PSD-95 Is Associated with the Postsynaptic Density and Not with the Presynaptic Membrane at Forebrain Synapses

PSD-95, a prominent protein component of the postsynaptic density (PSD) fraction from rat forebrain, has been localized by light microscopy to dendrites of hippocampal neurons (Cho et al., 1992) and to the presynaptic plexus of cerebellar basket cells (Kistner et al., 1993). Here we extend these studies to show that an affinity-purified antibody to PSD-95 labels the dendrites of most neurons in the forebrain and of a subset of neurons in the cerebellum. To confirm that PSD-95 is associated with the PSD at forebrain synapses and to clarify whether it is also associated with the presynaptic membrane, we employed immunogold electron microscopy of forebrain synaptosomes. Gold-labeled antibodies to PSD-95 labeled postsynaptic densities in both intact and lysed forebrain synaptosomes but did not label presynaptic terminals or the presynaptic membrane. The asymmetric distribution of PSD-95 at synapses contrasts with that of its homologs, disks-large and ZO-1, which are arranged symmetrically at septate and tight junctions, respectively

The Relation between Black Hole Mass, Bulge Mass, and Near-Infrared Luminosity

We present new accurate near-infrared (NIR) spheroid (bulge) structural parameters obtained by two-dimensional image analysis for all galaxies with a direct black hole (BH) mass determination. As expected, NIR bulge luminosities Lbul and BH masses are tightly correlated, and if we consider only those galaxies with secure BH mass measurement and accurate Lbul (27 objects), the spread of MBH-Lbul is similar to MBH-sigma, where sigma is the effective stellar velocity dispersion. We find an intrinsic rms scatter of ~0.3 dex in log MBH. By combining the bulge effective radii R_e measured in our analysis with sigma, we find a tight linear correlation (rms ~ 0.25 dex) between MBH and the virial bulge mass (propto R_e sigma^2), with ~ 0.002. A partial correlation analysis shows that MBH depends on both sigma and R_e, and that both variables are necessary to drive the correlations between MBH and other bulge properties.Comment: Astrophysical Journal Letters, in pres

Quantifying non-star formation associated 8um dust emission in NGC 628

Combining Ha and IRAC images of the nearby spiral galaxy NGC 628, we find that between 30-43% of its 8um dust emission is not related to recent star formation. Contributions from dust heated by young stars are separated by identifying HII regions in the Ha map and using these areas as a mask to determine the 8um dust emission that must be due to heating by older stars. Corrections are made for sub-detection-threshold HII regions, photons escaping from HII regions and for young stars not directly associated to HII regions (i.e. 10-100 Myr old stars). A simple model confirms this amount of 8um emission can be expected given dust and PAH absorption cross-sections, a realistic star-formation history, and the observed optical extinction values. A Fourier power spectrum analysis indicates that the 8um dust emission is more diffuse than the Ha emission (and similar to observed HI), supporting our analysis that much of the 8um-emitting dust is heated by older stars. The 8um dust-to-Ha emission ratio declines with galactocentric radius both within and outside of HII regions, probably due to a radial increase in disk transparency. In the course of this work, we have also found that intrinsic diffuse Ha fractions may be lower than previously thought in galaxies, if the differential extinction between HII regions and diffuse regions is taken into account.Comment: 14 pages, 11 figures, accepted in Ap

Effects of aging on the relationship between cognitive demand and step variability during dual-task walking

A U-shaped relationship between cognitive demand and gait control may exist in dual-task situations, reflecting opposing effects of external focus of attention and attentional resource competition. The purpose of the study was twofold: to examine whether gait control, as evaluated from step-to-step variability, is related to cognitive task difficulty in a U-shaped manner and to determine whether age modifies this relationship. Young and older adults walked on a treadmill without attentional requirement and while performing a dichotic listening task under three attention conditions: non-forced (NF), forced-right (FR), and forced-left (FL). The conditions increased in their attentional demand and requirement for inhibitory control. Gait control was evaluated by the variability of step parameters related to balance control (step width) and rhythmic stepping pattern (step length and step time). A U-shaped relationship was found for step width variability in both young and older adults and for step time variability in older adults only. Cognitive performance during dual tasking was maintained in both young and older adults. The U-shaped relationship, which presumably results from a trade-off between an external focus of attention and competition for attentional resources, implies that higher-level cognitive processes are involved in walking in young and older adults. Specifically, while these processes are initially involved only in the control of (lateral) balance during gait, they become necessary for the control of (fore-aft) rhythmic stepping pattern in older adults, suggesting that attentional resources turn out to be needed in all facets of walking with aging. Finally, despite the cognitive resources required by walking, both young and older adults spontaneously adopted a “posture second” strategy, prioritizing the cognitive task over the gait task

HIghMass - High HI Mass, HI-Rich Galaxies at z∼0z\sim0: Combined HI and H2_2 Observations

We present resolved HI and CO observations of three galaxies from the HIghMass sample, a sample of HI-massive ($M_{HI} > 10^{10} M_\odot$), gas-rich ($M_{HI}$ in top $5\%$ for their $M_*$) galaxies identified in the ALFALFA survey. Despite their high gas fractions, these are not low surface brightness galaxies, and have typical specific star formation rates (SFR$/M_*$) for their stellar masses. The three galaxies have normal star formation rates for their HI masses, but unusually short star formation efficiency scale lengths, indicating that the star formation bottleneck in these galaxies is in the conversion of HI to H$_2$, not in converting H$_2$ to stars. In addition, their dark matter spin parameters ($\lambda$) are above average, but not exceptionally high, suggesting that their star formation has been suppressed over cosmic time but are now becoming active, in agreement with prior H$\alpha$ observations.Comment: 20 pages, 13 figure

The Origins of [CII] Emission in Local Star-forming Galaxies

The [CII] 158um fine-structure line is the brightest emission line observed in local star-forming galaxies. As a major coolant of the gas-phase interstellar medium, [CII] balances the heating, including that due to far-ultraviolet photons, which heat the gas via the photoelectric effect. However, the origin of [CII] emission remains unclear, because C+ can be found in multiple phases of the interstellar medium. Here we measure the fractions of [CII] emission originating in the ionized and neutral gas phases of a sample of nearby galaxies. We use the [NII] 205um fine-structure line to trace the ionized medium, thereby eliminating the strong density dependence that exists in the ratio of [CII]/[NII] 122um. Using the FIR [CII] and [NII] emission detected by the KINGFISH and Beyond the Peak Herschel programs, we show that 60-80% of [CII] emission originates from neutral gas. We find that the fraction of [CII] originating in the neutral medium has a weak dependence on dust temperature and the surface density of star formation, and a stronger dependence on the gas-phase metallicity. In metal-rich environments, the relatively cooler ionized gas makes substantially larger contributions to total [CII] emission than at low abundance, contrary to prior expectations. Approximate calibrations of this metallicity trend are provided.Comment: 8 pages, accepted for publication in Ap

Comparison of Assertive Community Treatment Fidelity Assessment Methods: Reliability and Validity

Assertive community treatment is known for improving consumer outcomes, but is difficult to implement. On-site fidelity measurement can help ensure model adherence, but is costly in large systems. This study compared reliability and validity of three methods of fidelity assessment (on-site, phone-administered, and expert-scored self-report) using a stratified random sample of 32 mental health intensive case management teams from the Department of Veterans Affairs. Overall, phone, and to a lesser extent, expert-scored self-report fidelity assessments compared favorably to on-site methods in inter-rater reliability and concurrent validity. If used appropriately, these alternative protocols hold promise in monitoring large-scale program fidelity with limited resources