A study was conducted in which 133 participants performed 11 memory
tasks (some thought to reflect working memory and some thought to reflect
short-term memory), 2 tests of general fluid
...intelligence, and the Verbal and Quantitative Scholastic Aptitude
Tests. Structural equation modeling suggested that short-term and
working memories reflect separate but highly related constructs and that many
of the tasks used in the literature as working memory tasks reflect a common
construct. Working memory shows a strong connection to fluid
intelligence, but short-term memory does not. A theory of
working memory capacity and general fluid intelligence is proposed: The
authors argue that working memory capacity and fluid intelligence reflect the
ability to keep a representation active, particularly in the face of
interference and distraction. The authors also discuss the relationship
of this capability to controlled attention, and the functions of the
prefrontal cortex.
We present results based on new Chandra and multi-frequency radio observations of the disturbed cool core cluster Abell 133. The diffuse gas has a complex bird-like morphology, with a plume of ...emission extending from two symmetric wing-like features. The plume is capped with a filamentary radio structure that has been previously classified as a radio relic. X-ray spectral fits in the region of the relic indicate the presence of either high-temperature gas or non-thermal emission, although the measured photon index is flatter than would be expected if the non-thermal emission is from inverse Compton scattering of the cosmic microwave background by the radio-emitting particles. We find evidence for a weak elliptical X-ray surface brightness edge surrounding the core, which we show is consistent with a sloshing cold front. The plume is consistent with having formed due to uplift by a buoyantly rising radio bubble, now seen as the radio relic, and has properties consistent with buoyantly lifted plumes seen in other systems (e.g., M87). Alternatively, the plume may be a gas sloshing spiral viewed edge-on. Results from spectral analysis of the wing-like features are inconsistent with the previous suggestion that the wings formed due to the passage of a weak shock through the cool core. We instead conclude that the wings are due to X-ray cavities formed by displacement of X-ray gas by the radio relic. The central cD galaxy contains two small-scale cold gas clumps that are slightly offset from their optical and UV counterparts, suggestive of a galaxy-galaxy merger event. On larger scales, there is evidence for cluster substructure in both optical observations and the X-ray temperature map. We suggest that the Abell 133 cluster has recently undergone a merger event with an interloping subgroup, initialing gas sloshing in the core. The torus of sloshed gas is seen close to edge-on, leading to the somewhat ragged appearance of the elliptical surface brightness edge. We show that the additional buoyant force from a passing subcluster can have a significant effect on the rise trajectories of buoyant bubbles, although this effect alone cannot fully explain the morphology of Abell 133. The radio observations reveal a large-scale double-lobed structure not previously identified in the literature. We conclude that this structure represents a previously unreported background giant radio galaxy at z = 0.293, the northern lobe of which overlies the radio relic in the core of Abell 133. A rough estimate indicates that the contribution of this background lobe to the total radio emission in the region of the relic is modest (<13%).
We present a new Chandra X-ray observation of the intracluster medium in the galaxy cluster A2443, hosting an ultra-steep spectrum radio source. The data reveal that the intracluster medium is highly ...disturbed. The thermal gas in the core is elongated along a northwest to southeast axis and there is a cool tail to the north. We also detect two X-ray surface brightness edges near the cluster core. The edges appear to be consistent with an inner cold front to the northeast of the core and an outer shock front to the southeast of the core. The southeastern edge is coincident with the location of the radio relic as expected for shock (re)acceleration or adiabatic compression of fossil relativistic electrons.
Background and purpose:
The endocannabinoids, N‐arachidonoylethanolamide (anandamide) and 2‐arachidonoylglycerol (2‐AG) are rapidly degraded by fatty acid amide hydrolase (FAAH) and monoacylglycerol ...lipase (MGL). Whilst these lipid mediators are known to modulate vascular tone, the extent to which they are inactivated via local metabolism in the vasculature remains unclear.
Experimental approach:
In rat isolated small mesenteric arteries, the regulatory role of FAAH, MGL and cyclooxygenase (COX) in relaxant responses to anandamide and 2‐AG was evaluated by using inhibitors of these enzymes. Relaxations to non‐hydrolysable analogues of endocannabinoids and arachidonic acid were also examined.
Key results:
Relaxation to anandamide but not 2‐AG was potentiated by the selective FAAH inhibitor, URB597 (1 μM). In contrast, MAFP (10 μM; an inhibitor of FAAH and MGL) enhanced responses to both anandamide and 2‐AG. Inhibition of COX‐1 by indomethacin (10 μM) potentiated relaxations to 2‐AG, whereas inhibition of COX‐2 by nimesulide (10 μM) potentiated anandamide‐induced relaxation. With the exception of MAFP, effects of FAAH and COX inhibitors were dependent on the endothelium. Relaxation to methanandamide and noladin ether, the non‐hydrolysable analogues of anandamide and 2‐AG respectively, were insensitive to the enzyme inhibitors.
Conclusion and implications:
This study shows that local activity of FAAH, MGL and COX, which is present largely in the endothelium, limits the vasodilator action of endocannabinoids in rat small mesenteric arteries. Despite the differential roles played by these enzymes on relaxation to anandamide versus 2‐AG, our results suggest that inhibitors of these enzymes enhance the vascular impact of endocannabinoids.
British Journal of Pharmacology (2007) 150, 641–651. doi:10.1038/sj.bjp.0707141
We present results from Chandra observations of the galaxy pair NGC 7619 and NGC 7626, the two dominant members of the Pegasus group. The X-ray images show a brightness edge associated with each ...galaxy, which we identify as merger cold fronts. The edges are sharp, and the axes of symmetry of the edges are roughly antiparallel, suggesting that these galaxies are falling toward one another in the plane of the sky. The detection of merger cold fronts in each of the two dominant member galaxies implies a merging subgroup scenario, since the alternative is that the galaxies are falling into a preexisting ~1 keV halo without a dominant galaxy of its own, and such objects are not observed. We estimate the three-dimensional velocities from the cold fronts and, using the observed radial velocities of the galaxies, show that the velocity vectors are indeed most likely close to the plane of the sky, with a relative velocity of ~1190 km s-1. The relative velocity is consistent with what is expected from the infall of two roughly equal mass subgroups whose total viral mass equals that of the Pegasus group. We conclude that the Pegasus cluster is most likely currently forming from a major merger of two subgroups, dominated by NGC 7619 and NGC 7626. NGC 7626 contains a strong radio source, consisting of a core with two symmetric jets, and radio lobes. Although we find no associated structure in the X-ray surface brightness map, the temperature map reveals a clump of cool gas just outside the southern lobe, presumably entrained by the lobe, and possibly an extension of cooler gas into the lobe itself. The jet axis is parallel with the projected direction of motion of NGC 7626 (inferred from the symmetry axis of the merger cold front), and the southern leading jet is foreshortened as compared to the northern trailing one, possibly due to the additional ram pressure encountered by the forward jet.
ABSTRACT We present results based on X-ray, optical, and radio observations of the massive galaxy cluster CIZA J0107.7+5408. We find that this system is a post-core-passage, dissociative, binary ...merger, with the optical galaxy density peaks of each subcluster leading their associated X-ray emission peaks. This separation occurs because the diffuse gas experiences ram pressure forces, while the effectively collisionless galaxies (and presumably their associated dark matter (DM) halos) do not. This system contains double-peaked diffuse radio emission, possibly a double radio relic with the relics lying along the merger axis and also leading the X-ray cores. We find evidence for a temperature peak associated with the SW relic, likely created by the same merger shock that is powering the relic radio emission in this region. Thus, this system is a relatively rare, clean example of a dissociative binary merger, which can in principle be used to place constraints on the self-interaction cross-section of DM. Low-frequency radio observations reveal ultra-steep spectrum diffuse radio emission that is not correlated with the X-ray, optical, or high-frequency radio emission. We suggest that these sources are radio phoenixes, which are preexisting non-thermal particle populations that have been re-energized through adiabatic compression by the same merger shocks that power the radio relics. Finally, we place upper limits on inverse Compton emission from the SW radio relic.
Fabrication of ultrasharp probes is of interest for many applications, including scanning probe microscopy and electron-stimulated patterning of surfaces. These techniques require reproducible ...ultrasharp metallic tips, yet the efficient and reproducible fabrication of these consumable items has remained an elusive goal. Here we describe a novel biased-probe field-directed sputter sharpening technique applicable to conductive materials, which produces nanometer and sub-nanometer sharp W, Pt-Ir and W-HfB(2) tips able to perform atomic-scale lithography on Si. Compared with traditional probes fabricated by etching or conventional sputter erosion, field-directed sputter sharpened probes have smaller radii and produce lithographic patterns 18-26% sharper with atomic-scale lithographic fidelity.
To determine the difference, if any, in grooving efficiency at various settings on the Whitestar Signature Pro phacoemulsification (phaco) system.
Cataractous lenses were simulated by exposing ...porcine lenses to formalin for 2 hours. A total of 120 lenses were analyzed at various power settings on both longitudinal and transversal handpieces. Twenty trials each were performed with power set to 25%, 50%, and 75% on both handpieces. A Whitestar Phaco Handpiece System was used to provide longitudinal power, and a Whitestar Signature Ellipsis Handpiece provided transversal power. Lenses were placed within a plastic chamber and grooved by an investigator blinded to settings. A second investigator recorded times and adjusted settings. The Whitestar Signature Pro phaco system was used for grooving.
There was no significant difference in grooving times between the longitudinal and transverse handpieces at any power setting (P > 0.05). There was a significant decrease in grooving times when comparing the 25% power setting with the 75% power setting for the transversal handpiece (
=0.021).
Both longitudinal and transversal handpieces on the Whitestar Signature Pro phaco system produce similar results to one another at each power setting. There is a general trend toward shorter grooving times, reflecting greater efficiency, at higher power settings. Grooving efficiency on the transversal handpiece may be more affected by changes in the power settings as compared with the longitudinal settings.
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