phase naturally explains some of the prompt
GRB spectra seen by the Fermi satellite over its entire energy band. The
sub-MeV peak is explained as multi-color black body emission, and the high
energy tail, extending up to the GeV band, results from roughly similar
contributions of synchrotron emission, synchrotron self Compton(SSC) and
Comptonization of the thermal photons by energetic electrons originating after
dissipation of the kinetic energy above the photosphere. We show how this
analysis method results in a complete, self consistent picture of the physical
conditions at both emission sites of the thermal and non-thermal radiation. We
study the connection between the thermal and non-thermal parts of the spectrum,
and show how the values of the free model parameters are deduced from the data.
We demonstrate our analysis method on GRB090902B: We deduce a Lorentz factor in
the range 920 <= \eta <= 1070, photospheric radius r_{ph} ~ 7.2 - 8.4 * 10^{11}
cm and dissipation radius r_\gamma >= 3.5 - 4.1 * 10^{15} cm. By comparison to
afterglow data, we deduce that a large fraction, epsilon_d ~85% - 95% of the
kinetic energy is dissipated, and that large fraction, ~equipartition of this
energy is carried by the electrons and the magnetic field. This high value of
epsilon_d questions the "internal shock" scenario as the main energy
dissipation mechanism for this GRB.Comment: 15 pages, 5 figures; minor revisions, typos corrected. Accepted for
publication in MNRA
PTF10iya: A short-lived, luminous flare from the nuclear region of a star-forming galaxy
We present the discovery and characterisation of PTF10iya, a short-lived (dt
~ 10 d, with an optical decay rate of ~ 0.3 mag per d), luminous (M_g ~ -21
mag) transient source found by the Palomar Transient Factory. The
ultraviolet/optical spectral energy distribution is reasonably well fit by a
blackbody with T ~ 1-2 x 10^4 K and peak bolometric luminosity L_BB ~ 1-5 x
10^44 erg per s (depending on the details of the extinction correction). A
comparable amount of energy is radiated in the X-ray band that appears to
result from a distinct physical process. The location of PTF10iya is consistent
with the nucleus of a star-forming galaxy (z = 0.22405 +/- 0.00006) to within
350 mas (99.7 per cent confidence radius), or a projected distance of less than
1.2 kpc. At first glance, these properties appear reminiscent of the
characteristic "big blue bump" seen in the near-ultraviolet spectra of many
active galactic nuclei (AGNs). However, emission-line diagnostics of the host
galaxy, along with a historical light curve extending back to 2007, show no
evidence for AGN-like activity. We therefore consider whether the tidal
disruption of a star by an otherwise quiescent supermassive black hole may
account for our observations. Though with limited temporal information,
PTF10iya appears broadly consistent with the predictions for the early
"super-Eddington" phase of a solar-type star disrupted by a ~ 10^7 M_sun black
hole. Regardless of the precise physical origin of the accreting material, the
large luminosity and short duration suggest that otherwise quiescent galaxies
can transition extremely rapidly to radiate near the Eddington limit; many such
outbursts may have been missed by previous surveys lacking sufficient cadence.Comment: 18 pages, 8 figures; revised following referee's comment
Psychosocial Treatment of Children in Foster Care: A Review
A substantial number of children in foster care exhibit psychiatric difficulties. Recent epidemiologi-cal and historical trends in foster care, clinical findings about the adjustment of children in foster care, and adult outcomes are reviewed, followed by a description of current approaches to treatment and extant empirical support. Available interventions for these children can be categorized as either symptom-focused or systemic, with empirical support for specific methods ranging from scant to substantial. Even with treatment, behavioral and emotional problems often persist into adulthood, resulting in poor functional outcomes. We suggest that self-regulation may be an important mediat-ing factor in the appearance of emotional and behavioral disturbance in these children
All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe
The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class
mission concept that will provide essential contributions to multimessenger
astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in
the 200 keV to 10 GeV energy range with a wide field of view, good spectral
resolution, and polarization sensitivity. Therefore, AMEGO is key in the study
of multimessenger astrophysical objects that have unique signatures in the
gamma-ray regime, such as neutron star mergers, supernovae, and flaring active
galactic nuclei. The order-of-magnitude improvement compared to previous MeV
missions also enables discoveries of a wide range of phenomena whose energy
output peaks in the relatively unexplored medium-energy gamma-ray band