The Orbiting Carbon Observatory-2 early science investigations of regional carbon dioxide fluxes.

NASA's Orbiting Carbon Observatory-2 (OCO-2) mission was motivated by the need to diagnose how the increasing concentration of atmospheric carbon dioxide (CO2) is altering the productivity of the biosphere and the uptake of CO2 by the oceans. Launched on 2 July 2014, OCO-2 provides retrievals of the column-averaged CO2 dry-air mole fraction ([Formula: see text]) as well as the fluorescence from chlorophyll in terrestrial plants. The seasonal pattern of uptake by the terrestrial biosphere is recorded in fluorescence and the drawdown of [Formula: see text] during summer. Launched just before one of the most intense El Niños of the past century, OCO-2 measurements of [Formula: see text] and fluorescence record the impact of the large change in ocean temperature and rainfall on uptake and release of CO2 by the oceans and biosphere.

Influence of El Niño on atmospheric CO2 over the tropical Pacific Ocean: Findings from NASA's OCO-2 mission.

Spaceborne observations of carbon dioxide (CO2) from the Orbiting Carbon Observatory-2 are used to characterize the response of tropical atmospheric CO2 concentrations to the strong El Niño event of 2015-2016. Although correlations between the growth rate of atmospheric CO2 concentrations and the El Niño-Southern Oscillation are well known, the magnitude of the correlation and the timing of the responses of oceanic and terrestrial carbon cycle remain poorly constrained in space and time. We used space-based CO2 observations to confirm that the tropical Pacific Ocean does play an early and important role in modulating the changes in atmospheric CO2 concentrations during El Niño events-a phenomenon inferred but not previously observed because of insufficient high-density, broad-scale CO2 observations over the tropics.

The prospective evaluation of the TB strain typing service in England: a mixed methods study.

BACKGROUND: In response to rising TB notification rates in England, universal strain typing was introduced in 2010. We evaluated the acceptability, effectiveness and cost-effectiveness of the TB strain typing service (TB-STS). METHODS: We conducted a mixed-methods evaluation using routine laboratory, clinic and public health data. We estimated the effect of the TB-STS on detection of false positive Mycobacterium tuberculosis diagnoses (2010-2012); contact tracing yield (number of infections or active disease per pulmonary TB case); and diagnostic delay. We developed a deterministic age-structured compartmental model to explore the effectiveness of the TB-STS, which informed a cost-effectiveness analysis. RESULTS: Semi-structured interviews explored user experience. Strain typing identified 17 additional false positive diagnoses. The TB-STS had no significant effect on contact tracing yield or diagnostic delay. Mathematical modelling suggested increasing the proportion of infections detected would have little value in reducing TB incidence in the white UK-born population. However, in the non-white UK-born and non-UK-born populations, over 20 years, if detection of latent infection increases from 3% to 13% per year, then TB incidence would decrease by 11%; reducing diagnostic delay by one week could lead to 25% reduction in incidence. The current TB-STS was not predicted to be cost-effective over 20 years (£95 628/quality-adjusted life-years). Interviews found people had mixed experiences, but identified broader benefits, of the TB-STS. CONCLUSIONS: To reduce costs, improve efficiency and increase effectiveness, we recommend changes to the TB-STS, including discontinuing routine cluster investigations and focusing on reducing diagnostic delay across the TB programme. This evaluation of a complex intervention informs the future of strain typing in the era of rapidly advancing technologies.

H(-) ion source developments at the SNS.

The U.S. Spallation Neutron Source (SNS) will require substantially higher average and pulse H(-) beam currents than can be produced from conventional ion sources such as the base line SNS source. H(-) currents of 40-50 mA (SNS operations) and 70-100 mA (power upgrade project) with a rms emittance of 0.20-0.35pi mm mrad and a approximately 7% duty factor will be needed. We are therefore investigating several advanced ion source concepts based on rf plasma excitation. First, the performance characteristics of an external antenna source based on an Al(2)O(3) plasma chamber combined with an external multicusp magnetic configuration, an elemental Cs system, and plasma gun will be discussed. Second, the first plasma measurements of a helicon-driven H(-) ion source will also be presented.

Electrophysiological and biochemical changes in rabbit hearts stored at 4 degrees C for 6 or 24 h.

This study examines the electrophysiological and metabolic changes that occur in rabbit hearts during hypothermic storage in vitro. Hearts were microperfused at 4 degrees C for 6 or 24 h with either normal Krebs-Henseleit buffer (KHB) or KHB containing 2,3-butanedione monoxime (BDM). After hypothermic storage, hearts were rewarmed to 37 degrees C with KHB. Cardiac function was then assessed in Langendorff perfusion mode. Electrophysiological changes were also assessed from the ventricular paced-evoked responses. After storage, mitochondria were isolated from the hearts and their respiratory control ratio, rate of ATP synthesis and outer membrane intactness were assessed. Compared with values from fresh non-stored hearts, hearts stored hypothermically for 24 h showed significant decreases in both left ventricular developed pressure and coronary flow when reperfused in Langendorff mode. On the other hand, the decrease in left ventricular developed pressure in hearts that were stored for only 6 h (with or without BDM) was not significant. Compared with values obtained from fresh non-stored hearts, hypothermic storage significantly decreased the R-wave amplitude, and both the R-E and ST-E intervals of paced-evoked responses. This was true for hearts microperfused for 6 h (with or without BDM) and for hearts microperfused with buffer containing BDM for 24 h. The ST-R intervals in hearts microperfused hypothermically for 6 h were prolonged, but this change was not statistically significant compared with those obtained from unstored hearts. In hearts microperfused with KHB containing BDM for 24 h, the ST-R interval was significantly prolonged. Hypothermic microperfusion for 24 h significantly decreased both the mitochondrial coupling ratio and the rate of ATP synthesis. In hearts microperfused with BDM for 6 h, mitochondrial coupling ratios and the rate of ATP synthesis were not significantly different from those in fresh hearts. In conclusion, the present study has shown that long-term hypothermic storage significantly impaired both paced-evoked responses and mitochondrial function. Inclusion of BDM in the perfusion buffer during storage significantly ameliorated some of these changes.

The state and future of Mars polar science and exploration.

As the planet's principal cold traps, the martian polar regions have accumulated extensive mantles of ice and dust that cover individual areas of approximately 10(6) km2 and total as much as 3-4 km thick. From the scarcity of superposed craters on their surface, these layered deposits are thought to be comparatively young--preserving a record of the seasonal and climatic cycling of atmospheric CO2, H2O, and dust over the past approximately 10(5)-10(8) years. For this reason, the martian polar deposits may serve as a Rosetta Stone for understanding the geologic and climatic history of the planet--documenting variations in insolation (due to quasiperiodic oscillations in the planet's obliquity and orbital elements), volatile mass balance, atmospheric composition, dust storm activity, volcanic eruptions, large impacts, catastrophic floods, solar luminosity, supernovae, and perhaps even a record of microbial life. Beyond their scientific value, the polar regions may soon prove important for another reason--providing a valuable and accessible reservoir of water to support the long-term human exploration of Mars. In this paper we assess the current state of Mars polar research, identify the key questions that motivate the exploration of the polar regions, discuss the extent to which current missions will address these questions, and speculate about what additional capabilities and investigations may be required to address the issues that remain outstanding.

The Absorption Spectrum of H2S Between 2150 and 4260 cm-1: Analysis of the Positions and Intensities in the First (2nu2, nu1, and nu3) and Second (3nu2, nu1 + nu2, and nu2 + nu3) Triad Regions

The two triad systems of hydrogen sulfide (2nu2, nu1, and nu3 near 4 µm and 3nu2, nu1 + nu2, and nu2 + nu3 near 2.7 µm) were analyzed using 14 spectra recorded at 0.0056 and 0.011 cm-1 resolution with the McMath Fourier transform spectrometer located at Kitt Peak National Observatory. Experimental upper state levels of H232S, H234S, and H233S were obtained from assigned positions (as high as J = 20 and Ka = 15 for the main isotope). These were fitted to the A-reduced Watson Hamiltonian to determine precise sets of rotational constants through J10 and up to nine Fermi and Coriolis coupling parameters. Intensities of the two H232S triads were modeled with rms values of 2.5%, using the transformed transition moment expansion with 19 terms for 568 intensities of the first triad and 11 terms for the 526 intensities of the second triad. The second derivatives of the dipole moment with respect to normal coordinates were estimated in Debye to be: 22µx = -0.004873 (90); 12µx = 0.01372 (30); and 23µz = 0.01578 (30). This confirmed that for hydrogen sulfide some of the second derivatives are larger than the first derivatives. The calculated line intensities were summed yielding integrated band strengths (in cm-2/atm at 296 K) as follows: 0.3315 for 2nu2, 0.4522 for nu1, 0.1201 for nu3, 0.0303 for 3nu2, 1.820 for nu1 + nu2, and 2.869 for nu2 + nu3. In addition, the hot band transitions were identified in both regions. Finally, a composite database of hydrogen sulfide line parameters was predicted for the 5- to 2.5-µm region. Copyright 1998 Academic Press.

The Mars Pathfinder atmospheric structure investigation/meteorology (ASI/MET) experiment.

The Mars Pathfinder atmospheric structure investigation/meteorology (ASI/MET) experiment measured the vertical density, pressure, and temperature structure of the martian atmosphere from the surface to 160 km, and monitored surface meteorology and climate for 83 sols (1 sol = 1 martian day = 24.7 hours). The atmospheric structure and the weather record are similar to those observed by the Viking 1 lander (VL-1) at the same latitude, altitude, and season 21 years ago, but there are differences related to diurnal effects and the surface properties of the landing site. These include a cold nighttime upper atmosphere; atmospheric temperatures that are 10 to 12 degrees kelvin warmer near the surface; light slope-controlled winds; and dust devils, identified by their pressure, wind, and temperature signatures. The results are consistent with the warm, moderately dusty atmosphere seen by VL-1.

Detection of acetylene in the infrared spectrum of comet Hyakutake.

Comets are rich in volatile materials, of which roughly 80% (by number) are water molecules. Considerable progress is being made in identifying the other volatile species, the abundances of which should enable us to determine whether comets formed primarily from ice-covered interstellar grains, or from material that was chemically processed in the early solar nebula. Here we report the detection of acetylene (C2H2) in the infrared spectrum of comet C/1996 B2 (Hyakutake). The estimated abundance is 0.3-0.9%, relative to water, which is comparable to the predicted solid-phase abundance in cold interstellar clouds. This suggests that the volatiles in comet Hyakotake may have come from ice-covered interstellar grains, rather than material processed in the accretion disk out of which the Solar System formed.

Enhancement of atmospheric radiation by an aerosol layer.

The presence of a stratospheric haze layer may produce increases in both the actinic flux and the irradiance below this layer. Such haze layers result from the injection of aerosol-forming material into the stratosphere by volcanic eruptions. Simple heuristic arguments show that the increase in flux below the haze layer, relative to a clear sky case, is a consequence of "photon trapping." We explore the magnitude of these flux perturbations, as a function of aerosol properties and illumination conditions, with a new radiative transfer model that can accurately compute fluxes in an inhomogenous atmosphere with nonconservative scatterers having arbitrary phase function. One calculated consequence of the El Chichon volcanic eruption is an increase in the midday surface actinic flux at 20 degrees N latitude, summer, by as much as 45% at 2900 angstroms. This increase in flux in the UV-B wavelength range was caused entirely by aerosol scattering, without any reduction in the overhead ozone column.

Imaging techniques in the localization of epileptiform abnormalities.

The success of surgical intervention in the partial epilepsies is crucially affected by the accuracy of pre- and intraoperative source location techniques. Several approaches to the localization problem have been employed, that with the longest history being scalp-recorded EEG. Despite considerable advances in other imaging technologies such as MRI and PET, localization via the electrical signals generated by epileptic brain continues to provide the data most relied upon in pre-operative assessment. The present paper presents an overview of the contribution of various localization techniques. It is argued that electrical signals of the brain, as represented by EEG and MEG, remain the best methods to locate sources, and that the application of analysis techniques presently under investigation will further improve the accuracy of the non-invasive scalp-EEG approach.

Ground-based near-infrared imaging observations of venus during the galileo encounter.

Near-infrared images of Venus, obtained from a global network of ground-based observatories during January and February 1990, document the morphology and motions of the night-side near-infrared markings before, during, and after the Galileo Venus encounter. A dark cloud extended halfway around the planet at low latitudes (>+/-40 degrees ) and persisted throughout the observing program. It had a rotation period of 5.5 +/- 0.15 days. The remainder of this latitude band was characterized by small-scale (400 to 1000 kilometers) dark and bright markings with rotation periods of 7.4 +/- 1 days. The different rotation periods for the large dark cloud and the smaller markings suggests that they are produced at different altitudes. Mid-latitudes (+/-40 degrees to 60 degrees ) were usually occupied by bright east-west bands. The highest observable latitudes (+/-60 degrees to 70 degrees ) were always dark and featureless, indicating greater cloud opacity. Maps of the water vapor distribution show no evidence for large horizontal gradients in the lower atmosphere of Venus.

The dark side of Venus: near-infrared images and spectra from the Anglo-Australian observatory.

Near-infrared images and spectra of the night side of Venus taken at the Anglo-Australian Telescope during February 1990 reveal four new thermal emission windows at 1.10, 1.18, 1.27, and 1.31 micrometers, in addition to the previously discovered windows at 1.74 and 2.3 micrometers. Images of the Venus night side show similar bright and dark markings in all windows, but their contrast is much lower at short wavelengths. The 1.27-micrometers window includes a bright, high-altitude O2 airglow feature in addition to a thermal contribution from the deep atmosphere. Simulations of the 1.27- and 2.3 micrometers spectra indicate water vapor mixing ratios near 40 +/- 20 parts per million by volume between the surface and the cloud base. No large horizontal gradients in the water vapor mixing ratios were detected at these altitudes.

Spectroscopic observations of bright and dark emission features on the night side of venus.

Near-infrared spectra of a bright and a dark thermal emission feature on the night side of Venus have been obtained from 2.2 to 2.5 micrometers (microm) at a spectral resolution of 1200 to 1500. Both bright and dark features show numerous weak absorption bands produced by CO(2), CO, water vapor, and other gases. The bright feature (hot spot) emits more radiation than the dark feature (cold spot) throughout this spectral region, but the largest contrasts occur between 2.21 and 2.32 microm, where H(2)SO(4) clouds and a weak CO(2) band provide the only known sources of extinction. The contrast decreases by 55 to 65 percent at wavelengths longer than 2.34 microm, where CO, clouds, and water vapor also absorb and scatter upwelling radiation. This contrast reduction may provide direct spectroscopic evidence for horizontal variations in the water vapor concentrations in the Venus atmosphere at levels below the cloud tops.

Deuterium on Venus: observations from Earth.

Absorption lines of HDO and H2O have been detected in a 0.23-wave number resolution spectrum of the dark side of Venus in the interval 2.34 to 2.43 micrometers, where the atmosphere is sounded in the altitude range from 32 to 42 kilometers (8 to 3 bars). The resulting value of the deuterium-to-hydrogen ratio (D/H) is 120 +/- 40 times the telluric ratio, providing unequivocal confirmation of in situ Pioneer Venus mass spectrometer measurements that were in apparent conflict with an upper limit set from International Ultraviolet Explorer spectra. The 100-fold enrichment of the D/H ratio on Venus compared to Earth is thus a fundamental constraint on models for its atmospheric evolution.

Factor XIII deficiency and intracranial hemorrhages in infancy.

We report an infant with Factor XIII deficiency who had 2 seemingly spontaneous intracranial hemorrhages. It is important to consider Factor XIII deficiency as a possible cause of unexplained intracranial hemorrhages in infancy. Ongoing factor replacement therapy is recommended to prevent further bleeding episodes.

Spatial variation of ozone depletion rates in the springtime Antarctic polar vortex.

An area-mapping technique, designed to filter out synoptic perturbations of the Antarctic polar vortex such as distortion or displacement away from the pole, was applied to the Nimbus-7 TOMS (Total Ozone Mapping Spectrometer) data. This procedure reveals the detailed morphology of the temporal evolution of column O3. The results for the austral spring of 1987 suggest the existence of a relatively stable collar region enclosing an interior that is undergoing large variations. There is tentative evidence for quasi-periodic (15 to 20 days) O3 fluctuations in the collar and for upwelling of tropospheric air in late spring. A simplified photochemical model of O3 loss and the temporal evolution of the area-mapped polar O3 are used to constrain the chlorine monoxide (ClO) concentrations in the springtime Antarctic vortex. The concentrations required to account for the observed loss of O3 are higher than those previously reported by Anderson et al. but are comparable to their recently revised values. However, the O3 loss rates could be larger than deduced here because of underestimates of total O3 by TOMS near the terminator. This uncertainty, together with the uncertainties associated with measurements acquired during the Airborne Antarctic Ozone Experiment, suggests that in early spring, closer to the vortex center, there may be even larger ClO concentrations than have yet been detected.