181 research outputs found

    Mean, tidal, and fluctuating winds in the middle atmosphere and lower thermosphere observed during MAP/WINE in Northern Scandinavia

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    During the MAP/WINE campaign in winter 1983 to 1984 several instrumental techniques, such as meteorological rockets, sounding rockets, MST radar and incoherent scatter radar, were applied to measure wind velocities in the middle atmosphere. Profiles of mean, tidal and fluctuating wind velocities were obtained up to 90 to 100 km altitude. These are compared with profiles from models, measurements at other locations and at other times as well as satellite derived data. The results are discussed in terms of ageostropic winds, planetary waves, tidal modes and the possibility of a saturated gravity wave spectrum in the mesosphere

    EISCAT observations during MAC/SINE and MAC/Epsilon

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    The EISCAT incoherent scatter radar facility in Tromsoe, Norway was operated during the MAC/SINE campaign for 78 hours in the period 10 June to 17 July 1987, and during the MAC/Epsilon campaign for 90 hours in the period 15 October to 5 November 1987. The VHF (224 MHz) radar operations during MAC/SINE yielded most interesting observations of strong coherent echoes from the mesopause region. Characteristic data of these polar mesospheric summer echoes are presented. The UHF (933 MHz) radar operations during MAC/Epsilon were done with 18 deg off zenith beam and allows the deduction of meridonal and horizontal wind components as well as radial velocity spectra in addition to the usual electron density profiles in the D and lower E regions. Some results from the VHF and UHF radars indicating the presence of gravity waves are examined

    Subtropical middle atmosphere dynamics observed by the Chung Li radar

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    The Chung Li Radar (24.91 N; 121.24 E) has been operating since 1986. A five beam observational configuration was used on a regular basis to study the various dynamics processes in the atmosphere-lower stratosphere height region. Due to its geographical location, the annual Typhoon and Mei-Yu seasons provide good opportunities to study the various interesting dynamic processes such as instabilities, generation of gravity waves, wave mean field interaction, etc. Three dimensional air motions due to these fronts are presented. Special cases of gravity wave generation, propagation and their effects on the turbulent layers are discussed

    Preparing for the Unexpected: Recognizing a Tortuous Thoracic Aorta During Ultrasound-guided Thoracentesis

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    Ultrasound-guidance has become the standard of care for bedside thoracentesis. This manuscript describes the importance of utilizing point-of-care-ultrasound (POCUS) and color Doppler in avoiding an unusual, but potentially catastrophic aortic puncture during thoracentesis. The case describes a 70 year-old man who presented with one week of shortness of breath. He was found to have a large left-sided pleural effusion on imaging studies. During a bedside POCUS examination, he was found to have a hyperechoic linear structure in his posterior left hemithorax. Ultrasound application of color Doppler revealed a pulsatile flow, confirming visualization of the aorta. The site of needle insertion for thoracentesis was placed more laterally to avoid aortic puncture. The thoracentesis was performed successfully with removal of about 1000ml of sanguinous fluid. This clinical case demonstrates the importance of considering anatomic variants when performing a thoracentesis. As in this patient’s case, ultrasonography and color Doppler during thoracentesis can be useful in avoiding a potentially life-threatening puncture of the aorta

    Ultraviolet and visible photometry of asteroid (21) Lutetia using the Hubble Space Telescope

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    The asteroid (21) Lutetia is the target of a planned close encounter by the Rosetta spacecraft in July 2010. To prepare for that flyby, Lutetia has been extensively observed by a variety of astronomical facilities. We used the Hubble Space Telescope (HST) to determine the albedo of Lutetia over a wide wavelength range, extending from ~150 nm to ~700 nm. Using data from a variety of HST filters and a ground-based visible light spectrum, we employed synthetic photometry techniques to derive absolute fluxes for Lutetia. New results from ground-based measurements of Lutetia's size and shape were used to convert the absolute fluxes into albedos. We present our best model for the spectral energy distribution of Lutetia over the wavelength range 120-800 nm. There appears to be a steep drop in the albedo (by a factor of ~2) for wavelengths shorter than ~300 nm. Nevertheless, the far ultraviolet albedo of Lutetia (~10%) is considerably larger than that of typical C-chondrite material (~4%). The geometric albedo at 550 nm is 16.5 +/- 1%. Lutetia's reflectivity is not consistent with a metal-dominated surface at infrared or radar wavelengths, and its albedo at all wavelengths (UV-visibile-IR-radar) is larger than observed for typical primitive, chondritic material. We derive a relatively high FUV albedo of ~10%, a result that will be tested by observations with the Alice spectrograph during the Rosetta flyby of Lutetia in July 2010.Comment: 14 pages, 2 tables, 8 figure

    Ultraviolet Spectroscopy of Asteroid (4) Vesta

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    We report a comprehensive review of the UV-visible spectrum and rotational lightcurve of Vesta combining new observations by Hubble Space Telescope and Swift Gamma-ray Burst Observatory with archival International Ultraviolet Explorer observations. The geometric albedos of Vesta from 220 nm to 953 nm are derived by carefully comparing these observations from various instruments at different times and observing geometries. Vesta has a rotationally averaged geometric albedo of 0.09 at 250 nm, 0.14 at 300 nm, 0.26 at 373 nm, 0.38 at 673 nm, and 0.30 at 950 nm. The linear spectral slope as measured between 240 and 320 nm in the ultraviolet displays a sharp minimum near a sub-Earth longitude of 20^{\circ}, and maximum in the eastern hemisphere. This is consistent with the longitudinal distribution of the spectral slope in the visible wavelength. The photometric uncertainty in the ultraviolet is ~20%, and in the visible wavelengths it is better than 10%. The amplitude of Vesta's rotational lightcurves is ~10% throughout the range of wavelengths we observed, but is smaller at 950 nm (~6%) near the 1-\mum band center. Contrary to earlier reports, we found no evidence for any difference between the phasing of the ultraviolet and visible/near-infrared lightcurves with respect to sub-Earth longitude. Vesta's average spectrum between 220 and 950 nm can well be described by measured reflectance spectra of fine particle howardite-like materials of basaltic achondrite meteorites. Combining this with the in-phase behavior of the ultraviolet, visible, and near-infrared lightcurves, and the spectral slopes with respect to the rotational phase, we conclude that there is no global ultraviolet/visible reversal on Vesta. Consequently, this implies a lack of global space weathering on Vesta, as previously inferred from visible-near-infrared data.Comment: 44 pages, 5 figures, 1 tabl

    Effectiveness of progressive muscle relaxation, deep breathing, and guided imagery in promoting psychological and physiological states of relaxation

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    Research suggests that multiple forms of relaxation training (e.g., progressive muscle relaxation, meditation, breathing exercises, visualization, and autogenics) can help individuals reduce stress, enhance relaxation states, and improve overall well-being. We examined three different, commonly used approaches to stress relaxation—progressive muscle relaxation, deep breathing, and guided imagery—and evaluated them in a head-to-head comparison against each other and a control condition. Sixty healthy undergraduate participants were randomized to one of the four conditions and completed 20 minutes of progressive muscle relaxation, deep breathing, or guided imagery training that was delivered by recorded audio instruction. Baseline and follow-up assessment of psychological relaxation states were completed. Physiological relaxation was also assessed continuously using measures of electrodermal activity and heart rate. Results showed that progressive muscle relaxation, deep breathing, and guided imagery all increased the state of relaxation for participants in those groups, compared to participants in the control group. In each case, the increase was statistically significant and although the groups did not differ on relaxation before training, all groups were significantly higher on relaxation after training, as compared to the control group. Progressive muscle relaxation and guided imagery showed an immediate linear trend toward physiological relaxation, compared to the control group, and the deep breathing group showed an immediate increase in physiological arousal followed quickly by a return to initial levels. Our results lend support to the body of research showing that stress relaxation training can be effective in improving relaxation states at both the psychological and physiological level. Future research could examine stress relaxation techniques in a similar manner using designs where multiple techniques can be compared in the same samples

    Swift UVOT Grism Spectroscopy of Comets: A First Application to C/2007 N3 (Lulin)

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    We observed comet C/2007 N3 (Lulin) twice on UT 28 January 2009, using the UV grism of the Ultraviolet and Optical Telescope (UVOT) on board the Swift Gamma Ray Burst space observatory. Grism spectroscopy provides spatially resolved spectroscopy over large apertures for faint objects. We developed a novel methodology to analyze grism observations of comets, and applied a Haser comet model to extract production rates of OH, CS, NH, CN, C3, C2, and dust. The water production rates retrieved from two visits on this date were 6.7±0.76.7 \pm 0.7 and 7.9 ±\pm 0.7 x 1E28 molecules s-1, respectively. Jets were sought (but not found) in the white-light and `OH' images reported here, suggesting that the jets reported by Knight and Schleicher (2009) are unique to CN. Based on the abundances of its carbon-bearing species, comet Lulin is `typical' (i.e., not `depleted') in its composition
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