As part of the ground‐based program for the International Magnetospheric Study (IMS), a new two‐station VHF radar auroral experiment, STARE, has been constructed in northern Scandinavia. Each of these stations can provide good spatial and temporal resolution measurements of the intensity and Doppler velocity of radar auroral irregularities within a 300,000 km2 scattering region. Approximately 230,000 km2 of these scattering regions are common to both radars and within this area it is possible to compare the backscattered signals observed by the two radars and to combine the Doppler data to derive the mean irregularity drift velocity. The drift velocity can ultimately be related to the ionospheric electric field. In this paper we describe the operation of these radars and the method by which the data are processed. We also describe the assumptions used in the drift velocity analysis and present some initial measurements supporting their validity. Finally, we present several examples of the STARE data during two periods of counterstreaming currents in the late evening auroral oval. The irregularity drift patterns are consistent with the expected electron drift patterns for these periods and, from these patterns, one can determine the two‐dimensional structure of the ionospheric electric field.
Slowed relaxation in diabetic cardiomyopathy (CM) is partially related to diminished expression of the sarcoplasmic reticulum (SR) Ca2+-ATPase SERCA2a. To evaluate the impact of SERCA2a overexpression on SR Ca2+ handling in diabetic CM, we 1) generated transgenic rats harboring a human cytomegalovirus enhancer/chicken beta-actin promotor-controlled rat SERCA2 transgene (SERCA2-TGR), 2) characterized their SR phenotype, and 3) examined whether transgene expression may rescue SR Ca2+ transport in streptozotocin-induced diabetes. The transgene was expressed in all heart chambers. Compared to wild-type (WT) rats, a heterozygous line exhibited increased SERCA2 mRNA (1.5-fold), SERCA2 protein (+26%) and SR Ca2+ uptake (+37%). Phospholamban expression was not altered. In SERCA2-TGR, contraction amplitude (+48%) and rates of contraction (+34%) and relaxation (+35%) of isolated papillary muscles (PM) were increased (P2+ uptake and SERCA2 protein of SERCA2-TGR were 1.3-fold higher (P2+ uptake, accelerates relaxation and compensates, in part, for depressed Ca2+ uptake in diabetic CM. Therefore, SERCA2 expression might constitute an important therapeutic target to rescue cardiac SR Ca2+ handling in diabetes.
Spinach (Spinacia oleracea L. cv. Matador) chloroplasts were irradiated with several levels of UV‐B radiation. Measurements which reflect characteristic steps of photosynthetic electron transport were made to localize the site of impairment of photosynthesis by UV‐B radiation. Variable fluorescence, the μs‐kinetics of the 320 nm absorption changes and also oxygen evolution were substantially reduced in chloroplasts irradiated with UV‐B. It was not possible to restore the amplitude of the 320 nm absorption changes nor the signal of the transmembrane electric field measured at 520 nm by adding the photo‐system II donor couple hydroquinone/ascorbate to UV‐B treated chloroplast samples. This indicates that impairment of photosystem II activity is not caused by selective inhibition of the water‐splitting enzyme system Y, but rather is due to blockage of photosystem II reaction centers. Photosystem 1 is inferred to be highly resistant to UV‐B radiation. These results suggest that the reaction centers of photosystem II are transformed into dissipative sinks for excitation energy by action of UV‐B radiation.
The magnetospheric ion composition spectrometer (MICS) in the CRRES scientific payload utilizes time-offlight and energy spectroscopy in combination with an electrostatic entrance filter to measure the mass A , energy E, and ionic charge Q of particles with energies between 1 keV/charge and 430 keV/charge. An advanced ogive design of the electrostatic filter system provides a narrow angle of acceptance and high sensitivity. Incident particles are postaccelerated prior to entering the detection segment in order to improve the resolution at the lower end of the useful energy range. The principle features of the MICS spectrometer are described in some detail. Selected data gathered in-flight are shown as an illustration of the instrument performance in the operational orbit.
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