8,318 research outputs found
The Effects of Negative Legacies on the Adjustment of Parentally Bereaved Children and Adolescents
This is a report of a qualitative analysis of a sample of bereaved families in which one parent died and in which children scored in the clinical range on the Child Behavior Check List. The purpose of this analysis was to learn more about the lives of these children. They were considered to be at risk of developing emotional and behavioral problems associated with the death. We discovered that many of these âhigh riskâ children had a continuing bond with the deceased that was primarily negative and troubling for them in contrast to a comparison group of children not at risk from the same study. Five types of legacies, not mutually exclusive, were identified: health related, role related, personal qualities, legacy of blame, and an emotional legacy. Coping behavior on the part of the surviving parent seemed to make a difference in whether or not a legacy was experienced as negative
Some genus 3 curves with many points
Using an explicit family of plane quartic curves, we prove the existence of a
genus 3 curve over any finite field of characteristic 3 whose number of
rational points stays within a fixed distance from the Hasse-Weil-Serre upper
bound. We also provide an intrinsic characterization of so-called Legendre
elliptic curves
Chiral molecules split light: Reflection and refraction in a chiral liquid
A light beam changes direction as it enters a liquid at an angle from another
medium, such as air. Should the liquid contain molecules that lack mirror
symmetry, then it has been predicted by Fresnel that the light beam will not
only change direction, but will actually split into two separate beams with a
small difference in the respective angles of refraction. Here we report the
observation of this phenomenon. We also demonstrate that the angle of
reflection does not equal the angle of incidence in a chiral medium. Unlike
conventional optical rotation, which depends on the path-length through the
sample, the reported reflection and refraction phenomena arise within a few
wavelengths at the interface and thereby suggest a new approach to polarimetry
that can be used in microfluidic volumes
The Full Range of Predictions for B Physics From Iso-singlet Down Quark Mixing
We extend the range of predictions of the isosinglet (or vector) down quark
model to the fully allowed physical ranges, and also update this with the
effect of new physics constraints. We constrain the present allowed ranges of
sin(2*beta) and sin(2*alpha), gamma, x_s, and A_{B_s}. In models allowing
mixing to a new isosinglet down quark (as in E_6) flavor changing neutral
currents are induced that allow a Z^0 mediated contribution to B-Bbar mixing
and which bring in new phases. In (rho, eta), (x_s, sin(gamma)), and (x_s,
A_{B_s}) plots for the extra isosinglet down quark model which are herein
extended to the full physical range, we find new allowed regions that will
require experiments on sin(gamma) and/or x_s to verify or to rule out an extra
down quark contribution.Comment: 13 pages in RevTeX, 7 postscript figure
Iso-singlet Down Quark Mixing And CP Violation Experiments
We confront the new physics models with extra iso-singlet down quarks in the
new CP violation experimental era with and
measurements, events, and
limits. The closeness of the new experimental results to the standard
model theory requires us to include full SM amplitudes in the analysis. In
models allowing mixing to a new isosinglet down quark, as in E, flavor
changing neutral currents are induced that allow a mediated contribution
to mixing and which bring in new phases. In ,
, and plots we still find much
larger regions in the four down quark model than in the SM, reaching down to
, , , and down to zero, all at 1. We elucidate
the nature of the cancellation in an order four down quark mixing
matrix element which satisfies the experiments and reduces the number of
independent angles and phases. We also evaluate tests of unitarity for the
CKM submatrix.Comment: 14 pages, 16 figures, REVTeX
The Distribution of Nearby Stars in Velocity Space Inferred from Hipparcos Data
(abridged) The velocity distribution f(v) of nearby stars is estimated, via a
maximum- likelihood algorithm, from the positions and tangential velocities of
a kinematically unbiased sample of 14369 stars observed by the HIPPARCOS
satellite. f(v) shows rich structure in the radial and azimuthal motions, v_R
and v_phi, but not in the vertical velocity, v_z: there are four prominent and
many smaller maxima, many of which correspond to well known moving groups.
While samples of early-type stars are dominated by these maxima, also up to 25%
of red main-sequence stars are associated with them. These moving groups are
responsible for the vertex deviation measured even for samples of late-type
stars; they appear more frequently for ever redder samples; and as a whole they
follow an asymmetric-drift relation, in the sense that those only present in
red samples predominantly have large |v_R| and lag in v_phi w.r.t. the local
standard of rest (LSR). The question arise, how these old moving groups got on
their eccentric orbits. A plausible mechanism, known from solar system
dynamics, which is able to manage a shift in orbit space involves locking into
an orbital resonance.
Apart from these moving groups, there is a smooth background distribution,
akin to Schwarzschild's ellipsoidal model, with axis ratio of about 1:0.6:0.35
in v_R, v_phi, and v_z. The contours are aligned with the direction, but
not w.r.t. the v_phi and v_z axes: the mean v_z increases for stars rotating
faster than the LSR. This effect can be explained by the stellar warp of the
Galactic disk. If this explanation is correct, the warp's inner edge must not
be within the solar circle, while its pattern rotates with frequency of about
13 km/s/kpc or more retrograde w.r.t. the stellar orbits.Comment: 16 pages LaTeX (aas2pp4.sty), 6 figures, accepted by A
Hard X-ray emitting Active Galactic Nuclei selected by the Chandra Multi-wavelength Project
We present X-ray and optical analysis of 188 AGN identified from 497 hard
X-ray (f (2.0-8.0 keV) > 2.7x10^-15 erg cm^-2 s^-1) sources in 20 Chandra
fields (1.5 deg^2) forming part of the Chandra Multi-wavelength Project. These
medium depth X-ray observations enable us to detect a representative subset of
those sources responsible for the bulk of the 2-8 keV Cosmic X-ray Background.
Brighter than our optical spectroscopic limit, we achieve a reasonable degree
of completeness (77% of X-ray sources with counter-parts r'< 22.5 have been
classified): broad emission line AGN (62%), narrow emission line galaxies
(24%), absorption line galaxies (7%), stars (5%) or clusters (2%). We find that
most X-ray unabsorbed AGN (NH<10^22 cm^-2) have optical properties
characterized by broad emission lines and blue colors, similiar to
optically-selected quasars from the Sloan Digital Sky Survey but with a slighly
broader color distribution. However, we also find a significant population of
redder (g'-i'>1.0) AGN with broad optical emission lines. Most of the X-ray
absorbed AGN (10^22<NH<10^24 cm^-2) are associated with narrow emission line
galaxies, with red optical colors characteristically dominated by luminous,
early type galaxy hosts rather than from dust reddening of an AGN. We also find
a number of atypical AGN; for instance, several luminous AGN show both strong
X-ray absorption (NH>10^22 cm^-2) and broad emission lines. Overall, we find
that 81% of X-ray selected AGN can be easily interpreted in the context of
current AGN unification models. Most of the deviations seem to be due to an
optical contribution from the host galaxies of the low luminosity AGN.Comment: 26 pages; 13 figures (7 color); accepted for publication in the
Astrophysical Journa
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Psychopathology in Williams syndrome: the effect of individual differences across the lifespan
The present research aimed to comprehensively explore psychopathology in Williams syndrome (WS) across the lifespan and evaluate the relationship between psychopathology and age category (child or adult), gender and cognitive ability. The parents of 50 participants with WS, aged 6-50 years, were interviewed using the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS-PL). The prevalence of a wide range of Axis I DSM-IV disorders was assessed. In addition to high rates of anxiety and Attention Deficit Hyperactivity Disorder (ADHD) (38% and 20% respectively), 14% of our sample met criteria for a depressive disorder and 42% of participants were not experiencing any significant psychopathological difficulties. There was some evidence for different patterns of psychopathology between children and adults with WS and between males and females. These relationships were largely in keeping with those found in the typically developing population, thus supporting the validity of applying theory and treatment approaches for psychopathology in the typically developing population to WS
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