Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites.

The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu's surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.

The geomorphology of Ceres.

Analysis of Dawn spacecraft Framing Camera image data allows evaluation of the topography and geomorphology of features on the surface of Ceres. The dwarf planet is dominated by numerous craters, but other features are also common. Linear structures include both those associated with impact craters and those that do not appear to have any correlation to an impact event. Abundant lobate flows are identified, and numerous domical features are found at a range of scales. Features suggestive of near-surface ice, cryomagmatism, and cryovolcanism have been identified. Although spectroscopic analysis has currently detected surface water ice at only one location on Ceres, the identification of these potentially ice-related features suggests that there may be at least some ice in localized regions in the crust.

COMETARY SCIENCE. The structure of the regolith on 67P/Churyumov-Gerasimenko from ROLIS descent imaging.

The structure of the upper layer of a comet is a product of its surface activity. The Rosetta Lander Imaging System (ROLIS) on board Philae acquired close-range images of the Agilkia site during its descent onto comet 67P/Churyumov-Gerasimenko. These images reveal a photometrically uniform surface covered by regolith composed of debris and blocks ranging in size from centimeters to 5 meters. At the highest resolution of 1 centimeter per pixel, the surface appears granular, with no apparent deposits of unresolved sand-sized particles. The thickness of the regolith varies across the imaged field from 0 to 1 to 2 meters. The presence of aeolian-like features resembling wind tails hints at regolith mobilization and erosion processes. Modeling suggests that abrasion driven by airfall-induced particle "splashing" is responsible for the observed formations.

Comparison of simultaneous changes in electroencephalographic and haemodynamic variables in sheep anaesthetised with halothane.

Haemodynamic responses are routinely used for monitoring anaesthesia, but they can be elicited at spinal or brainstem levels and therefore do not provide information on cerebrocortical activity. To test the possibility that electroencephalography (EEG) might provide an objective assessment of unconsciousness and depth of anaesthesia the haemodynamic and EEG data from 17 ewes anaesthetised with halothane were analysed. Data were recorded at least every five minutes. An increase of 10 per cent or more in heart rate, systolic arterial pressure (SAP), or mean arterial pressure (MAP) was defined as a positive haemodynamic response to surgical stimulation. Simultaneously recorded EEG variables included delta-, theta-, and beta-frequency band power, power ratios (theta/delta, alpha/delta, beta/delta), 80 per cent spectral edge frequency (SEF 80), and median frequency. In 11 of the ewes, a positive haemodynamic response was accompanied by a significant decrease in delta activity and significant increases in alpha/delta ratio, beta/delta ratio, and SEF 80, and there were significant correlations between the changes in heart rate, and delta activity and beta/delta ratio. In the other six ewes, there were no significant EEG responses in association with haemodynamic changes of less than 10 per cent.

Retrospective evaluation of cardiopulmonary and acid-base variables during long-term balanced anesthesia for experimental surgery in dogs.

Cardiopulmonary and acid-base variables recorded during long-term balanced anesthesia lasting between 12.5 and 16.9 h were evaluated retrospectively in 15 healthy foxhounds that underwent experimental bulla osteotomy with implantation of hearing aids. After premedication with propionylpromazine (0.11 +/- 0.02 mg/kg of body weight) and L-methadone (0.71 +/- 0.06 mg/kg) intravenously (i.v.) and induction with pentobarbital sodium (6.02 +/- 0.83 mg/kg i.v.), anesthesia was maintained with halothane (end-tidal concentration; ETHAL: 0.4 to 1.5%) in nitrous oxide (2 L/min) and oxygen (1 L/min). Because of positional changes from sternal to right lateral recumbency after presurgical brain stem electric response audiometry and differences in duration of surgery, data obtained between 4 (baseline) and 14 h after induction of anesthesia were analyzed. Arterial (PaO2) and alveolar (PAO2) O2 tensions, arterial-to-alveolar O2 tension ratio (PaO2/PAO2), and arterial O2 content (CaO2) remained relatively stable throughout anesthesia. Arterial carbon dioxide tension (PaCO2) was significantly increased above baseline (39, 33 to 46 mm Hg [median, range]) between 7 (39.8, 36.5 to 48.9 mm Hg) and 9 (42, 37.5 to 49.5 mm Hg) h after induction. Because changes in PaCO2 were accompanied by significant increases in body temperature from baseline (36.3, 34.6 to 37.4 degrees C) between 8 (37.1, 35 to 38 degrees C) and 11 (37.6, 35.3 to 38.1 degrees C) h after anesthesia induction as well as by slight increases in arterial blood pressure, the PaCO2 increase may have been caused by increase in metabolic CO2 production and enhanced drainage of CO2 from the tissues into systemic circulation. Furthermore, mild metabolic acidosis (pHa: 7.31, 7.26 to 7.38; HCO3-: 18.9, 16.7 to 21.8 mEq/L; base deficit [BD]: -6.3, -8.5 to -3.4 mEq/L) already existed at 4 h after induction and was related in part to tissue hypoperfusion. Small increases in pHa during the course of anesthesia were accompanied by significant increases in HCO3- concentration and significant decreases in BD between 5 and 10 h after induction. Minor circumscribed swelling of the dependent triceps or masseter muscle was noticed on the first postoperative day in two dogs, and marked tissue swelling with hematoma formation at the medial side of one hind limb was noticed in a third dog. All dogs recovered completely and were submitted to follow-up studies. The anesthetic protocol and extent of monitoring used were adequate to provide safe long-term anesthesia for an experimental surgical procedure with a 100% survival rate and uneventful recovery in most of the dogs.

Differences in quantitated electroencephalographic variables during surgical stimulation of horses anesthetized with isoflurane.

The effects of noxious surgical stimulation on the electroencephalogram (EEG) in 15 horses anesthetized with isoflurane were evaluated during orthopedic (group 1) and soft tissue (group 2) procedures. The quantitative EEG variables theta/delta ratio (T/D), alpha/delta ratio (A/D), beta/delta ratio (B/D), median power frequency (MED), and 80% spectral edge frequency (SEF 80) recorded during Surgeries at 1.7% end-tidal concentration of isoflurane (ET(iso)) were compared with values from five nonstimulated control horses anesthetized at 1,7% ET(iso). The EEG variables T/D, A/D, MED, and SEF 80 from surgically stimulated horses were significantly higher compared with controls. These differences in measured EEG variables were accompanied by a significantly lower relative power in the delta frequency band and a concomitant significantly higher alpha activity. Because the A/D ratio, MED, and SEF 80 in surgically stimulated horses were significantly higher than in nonstimulated control horses these measured EEG variables may provide a valuable tool for identification of nociceptive transmission in isoflurane anesthetized horses.