Discovery of diffuse aurora on Mars.

Planetary auroras reveal the complex interplay between an atmosphere and the surrounding plasma environment. We report the discovery of low-altitude, diffuse auroras spanning much of Mars' northern hemisphere, coincident with a solar energetic particle outburst. The Imaging Ultraviolet Spectrograph, a remote sensing instrument on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, detected auroral emission in virtually all nightside observations for ~5 days, spanning nearly all geographic longitudes. Emission extended down to ~60 kilometer (km) altitude (1 microbar), deeper than confirmed at any other planet. Solar energetic particles were observed up to 200 kilo--electron volts; these particles are capable of penetrating down to the 60 km altitude. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit auroras more globally than Earth.

Comparison of the imaging characteristics of curved-channel and straight-channel microchannel plates.

We have measured and compared the spatial fidelity of two types of microchannel plates over roughly half of their active area. Measurements of the spatial fidelity of curved-channel microchannel plates confirm earlier reports of large (>25 microm), irregular position offsets between the front and the back of the microchannel plates. Straight-pore microchannel plates used in a chevron configuration, on the other hand, showed almost no such position offsets (<4 microm).

Galileo ultraviolet spectrometer experiment: initial venus and interplanetary cruise results.

The Galileo Extreme Ultraviolet Spectrometer obtained a spectrum of Venus atmospheric emissions in the 55.0- to 125.0-nanometer (nm) wavelength region. Emissions of helium (58.4 nm), ionized atomic oxygen (83.4 nm), and atomic hydrogen (121.6 nm), as well as a blended spectral feature of atomic hydrogen (Lyman-beta) and atomic oxygen (102.5 nm), were observed at 3.5-nm resolution. During the Galileo spacecraft cruise from Venus to Earth, Lyman-alpha emission from solar system atomic hydrogen (121.6 nm) was measured. The dominant source of the Lyman-alpha emission is atomic hydrogen from the interstellar medium. A model of Galileo observations at solar maximum indicates a decrease in the solar Lyman-alpha flux near the solar poles. A strong day-to-day variation also occurs with the 27-day periodicity of the rotation of the sun.

A stopped-flow mixer device for a batch microcalorimeter application to NAD-NADase reaction.

A new molded polypropylene, diamond-like carbon (DLC)-coated mixing cell has been developed for use in the batch microcalorimeter. Reagent volume can be varied from 25 microliters to 100 microliters. A 10 microcalorie reaction heat can be measured to 5%. Repeat reactions can be done as often as every 10 min for a fast reaction. Reactions can be started within 1 h or less after loading. A pre-equilibrator and a temperature-controlled syringe drive unit permit solutions to be stored at 4 degrees C while being run at any temperature from -20 degrees C to 40 degrees C. The kinetics and enthalpy of reaction of NAD-NADase have been measured. delta H is about 21 kcal/mol endothermic.

Simple ultraviolet calibration source with reference spectra and its use with the Galileo orbiter ultraviolet spectrometer.

We have developed a simple compact electron impact laboratory source of UV radiation whose relative intensity as a function of wavelength has an accuracy traceable to the fundamental physical constants (transitions probabilities and excitation cross sections) for an atomic or molecular system. Using this laboratory source, calibrated optically thin vacuum ultraviolet (VUV) spectra have been obtained and synthetic spectral models developed for important molecular band systems of H(2) and N(2) and the n(1)P(0) Itydberg series of He. The model spectrum from H(2) represents an extension of the molecular branching ratio technique to include spectral line intensities from more than one electronic upper state. The accuracy of the model fit to the VUV spectra of H(2) and N(2) is sufficient to predict the relative spectral intensity of the electron impact source and to serve as a primary calibration standard for VUV instrumentation in the 80-230-nm wavelength range. The model is applicable to VUV instrumentation with full width at half-maximum >/= 0.4 nm. The present accuracy is 10% in the far ultraviolet (120-230 nm), 10% in the extreme ultraviolet (EUV) (90-120 nm), and 20% in the EUV (80-90 nm). The n(1)P(0) Rydberg series of He has been modeled to 10% accuracy and can be considered a primary calibration standard in the EUV (52.2-58.4 nm). A calibrated optically thin spectrum of Ar has been obtained at 0.5-nm resolution and 200-eV electron impact energy to 35% accuracy without benefit of models over the EUV spectral range of 50-95 nm. The Ar spectrum expands the ultimate range of the VUV relative calibration using this source with the four gases, He, Ar, H(2), and N(2), to 50-230 nm. The calibration of the Galileo orbiter ultraviolet spectrometer for the upcoming Jupiter mission has been demonstrated and compared to results from other methods.

Effectiveness of trihexyphenidyl against pendular nystagmus and palatal myoclonus: evidence of cholinergic dysfunction.

Palatal myoclonus and acquired pendular nystagmus result from lesions in dentatorubroolivary pathways. We have investigated the effect of high doses of the anticholinergic drug trihexyphenidyl in four patients with palatal myoclonus and in four patients with acquired pendular nystagmus. The movements of each patient were videotaped three times: before administration of trihexyphenidyl, at the time of maximum or effective dosage, and after withdrawal from trihexyphenidyl. In five patients the movements were also electrographically recorded. A neurologist not familiar with the patients reviewed the tapes and rated the changes. In seven of eight patients, administration of trihexyphenidyl resulted in marked improvement of both movements and complaints by patients. This observation indicates that disturbance of cholinergic mechanisms plays an important role in the pathophysiology of these two movement disorders.

Rocket-borne instrument with a high-resolution microchannel plate detector for planetary UV spectroscopy.

A telescope-spectrograph employing a photon-counting microchannel plate (MCP)-CODACON detector has been built, tested, and flown on a sounding rocket. The detector uses a curved-channel MCP proximity focused onto a coded anode array of 1024 channels spaced 25.4-mm center to center. High quantum efficiency is obtained by depositing a cesium iodide photocathode on the front surface of the MCP. The instrument has obtained an ultraviolet (1500-1800-A) spectrum of Jupiter with a spectral resolution of 8 A, which is higher than that of any previously reported observation in this wavelength range.

A column chromatographic method for the combined analysis of creatine kinase-MB (CPK-MB) and lactate dehydrogenase 1,2 (LDH 1,2) isoenzymes.

A column chromatographic method for the simultaneous single-eluate isolation of CPK-MB and LDH 1,2 has been evaluated. The method is rapid in that the entire isolation is completed in less than an hour and subsequent analysis can be performed using presently available spectrophotometric methods and reagents without the need for electrophoresis equipment. In addition, since the isoenzymes are directly isolated, quantitation of enzymatic activity can be performed with precision. This technic permits detection of CPK-MB and LDH 1,2 in samples with normal values of total CPK and LDH utilizing a routine laboratory spectrophotometer. The sensitivities for diagnosis of acute myocardial infarction are 95% for LDH 1,2 and 100% for CPK-MB. The specificities for diagnosis of acute myocardial infarction are 86% for LDH 1,2 and 96% for CPK-MB.