HAEMODYNAMIC EFFECTS OF TRANSIENT ATRIOVENTRICULAR DISSOCIATION IN GENERAL ANAESTHESIA

SUMMARY Isorhythmic atrioventricular dissociation occurs frequently under general anaesthesia but is rarely recognized without continuous electrocardiographic monitoring. Since this arrhythmia was observed in about 50 per cent of the cases during the onset of the neuromuscular blocking action of alcuronium or pancuronium during halothane anaesthesia, the opportunity was taken to investigate the haemodynamic parameters during atrioventricular dissociation. In nine patients the haemodynamic parameters during atrioventricular dissociation as compared to sinus rhythm were characterized by an absence of significant differences in cardiac rate, by a mean lowering in arterial mean pressure of 14 per cent and by a mean decrease in cardiac output of 15 per cent. The calculated peripheral resistance remained unaltere

Martian oases? Feasibility of orbital thermal emission detection

We review the motivation for searching out modem "oases" on Mars, and examine methods of detecting them from orbit. We use the term "oasis" to refer to sites with anomalous thermal behavior at, or near the planet's surface. Such sites may be more likely than other locations on Mars to have liquid water nearby, hence the terminology reminiscent of Earth's deserts. Three types of "oases" are considered here: small-scale volcanic eruptions, hot springs, and subsurface intrusions. The general consensus is that such oases are highly unlikely on Mars today, and probably do not exist at all. How much investment is worthy of such a high-risk, unlikely return? We argue that the potential long-term importance of such a discovery does merit a significant investment. We propose a detection strategy based on a high spatial resolution infra-red thermal emission instrument, though other techniques are briefly discussed. We conclude that such an instrument could feasibly detect surface lavas, and quite likely any surface hot springs, but would not be able to unambiguously determine the presence of a buried geothermal anomaly that does not manifest itself sufficiently at the surface in one of the two other forms

The Nominal Range of Rocky Planet Masses, Radii, Surface Gravities and Bulk Densities

The two primary observable quantities of an exoplanet--its mass and radius--alone are not sufficient to probe a rocky exoplanet's interior composition and mineralogy. To overcome this, host-star abundances of the primary planet-building elements (Mg, Si, Fe) are typically used as a proxy for the planet's bulk composition. The majority of small exoplanet hosts, however, do not have available abundance data. Here we present the open-source ExoPlex mass-radius-composition solver. Unlike previous open-source mass-radius solvers, ExoPlex calculates the core chemistry and equilibrium mantle mineralogy for a bulk composition, including effects of mantle FeO content, core light elements and surface water/ice. We utilize ExoPlex to calculate the planetary radii, surface gravities and bulk densities for 10$^6$ model planets up to 2 R$_\oplus$ across these geochemistries, adopting the distribution of FGK stellar abundances to estimate of the range of bulk exoplanet compositions. We outline the $99.7\%$ distribution of radii, surface gravity and bulk densities that define planets as "nominally rocky." Planets outside this range require compositions outside those expected from stellar abundance data, likely making them either Fe-enriched super-Mercuries, or volatile-enriched mini-Neptunes. We apply our classification scheme to a sample of 85 well-resolved exoplanets without available host-star abundances. We estimate only 9 planets are within the "nominally rocky planet zone" at $>70\%$ confidence, while $\sim20\%$ and $\sim30\%$ of this sample can be reasonably classified as super-Mercuries or volatile-rich, respectively. Our results provide observers with a self-consistent way to broadly classify a planet as likely rocky, Mercury-like or volatile-enriched, using mass and radius measurements alone.Comment: 41 pages, 21 figures, 2 tables. Accepted to Ap

Volatiles in the Desert: Subtle Remote-sensing Signatures of the Dakhleh Oasis Catastrophic Event, Western Desert, Egypt

Over the past decade members of the Dakhleh Oasis Project have studied enigmatic signatures in the Pleistocene geologic record of portions of the Dakhleh oasis and palaeo-oasis in Egypt's Western Desert [1,2]. In particular, Si-Ca-Al rich glass melt (Dakhleh Glass, Fig. 1) points to a catastrophic event between c.100,000-200,000 years ago [3] in this well-studied African savannah and freshwater lake Middle Stone Age environment [4,5]

Potentiometric measurement of urinary iodine concentration in patients with thyroid diseases with and without previous exposure to non-radioactive iodine

Background: Extensive application of measurement of urinary iodine concentration (UIC) in several benign and malignant thyroid diseases could profit by the availability of rapid and inexpensive measuring techniques. Aim of this study was to apply a simple and inexpensive commercially available potentiometric method for the quantification of UIC based on iodine-specific ion-selective electrodes (ISE) in patients with thyroid diseases. Methods: This retrospective study included patients with differentiated thyroid cancer (n=286) and patients with hyperthyroidism of different etiologies (n=203). Within the whole sample (n=489) 20 patients had previously (1 week-6 months) been exposed to iodine overload, either from contrast media (n=8) or amiodarone (n=12). Results: In patients not exposed to iodine, the histogram showed that the distribution of UIC violated normality. The peak of the curve occurred between 5.0 μmol/L and 6.0 μmol/L. Variability was sizeable (percent coefficient of variation, %CV: 66%, 95% confidence interval: 1.48-18.72 μmol/L). The group of exposed patients could be easily distinguished from not exposed patients (median UIC: 47.5 μmol/L vs. 5.42 μmol/L). UIC was significantly correlated to urinary creatinine concentration, but normalization to urinary creatinine increased the inter-subject variability of UIC (%CV=96% vs. 66%). In test-retest studies (n=25) the intra-class correlation coefficient was 0.73 for UIC, 0.82 for creatinine and 0.64 for the UIC: creatinine ratio. Conclusions: Iodine-specific ISE-based potentiometric methods can be successfully applied as an alternative to existing methods in patients with thyroid diseases. The promising characteristics of the method need to be confirmed in future larger prospective studies

Warm terrestrial planet with half the mass of Venus transiting a nearby star

The advent of a new generation of radial velocity instruments has allowed us to break the one Earth-mass barrier. We report a new milestone in this context with the detection of the lowest-mass planet measured so far using radial velocities: L 98-59 b, a rocky planet with half the mass of Venus. It is part of a system composed of three known transiting terrestrial planets (planets b to d). We announce the discovery of a fourth nontransiting planet with a minimum mass of 3.06_{-0.37}^{+0.33} MEarth and an orbital period of 12.796_{-0.019}^{+0.020} days and report indications for the presence of a fifth nontransiting terrestrial planet. With a minimum mass of 2.46_{-0.82}^{+0.66} MEarth and an orbital period 23.15_{-0.17}^{+0.60} days, this planet, if confirmed, would sit in the middle of the habitable zone of the L 98-59 system. L 98-59 is a bright M dwarf located 10.6 pc away. Positioned at the border of the continuous viewing zone of the James Webb Space Telescope, this system is destined to become a corner stone for comparative exoplanetology of terrestrial planets. The three transiting planets have transmission spectrum metrics ranging from 49 to 255, which makes them prime targets for an atmospheric characterization with the James Webb Space Telescope, the Hubble Space Telescope, Ariel, or ground-based facilities such as NIRPS or ESPRESSO. With an equilibrium temperature ranging from 416 to 627 K, they offer a unique opportunity to study the diversity of warm terrestrial planets. L 98-59 b and c have densities of 3.6_{-1.5}^{+1.4} and 4.57_{-0.85}^{+0.77} this http URL^{-3}, respectively, and have very similar bulk compositions with a small iron core that represents only 12 to 14 % of the total mass, and a small amount of water. However, with a density of 2.95_{-0.51}^{+0.79} this http URL^{-3} and despite a similar core mass fraction, up to 30 % of the mass of L 98-59 d might be water

TESS Reveals a Short-period Sub-Neptune Sibling (HD 86226c) to a Known Long-period Giant Planet

The Transiting Exoplanet Survey Satellite mission was designed to find transiting planets around bright, nearby stars. Here, we present the detection and mass measurement of a small, short-period (≈4 days) transiting planet around the bright (V = 7.9), solar-type star HD 86226 (TOI-652, TIC 22221375), previously known to host a long-period (~1600 days) giant planet. HD 86226c (TOI-652.01) has a radius of 2.16 ± 0.08 R⊕ and a mass of ${7.25}_{-1.12}^{+1.19}$ M⊕, based on archival and new radial velocity data. We also update the parameters of the longer-period, not-known-to-transit planet, and find it to be less eccentric and less massive than previously reported. The density of the transiting planet is 3.97 g cm−3, which is low enough to suggest that the planet has at least a small volatile envelope, but the mass fractions of rock, iron, and water are not well-constrained. Given the host star brightness, planet period, and location of the planet near both the "radius gap" and the "hot Neptune desert," HD 86226c is an interesting candidate for transmission spectroscopy to further refine its composition

Field reconnaissance geologic mapping of the Columbia Hills, Mars, based on Mars Exploration Rover Spirit and MRO HiRISE observations

Chemical, mineralogic, and lithologic ground truth was acquired for the first time on Mars in terrain units mapped using orbital Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (MRO HiRISE) image data. Examination of several dozen outcrops shows that Mars is geologically complex at meter length scales, the record of its geologic history is well exposed, stratigraphic units may be identified and correlated across significant areas on the ground, and outcrops and geologic relationships between materials may be analyzed with techniques commonly employed in terrestrial field geology. Despite their burial during the course of Martian geologic time by widespread epiclastic materials, mobile fines, and fall deposits, the selective exhumation of deep and well‐preserved geologic units has exposed undisturbed outcrops, stratigraphic sections, and structural information much as they are preserved and exposed on Earth. A rich geologic record awaits skilled future field investigators on Mars. The correlation of ground observations and orbital images enables construction of a corresponding geologic reconnaissance map. Most of the outcrops visited are interpreted to be pyroclastic, impactite, and epiclastic deposits overlying an unexposed substrate, probably related to a modified Gusev crater central peak. Fluids have altered chemistry and mineralogy of these protoliths in degrees that vary substantially within the same map unit. Examination of the rocks exposed above and below the major unconformity between the plains lavas and the Columbia Hills directly confirms the general conclusion from remote sensing in previous studies over past years that the early history of Mars was a time of more intense deposition and modification of the surface. Although the availability of fluids and the chemical and mineral activity declined from this early period, significant later volcanism and fluid convection enabled additional, if localized, chemical activity.Additional co-authors: D DesMarais, M Schmidt, NA Cabrol, A Haldemann, Kevin W Lewis, AE Wang, D Blaney, B Cohen, A Yen, J Farmer, R Gellert, EA Guinness, KE Herkenhoff, JR Johnson, G Klingelhöfer, A McEwen, JW Rice Jr, M Rice, P deSouza, J Hurowit

TESS Reveals A Short-Period Sub-Neptune Sibling (HD 86226c) To A Known Long-Period Giant Planet

The Transiting Exoplanet Survey Satellite mission was designed to find transiting planets around bright, nearby stars. Here, we present the detection and mass measurement of a small, short-period (≈4 days) transiting planet around the bright (V = 7.9), solar-type star HD 86226 (TOI-652, TIC 22221375), previously known to host a long-period (~1600 days) giant planet. HD 86226c (TOI-652.01) has a radius of 2.16 ± 0.08 R⊕ and a mass of ${7.25}_{-1.12}^{+1.19}$M⊕, based on archival and new radial velocity data. We also update the parameters of the longer-period, not-known-to-transit planet, and find it to be less eccentric and less massive than previously reported. The density of the transiting planet is 3.97 g cm−3, which is low enough to suggest that the planet has at least a small volatile envelope, but the mass fractions of rock, iron, and water are not well-constrained. Given the host star brightness, planet period, and location of the planet near both the radius gap and the hot Neptune desert, HD 86226c is an interesting candidate for transmission spectroscopy to further refine its composition

A super-Earth and a sub-Neptune orbiting the bright, quiet M3 dwarf TOI-1266

We report the discovery and characterisation of a super-Earth and a sub-Neptune transiting the bright ($K=8.8$), quiet, and nearby (37 pc) M3V dwarf TOI-1266. We validate the planetary nature of TOI-1266 b and c using four sectors of TESS photometry and data from the newly-commissioned 1-m SAINT-EX telescope located in San Pedro M\'artir (Mexico). We also include additional ground-based follow-up photometry as well as high-resolution spectroscopy and high-angular imaging observations. The inner, larger planet has a radius of $R=2.37_{-0.12}^{+0.16}$ R$_{\oplus}$ and an orbital period of 10.9 days. The outer, smaller planet has a radius of $R=1.56_{-0.13}^{+0.15}$ R$_{\oplus}$ on an 18.8-day orbit. The data are found to be consistent with circular, co-planar and stable orbits that are weakly influenced by the 2:1 mean motion resonance. Our TTV analysis of the combined dataset enables model-independent constraints on the masses and eccentricities of the planets. We find planetary masses of $M_\mathrm{p}$ = $13.5_{-9.0}^{+11.0}$ $\mathrm{M_{\oplus}}$ ($<36.8$ $\mathrm{M_{\oplus}}$ at 2-$\sigma$) for TOI-1266 b and $2.2_{-1.5}^{+2.0}$ $\mathrm{M_{\oplus}}$ ($<5.7$ $\mathrm{M_{\oplus}}$ at 2-$\sigma$) for TOI-1266 c. We find small but non-zero orbital eccentricities of $0.09_{-0.05}^{+0.06}$ ($<0.21$ at 2-$\sigma$) for TOI-1266 b and $0.04\pm0.03$ ($<0.10$ at 2-$\sigma$) for TOI-1266 c. The equilibrium temperatures of both planets are of $413\pm20$ K and $344\pm16$ K, respectively, assuming a null Bond albedo and uniform heat redistribution from the day-side to the night-side hemisphere. The host brightness and negligible activity combined with the planetary system architecture and favourable planet-to-star radii ratios makes TOI-1266 an exquisite system for a detailed characterisation