Emerging depression in adolescence coincides with accelerated frontal cortical thinning.

BACKGROUND: Adolescence is a transition period characterized by heightened emotional reactivity, which for some sets the stage for emerging depressive symptoms. Prior studies suggest that adolescent depression is associated with deviant cortical and subcortical brain structure. Longitudinal studies are, however, currently scarce, but critical to detect which adolescents are at risk for developing depressive symptoms. METHODS: In this longitudinal study, a community sample of 205 participants underwent magnetic resonance imaging (MRI) in three biennial waves (522 scans) spanning 5 years across ages 8-25 years. Depressive symptomatology was assessed using self-report at the third time point. Mixed models were used to examine the relations between structural brain development, specifically regional change in cortical thickness, surface area and subcortical volumes (hippocampus and amygdala), and depressive symptoms. RESULTS: Accelerated frontal lobe cortical thinning was observed in adolescents who developed depressive symptoms at the third time point. This effect remained after controlling for parent-reported affective problems at the first time point. Moreover, the effect was driven by specific lateral orbitofrontal and precentral regions. In addition, differential developmental trajectories of parietal cortical thickness and surface area in several regions were found for participants reporting higher depressive symptomatology, but these results did not survive correction for multiple comparisons. Volumes or developmental volume changes in hippocampus or amygdala were not related to depressive symptoms. CONCLUSIONS: This study showed that emerging depression is associated with cortical thinning in frontal regions within individuals. These findings move beyond detecting cross-sectional correlations and set the stage for early detection, which may inform future intervention.

Measurements of the electric form factor of the neutron up to Q2=3.4 GeV2 using the reaction 3He(e,e'n)pp.

The electric form factor of the neutron was determined from studies of the reaction 3He(e,e'n)pp in quasielastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2 range over which it is known, we find G(E)(n)=0.0236±0.0017(stat)±0.0026(syst), 0.0208±0.0024±0.0019, and 0.0147±0.0020±0.0014 for Q(2)=1.72, 2.48, and 3.41 GeV2, respectively.

New nanosized Gd-Ho-Sm doped M-type strontium hexaferrite for water treatment application: experimental and theoretical investigations.

In this paper, rare-earth doped M-type strontium hexaferrite magnetic nanoparticles SrHo x Gd y Sm z Fe(12-(x+z+y))O19 (x = y = z = 0.01) have been prepared by the sol-gel combustion method for the first time. The properties of the material were investigated using XRD, FTIR spectroscopy, Raman spectroscopy, SEM, UV-Vis spectroscopy, and VSM. X-ray analysis revealed that a magnetic single-phase was formed with a crystallite average size of 49 nm. FTIR spectra confirmed the formation of the structure of the hexaferrite phase. Raman analysis confirmed the formation of all crystallographic hexaferrite sites. A shift in the octahedral site frequencies and a significant shift were observed at site 12k and 2a, indicating that the doping elements occupied these sites. The SEM analysis showed that the particles were different in shape and slightly agglomerated. The EDS result confirmed the purity of the sample. The calculated band gap from the UV-Vis NIR spectroscopy spectra of the sample was 1.62 eV. The magnetic analysis of the sample material at room temperature revealed a coercivity of 5257.63 Oe, saturation magnetization of 67.72 emu g-1, remanence ratio of 0.52, a maximum magnetic energy product of 1.06 MGOe and Curie temperature of T c = 765 K. First-principles calculations were conducted on multiple configurations of SrFe12-x X x O19 with x = 0, 0.5 and X = Sm, Gd, Ho. The site preference of each doping element was determined, and the effect of the doping on the structural, electronic, and magnetic properties of the compound was studied. The magnetic properties of this rare earth (Gd, Ho, Sm) doped strontium hexaferrite indicated that this compound could be used in both permanent magnets and water treatment application.

High-resolution spectroscopy of Lambda16N by electroproduction.

An experimental study of the (16)O(e,e'K(+))(Lambda)(16)N reaction has been performed at Jefferson Lab. A thin film of falling water was used as a target. This permitted a simultaneous measurement of the p(e,e'K(+))Lambda, Sigma(0) exclusive reactions and a precise calibration of the energy scale. A ground-state binding energy of 13.76+/-0.16 MeV was obtained for (Lambda)(16)N with better precision than previous measurements on the mirror hypernucleus (Lambda)(16)O. Precise energies have been determined for peaks arising from a Lambda in s and p orbits coupled to the p(1/2) and p(3/2) hole states of the (15)N core nucleus.

Longitudinal development of hippocampal subregions from childhood to adulthood.

Detailed descriptions of the development of the hippocampus promise to shed light on the neural foundation of development of memory and other cognitive functions, as well as the emergence of major mental disorders. Hippocampus is a heterogeneous structure with a well characterized internal complexity, but development of its distinct subregions in humans has remained poorly described. We analyzed magnetic resonance imaging (MRI) data from a large longitudinal sample (270 participants, 678 scans) using an automated segmentation tool and mixed models to delineate the development of hippocampal subregion volumes from childhood to adulthood. We also examined sex differences in subregion volumes and their development, and associations between hippocampal subregions and general cognitive ability. Nonlinear developmental trajectories with early volume increases were observed for subiculum, cornu ammonis (CA) 1, molecular layer (ML) and fimbria. In contrast, parasubiculum, presubiculum, CA2/3, CA4 and the granule cell layer of the dentate gyrus (GC-DG) showed linear volume decreases. No sex differences were found in hippocampal subregion development. Finally, general cognitive ability was positively associated with CA2/3 and CA4 volumes, as well as with ML development. In conclusion, hippocampal subregions appear to develop in diversified ways across adolescence, and specific subregions may link to general cognitive level.

High resolution spectroscopy of (lambda)(12)B by electroproduction.

An experiment measuring electroproduction of hypernuclei has been performed in hall A at Jefferson Lab on a 12C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring imaging Cherenkov detector were added to the hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed (Lambda)(12)B spectrum shows for the first time identifiable strength in the core-excited region between the ground-state s-wave Lambda peak and the 11 MeV p-wave Lambda peak.

Deeply virtual compton scattering off the neutron.

The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e,e'gamma)X cross section measured at Q2=1.9 GeV2 and xB=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to E_{q}, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

Scaling tests of the cross section for deeply virtual Compton scattering.

We present the first measurements of the e[over -->]p-->epgamma cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q(2) dependence (from 1.5 to 2.3 GeV(2)) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q(2). The helicity-independent cross section is also measured at Q(2)=2.3 GeV(2). We present the first model-independent measurement of linear combinations of GPDs and GPD integrals up to the twist-3 approximation.

Parity-violating electron scattering from 4He and the strange electric form factor of the nucleon.

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 4He at an average scattering angle = 5.7 degrees and a four-momentum transfer Q2 = 0.091 GeV2 . From these data, for the first time, the strange electric form factor of the nucleon G(E)s can be isolated. The measured asymmetry of A(PV) = (6.72 +/- 0.84(stat) +/- 0.21(syst) x 10(-6) yields a value of G(E)s = -0.038 +/- 0.042(stat) +/- 0.010(syst), consistent with zero.