Different Species Choose Their Own Paths to Pluripotency

Pluripotency is well defined functionally but ambiguously defined at the molecular level. In this issue of Developmental Cell, Boroviak and colleagues (2015) use a multi-species approach to differentiate between fundamental features of pluripotency in mammals and those that exhibit evolutionary plasticity

Characterization of the OCO-2 instrument line shape functions using on-orbit solar measurements

Accurately characterizing the instrument line shape (ILS) of the Orbiting Carbon Observatory-2 (OCO-2) is challenging and highly important due to its high spectral resolution and requirement for retrieval accuracy (0. 25 %) compared to previous spaceborne grating spectrometers. On-orbit ILS functions for all three bands of the OCO-2 instrument have been derived using its frequent solar measurements and high-resolution solar reference spectra. The solar reference spectrum generated from the 2016 version of the Total Carbon Column Observing Network (TCCON) solar line list shows significant improvements in the fitting residual compared to the solar reference spectrum currently used in the version 7 Level 2 algorithm in the O₂ A band. The analytical functions used to represent the ILS of previous grating spectrometers are found to be inadequate for the OCO-2 ILS. Particularly, the hybrid Gaussian and super-Gaussian functions may introduce spurious variations, up to 5 % of the ILS width, depending on the spectral sampling position, when there is a spectral undersampling. Fitting a homogeneous stretch of the preflight ILS together with the relative widening of the wings of the ILS is insensitive to the sampling grid position and accurately captures the variation of ILS in the O₂ A band between decontamination events. These temporal changes of ILS may explain the spurious signals observed in the solar-induced fluorescence retrieval in barren areas

Stress analysis of PLT coil

The toroidal field coils of tokamak devices create a field within the torus whose strength varies inversely with distance from the machine center. This field, crossing the current in the TF coils, creates a magnetic pressure on the coil. The pressure produces a net inward centering force, countered by pressure on the wedge face, and a vertical separating force, causing tensile stress across the horizontal mid-plane. In the past these forces have been analyzed by superposition and beam theory. Because of the size and complexity of the PLT machine it was decided to also initiate a finite element analysis of the coil. This paper describes both methods of analysis. (auth

Mapping of North American methane emissions with high spatial resolution by inversion of SCIAMACHY satellite data

We estimate methane emissions from North America with high spatial resolution by inversion of Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) satellite observations using the Goddard Earth Observing System Chemistry (GEOS‐Chem) chemical transport model and its adjoint. The inversion focuses on summer 2004 when data from the Intercontinental Chemical Transport Experiment‐North America (INTEX‐A) aircraft campaign over the eastern U.S. are available to validate the SCIAMACHY retrievals and evaluate the inversion. From the INTEX‐A data we identify and correct a water vapor‐dependent bias in the SCIAMACHY data. We conduct an initial inversion of emissions on the horizontal grid of GEOS‐Chem (1/2° × 2/3°) to identify correction tendencies relative to the Emission Database for Global Atmospheric Research (EDGAR) v4.2 emission inventory used as a priori. We then cluster these grid cells with a hierarchical algorithm to extract the maximum information from the SCIAMACHY observations. A 1000 cluster ensemble can be adequately constrained, providing ~100 km resolution across North America. Analysis of results indicates that the Hudson Bay Lowland wetlands source is 2.1 Tg a^(−1), lower than the a priori but consistent with other recent estimates. Anthropogenic U.S. emissions are 30.1 ± 1.3 Tg a^(−1), compared to 25.8 Tg a^(−1) and 28.3 Tg a^(−1) in the EDGAR v4.2 and Environmental Protection Agency (EPA) inventories, respectively. We find that U.S. livestock emissions are 40% greater than in these two inventories. No such discrepancy is apparent for overall U.S. oil and gas emissions, although this may reflect some compensation between overestimate of emissions from storage/distribution and underestimate from production. We find that U.S. livestock emissions are 70% greater than the oil and gas emissions, in contrast to the EDGAR v4.2 and EPA inventories where these two sources are of comparable magnitude

PLT toroidal field coil power tests

The PLT toroidal field coil power tests were initiated in October, 1974 to gain information in several areas. The most important objectives during the tests were the verification of deflections and stresses as predicted by Frankenberg and Smith. Also, the stability of the toroidal field coils against radial self-field loading was to be determined. Lastly, the predicted thermal characteristics of the coils were to be verified. (auth

Pressure broadening in the 2v_3 band of methane and its implication on atmospheric retrievals

N_2-broadened half widths and pressure shifts were obtained for transitions in the 2ν_3 methane band. Laboratory measurements recorded at 0.011 cm^(−1) resolution with a Bruker 120 HR Fouriertransform spectrometer were analysed from 5860 to 6185 cm^(−1). A 140 cm gas cell was filled with methane at room temperature and N_2 as foreign gas at pressures ranging from 125 to 900 hPa. A multispectrum nonlinear constrained least squares approach based on Optimal Estimation was applied to derive the spectroscopic parameters by simultaneously fitting laboratory spectra at different ambient pressures assuming a Voigt line-shape. At room temperature, the half widths ranged between 0.030 and 0.071 cm^(−1) atm^(−1), and the pressure shifts varied from –0.002 to –0.025 cm^(−1) atm^(−1) for transitions up to J"=10. Especially for higher rotational levels, we find systematically narrower lines than HITRAN predicts. The Q and R branch of the new set of spectroscopic parameters is further tested with ground based direct sun Fourier transform infrared (FTIR) measurements where systematic fit residuals reduce by about a factor of 3–4. We report the implication of those differences on atmospheric methane measurements using high-resolution ground based FTIR measurements as well as low-resolution spectra from the SCanning Imaging Absorption SpectroMeter for Atmospheric ChartographY (SCIAMACHY) instrument onboard ENVISAT. We find that for SCIAMACHY, a latitudinal and seasonally varying bias of about 1% can be introduced by erroneous broadening parameters

Methane spectroscopy in the near infrared and its implication on atmospheric retrievals

International audienceN2-broadened half widths and pressure shifts were obtained for transitions in the Q and R branches of the 2?3 methane band. Laboratory measurements were done from 5985 to 6185 cm?1 using spectra recorded at 0.011 cm?1 resolution with a Bruker 120 HR Fourier transform spectrometer. A 140 cm gas cell was filled with methane at room temperature and N2 as foreign gas at pressures ranging from 125 to 900 hPa. A multispectrum nonlinear constrained least squares approach based on Optimal Estimation was applied to derive the spectroscopic parameters by simultaneously fitting laboratory spectra at different ambient pressures assuming a Voigt line-shape. At room temperature, the half widths ranged between 0.030 and 0.071 cm?1 atm?1, and the pressure shifts varied from ?0.002 to ?0.025 cm?1 atm?1 for transitions up to J"=10. Especially for higher rotational levels, we find systematically narrower lines than HITRAN predicts. The new set of spectroscopic parameters is further tested with ground based direct sun FTIR measurements where fit residuals reduce by about a factor of 3?4. We report the implication of those differences on atmospheric methane measurements using high-resolution ground based FTIR measurements as well as low-resolution spectra from the SCIAMACHY instrument onboard ENVISAT. We find that for SCIAMACHY, a latitudinal and seasonally varying bias of about 1% can be introduced by erroneous broadening parameters

Space-based remote imaging spectroscopy of the Aliso Canyon CH_4 superemitter

The Aliso Canyon gas storage facility near Porter Ranch, California, produced a large accidental CH_4 release from October 2015 to February 2016. The Hyperion imaging spectrometer on board the EO-1 satellite successfully detected this event, achieving the first orbital attribution of CH_4 to a single anthropogenic superemitter. Hyperion measured shortwave infrared signatures of CH_4 near 2.3 μm at 0.01 μm spectral resolution and 30 m spatial resolution. It detected the plume on three overpasses, mapping its magnitude and morphology. These orbital observations were consistent with measurements by airborne instruments. We evaluate Hyperion instrument performance, draw implications for future orbital instruments, and extrapolate the potential for a global survey of CH_4 superemitters