Uranus's and Neptune’s stratospheric water abundance and vertical profile from Herschel-HIFI

Here we present new constraints on Uranus’s and Neptune’s externally sourced stratospheric water abundance using disk-averaged observations of the 557 GHz emission line from Herschel’s Heterodyne Instrument for the Far-Infrared. Derived stratospheric column water abundances are × 1014 cm−2 for Uranus and ×1014 cm−2 for Neptune, consistent with previous determinations using ISO-SWS and Herschel-PACS. For Uranus, excellent observational fits are obtained by scaling photochemical model profiles or with step-type profiles with water vapor limited to ≤0.6 mbar. However, Uranus’s cold stratospheric temperatures imply a ∼0.03 mbar condensation level, which further limits water vapor to pressures ≤0.03 mbar. Neptune’s warmer stratosphere has a deeper ∼1 mbar condensation level, so emission-line pressure broadening can be used to further constrain the water profile. For Neptune, excellent fits are obtained using step-type profiles with cutoffs of ∼0.3–0.6 mbar or by scaling a photochemical model profile. Step-type profiles with cutoffs ≥1.0 mbar or ≤0.1 mbar can be rejected with 4σ significance. Rescaling photochemical model profiles from Moses & Poppe to match our observed column abundances implies similar external water fluxes for both planets: × 104 cm−2 s−1 for Uranus and ×104 cm−2 s−1 for Neptune. This suggests that Neptune’s ∼4 times greater observed water column abundance is primarily caused by its warmer stratosphere preventing loss by condensation, rather than by a significantly more intense external source. To reconcile these water fluxes with other stratospheric oxygen species (CO and CO2) requires either a significant CO component in interplanetary dust particles (Uranus) or contributions from cometary impacts (Uranus, Neptune

Ethane in Titan's Stratosphere from Cassini CIRS Far- and Mid-Infrared Spectra

The Cassini Composite Infrared Spectrometer (CIRS) observed thermal emission in the far- and mid-infrared (from 10 to 1500 cm(exp 1)), enabling spatiotemporal studies of ethane on Titan across the span of the Cassini mission from 2004 through 2017. Many previous measurements of ethane on Titan have relied on modeling the molecules mid-infrared (sub 12) band, centered on 822 cm(exp 1). Other bands of ethane at shorter and longer wavelengths were seen, but have not been modeled to measure ethane abundance. Spectral line lists of the far-infrared (sub 4) torsional band at 289 cm(exp 1) and the mid-infrared (sub 8) band centered at 1468 cm(exp 1) have recently been studied in the laboratory. We model CIRS observations of each of these bands (along with the (sub 12) band) separately and compare the retrieved mixing ratios from each spectral region. Nadir observations of the (sub 4) band probe the low stratosphere below 100 km. Our equatorial measurements at 289 cm(exp 1) show an abundance of (1.00.4)x10(exp 5) at 88 km from 2007 to 2017. This mixing ratio is consistent with measurements at higher altitudes, in contrast to the depletion that many photochemical models predict. Measurements from the (sub 12) and (sub 8) bands are comparable to each other, with the (sub 12) band probing an altitude range that extends deeper in the atmosphere. We suggest that future studies of planetary atmospheres may observe the (sub 8) band, enabling shorter wavelength studies of ethane. There may also be an advantage to observing both the ethane (sub 8) band and nearby methane (sub 4) band in the same spectral window

Ethane in Titan's Stratosphere from Cassini CIRS Far- And Mid-infrared Spectra

The Cassini Composite Infrared Spectrometer (CIRS) observed thermal emission in the far- and mid-infrared (from 10 cm$^{-1}$ to 1500 cm$^{-1}$), enabling spatiotemporal studies of ethane on Titan across the span of the Cassini mission from 2004 through 2017. Many previous measurements of ethane on Titan have relied on modeling the molecule's mid-infrared $\nu_{12}$ band, centered on 822 cm$^{-1}$. Other bands of ethane at shorter and longer wavelengths were seen, but have not been modeled to measure ethane abundance. Spectral line lists of the far-infrared $\nu_{4}$ torsional band at 289 cm$^{-1}$ and the mid-infrared $\nu_{8}$ band centered ay 1468 cm$^{-1}$ have recently been studied in the laboratory. We model CIRS observations of each of these bands (along with the $\nu_{12}$ band) separately and compare retrieved mixing ratios from each spectral region. Nadir observations of of the $\nu_{4}$ band probe the low stratosphere below 100 km. Our equatorial measurements at 289 cm$^{-1}$ show an abundance of (1.0$\pm$0.4) $\times$10$^{-5}$ at 88 km, from 2007 to 2017. This mixing ratio is consistent with measurements at higher altitudes, in contrast to the depletion that many photochemical models predict. Measurements from the $\nu_{12}$ and $\nu_{8}$ bands are comparable to each other, with the $\nu_{12}$ band probing an altitude range that extends deeper in the atmosphere. We suggest future studies of planetary atmospheres may observe the $\nu_{8}$ band, enabling shorter wavelength studies of ethane. There may also be an advantage to observing both the ethane $\nu_{8}$ band and nearby methane $\nu_{4}$ band in the same spectral window.Comment: 19 pages, 10 figure

The Origin of Titan’s External Oxygen:Further Constraints from ALMA Upper Limits on CS and CH₂NH

Titan's atmospheric inventory of oxygen compounds (H2O, CO2, CO) are thought to result from photochemistry acting on externally supplied oxygen species (O+, OH, H2O). These species potentially originate from two main sources: (1) cryogenic plumes from the active moon Enceladus and (2) micrometeoroid ablation. Enceladus is already suspected to be the major O+ source, which is required for CO creation. However, photochemical models also require H2O and OH influx to reproduce observed quantities of CO2 and H2O. Here, we exploit sulphur as a tracer to investigate the oxygen source because it has very different relative abundances in micrometeorites (S/O ~ 10−2) and Enceladus' plumes (S/O ~ 10−5). Photochemical models predict most sulphur is converted to CS in the upper atmosphere, so we use Atacama Large Millimeter/submillimeter Array (ALMA) observations at ~340 GHz to search for CS emission. We determined stringent CS 3σ stratospheric upper limits of 0.0074 ppb (uniform above 100 km) and 0.0256 ppb (uniform above 200 km). These upper limits are not quite stringent enough to distinguish between Enceladus and micrometeorite sources at the 3σ level and a contribution from micrometeorites cannot be ruled out, especially if external flux is toward the lower end of current estimates. Only the high-flux micrometeorite source model of Hickson et al. can be rejected at 3σ. We determined a 3σ stratospheric upper limit for CH2NH of 0.35 ppb, which suggests cosmic rays may have a smaller influence in the lower stratosphere than predicted by some photochemical models. Disk-averaged C3H4 and C2H5CN profiles were determined and are consistent with previous ALMA and Cassini/CIRS measurements

The formation and evolution of Titan's winter polar vortex

The polar hot-spot appeared in Titan after equinox in 2010 suddenly cooled in early 2012, which wasn’t predicted by models. Here the authors use observations to show that the increase in trace gases during the hot-spot resulted in radiative cooling feedback

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]

Evidence synthesis to inform model-based cost-effectiveness evaluations of diagnostic tests: a methodological systematic review of health technology assessments

Background: Evaluations of diagnostic tests are challenging because of the indirect nature of their impact on patient outcomes. Model-based health economic evaluations of tests allow different types of evidence from various sources to be incorporated and enable cost-effectiveness estimates to be made beyond the duration of available study data. To parameterize a health-economic model fully, all the ways a test impacts on patient health must be quantified, including but not limited to diagnostic test accuracy. Methods: We assessed all UK NIHR HTA reports published May 2009-July 2015. Reports were included if they evaluated a diagnostic test, included a model-based health economic evaluation and included a systematic review and meta-analysis of test accuracy. From each eligible report we extracted information on the following topics: 1) what evidence aside from test accuracy was searched for and synthesised, 2) which methods were used to synthesise test accuracy evidence and how did the results inform the economic model, 3) how/whether threshold effects were explored, 4) how the potential dependency between multiple tests in a pathway was accounted for, and 5) for evaluations of tests targeted at the primary care setting, how evidence from differing healthcare settings was incorporated. Results: The bivariate or HSROC model was implemented in 20/22 reports that met all inclusion criteria. Test accuracy data for health economic modelling was obtained from meta-analyses completely in four reports, partially in fourteen reports and not at all in four reports. Only 2/7 reports that used a quantitative test gave clear threshold recommendations. All 22 reports explored the effect of uncertainty in accuracy parameters but most of those that used multiple tests did not allow for dependence between test results. 7/22 tests were potentially suitable for primary care but the majority found limited evidence on test accuracy in primary care settings. Conclusions: The uptake of appropriate meta-analysis methods for synthesising evidence on diagnostic test accuracy in UK NIHR HTAs has improved in recent years. Future research should focus on other evidence requirements for cost-effectiveness assessment, threshold effects for quantitative tests and the impact of multiple diagnostic tests

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]

El dilema de la Malinche en Centroamérica contemporánea: Negociando fronteras cambiantes en Retrato de mujer en terraza y Con pasión absoluta

Ce travail analyse deux romans récents d’écrivaines centre-américaines, Retrato de mujer en terraza (1995) de Dorelia Barahona et Con pasión absoluta (2007) de Carol Zardetto. Il se veut le début d’un projet approfondi qui étudiera les réponses et les réactions des écrivaines contemporaines envers certains phénomènes issus de la globalisation et du néo-libéralisme percep-tibles actuellement dans la région. On démontre que les protagonistes des deux romans se trouvent face à un dilemme fort similaire et ancien: celui de la Malinche, cette femme autochtone perçue comme une traîtresse mais en même temps comme celle qui a été trahie non seulement par ses relations intimes avec un étranger mais aussi par l’univers de celui-ci. Les protagonistes doivent se trouver un lieu plus sûr et dépourvu de toute influence, dans un contexte changeant, marqué par le déracinement et par de troubles alliances portées par la globalisation. Dans chaque roman, les Malinches modernes se rachètent et se répositionnent pour en même temps s’enraciner et se libérer