1,444 research outputs found
Anxiety and Depression During Childhood and Adolescence: Testing Theoretical Models of Continuity and Discontinuity
The present study sought to clarify the trajectory (i.e., continuous vs. discontinuous) and expression (i.e., homotypic vs. heterotypic) of anxiety and depressive symptoms across childhood and adolescence. We utilized a state-of-the-science analytic approach to simultaneously test theoretical models that describe the development of internalizing symptoms in youth. In a sample of 636 children (53% female; M age = 7.04; SD age = 0.35) self-report measures of anxiety and depression were completed annually by youth through their freshman year of high school. For both anxiety and depression, a piecewise growth curve model provided the best fit for the data, with symptoms decreasing until age 12 (the âdevelopmental knotâ) and then increasing into early adolescence. The trajectory of anxiety symptoms was best described by a discontinuous homotypic pattern in which childhood anxiety predicted adolescent anxiety. For depression, two distinct pathways were discovered: A discontinuous homotypic pathway in which childhood depression predicted adolescent depression and a discontinuous heterotypic pathway in which childhood anxiety predicted adolescent depression. Analytical, methodological, and clinical implications of these findings are discussed
At risk of being risky: The relationship between "brain age" under emotional states and risk preference.
Developmental differences regarding decision making are often reported in the absence of emotional stimuli and without context, failing to explain why some individuals are more likely to have a greater inclination toward risk. The current study (N=212; 10-25y) examined the influence of emotional context on underlying functional brain connectivity over development and its impact on risk preference. Using functional imaging data in a neutral brain-state we first identify the "brain age" of a given individual then validate it with an independent measure of cortical thickness. We then show, on average, that "brain age" across the group during the teen years has the propensity to look younger in emotional contexts. Further, we show this phenotype (i.e. a younger brain age in emotional contexts) relates to a group mean difference in risk perception - a pattern exemplified greatest in young-adults (ages 18-21). The results are suggestive of a specified functional brain phenotype that relates to being at "risk to be risky.
Quantum interference in a driven two-level atom
We show that a dynamical suppression of spontaneous emission, predicted for a three-level atom [S.-Y. Zhu and M. O. Scully, Phys. Rev. Lett. 76, 388 (1996)] can occur in a two-level atom driven by st polychromatic field. We find that the quantum interference, responsible for the cancellation of spontaneous emission, appears between different channels of transitions among the dressed states of the driven atom. We discuss the effect for bichromatic and trichromatic (amplitude-modulated) fields and fmd that these two cases lead to the cancellation of spontaneous emission in different parts of the fluorescence spectrum. Our system has the advantage of being easily accessible by current experiments. [S1050-2947(99)50712-9]
Effective interaction for pf-shell nuclei
An effective interaction is derived for use in the full pf basis. Starting
from a realistic G-matrix interaction, 195 two-body matrix elements and 4
single-particle energies are determined by fitting to 699 energy data in the
mass range 47 to 66. The derived interaction successfully describes various
structures of pf-shell nuclei. As examples, systematics of the energies of the
first 2+ states in the Ca, Ti, Cr, Fe, and Ni isotope chains and energy levels
of 56,57,58Ni are presented. The appearance of a new magic number 34 is seen.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
Maternal Effects of Aseptic and Septic Injury on Embryonic Larval Gene Expression in the Tobacco Hornworm, Manduca Sexta
Cross-generational effects of physical and pathogenic stress have been demonstrated in several insect groups, including our model insect Manduca sexta. Prior studies in our laboratory have shown that maternal exposure to the soil-dwelling gram-negative bacteria, Serratia marcescens, just prior to adult eclosion alters egg morphology and larval immunity. Our goal is to identify mechanisms underlaying pathogen-associated parental effects on offspring. The current study advances this goal through measurement of embryonic size, embryonic histone modification, and both embryonic and larval gene expression. Two days prior to eclosion, parents were injected with saline, heat killed S. marcescens, or live S. marcescens. Embryos were collected at 24 (+/- 2) h or permitted to hatch for clearance assays (first instar) or measurement of fat body gene expression (fourth instar). We find that maternal, but not paternal, pathogen exposure significantly increases egg volume variability, and that maternal pathogen exposure may delay hatching. Furthermore, maternal injection with bacteria conferred on their offspring an enhanced ability to clear infection when compared to their saline injected peers. Histone analysis revealed that maternal treatment does not globally alter embryonic histones, however, several immune-related genes demonstrated altered expression in both embryos and fourth instar larvae
Ionization balance of Ti in the photospheres of the Sun and four late-type stars
In this paper we investigate statistical equilibrium of Ti in the atmospheres
of late-type stars. The Ti I/Ti II level populations are computed with
available experimental atomic data, except for photoionization and collision
induced transition rates, for which we have to rely on theoretical
approximations. For the Sun, the NLTE line formation with adjusted H I
inelastic collision rates and MAFAGS-OS model atmosphere solve the
long-standing discrepancy between Ti I and Ti II lines. The NLTE abundances
determined from both ionization stages agree within dex with each other
and with the Ti abundance in C I meteorites. The Ti NLTE model does not perform
similarly well for the metal-poor stars, overestimating NLTE effects in the
atmospheres of dwarfs, but underestimating overionization for giants.
Investigating different sources of errors, we find that only [Ti/Fe] ratios
based on Ti II and Fe II lines can be safely used in studies of Galactic
chemical evolution. To avoid spurious abundance trends with metallicity and
dwarf/giant discrepancies, it is strongly recommended to disregard Ti I lines
in abundance analyses, as well as in determination of surface gravities.Comment: 16 pages, accepted for publication in MNRA
Altered cortical brain activity in end stage liver disease assessed by multi-channel near-infrared spectroscopy: associations with delirium
Quantitative spectroscopy of Galactic BA-type supergiants. I. Atmospheric parameters
BA-type supergiants show a high potential as versatile indicators for modern
astronomy. The focus here is on the determination of accurate and precise
atmospheric parameters for a sample of 35 Galactic BA-type supergiants. Some
first applications include a recalibration of functional relationships between
spectral-type, intrinsic colours, bolometric corrections and effective
temperature, and an exploration of the reddening-free Johnson Q and Str\"omgren
[c_1] and beta-indices as photometric indicators for effective temperatures and
gravities of BA-type supergiants. An extensive grid of theoretical spectra is
computed based on a hybrid non-LTE approach. The atmospheric parameters are
derived spectroscopically by line-profile fits to high-resolution and high-S/N
spectra obtained at various observatories. Ionization equilibria of multiple
metals and the Stark-broadened H and the neutral He lines constitute our
primary indicators for the parameter determination, supplemented by
(spectro-)photometry. Data on Teff, logg, helium abundances, microturbulence,
macroturbulence and rotational velocities are presented. The interstellar
reddening and the ratio of total-to-selective extinction towards the stars are
determined. Our empirical spectral-type-Teff scale is steeper than reference
relations, the stars are significantly bluer, and bolometric corrections differ
significantly from established literature values. Photometric
Teff-determinations based on the reddening-free Q-index are found to be of
limited use for studies of BA-type supergiants because of large errors of
typically +-5%+-3% (1sigma statistical, 1sigma systematic), compared to a
spectroscopically achieved precision of 1-2%. The reddening-free [c_1]-index
and beta on the other hand are found to provide useful starting values for
further analyses, with uncertainties of +-1%+-2.5% in Teff, and +-0.04+-0.13dex
in log g. [abriged]Comment: 18 pages, 18 figures; A&
Highly deformed Ca configurations in Si + C
The possible occurrence of highly deformed configurations in the Ca
di-nuclear system formed in the Si + C reaction is investigated
by analyzing the spectra of emitted light charged particles. Both inclusive and
exclusive measurements of the heavy fragments (A 10) and their
associated light charged particles (protons and particles) have been
made at the IReS Strasbourg {\sc VIVITRON} Tandem facility at bombarding
energies of Si) = 112 MeV and 180 MeV by using the {\sc ICARE}
charged particle multidetector array. The energy spectra, velocity
distributions, and both in-plane and out-of-plane angular correlations of light
charged particles are compared to statistical-model calculations using a
consistent set of parameters with spin-dependent level densities. The analysis
suggests the onset of large nuclear deformation in Ca at high spin.Comment: 33 pages, 11 figure
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