Epigenetic and genetic variation at SKA2 predict suicidal behavior and post-traumatic stress disorder

Traumatic stress results in hypothalamic pituitary adrenal (HPA) axis abnormalities and an increased risk to both suicidal behaviors and post-traumatic stress disorder (PTSD). Previous work out of our laboratory identified SKA2 DNA methylation associations with suicidal behavior in the blood and brain of multiple cohorts. Interaction of SKA2 with stress predicted suicidal behavior with ~80% accuracy. SKA2 is hypothesized to reduce the ability to suppress cortisol following stress, which is of potentially high relevance in traumatized populations. Our objective was to investigate the interaction of SKA2 and trauma exposure on HPA axis function, suicide attempt and PTSD. SKA2 DNA methylation at Illumina HM450 probe cg13989295 was assessed for association with suicidal behavior and PTSD metrics in the context of Child Trauma Questionnaire (CTQ) scores in 421 blood and 61 saliva samples from the Grady Trauma Project (GTP) cohort. Dexamethasone suppression test (DST) data were evaluated for a subset of 209 GTP subjects. SKA2 methylation interacted with CTQ scores to predict lifetime suicide attempt in saliva and blood with areas under the receiver operator characteristic curve (AUCs) of 0.76 and 0.73 (95% confidence interval (CI): 0.6–0.92, P=0.003, and CI: 0.65–0.78, P<0.0001) and to mediate the suppression of cortisol following DST (β=0.5±0.19, F=1.51, degrees of freedom (df)=12/167, P=0.0096). Cumulatively, the data suggest that epigenetic variation at SKA2 mediates vulnerability to suicidal behaviors and PTSD through dysregulation of the HPA axis in response to stress

Interface Tension in Quenched QCD

We calculate the tension $\sigma$ of the interface between the confined and deconfined phases by the histogram method in SU(3) lattice gauge theory for temporal extents of 4 and 6 using the recent high-statistics data by QCDPAX collaboration. The results are $\sigma/T_c^3 = 0.0292(22)$ and 0.0218(33) for $N_t=4$ and 6, respectively. The ratio $\sigma/T_c^3$ shows a scaling violation similar to that already observed for the latent heat \latent. However, we find that the physically interesting dimensionless combinations (\sigma^{3}/\latent^2 T)^{1/2} and \sigma T/ \latent scale within the statistical errors.Comment: 13 pages with 2 PostScript figures, LaTeX, CERN-TH.6798/93, AZPH-TH/93-04, UTHEP-25

High-Resolution Sampling of a Broad Marine Life Size Spectrum Reveals Differing Size- and Composition-Based Associations With Physical Oceanographic Structure

Observing multiple size classes of organisms, along with oceanographic properties and water mass origins, can improve our understanding of the drivers of aggregations, yet acquiring these measurements remains a fundamental challenge in biological oceanography. By deploying multiple biological sampling systems, from conventional bottle and net sampling to in situ imaging and acoustics, we describe the spatial patterns of different size classes of marine organisms (several microns to ∼10 cm) in relation to local and regional (m to km) physical oceanographic conditions on the Delaware continental shelf. The imaging and acoustic systems deployed included (in ascending order of target organism size) an imaging flow cytometer (CytoSense), a digital holographic imaging system (HOLOCAM), an In Situ Ichthyoplankton Imaging System (ISIIS, 2 cameras with different pixel resolutions), and multi-frequency acoustics (SIMRAD, 18 and 38 kHz). Spatial patterns generated by the different systems showed size-dependent aggregations and differing connections to horizontal and vertical salinity and temperature gradients that would not have been detected with traditional station-based sampling (∼9-km resolution). A direct comparison of the two ISIIS cameras showed composition and spatial patchiness changes that depended on the organism size, morphology, and camera pixel resolution. Large zooplankton near the surface, primarily composed of appendicularians and gelatinous organisms, tended to be more abundant offshore near the shelf break. This region was also associated with high phytoplankton biomass and higher overall organism abundances in the ISIIS, acoustics, and targeted net sampling. In contrast, the inshore region was dominated by hard-bodied zooplankton and had relatively low acoustic backscatter. The nets showed a community dominated by copepods, but they also showed high relative abundances of soft-bodied organisms in the offshore region where these organisms were quantified by the ISIIS. The HOLOCAM detected dense patches of ciliates that were too small to be captured in the nets or ISIIS imagery. This near-simultaneous deployment of different systems enables the description of the spatial patterns of different organism size classes, their spatial relation to potential prey and predators, and their association with specific oceanographic conditions. These datasets can also be used to evaluate the efficacy of sampling techniques, ultimately aiding in the design of efficient, hypothesis-driven sampling programs that incorporate these complementary technologies

Ultrafast carrier relaxation and vertical-transport phenomena in semiconductor superlattices: A Monte Carlo analysis

The ultrafast dynamics of photoexcited carriers in semiconductor superlattices is studied theoretically on the basis of a Monte Carlo solution of the coupled Boltzmann transport equations for electrons and holes. The approach allows a kinetic description of the relevant interaction mechanisms such as intra- miniband and interminiband carrier-phonon scattering processes. The energy relaxation of photoexcited carriers, as well as their vertical transport, is investigated in detail. The effects of the multiminiband nature of the superlattice spectrum on the energy relaxation process are discussed with particular emphasis on the presence of Bloch oscillations induced by an external electric field. The analysis is performed for different superlattice structures and excitation conditions. It shows the dominant role of carrier-polar-optical-phonon interaction in determining the nature of the carrier dynamics in the low-density limit. In particular, the miniband width, compared to the phonon energy, turns out to be a relevant quantity in predicting the existence of Bloch oscillations

Disorder-Driven Pretransitional Tweed in Martensitic Transformations

Defying the conventional wisdom regarding first--order transitions, {\it solid--solid displacive transformations} are often accompanied by pronounced pretransitional phenomena. Generally, these phenomena are indicative of some mesoscopic lattice deformation that ``anticipates'' the upcoming phase transition. Among these precursive effects is the observation of the so-called ``tweed'' pattern in transmission electron microscopy in a wide variety of materials. We have investigated the tweed deformation in a two dimensional model system, and found that it arises because the compositional disorder intrinsic to any alloy conspires with the natural geometric constraints of the lattice to produce a frustrated, glassy phase. The predicted phase diagram and glassy behavior have been verified by numerical simulations, and diffraction patterns of simulated systems are found to compare well with experimental data. Analytically comparing to alternative models of strain-disorder coupling, we show that the present model best accounts for experimental observations.Comment: 43 pages in TeX, plus figures. Most figures supplied separately in uuencoded format. Three other figures available via anonymous ftp

Optical Propagation and Communication

Contains an introduction and reports on five research projects.Maryland Procurement Office Contract MDA 904-90-C-5070National Science Foundation Grant ECS 87-18970National Institute of Standards and Technology Grant 60-NANBOD-1052U.S. Army Research Office Grant DAAL03-90-G-0128U.S. Army Research Office Contract DAAL03-87-K-0117U.S. Navy - Office of Naval Research Grant N00014-89-J-1163U.S. Air Force - Office of Scientific Research Contract F49620-90-C-003

The superconductor-insulator transition in 2D dirty boson systems

Universal properties of the zero temperature superconductor-insulator transition in two-dimensional amorphous films are studied by extensive Monte Carlo simulations of bosons in a disordered medium. We report results for both short-range and long-range Coulomb interactions for several different points in parameter space. In all cases we observe a transition from a superconducting phase to an insulating Bose glass phase. {}From finite-size scaling of our Monte Carlo data we determine the universal conductivity $\sigma^*$ and the critical exponents at the transition. The result $\sigma^* = (0.55 \pm 0.06) (2e)^2/h$ for bosons with long-range Coulomb interaction is roughly consistent with experiments reported so far. We also find $\sigma^* = (0.14 \pm 0.03) (2e)^2/h$ for bosons with short-range interactions.Comment: Revtex 3.0, 54 pages, 17 figures included, UBCTP-93-01

Optical Propagation and Communication

Contains research summary and reports on four research projects.National Science Foundation (Grant ECS81-20637)National Science Foundation (Grant ECS85-09143)Maryland Procurement Office (Contract MDA904-84-C-6037)National Science Foundation (Grant ECS84-15580)U.S. Army Research Office - Durham (Contract DAAG29-84-K-0095)U.S. Navy - Office of Naval Research (Contract NO0014-80-C-0941

Optical Propagation and Communication

Contains research objectives and reports on four research projects.National Science Foundation (Grant ECS 85-09143)Maryland Procurement Office (Contract MDA 904-84-C-6037)National Science Foundation (Grant ECS 84-15580)U.S. Army Research Office - Durham (Contract DAAG29-84-K-0095)U.S. Navy - Office of Naval Research (Contract N00014-80-C-0941