4,913 research outputs found

    Far-Infrared Emission From E and E/S0 Galaxies

    Get PDF
    Studies of cold material through IRAS 60um and 100um observations indicated that half of ordinary E and E/S0 galaxies were detected above the 3 sigma level, indicating that cold gas is common, although no correlation was found between the optical and far- infrared fluxes. Most detections were near the instrumental threshold, and given an improved understanding of detection confidence, we reconsider the 60um and 100um detection rate. After excluding active galactic nuclei, peculiar systems, and background contamination, only 15 non-peculiar E and E/S0 galaxies from the RSA catalog are detected above the 98% confidence level, about 12% of the sample. An unusually high percentage of these 15 galaxies possess cold gas (HI, CO) and optical emission lines (Halpha), supporting the presence of gas cooler than 10E4 K. The 60um to 100um flux ratios imply a median dust temperature for the sample of 30 K, with a range of 23-38 K. These detections define the upper envelope of the optical to far-infrared relationship, F_fir propto F_B^0.24+/-0.08, showing that optically bright objects are also brighter in the infrared, although with considerable dispersion. A luminosity correlation is present with L_fir propto L_B^1.65+/-0.28, but the dust temperature is uncorrelated with luminosity. Models that contain large dust grains composed of amorphous carbon plus silicates come close to reproducing the typical 60um to 100um flux ratios, the far-infrared luminosity, and the L_fir - L_B relationship.Comment: 10 postscript pages, 2 tables, and 2 figure

    Single-electron latch with granular film charge leakage suppressor

    Full text link
    A single-electron latch is a device that can be used as a building block for Quantum-dot Cellular Automata (QCA) circuits. It consists of three nanoscale metal "dots" connected in series by tunnel junctions; charging of the dots is controlled by three electrostatic gates. One very important feature of a single-electron latch is its ability to store ("latch") information represented by the location of a single electron within the three dots. To obtain latching, the undesired leakage of charge during the retention time must be suppressed. Previously, to achieve this goal, multiple tunnel junctions were used to connect the three dots. However, this method of charge leakage suppression requires an additional compensation of the background charges affecting each parasitic dot in the array of junctions. We report a single-electron latch where a granular metal film is used to fabricate the middle dot in the latch which concurrently acts as a charge leakage suppressor. This latch has no parasitic dots, therefore the background charge compensation procedure is greatly simplified. We discuss the origins of charge leakage suppression and possible applications of granular metal dots for various single-electron circuits.Comment: 21 pages, 4 figure

    Transient interference of transmission and incidence

    Get PDF
    Due to a transient quantum interference during a wavepacket collision with a potential barrier, a particular momentum, that depends on the potential parameters but is close to the initial average momentum, becomes suppressed. The hole left pushes the momentum distribution outwards leading to a significant constructive enhancement of lower and higher momenta. This is explained in the momentum complex-plane language in terms of a saddle point and two contiguous ``structural'' poles, which are not associated with resonances but with incident and transmitted components of the wavefunction.Comment: 4 pages of text, 6 postscript figures, revte

    Comparison of OLYMPUS beacon and radiometric attenuation measurements at Blacksburg, Virginia

    Get PDF
    Measurements of attenuation of the 20 and 30 GHz beacons onboard the OLYMPUS satellite are compared to simultaneous observations of atmospheric attenuation by a multichannel microwave radiometer along the same path. Departures from high correlation between the two measurements are believed to be related to differences in antenna beamwidths. Mean equivalent zenith attenuations derived from the slant path data are compared to zenith observations made at previous locations

    Seeking Sunlight: Rapid Phototactic Motility of Filamentous Mat-Forming Cyanobacteria Optimize Photosynthesis and Enhance Carbon Burial in Lake Huron’s Submerged Sinkholes

    Get PDF
    We studied the motility of filamentous mat-forming cyanobacteria consisting primarily ofOscillatoria-like cells growing under low-light, low-oxygen, and high-sulfur conditions in Lake Huron’s submerged sinkholes using in situ observations, in vitro measurements and time-lapse microscopy. Gliding movement of the cyanobacterial trichomes (100–10,000 μm long filaments, composed of cells ~10 μm wide and ~3 μm tall) revealed individual as well as group-coordinated motility. When placed in a petri dish and dispersed in ground water from the sinkhole, filaments re-aggregated into defined colonies within minutes, then dispersed again. Speed of individual filaments increased with temperature from ~50 μm min-1 or ~15 body lengths min-1 at 10∘C to ~215 μm min-1 or ~70 body lengths min-1 at 35∘C – rates that are rapid relative to non-flagellated/ciliated microbes. Filaments exhibited precise and coordinated positive phototaxis toward pinpoints of light and congregated under the light of foil cutouts. Such light-responsive clusters showed an increase in photosynthetic yield – suggesting phototactic motility aids in light acquisition as well as photosynthesis. Once light source was removed, filaments slowly spread out evenly and re-aggregated, demonstrating coordinated movement through inter-filament communication regardless of light. Pebbles and pieces of broken shells placed upon intact mat were quickly covered by vertically motile filaments within hours and became fully buried in the anoxic sediments over 3–4 diurnal cycles – likely facilitating the preservation of falling debris. Coordinated horizontal and vertical filament motility optimize mat cohesion and dynamics, photosynthetic efficiency and sedimentary carbon burial in modern-day sinkhole habitats that resemble the shallow seas in Earth’s early history. Analogous cyanobacterial motility may have played a key role in the oxygenation of the planet by optimizing photosynthesis while favoring carbon burial

    Detection of Gravitational Redshift on the Solar Disk by Using Iodine-Cell Technique

    Full text link
    With an aim to examine whether the predicted solar gravitational redshift can be observationally confirmed under the influence of the convective Doppler shift due to granular motions, we attempted measuring the absolute spectral line-shifts on a large number of points over the solar disk based on an extensive set of 5188-5212A region spectra taken through an iodine-cell with the Solar Domeless Telescope at Hida Observatory. The resulting heliocentric line shifts at the meridian line (where no rotational shift exists), which were derived by finding the best-fit parameterized model spectrum with the observed spectrum and corrected for the earth's motion, turned out to be weakly position-dependent as ~ +400 m/s near the disk center and increasing toward the limb up to ~ +600 m/s (both with a standard deviation of sigma ~ 100 m/s). Interestingly, this trend tends to disappear when the convectiveshift due to granular motions (~-300 m/s at the disk center and increasing toward the limb; simulated based on the two-component model along with the empirical center-to-limb variation) is subtracted, finally resulting in the averaged shift of 698 m/s (sigma = 113 m/s). Considering the ambiguities involved in the absolute wavelength calibration or in the correction due to convective Doppler shifts (at least several tens m/s, or more likely up to <~100 m/s), we may regard that this value is well consistent with the expected gravitational redshift of 633 m/s.Comment: 28 pages, 12 figures, electronic materials as ancillary data (table3, table 4, ReadMe); accepted for publication in Solar Physic

    A randomized, placebo controlled, trial of preoperative sustained release Betamethasone plus non-controlled intraoperative Ketorolac or Fentanyl on pain after diagnostic laparoscopy or laparoscopic tubal ligation [ISRCTN52633712]

    Get PDF
    BACKGROUND: Gynecological laparoscopic surgery procedures are often complicated by postoperative pain resulting in an unpleasant experience for the patient, delayed discharge, and increased cost. Glucocorticosteroids have been suggested to reduce the severity and incidence of postoperative pain. METHODS: This study examines the efficacy of a sustained release betamethasone preparation to reduce postoperative pain and the requirement for pain relief drugs after either diagnostic laparoscopy or tubal ligation. Patients were recruited, as presenting, after obtaining informed consent. Prior to surgery, patients were randomly selected by a computer generated table to receive either pharmacy-coded betamethasone (12 mg IM Celestoneâ„¢) or an optically identical placebo injection of Intralipidâ„¢ and isotonic saline mixture. The effect of non-controlled prophylactic intraoperative treatment with either fentanyl or ketorolac per surgeon's orders was also noted in this study. Blood samples taken at recovery and at discharge times were extracted and analyzed for circulating betamethasone. Visual analog scale data on pain was gathered at six post-recovery time points in a triple blind fashion and statistically compared. The postoperative requirement for pain relief drugs was also examined. RESULTS: Although the injection achieved a sustained therapeutic concentration, no beneficial effect of IM betamethasone on postoperative pain or reduction in pain relief drugs was observed during the postoperative period. Indeed, the mean combined pain scores during the 2 hour postoperative period, adjusted for postoperative opioids as the major confounding factor, were higher approaching statistical significance (P = 0.056) in the treatment group. Higher pain scores were also observed for the tubal ligation patients relative to diagnostic laparoscopy. Intraoperative fentanyl treatment did not significantly lower the average pain score during the 2 hour postoperative period. Intraoperative ketorolac treatment significantly lowered (P = 0.027) pain scores and reduced the postoperative requirement for additional pain relief drugs. CONCLUSIONS: There was a lack of efficacy of preoperative sustained release betamethasone in reducing postoperative pain despite maintaining a therapeutic concentration during the postoperative period. Intraoperative Ketorolac did afford some short-term pain relief in the postoperative period and reduced the need for additional pain relief drugs

    TSH-CHECK-1 test: diagnostic accuracy and potential application to initiating treatment for hypothyroidism in patients on anti-tuberculosis drugs.

    Get PDF
    Thyroid-stimulating hormone (TSH) promotes expression of thyroid hormones which are essential for metabolism, growth, and development. Second-line drugs to treat tuberculosis (TB) can cause hypothyroidism by suppressing thyroid hormone synthesis. Therefore, TSH levels are routinely measured in TB patients receiving second-line drugs, and thyroxin treatment is initiated where indicated. However, standard TSH tests are technically demanding for many low-resource settings where TB is prevalent; a simple and inexpensive test is urgently needed
    • …
    corecore